Adaptive significance of antipredator behaviour in artiodactyls

ANIMAL BEHAVIOUR, 2004, 67, 205e228 doi:10.1016/j.anbehav.2002.12.007

Adaptive significance of antipredator behaviour in artiodactyls T . M . CA RO, C. M. G RAH A M, C. J . S TON ER & J . K . VAR GA S

Department of Wildlife, Fish and Conservation Biology, University of California, Davis (Received 3 December 2001; initial acceptance 29 April 2002; final acceptance 31 December 2002; MS. number: ARV-20)

We used comparative data to test functional hypotheses for 17 antipredator behaviour patterns in artiodactyls. We examined the literature for hypotheses about auditory and visual signals, defensive behaviour and group-related antipredator behaviour in this taxon and derived a series of predictions for each hypothesis. Next, we documented occurrences of these behaviour patterns and morphological, ecological and behavioural variables for 200 species and coded them in binary format. We then pitted presence of an antipredator behaviour against presence of an independent variable for cervids, bovids and all artiodactyls together using nonparametric tests. Finally, we reanalysed the data using Maddison’s (1990, Evolution, 44, 539e557) concentrated-changes tests and a consensus molecular and taxonomic phylogeny. We found evidence that snorting is both a warning signal to conspecifics and a pursuit-deterrent signal, lack of evidence that whistling alerts conspecifics and indications that foot stamping is a visual signal to warn group members. Evidence suggested that tail flagging was a signal to both conspecifics and predators, that bounding, leaping and stotting were used both as a signal and to clear obstacles and that prancing functioned similarly to foot stamping. Analyses of tail flicking, zigzagging and tacking were equivocal. We confirmed that inspection occurs in large groups, freezing enhances crypticity, and species seeking refuge in cliffs tend to be small. Entering water and attacks on predators had few correlates. Finally, group living, a putative antipredator adaptation, was associated with large body size and species living in open habitats, confirming Jarman’s (1974, Behaviour, 48, 215e267) classic hypothesis. Bunching and group attack apparently deter predators. Despite limitations, comparative and systematic analyses can bolster adaptive hypotheses and raise new functional explanations for antipredator behaviour patterns in general. Ó 2003 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

Animals show a great variety of behaviour patterns when threatened by predators, including auditory and visual signals, peculiar gaits during flight, specific forms of escape and even attacking the predator (Hamilton 1971; Edmunds 1974; Sherman 1977; Bertram 1978; Elgar 1989). Unfortunately, the function of behaviours shown to predators is often unclear and open to debate (e.g. Caro 1986a). For example, arguments have been put forward that tail flagging in white-tailed deer, Odocoileus virginianus, serves as a signal to entice a predator into a chase in which it has a low probability of success (Smythe 1970), a signal to alert conspecifics of danger (Hirth & McCullough 1977), or a mechanism by which prey suddenly blend in with their background when they stop tail flagging (reviews in Edmunds 1974; Caro et al. 1995). Study of the adaptive significance of antipredator behaviour suffers from three impediments. First, the many intriguing ideas that have been advanced concerning the function of antipredator behaviours far outweigh Correspondence: T. M. Caro, Department of Wildlife, Fish, and Conservation Biology, University of California, Davis, CA 95616, U.S.A. (email: [email protected]). 0003e3472/03/$30.00/0

systematic tests of these hypotheses. Second, tests are often based on occasional observations or on detailed information collected on one or a limited set of species. Finally, findings that do emerge may apply to the species in question, but the extent to which they apply to other species is usually unknown. The purpose of this study, therefore, was to document the distribution of 17 antipredator behaviour patterns across one taxonomic group, the Artiodactyla, then systematically relate these patterns to morphological, ecological and behavioural variables. These analyses provide a case study in testing conflicting adaptive hypotheses for antipredator behaviour using a comparative approach. For 200 even-toed ungulate species, we extracted data on species’ antipredator behaviour patterns from the literature (Appendix, Table A1). First, we recorded whether species displayed auditory signals that might be involved with communication to conspecifics or to predators, such as snorts, whistles or foot stamps. Second, we recorded data on visual signals given in the presence of predators: tail flicking, tail flagging, bounding/leaping/ stotting (combined into one category), and zigzagging/ tacking (also combined). Third, we examined defensive

205 Ó 2003 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

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behaviours, including inspecting predators, freezing, finding refuge in cliffs and burrows and entering a body of water. We also scored whether a species attacks predators. Last, we collated data on patterns of aggregation and on behaviour patterns shown by groups (i.e. whether species scattered, bunched or launched group attacks against predators). We review hypotheses for these antipredator behaviour patterns in turn.

Auditory Signals

reevesi (Yahner 1980) and roe deer, Capreolus capreolus (Reby et al. 1999). We therefore tested whether snorting might be a signal to conspecifics by first examining whether species that snort live principally in groups or, alternatively, whether snorting might signal to predators that they have been detected (perception advertisement signal), by examining whether snorting occurred in prey species attacked by terrestrial predators, especially stalking predators (independent variables defined in Table 2).

Whistling

Snorting Many ungulates snort (see Table 1 for definitions of behaviour patterns) when in danger. For example, Kingdon (1997) suggested that bongos, Tragelaphus scriptus, snort to contact others in their group when faced with danger. Similarly, the deep snorts uttered by hippopotami, Hippopotamus amphibious, could serve to alert conspecifics (Stuart & Stuart 1997). LaGory (1987), however, stated that white-tailed deer snort to alert the predator that it has been sighted. Hasson (1991) concurred, believing that snorting in Thomson’s gazelles, Gazella thomsoni, informs the predator that it has been detected. Similar conclusions were reached for snorting in adult male topis, Damaliscus korrigum (Caro 1994), and barking in muntjacs, Muniaucs

In African bovids, whistling is common in species living in woodland and riverine habitats where visibility is poor, and could thus be an alarm signal to conspecifics (Caro 1994). Kingdon (1997) noted that oribis, Ourebia ourebi, will whistle when threatened to alert others of the danger as well as to advertise the direction in which they are moving. Stuart & Stuart (1997), however, stated that oribis will give a sharp whistle directed towards the predator, then run off rapidly if disturbed, perhaps letting the predator know that it has been spotted. Tilson & Norton (1981) reached a similar conclusion for alarm-duetting in klipspringers, Oreotragus oreotragus. We therefore tested whether whistling might be a signal to conspecifics by examining whether those species that whistle live in

Table 1. Descriptions of behavioural variables Antipredator behaviour Auditory signal Snort Whistle Foot stamp Visual signal Tail flick Tail flag Bound/leap/stott

Zigzag/tack Prance Defence Inspection Freeze Refuge in cliffs/burrows Enter water Attack Group behaviour Scatter Bunch Group attack

Definition

Low-frequency barking sound resulting from a sharp expellation of air through the nostrils Long high-pitched sound given just before the animal first flees Lifting the foreleg and suddenly striking the ground with the hoof one or more times Flicking the tail from side to side, so that the rump is momentarily exposed Raising the tail vertically so that the underside of the tail is conspicuously displayed A long jump that carries the animal over at least double the distance covered by one galloping stride/a high jump where the animal rises almost vertically off the ground/or a bouncing gait with all four legs held stiff and straight A sharp turn in which the animal suddenly changes course by approximately 90( after moving only 1e2 strides in a given direction A series of pronounced and exaggerated high steps made at a slow trotting speed Approaching potential predators at a distance Standing or lying immobile Retreating into cliffs or burrows in the presence of a potential predator Entering a body of water during or after flight* Solitary animal reacting aggressively towards a predator Group of animals dispersing in varying directions in the presence of a potential predator Group of animals gathering close together in the presence of a potential predator More than one animal simultaneously acting aggressively towards a predator

*Presence or absence of this behaviour was problematic, because it could be displayed only in populations studied near sources of water.

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Table 2. Descriptions of morphological, ecological and behavioural variables Variables Body size Large body size Small body size Coloration categories Colour patterns Presence of spots on adults Presence of stripes (vertical or horizontal) on adults Legs Conspicuous dark markings Conspicuous light markings Tail Dark Light Rump White markings Habitat categories Grassland/scrubland Dense forest Desert Rocky Tundra Swamps Environmental categories Open Group size categories Solitary Intermediate-sized groups Large groups Hider behaviour Hider Follower Type of predator Aerial predator Predator hunting style Stalker Courser

Descriptions

Animal weighs more than 20 kg* Animal weighs 20 kg or less* Black or white spots on dorsal surface, rear or legs Black or white stripes on dorsal surface, rear or legs

Dark or black markings on legs that contrast with the overall coloration White or light markings on legs that contrast with the overall coloration Markings on tail black or darker than coloration of rump Markings on tail white or lighter than coloration of rump Presence of rump patch or white markings on rump Prairie, savannah, meadows or steppe grasses habitats/occupies scrub or shrub vegetation habitats Alpine, tropical, boreal, deciduous, mixed, timberland or dense forests Deserts or semideserts Rocky areas such as talus, boulders, rocky outcrops, crevices or cliffs Tundra Swamp, marsh, bogland, moorland, reedbeds or riverine habitats Grasslands, deserts and tundra habitats Primarily found alone or in pairs Groups of 3e50 individuals Aggregations of over 50 individuals Young lie concealed for over 1 week following birthy Young follow mothers within 1 week of birthy Predator attacks from airz Ground predator observes/follows/stalks prey before attacking Ground predator runs down/exhausts prey singly or as a group

*We chose 20 kg as a division between large and small species because there is a gap in African antelope weight distributions at this point (Packer 1983). yVariation exists in these behaviours (e.g. Green & Rothstein 1993; Bowyer et al. 1998, 1999), so they should be interpreted with caution. zPoor data prevented us from distinguishing whether all ageesex classes or only young were subject to attack.

groups, and whether they inhabit thick vegetation where conspecifics might be unable to detect a predator easily. As an alternative, we tested whether whistling might inform stalking predators that they have been detected.

Foot stamping Foot stamping produces a loud, drumming sound that travels some distance. According to Wood (1992), Arabian tahrs, Hemitragus jayakar, foot-stamp when they are disturbed from cover and this acts as an intraspecific warning. Caro et al. (1995) suggested that white-tailed deer foot-stamp to alert other deer to the presence of a predator. They found that deer were more likely to footstamp in open habitats where sound carried well. Therefore, we tested whether foot stamping might be

a signal to conspecifics by examining whether those species that foot-stamp live in groups, and whether they inhabit dense vegetation where conspecifics might be unable to detect a predator easily. We also tested whether foot stamping might be a visual signal by examining whether the behaviour occurred in open-country species where the signal would be easy for conspecifics or a predator to see, and whether such species have contrasting leg coloration that could enhance the signal.

Visual Signals Tail flicking Stuart & Stuart (1997) noted that Thomson’s gazelles flick their tails at predators when they are threatened. None the

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less, tail flicking is also seen in the absence of predators. LaGory (1981), for example, suggested that in white-tailed deer, group members use tail flicking as a cue of lack of disturbance, and that tail flicking may facilitate group cohesion when animals forage in dense habitats. Fallow deer, Dama dama, also flick their tails from side to side when conditions are calm (Alvarez et al. 1976). Alternatively, tail flicking might simply be a means to keep biting insects away from the anal region. We therefore tested whether tail flicking might be a signal by examining whether those species that tail-flick inhabit open habitats where conspecifics or predators could see the signal easily. We also evaluated whether those species that tail-flick have a coloured tail since a contrasting tail colour might accentuate the signal (Stoner et al. 2003). We tested whether tail flicking might signal conspecifics by examining whether it occurred in species living in large or intermediate-sized groups.

Tail flagging Tail flagging is sometimes observed when ungulates flee from predators and could thus maintain cohesiveness between fleeing group members or between a mother and her young. We interpreted tail flagging as holding the tail vertically when alarmed (e.g. fallow deer: Alvarez et al. 1976; white-tailed deer: Hirth & McCullough 1977). According to Caro et al. (1995), however, there is little evidence that tail flagging is used to signal conspecifics, because solitary white-tailed deer are as likely to flag as those within a group. Moreover, when tail flagging occurs, most other deer are in front of the deer that flags rather than behind it where they could see the tail, suggesting that it must be a signal to predators (see also Bildstein 1983; but see Coblentz 1980). Tail flagging might inform the predator that it has been seen or confuse it if many exposed tails bob up and down in flight (Walther 1969; Caro 1986b). We tested whether tail flagging might be a signal to conspecifics by examining whether those species that tail-flag live in groups. As an alternative, we tested whether tail flagging might signal to terrestrial predators in open environments.

Bounding/leaping/stotting When ungulates bound away from a predator, they may be jumping over obstacles (Caro 1994) or ascertaining the location of a potential threat (Pitcher 1979; Danilkin 1996). Ungulates such as impalas, Aepyceros melampus, may leap to demonstrate some aspect of their health to potential predators (Caro 1994, 1995). Finally, stotting may also be an honest visual signal informing the predator of the individual’s ability to escape. FitzGibbon & Fanshawe (1989) found that hunting dogs, Lycaon pictus, pursue stotting gazelles at significantly lower rates than they do other gazelles, possibly because stotting gazelles are in better condition. Information on these three behaviour patterns is rarely separated in the literature, so we were forced to combine them in our comparative analyses. We first tested whether bounding, leaping or stotting might be simply a means of clearing obstacles by examining whether those species that bound,

leap or stott inhabit rocky habitats. We then asked whether these behaviours might be signals, first by examining whether bounding, leaping or stotting species have differing leg or tail coloration that might make the animal stand out, then whether these species inhabit open habitats where visibility of signals is high (Spinage 1986; Geist 1987). Finally, we examined whether these behaviours were associated with pursuit by stalkers or coursers.

Zigzagging/tacking Erratic flights of insect prey are thought to confuse a predator (Humphries & Driver 1967), but tacking and zigzagging in artiodactyls may serve a different function. At the start of a flight, tacking might show the predator that prey can rapidly change direction if a chase ensues (Markl 1985), or it could wrongfoot a predator, causing it to overshoot its quarry (Caro 1994). Zigzagging at the end of a flight in adult Thomson’s gazelles causes pursuing cheetahs, Acinonyx jubatus, to lose distance from their quarry (FitzGibbon 1990a), suggesting that zigzagging hinders close pursuit and does not act as a signal. On the other hand, when disturbed, suni, Neotragus moschatus, run off in a zigzag pattern, and once zigzagging is initiated, all group members flee (Stuart & Stuart 1997). We tested whether zigzagging and tacking might be restricted to open environments where signals can be easily seen or where prey cannot hide and are forced to foil pursuit. We then looked for associations with group living, because larger groups could increase the chance that the predator becomes confused (Landeau & Terborgh 1986). We could not test whether zigzagging hampers a predator’s ability to contact prey.

Prancing In African bovids, prancing may act as a perception advertisement signal indicating the prey’s alertness to the predator or that the prey has achieved a safe distance (Caro 1994). Alternatively, prancing might serve to confuse a predator (Ohguchi 1981; Danilkin 1996). Therefore, we tested whether those species that prance inhabit open environments or display conspicuous leg coloration, because these conditions would enhance its use as a signal. We also tested whether these species live in groups, because larger groups of prancing individuals could increase the chance that the predator becomes confused.

Defence Inspection Thomson’s gazelles sometimes approach and follow a predator rather than fleeing (FitzGibbon 1994). Gazelles are more likely to inspect predators if they are immature individuals and if they are in large groups. FitzGibbon found that inspection is relatively dangerous but that it does cause cheetahs to move out of the surrounding area; she suggested that inspection principally causes predators to leave an area, but that it might have other functions, including monitoring and learning about the predator. We therefore tested whether species that inspect

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predators tend to live in groups; are large, because large body size may help drive predators off and reduce risk of predation; or are subject to predation by stalkers or coursers.

Freezing Many ungulate species freeze or remain motionless when predators approach, and their coats may help them blend in with the surrounding rocks or vegetation (Smythe 1977; Wood 1992). For example, small forest species with spotted or striped coats will freeze or lie motionless until a predator approaches to within a few metres (Caro & FitzGibbon 1992; FitzGibbon 1994). Similarly, in species where young have spotted coats, mothers invariably hide their young after birth, suggesting that remaining motionless aids in concealment (Kingdon 1997; Stoner et al. 2003). We examined associations between species that freeze and those occupying dense habitats where the vegetation might assist in concealing the animal. We also tested associations between freezing and small body size, coat coloration that might assist the animal in remaining cryptic, and use of the ‘hider’ strategy (FitzGibbon 1990b).

Africa, wildebeest, Connochaetes taurinus, defend their calves against attack by cheetahs (Caro 1994) and adult eland, Taurotragus oryx, especially a female defending her calf, will attack an approaching predator (Estes 1991). We tried to examine the distribution of this behaviour across ungulates by first examining whether those species that attack are large, which would reduce predation risk and could increase the probability of driving the predator away. We then examined whether species that attack are solitary, because the need to attack may be greater for solitary animals that cannot rely on antipredator benefits of grouping (Stuart & Stuart 1997).

Group Behaviour Group living

Klipspringers seek refuge on rocky slopes when they are pursued by predators (Tilson & Norton 1981), whereas warthogs, Phacochoerus africanus, dive into burrows (Nowak 1999). We tested whether species that seek refuge inhabit rocky habitats where cliffs or burrows might be found, and whether they are small. We also tested the hypothesis that species that seek refuge in this way are those whose young follow their mothers immediately after birth and do not rely on remaining hidden (Estes 1976).

Over 25 years ago, researchers formulated classic hypotheses regarding the social organization of African antelopes in relation to feeding ecology, observing that selective browsers and grazers live alone or in small groups and defend territories, but unselective feeders live in large groups (Estes 1974; Jarman 1974; Leuthold 1977). They also noted that, across ungulate species, species living in small groups tend to be of small body size and inhabit closed vegetation. Conversely, species in larger groups are large and live in more open vegetation types. In part, observed group sizes may be driven by the relative importance of antipredator benefits in different habitats. We tested associations between group size and body size and ecology using our comparative database. This type of analysis has been attempted using a more restricted phylogeny of African antelopes (Brashares et al. 2000), and we evaluated those results using a larger phylogenetic tree. We also tried to test whether species that live in groups show the ‘follower’ strategy (Estes 1976).

Entering water

Scattering

Some ungulates run into water when fleeing from predators, presumably as a tactic of last resort. Although such antipredator behaviour would be seen only where water was present, several species live in swampy habitats. For instance, chital, Axis axis, tend to run into or across shallow water (Johnsingh 1983), lechwes, Kobus leche, will readily take to water when threatened (Stuart & Stuart 1997), and moose, Alces alces, sometimes run into water when chased by wolves, Canis lupus (Fuller & Keith 1980). We tested whether entering water might be a method to escape predators by examining whether those species that enter water inhabit open environments and are chased by coursers, situations where few alternative escape options may be open to them.

When many ungulates flee simultaneously, they sometimes take flight in many directions (Lingle 2001). This may cause the predator to become confused and therefore reduce the chance of a successful attack (Caro & FitzGibbon 1992). Alternatively, prey may scatter when coursing predators run into groups and attempt to separate slower individuals from the herd. We examined whether species that scatter live in large groups, because larger groups could increase the chance that the predator becomes confused. As an alternative, we examined whether scattering was associated with attack by coursers.

Refuge in cliffs or burrows

Attack Many ungulate species will attack predators, especially mothers with attendant offspring. For example, in North America, elk, Cervus elaphus, bison, Bison bison, and pronghorn antelope, Antilocapra americana, initiate aggressive behaviour towards coyotes, Canis latrans, that pose a threat to themselves or offspring (Gese 1999). In

Bunching Many animals move closer to each other under threat of predation (Hamilton 1971). Bunching together occurs in many ungulates: chital bunch together in the presence of dholes, Cuon alpinus (Johnsingh 1983), and mule deer, Odocoileus hemionus, bunch when coyotes appear (Lingle 2001). Large groups of ungulates are more effective at defending themselves than are solitary animals because they can join up and form defensive formations with their vulnerable rumps protected by other members of the group (Jarman 1974; Caro & FitzGibbon 1992). We

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therefore looked for associations between species that bunch and have larger group sizes. We also looked for an association between species that bunch and have large body size, since bunching by large animals could increase the chance of injuring the predator if it tried to attack (Jarman 1974; Johnsingh 1983). Brashares et al. (2000) conducted parallel analyses on African antelopes.

Group attack Many larger artiodactyls will mob a predator (e.g. Estes 1991). For example, Nowak (1999) reported that if a white-lipped peccary, Tayassu pecari, is wounded or pursued, the entire herd will come to its aid and attack the predator. Caro & FitzGibbon (1992) noted that large ungulate species and open-country species such as African buffalo, Synercus caffer, rely on direct physical defence to reduce susceptibility to predators. Thus, we evaluated whether group attacks were associated with those species that live in large groups and have large body size, because both factors may help keep predators at bay. We also examined whether species that conduct group attacks live in open habitats where fewer hiding places exist. METHODS

Species We began analyses using species listed in Nowak (1999) and refined this list to exclude (1) purely domesticated species, (2) species that are or once were extinct in the wild and (3) species for which we could find little morphological or behavioural data (Stoner et al. 2003). As a result of this selection process, our nonparametric analyses were based on a maximum total of 200 artiodactyl species (Fig. 1).

Analyses We related antipredator behaviours to morphological, ecological and behavioural variables in two ways, using standard nonparametric statistical tests to compare species (Price 1997) and phylogenetic comparative methods that take account of shared ancestry (Harvey & Pagel 1991). For each antipredator behaviour, we tested hypotheses about their adaptive significance first in Cervidae, then in Bovidae, then across all artiodactyls. Thus, we tested whether the function of these putative antipredator behaviours was isolated within particular families or shared across all artiodactyls.

Nonparametric tests To identify general trends between antipredator behaviours and morphological, ecological and behavioural variables, we first applied chi-square or Fisher’s exact probability tests separately to the two largest families, cervids (N ¼ 39 species) and bovids (N ¼ 125 species), to identify associations that were isolated independently within particular families. We then performed these analyses (termed cross-species comparisons for convenience) for all the artiodactyls (N ¼ 200 species) to

determine whether associations still held across the whole clade, acknowledging that these latter analyses are not entirely independent of the others. For each test, we included only those species for which information was available for the antipredator behaviour and independent variables of interest. We considered it important to include cross-species comparisons in light of current controversy over the applicability of phylogenetically controlled methods (Irschick et al. 1997; Price 1997).

Phylogenetic comparisons Cross-species comparisons fail to account for the nonindependence of species values: shared character states may reflect common ancestry rather than independent adaptations (Losos 1990; Harvey & Pagel 1991). To control for potential effects of shared ancestry, we analysed the same hypotheses as in the nonparametric tests using Maddison’s (1990) concentrated-changes test (CCT) as implemented in MacClade (Maddison & Maddison 1992). All analyses were based on a composite phylogenetic tree. Using the matrix depicting each species’ character states (‘1’, ‘0’ or ‘?’), we mapped the antipredator behaviour (dependent) and ecological (independent) variables onto the phylogenetic tree. From the distribution of character states across all species, MacClade reconstructs the evolutionary history of a given trait throughout the tree using parsimony; character states with a ‘?’ are reconstructed on the basis of parsimony relying on the character states of the most closely related species. This makes it possible to count the number of evolutionary gains (change in a character state from a ‘0’ to a ‘1’) and losses (change from a ‘1’ to a ‘0’) in either the dependent or independent variables (Maddison & Maddison 1992). In those instances where character reconstruction was ambiguous (i.e. the tree contained areas where both ‘0’ or ‘1’ were equally parsimonious), we used the ‘most parsimonious reconstruction mode’ within MacClade to generate all possible reconstructions of the character. Because multiple ambiguities for the same character can lead to many possible reconstructions, we selected the first and the last reconstructions for the first analysis (Ortolani & Caro 1996; Ortolani 1999), because these are the ones with the most gains and fewest losses, and the fewest gains and most losses, respectively. We used the univariate CCT rather than multivariate statistics, both because most hypotheses about antipredator behaviour in animals hinge on simple predictions involving one independent variable and to provide a direct check on our nonparametric findings. Concentrated-change tests were used to test the probability that gains in the antipredator behaviour were associated with a particular independent variable more than expected by chance, and losses in the antipredator behaviour variable occurred in the presence of the independent trait less than expected by chance. Thus, we examined whether the presence of the morphological, ecological or behavioural variable facilitated the maintenance of the antipredator behaviour trait over evolutionary time. The null hypothesis, tested against a distribution derived through simulation and 10 000 replicates, was that gains and losses in a given antipredator trait were

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randomly distributed on the tree with respect to the independent variable. When ambiguity in character reconstruction existed, multiple reconstructions resulted in two or four probability values for each test, depending on whether one or both of the dependent and independent variables displayed ambiguity. We examined significance values below 0.1, because we were searching for associations using very coarse ecological and behavioural measures, and applied standard Bonferroni corrections to these tests; this is the most stringent form of this test. Thus, if we conducted four tests, we considered an association significant at P!0:025 (i.e. 0.1/4). We discuss only these results.

RESULTS

Snorting There were significant associations between cervid species that snorted in the presence of a predator and species that lived in groups that were both intermediatesized (Fisher’s exact test: N ¼ 36 species, P ¼ 0:0517) and large (Fisher’s exact test: N ¼ 36, P ¼ 0:0734); these results also applied to bovids (chi-square test: c21 ¼ 13:58, N ¼ 114, P ¼ 0:0002 and c21 ¼ 13:28, N ¼ 114, P ¼ 0:0003, respectively) and artiodactyls (c21 ¼ 10:83, N ¼ 177, P ¼ 0:001 and c21 ¼ 14:70, N ¼ 177, P ¼ 0:0001, respectively). Bovids and artiodactyls that snorted were associated with attacks by coursing predators more than expected (c21 ¼ 20:22, N ¼ 111, P!0:0001 and c21 ¼ 24:37, N ¼ 176, P!0:0001, respectively). Interestingly, cervids, bovids and artiodactyls that snorted were less likely to be hunted by aerial predators than expected by chance (Fisher’s exact test: N ¼ 37, P ¼ 0:0107; chi-square tests: c21 ¼ 15:55, N ¼ 112, P!0:0001 and c21 ¼ 24:37, N ¼ 177, P!0:0001, respectively). None the less, all these associations using crossspecies comparisons disappeared with tests that controlled for phylogeny.

Whistling Bovids and artiodactyls that whistled were less likely to live in groups that were intermediate-sized (chi-square tests: c21 ¼ 19:56, N ¼ 92, P!0:0001 and c21 ¼ 6:73, N ¼ 148, P ¼ 0:0095, respectively) or large (c21 ¼ 17:15, N ¼ 92, P!0:0001 and c21 ¼ 10:78, N ¼ 148, P ¼ 0:001, respectively) and were more likely to be found in swamps than expected by chance (c21 ¼ 5:95, N ¼ 92, P ¼ 0:0147 and c21 ¼ 3:07, N ¼ 151, P ¼ 0:0795, respectively); bovids that whistled were also more likely to be found in dense forests (c21 ¼ 15:12, N ¼ 92, P ¼ 0:0001). Bovid and artiodactyl species that whistled were significantly more likely to be attacked by aerial predators (c21 ¼ 15:33, N ¼ 91, P!0:0001 and c21 ¼ 24:37, N ¼ 149, P!0:0001, respectively) and less likely to be hunted by terrestrial coursing predators than expected by chance (c21 ¼ 21:79, N ¼ 91, P!0:0001 and c21 ¼ 24:37, N ¼ 149, P!0:0001, respectively), but there was no association with stalkers. None of these results held after controlling for phylogeny, however.

Foot Stamping Bovids and artiodactyls that foot-stamped were more likely to live in groups that were intermediate-sized (c21 ¼ 25:33, N ¼ 106, P!0:0001 and c21 ¼ 17:40, N ¼ 159, P!0:0001, respectively) and large (c21 ¼ 4:14, N ¼ 106, P ¼ 0:0419 and c21 ¼ 6:82, N ¼ 159, P ¼ 0:009, respectively) than those that did not foot-stamp, based on cross-species comparisons, but significance disappeared in phylogenetically controlled tests. Foot-stamping species were actually less likely to inhabit dense forests and swamps than expected by chance (bovids and forests: c21 ¼ 24:37, N ¼ 106, P!0:0001; artiodactyls and forests: c21 ¼ 24:37, N ¼ 162, P!0:0001; artiodactyls and swamps: c21 ¼ 4:10, N ¼ 162, P ¼ 0:0428), but cervids were more likely to inhabit forests (Fisher’s exact test: N ¼ 34, P ¼ 0:0643), although none of these results held in phylogenetic tests. Therefore, there was little evidence that foot stamping is used to signal conspecifics of danger in dense vegetation. In contrast, foot stamping was more likely to occur than by chance in bovids and artiodactyls inhabiting open environments (grassland, desert and tundra; chi-square tests: c21 ¼ 15:35, N ¼ 106, P!0:0001 and c21 ¼ 17:09, N ¼ 162, P!0:0001, respectively). Foot stamping was also more likely to occur in artiodactyls with white legs (c21 ¼ 6:71, N ¼ 161, P ¼ 0:0096) but not in those with dark legs. Again, these results were not confirmed using CCTs.

Tail Flicking There was no evidence that tail flicking was associated with living in open environments; cervids were less likely to tail-flick in these areas (Fisher’s exact test: N ¼ 37, P ¼ 0:004). Cervids reported as tail flicking had dark tails (Fisher’s exact test: N ¼ 36, P ¼ 0:0139) and artiodactyls that tail-flicked had white tails (chi-square test: c21 ¼ 4:96, N ¼ 177, P ¼ 0:026) but these associations disappeared after controlling for phylogeny. Cervids that tail-flicked were less likely to be in intermediate-sized groups (Fisher’s exact test: N ¼ 35, P ¼ 0:0469), but tail-flicking bovids were more likely to be found in large groups than expected by chance (chi-square test: c21 ¼ 9:50, N ¼ 118, P ¼ 0:0021). Furthermore, there were associations between tail flicking and living in large groups in bovids and artiodactyls after controlling for phylogeny (CCTs: P ¼ 0:0708 and P ¼ 0:0664, respectively).

Tail Flagging Cervids, bovids and artiodactyls that tail-flagged were more likely than expected to live in intermediate-sized groups (c21 ¼ 10:30, N ¼ 35, P ¼ 0:0013, c21 ¼ 11:86, N ¼ 110, P ¼ 0:0006 and c21 ¼ 15:08, N ¼ 163, P ¼ 0:0001, respectively), and these associations held for both bovids and artiodactyls after controlling for phylogeny (CCTs: P ¼ 0:0162 and P ¼ 0:0616, respectively). Tail flagging was associated with species attacked by stalking predators (cervids: c21 ¼ 8:86, N ¼ 36, P ¼ 0:0034; bovids: c21 ¼ 2:92, N ¼ 73, P ¼ 0:0874; artiodactyls: c21 ¼ 12:86, N ¼ 160, P ¼ 0:0003), but these results were not upheld in

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Figure 1. Phylogenetic tree of the Artiodactyla from Stoner et al. (2003). Upper star denotes origin of the Cervidae; lower star the origin of the Bovidae.

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phylogenetic tests. Tail flagging was seen in species attacked by coursing predators (bovids: c21 ¼ 6:59, N ¼ 105, P ¼ 0:0102; artiodactyls: c21 ¼ 6:58, N ¼ 160, P ¼ 0:0103), but not after controlling for phylogeny. However, cervids, bovids and artiodactyls in general that tail-flagged were found in open environments more often than expected by chance (c21 ¼ 4:68, N ¼ 37, P ¼ 0:0305, c21 ¼ 5:09, N ¼ 110, P ¼ 0:0241 and c21 ¼ 10:41, N ¼ 166, P ¼ 0:0013, respectively) and these results were maintained in artiodactyls after controlling for phylogeny (CCT: P ¼ 0:0092). Thus, there was comparative support for the idea that tail flagging is used either to signal conspecifics of danger, because it occurs in group-living species, or possibly to confuse predators, because it occurs in open-country species and in group-living animals.

Bounding/Leaping/Stotting Perhaps because we were forced to combine three behaviour patterns for which there were already data to suggest that they had different functions, results lent weak support to a number of hypotheses. In cross-species comparisons between artiodactyls, there were significant associations between bounding, leaping or stotting and living in rocky habitats (c21 ¼ 6:44, N ¼ 170, P ¼ 0:0111), supporting the idea of clearing obstacles. However, there were also significant associations with having dark legs (chi-square test: artiodactyls: c21 ¼ 10:35, N ¼ 169, P ¼ 0:0013), dark tails (Fisher’s exact test: cervids: N ¼ 31, P ¼ 0:0016; chi-square test: bovids: c21 ¼ 3:37, N ¼ 115, P ¼ 0:0663; artiodactyls: c21 ¼ 7:28, N ¼ 169, P ¼ 0:0070), white tails (artiodactyls: c21 ¼ 16:50, N ¼ 169, P!0:0001) and white rumps (bovids: c21 ¼ 3:02, N ¼ 115, P ¼ 0:0821; artiodactyls: c21 ¼ 12:20, N ¼ 169, P ¼ 0:0005), suggesting that these behaviours may have been associated with signalling. Results pertaining to predator hunting style were mixed. Cervids hunted by stalkers were significantly less likely to bound, leap or stott (Fisher’s exact test: N ¼ 30, P ¼ 0:0215); conversely, bovids were more likely to do so (chi-square test: c21 ¼ 24:37, N ¼ 109, P!0:0001) and artiodactyls were less likely to bound, leap or stott to coursers (c21 ¼ 3:31, N ¼ 163, P ¼ 0:0688). There were no significant associations with independent variables using phylogenetic controls.

Zigzagging/Tacking Bovids reported as zigzagging or tacking were more likely to live in open environments (c21 ¼ 3:24, N ¼ 114, P ¼ 0:0719), but there was no significant association after controlling for phylogeny, and none between these behaviours and living in groups. These findings suggest that these behaviours are unlikely to be used as a signal or to wrongfoot predators, leaving zigzagging as a means of increasing distance from the predator as a (untested) viable candidate explanation.

Prancing There were no significant associations between prancing and living in open environments. Bovids and artiodactyls

that pranced did tend to have white leg markings, however (c21 ¼ 12:16, N ¼ 115, P ¼ 0:0005 and c21 ¼ 19:97, N ¼ 175, P!0:0001, respectively), although these results were not upheld after controlling for shared ancestry. Artiodactyls reported as prancing in response to threat were found in groups that were intermediate-sized (c21 ¼ 3:96, N ¼ 173, P ¼ 0:0467) and large (c21 ¼ 4:41, N ¼ 173, P ¼ 0:0357) and the result for large groups was still significant after controlling for phylogeny (CCT: P ¼ 0:0894).

Inspection Artiodactyls reported as showing inspection behaviour lived in intermediate-sized groups (c21 ¼ 4:02, N ¼ 194, P ¼ 0:0488); both bovids and artiodactyls that inspected were typically found in large groups of more than 50 animals (c21 ¼ 10:20, N ¼ 125, P ¼ 0:0014 and c21 ¼ 15:64, N ¼ 194, P!0:0001, respectively). This last result was also significant using CCTs (CCT: P ¼ 0:0702). Inspection was more likely than chance to occur in large-bodied artiodactyls (c21 ¼ 2:95, N ¼ 197, P ¼ 0:0856). Species showing inspection were no more likely to be pursued by stalkers or coursers than expected by chance.

Freezing Cervids, bovids and all artiodactyls reported as freezing when danger approaches tended to inhabit dense forests (Fisher’s exact test: N ¼ 37, P ¼ 0:0215; chi-square tests: c21 ¼ 3:04, N ¼ 115, P ¼ 0:081 and c21 ¼ 13:02, N ¼ 176, P ¼ 0:0003, respectively) and this result held in cervids after controlling for phylogeny (CCT: P ¼ 0:0816). ‘Freezers’ were not likely to be found in swamps, however. In all three taxonomic groups, freezing species were small (Fisher’s exact test: N ¼ 37, P ¼ 0:0474; chi-square tests: c21 ¼ 24:37, N ¼ 115, P!0:0001 and c21 ¼ 24:37, N ¼ 176, P!0:0001, respectively). Bovid species that freeze were significantly more likely to have spotted coats (c21 ¼ 6:33, N ¼ 115, P ¼ 0:0014) or striped coats (c21 ¼ 10:25, N ¼ 115, P ¼ 0:0014) as adults and the association between freezing and spotted coats was found in artiodactyls too (c21 ¼ 9:52, N ¼ 176, P ¼ 0:002). Finally, bovids and artiodactyls that freeze were more likely to leave their young hidden after birth (c21 ¼ 19:91, N ¼ 114, P!0:0001 and c21 ¼ 24:37, N ¼ 175, P!0:0001, respectively). Nevertheless, none of these results held after controlling for phylogeny.

Refuge in Cliffs or Burrows Bovids and artiodactyls that seek refuge in the face of danger inhabited rocky habitats (c21 ¼ 24:37, N ¼ 118, P!0:0001 and c21 ¼ 24:37, N ¼ 180, P!0:0001, respectively), although this association was found only in crossspecies comparisons. Artiodactyls seeking refuge tended to be small (CCT: P ¼ 0:099). Seeking refuge was associated with species whose young showed the follower strategy (bovids: c21 ¼ 24:37, N ¼ 117, P!0:0001; artiodactyls: c21 ¼ 24:37, N ¼ 179, P!0:0001), but only in cross-species comparisons.

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Entering Water Cervids that enter water during flight were more often found in open environments (c21 ¼ 6:84, N ¼ 34, P ¼ 0:0089), and artiodactyls showing this behaviour were subject to predation by coursers (c21 ¼ 4:64, N ¼ 158, P ¼ 0:0313). These findings disappeared in phylogenetic tests.

Attack Artiodactyls that attack their predators were large (O20 kg; c21 ¼ 6:22, N ¼ 197, P ¼ 0:0217), although this result did not hold after applying phylogenetic controls. There was no comparative support for attacking species living alone or in groups of two.

Group Living Solitary species were small in body weight in crossspecies comparisons; this result was also found in artiodactyls after controlling for phylogeny (Table 3). Bovids and artiodactyls were significantly more likely to be found in dense forests than expected by chance, although these results were not upheld when controlling for phylogeny. Bovids and artiodactyls were significantly more likely to inhabit swamps. In short, solitary species tended to be small and occupy closed habitats. There was evidence that group-living species are of large body size. Bovid and artiodactyl species that lived in intermediate-sized and large groups were both significantly more likely to weigh over 20 kg after controlling for phylogeny. Cervids, bovids and artiodactyls living in intermediate-sized groups (3e50 individuals) were significantly more likely to live in open environments, a result that was still highly significant in artiodactyls after controlling for phylogeny (Table 3). This association stemmed principally from species found in intermediatesized groups typically living in a particular open habitat, deserts. In all three clades, species living in large groups (>50 individuals) were also typically found in open environments, although this result was not upheld in phylogenetic comparisons. Species in large groups were found in desert, grassland, scrub and in tundra habitats. There was some evidence that group-living species adopted the follower strategy, but only in cross-species comparisons.

Scattering Scattering was associated with living in open environments in bovids (c21 ¼ 3:53, N ¼ 99, P ¼ 0:0604) and artiodactyls (c21 ¼ 4:90, N ¼ 162, P ¼ 0:0269) and in large groups (c21 ¼ 5:74, N ¼ 99, P ¼ 0:0166 and c21 ¼ 6:18, N ¼ 159, P ¼ 0:0129, respectively), but these associations disappeared in phylogenetic tests. Scattering was not associated with species pursued by coursing predators.

Bunching In cervids, bovids and artiodactyls, bunching was associated with living in groups that were intermediate-

sized (Fisher’s exact test: N ¼ 36, P ¼ 0:0227; chi-square tests: c21 ¼ 15:35, N ¼ 104, P ¼ 0:0106 and c21 ¼ 24:37, N ¼ 165, P ¼ 0:0003, respectively) and large (Fisher’s exact test: N ¼ 36, P ¼ 0:0561; chi-square tests: c21 ¼ 6:53, N ¼ 104, P!0:0001 and c21 ¼ 12:94, N ¼ 165, P! 0:0001, respectively). These associations were upheld in concentrated-changes tests for cervids and artiodactyls in intermediate-sized groups (P ¼ 0:0836 and P ¼ 0:0372, respectively) and for artiodactyls in large groups (P ¼ 0:048). In cross-species comparisons, bovid and artiodactyl species that bunched together were likely to be large in size (chi-square tests: c21 ¼ 16:51, N ¼ 104, P! 0:0001 and c21 ¼ 15:79, N ¼ 168, P!0:0001, respectively).

Group Attack Bovid and artiodactyl species showing a propensity to launch group attacks were associated with large groups in chi-square (c21 ¼ 10:40, N ¼ 110, P ¼ 0:0013 and c21 ¼ 6:75, N ¼ 172, P ¼ 0:0094, respectively) and CCTs (P ¼ 0:0164 and P ¼ 0:0012, respectively). There was also an association between this behaviour and living in intermediate-sized groups for artiodactyls (c21 ¼ 9:92, N ¼ 172, P ¼ 0:0016). Group attack and large body size were associated in these two clades but only in crossspecies comparisons (c21 ¼ 2:80, N ¼ 110, P ¼ 0:0941; c21 ¼ 7:20, N ¼ 175, P ¼ 0:0073). Group attacks were not restricted to open environments.

DISCUSSION

Limitations of Applying Comparative Analyses to Antipredator Behaviour Comparative analyses provide an opportunity to examine the generality of functional hypotheses formerly derived from observations of one or a handful of species. Comparisons across species may also be useful in detecting associations between variables that provide new clues for the adaptive significance of traits. Although comparative analyses provide a means to explore the function of antipredator behaviours across large taxonomic groups, the scale of these tests also generates limitations. For example, although this study included many ungulates species, we found that the presence or absence of antipredator behaviour patterns was often poorly documented. It is relatively easy to locate records of species showing a particular antipredator behaviour pattern, but it is far more difficult to be sure that the species does not show that pattern. We scored patterns as being absent only if this was explicitly mentioned in our review of the literature (Appendix, Table A1) and used a ‘?’ when there was no mention of whether the trait was either present or absent. There must have been many instances where authors did not remark on not seeing a behaviour pattern, so many of our ‘?’ scores might actually be zeros, indicating the absence of the trait. One way around this problem might be to survey fieldworkers as to whether they have specifically seen different antipredator behaviour patterns.

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Table 3. P values resulting from chi-square, Fisher’s exact probability tests or concentrated-changes tests between species that live in different-sized groups, and independent variables Chi-square and Fisher’s exact tests*

Concentrated-changes testsyz Cervid

Antipredator behaviour Solitary Small body size Dense forests Swamps Intermediate group size Large body size Open environments Deserts Grass/scrub Tundra Follower Large group size Large body size Open environments Deserts Grass/scrub Tundra Follower

Bovid

Artiodactyls

Cervid

Bovid

Artiodactyls

First

Last

First

Last

First

Last

0.0166* 0.2270 0.2016*

!0.0001 0.0004 0.0057

!0.0001 0.0001 0.0641

0.7090, 0.6870 0.0850, 0.9690 0.2140, 0.3800

0.3630, 0.3320 0.3600, 0.2370 0.2110, 0.5380

0.5390, 0.5900 0.5390, 0.5370 0.7860, 0.2350

0.0350, 0.0370 0.4450, 0.5310 0.5710, 0.3090

0.3430, 0.3260 0.3050, 0.8330 0.2590, 0.1380

0.0040, 0.0070 0.2800, 0.2920 0.0750, 0.1740

0.0049* 0.0002 0.2297* 0.0900* 0.4865* 0.2297*

!0.0001 !0.0001 0.0029 0.0900 0.2097 0.0009

!0.0001 !0.0001 !0.0001 0.0239 0.1042 !0.0001

0.3730, 0.1053, 0.9260, 0.9258, 0.0869 0.0790,

0.3950 0.1075 0.9236 0.9280

0.5710, 0.0724, 0.8814, 0.7048, 0.9733 0.9640,

0.0140, 0.1161, 0.2078, 0.6008, 0.8687 0.0510,

0.0030 0.3288 0.1693 0.5381

0.0140, 0.1161, 0.2078, 0.6008, 0.8687 0.0510,

0.0100 0.3288 0.1693 0.5381

0.0020, 0.0050, 0.2130, 0.1950, 0.0890 0.1830,

0.0 0.0120 0.1150 0.1820

0.0070, 0.0080 0.0, 0.0080 0.1780, 0.0750 0.1400, 0.1350 0.8750 0.1750, 0.1190

0.1516* 0.0191* 0.6096* 0.4086* 0.2162* 0.3484*

!0.0001 !0.0001 0.0090 0.0482 0.0127 0.0125

!0.0001 !0.0001 0.0028 0.0463 0.0014 0.0008

0.5250, 0.1963, 0.9263, 0.9636, 0.0600 0.0610,

0.5050 0.1924 0.9310 0.9674

0.0130, 0.0549, 0.6877, 0.5716, 0.0148 0.6750,

0.0070 0.1022 0.4836 0.6738

0.1715, 0.1653, 0.9686, 0.4210, 0.1141 0.3095,

0.1830 0.2938 0.7792 0.4918

0.0010, 0.0304, 0.5230, 0.7250, 0.0020 0.6250,

0.0010 0.0716 0.4000 0.8060

0.0860

0.0700

0.5250, 0.1963, 0.9263, 0.9636, 0.0600 0.0610,

0.5750 0.0756 0.8830 0.7072 0.9730 0.5050 0.1924 0.9310 0.9674 0.0700

0.0500

0.6900

0.0500

0.2015

0.1170

0.5580

0.0080, 0.1650, 0.8950, 0.4540, 0.0170 0.4440,

0.0120 0.2860 0.7780 0.5110 0.3640

) Significant values (P!0:1) are shown in bold. yFirst refers to the first reconstruction of the behavioural variable; last refers to the last. Within columns marked both first and last, the left-hand value indicates the P value for the first ecological reconstruction and the second value refers to the last reconstruction. If only one P value is given, there was only one reconstruction. zSignificant values on concentrated-changes tests are discussed in the text only if significant following a Bonferroni correction (see Methods).

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Another limitation of our study was the broad nature of the behavioural, and especially ecological, categories. Dense forest, for example, constituted alpine, tropical, boreal, deciduous, mixed dense forests and timberland, although differences in these habitat types would affect lighting conditions and habitat structure (Endler 1993) and thus the extent to which vegetation might enable prey to remain cryptic or impede flight. Nevertheless, we were constrained by lack of detailed data on most species and were forced to use a few categories that could be ascribed to most species, such as habitat or group size, which were necessarily coarse. A third problem is that antipredator behaviours and morphological and behavioural variables may occur under certain ecological or social conditions but not others. Thus, single studies conducted on one population may not represent the species as a whole. This makes it inappropriate to categorize a species as showing or not showing a particular antipredator behaviour (e.g. Lingle & Pellis 2002), group size (e.g. Hirth 1977; Molvar & Bowyer 1994) or even morphology (e.g. Cowan 1936; Bowyer et al. 1991). Ideally, comparative data, coded even in binary format, should use modal figures from several populations to derive dependent and independent variables, but such data are unavailable for most species at present. Fourth, many of the independent variables covaried. For example, group sizes are large in open environments (Jarman 1974), thus the association between an antipredator behaviour and both group size and open environment does not necessarily constitute two sources of evidence that the behaviour is an intraspecific signal. Although some independent variables are obviously related, others that we did not identify may have covaried too. Multivariate statistics that incorporate all independent variables together and control for phylogeny would make headway in tackling this problem. At this juncture, however, we advise focusing effort on improving the quality of the data on dependent antipredator variables, perhaps through the use of questionnaires on a smaller data set. As a practical point, few CCTs were significant in this study, making it unlikely that multivariate statistics would alter our findings. A fifth limitation of this analysis is that our attempts to tease out specific predictions that would support or cast doubt on functional hypotheses for antipredator behaviour may be misplaced. For example, it may be inappropriate to predict that if prancing serves as a communicative role, it should be associated with contrasting leg coloration; perhaps the leg is obvious without pelage markings. Despite all these concerns, our attempt to document the incidence of antipredator behaviours across species identifies gaps in knowledge, and our attempt to relate antipredator behaviour to morphological, ecological and behavioural variables enables us to revisit associations that have been made verbally but have never been confirmed systematically. Our results showed many highly significant correlations between antipredator behaviour patterns and morphological, behavioural and ecological variables using crossspecies comparisons based on chi-square and Fisher’s exact tests but far fewer when we controlled for shared

ancestry using MacClade CCTs. Why might there be such discrepancies between the two types of analyses? The most likely explanation is that sample sizes in the crossspecies analyses were inflated because of shared ancestry, increasing significance levels. However, lack of significant associations after controlling for phylogeny could also stem from closely related species with particular antipredator traits that choose (in evolutionary terms) to inhabit particular environments. If this were the case, the number of gains in the antipredator behaviour and associated gains in the environmental variable would be severely reduced across branches of the tree, resulting in loss of significance. Associations with particular environments over evolutionary time provide strong support for adaptive explanations of behaviour but are overlooked in CCTs; thus, we thought that this constituted a reason to refer to cross-species comparisons in interpreting our results. We also thought it necessary to perform cross-species comparisons because the phylogenetic reconstruction used in our analyses was of lower resolution than we would have wished. In the absence of a complete molecular phylogeny of artiodactyls, we constructed a composite tree based on the most recent molecular studies and supplemented this with taxonomies based on morphological traits. Certain species were also excluded because of lack of information or strong disagreements over their phylogenetic position, and we resolved polytomies using the arbitrary procedure of excluding species with fewest citations (see Stoner et al. 2003). Nevertheless, this is the most comprehensive tree available for Artiodactyla. Given that the production of a more resolved tree in the future might change our results, we think it premature to disregard results based on simple crossspecies comparisons at this stage. Another possible explanation for differences between the results of cross-species comparisons versus phylogenetically based analyses is that some of the independent variables are extremely labile. For example, group size varies enormously within species (e.g. LaGory 1987). In these cases, reconstruction of the history of such a variable is liable to be misleading, because it is based on the presence or absence of the variable on the terminal branches. If these variables vary according to demographic or environmental circumstances, gains and losses in the independent variable at nodes within the tree will be radically altered. We are unclear as to how these would influence results, but again, they suggest it would be incautious to dismiss nonparametric results out of hand.

Auditory Signals Snorting was associated with species that live in groups, suggesting that it might be a signal to inform conspecifics of danger. This result differs from those of some studies that indicate that snorting is a signal to predators. For example, snorting is heard in solitary individuals where there is no need to warn others, as well as in groups when conspecifics are already aware of danger (Caro 1994; Caro et al. 1995). Studies finding that philopatric females snort more than males point to intraspecific warning signals

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maintained by kin selection, however (Hirth & McCullough 1977). The function of snorting remains enigmatic, but our results reopen the debate on whether snorting is a warning to conspecifics. That snorting was associated with coursing predators may be simply an artefact of coursers living in open habitats where ungulate species are often gregarious (Jarman 1974); nevertheless, this finding is reminiscent of specific alarm calls given by ground squirrels to aerial and terrestrial predators (Sherman 1985). Whistling, on the other hand, was unlikely to be heard from species that live in groups and was often heard from species in closed habitats. Lack of significant association with coursers may reflect the absence of coursers in dense vegetation. Based on cross-species comparisons, at least, whistling does not seem to be a signal warning others of danger. By elimination, it may therefore be a signal to predators given by forest-living ungulates, but this conclusion is speculative. Foot stamping was associated with species in groups, inhabiting open environments, and having conspicuous white leg markings. All of these findings support predictions relating to foot stamping as a visual rather than auditory signal to conspecifics. This is a novel finding to emerge from these comparative data and suggests that future research should investigate the role of foot stamping as a visual signal. Although our systematic analyses suggest that snorting and foot stamping are signals to conspecifics and whistling is a pursuit-deterrent signal, these findings were not echoed in phylogenetic tests, so we are wary of pressing our conclusions too far.

may be used to jump over rocks, confirming observations in African bovids that bounding is used to jump over obstacles (Caro 1994). None the less, these behaviours are often seen in species with conspicuous colour patches, particularly with white tails and white rumps, suggesting a signal function. Some significant associations between species that display these antipredator behaviours and those that are ambushed by stalking predators also indicate that the signal may inform predators that they have been seen. Indeed, this is one of the proposed functions of stotting (Caro 1986a, b). These arguments need to be tempered by the lack of significance after controlling for phylogeny. The weakness of these comparative analyses is that we were forced to lump behaviour patterns that, in separate studies, have been shown to have different functions (Caro 1994). Future studies of individual species at least need to define the type of jump shown by ungulates, so that these behaviours can be better distinguished. Results did not support the idea that zigzagging or tacking were signals to predators, but we suspect that these behaviour patterns are poorly documented. By elimination, zigzagging could be a means to increase distance between prey and predator during flight (FitzGibbon 1994). There was some evidence that prancing is an intraspecific signal, because it is documented in species living in groups and having white leg markings. The ecocorrelates of prancing and foot stamping showed considerable similarity, raising the possibility that prancing is an exaggerated form of foot stamping and that both behaviours warn conspecifics.

Visual Signals We found strong associations between tail flicking and living in large groups for bovids and artiodactyls after controlling for phylogeny. This result supports the idea that tail flicking is used in intraspecific communication, even though the message that it conveys is unclear to us. Similar conclusions have been drawn for rails (Alvarez 1993). None the less, other explanations, such as that group-living species are disproportionately bothered by flies (Mooring & Hart 1992), cannot be excluded. After taking account of shared ancestry, there were also strong associations between tail flagging and species living in intermediate-sized groups or inhabiting open environments in bovid and artiodactyl clades. These findings suggest that tail flagging is a form of intraspecific communication, which runs contrary to several observational studies of white-tailed deer that refuted tail flagging as a warning signal to conspecifics (Caro et al. 1995). On the other hand, tail flagging was associated with being attacked by stalking predators in all three clades and approached significance in phylogenetic tests on artiodactyls. These results suggest that tail flagging may be involved in signalling to ambush predators, as occurs in some birds (Woodland et al. 1980). These contradictory results reopen the debate as to the function of this behaviour and raise the possibility of different functions in different species or even multiple functions in the same species. Bounding, leaping and stotting occurred in species inhabiting rocky habitats, suggesting in part that they

Defence Inspection is found predominantly in group-living bovids and artiodactyls, extending FitzGibbon’s (1994) observations that Thomson’s gazelles in large groups inspect cheetahs. These findings parallel inspection behaviour in wild guppies, Poecilia reticulata (Magurran & Seghers 1994), but contrast with those seen in other fish species, where as few as two individuals will routinely approach a predator (Milinski 1992). We found evidence that freezing behaviour makes ungulates inconspicuous as danger approaches: it was associated with dense vegetation, cryptic coloration and small body size. The association with body size mirrors Brashares et al.’s (2000) study of African antelopes, which showed an effect of body mass on freezing behaviour (after controlling for phylogeny). Some species that hide their young after birth use freezing behaviour as adults, suggesting that hiding and freezing may be causally related over the course of development. Freezing in response to predation threat is common in many taxa (e.g. Gabrielsen et al. 1985; Gerkema & Verhulst 1990). Not surprisingly, species that seek refuge in cliffs or burrows were found in rocky habitats and tended to be small. They also tended to use the follower strategy (Estes 1976), according to cross-species comparisons. Finally, there was some support for informal observations that open-country species seek refuge in water when chased by coursers. However, these associations were scattered across the three taxonomic

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groups and were not confirmed using phylogenetic controls.

Attack There were no clear patterns in the distribution of attacking predator behaviour in ungulates. The idea that only species of large body weight would attack predators if alone was supported only in cross-species comparisons of artiodactyls. There was no evidence that attacks were more prevalent in solitary species. We suspect that the ubiquity of mothers defending their offspring from predators (Montgomerie & Weatherhead 1988), which was included in this measure, masked associations between this antipredator strategy and other variables.

Group Living Solitary ungulates were small and lived in dense habitats. Ungulates living in intermediate-sized groups were large and lived in open environments, particularly deserts. Ungulates living in large groups (O50 individuals) were also large and lived in open environments, notably deserts, grass and scrubland and tundra. These findings, supported by analyses controlling for shared ancestry, confirm long-held dogma that group living is associated with large body size and inhabiting open habitat (Estes 1974; Jarman 1974). Nevertheless, they run counter to more sensitive phylogenetic analyses of African antelopes that used body mass as a continuous variable (Brashares et al. 2000). Clearly, the relation between group size and body size in ungulates requires further examination. For example, a more sensitive measure of ungulate body size relative to common predators might be appropriate. Cross-species comparisons lent support to Estes’ (1976) idea that group-living ungulates have young that follow their mother from birth. Scattering was associated with living in large groups but only in cross-species comparisons and was not confined to species pursued by coursers. Although we know that closely related species differ in the way they react to some types of predators (Lingle 2001), in general, we suspect that scattering is underreported in the literature. Bunching was found in large-bodied species and in group-living species. Finally, group attacks were associated with species living in large groups and, to some extent, with species of large body size. Both of these sets of findings provide comparative support that these group behaviours deter predators. In conclusion, our analyses using a comparative data set have drawn attention to the need to document presence and particularly absence of antipredator behaviours in field studies, have helped to support and refute contemporary functional hypotheses for these behaviour patterns, have systematically confirmed qualitative associations between variables, and have generated novel hypotheses for antipredator adaptations in artiodactyls. Comparative analyses need to be applied more widely to support or refute adaptive explanations for antipredator behaviour in other wellknown taxa.

Acknowledgments We thank Terry Bowyer, Dick Estes, Marco Festa-Bianchet, Luc-Alain Giraldeau and an anonymous referee for helpful comments.

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Appendix Table A1. Values of variables used in this study. For all variables, a value of ‘1’ was assigned to species demonstrating a given trait, ‘0’ to species that did not display the trait, and a ‘?’ for species for which little or no information on the variable was available

Peccaridae Catagonus wagneri Pecari tajacu Tayassu pecari Hippopotamidae Hippopotamus amphibius Hexaprotodon liberiensis Camelidae Lama guanicoe Vicugna vicugna Camelus bactrianus (wild)

Large body size Small body size Spotted adults Striped adults Dark legs White legs Dark tail White tail White rump Grasslands/scrublands Dense forest Desert Rocky Tundra Swamp Open environment Solitary Intermediate groups Large groups Hiders Followers Hunted by aerial predators Hunted by stalkers Hunted by coursers

Suidae Sus scrofa S. salvanius S. bucculentus S. verrucosus S. barbatus S. philippensis S. cebifrons Potamochoerus porcus P. larvatus Hylochoerus meinertzhageni Phacochoerus africanus P. aethiopicus Barbirusa babyrussa

Independent variables

Snort Whistle Foot stamp Tail flick Tail flag Bound/leap/stott Zigzag/tack Prance Inspection Freeze Refuge in cliffs/burrows Enters water Attack Scatter Bunch Group attack

Dependent variables

1 1 1 0 1 1 1 1

1 0 1 1 1 1 1 1

0 0 0 1 0 0 0 0

0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0

0 0 0 1 0 0 0 0

0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0

1 1 1 1 1 1 1 1

0 0 0 0 0 0 0 0

? ? ? ? ? ? ? 0

1 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0

1 0 0 0 0 0 0 0

1 1 1 1 1 1 1 1

0 1 0 0 0 0 0 0

0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0

0 0 ? 0 0 0 0 1

0 0 ? 0 0 0 0 0

1 0 ? 1 1 1 1 1

0 0 ? 0 0 0 0 1

0 0 ? 0 0 0 0 0

1 1 0 1 1 0 0 1

1 0 1 1 1 1 1 1

0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0

1 1 0 1 1 0 0 1

1 1 0 1 0 0 0 0

0 0 ? 0 0 0 0 0

1 1 ? 1 1 1 1 1

1 0 ? 0 1 0 0 1

1 1 1 1 1 1 1 1

0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0

1 1 1 1 1 1 1 1

1 1 1 1 1 1 1 1

1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 1

1 0 0 0 0 0 1 0 0 1 1 0 0 0 1 0 0 1 1 1 0 0 1 1 1 0 0 0 0 0 1 0 0 1 1 0 0 0 1 1 0 1 0 1 0 0 1 1

1 0 0 0 1 0 0 0 0 1 1 0 0 0 0 1

1 0 0 0 0 0 1 0 0 1 0 0 0 0 0 1 0 1 0 1 0 0 1 1

1 0 0 0 1 0 0 0 0 1 1 0 0 0 0 1 ? ? ? ? ? ? ? ? 0 ? ? ? 0 ? ? 1

1 0 0 0 0 0 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 1 0 0 0 0 0 0 0 0 1 1 0 0 0 1 0 0 1 0 0 1 0 1 1

1 0 ? ? ? ? ? ? 0 ? ? ? 0 ? ? 1

1 0 0 0 0 0 0 0 0 1 1 0 0 0 0 1 0 1 0 0 1 0 1 1

1 0 ? ? ? ? ? ? 0 ? ? ? 0 ? ? 1 1 0 ? ? ? ? ? ? 0 ? ? ? 0 ? ? 1

1 0 0 0 0 0 0 0 0 1 1 1 0 0 0 1 0 1 1 0 1 0 1 1 1 0 0 0 0 0 0 0 0 1 1 0 0 0 0 1 0 1 1 0 1 0 1 1

1 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1

1 0 0 0 0 0 0 0 0 1 0 0 0 0 1 1 1 1 1 0 1 0 1 1

1 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1

1 0 0 0 0 0 0 0 0 0 1 0 0 0 1 0 1 0 0 0 1 0 1 1

0 1 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 1 ? ? ? ? ? 0 ? 0 ? 0 ? ? ? 1 ? 0 0 0 0 0 0 0 0 0 0 0 0 0 0

1 0 0 0 1 1 1 0 1 1 0 1 0 0 0 1 0 1 0 0 1 0 1 0 1 0 0 0 1 0 0 1 1 1 0 1 0 0 0 1 0 1 0 0 1 0 1 0 1 0 0 0 0 0 1 0 0 1 0 1 0 0 0 1 1 1 0 0 1 0 0 0

Tragulidae Hyemoschus aquaticus Moschiola meminna Tragulus javanicus T. napu

? ? ? ? ? ? ? ? 0 ? 0 1 0 0 0 0

0 1 1 1 0 0 1 1 0 0 1 0 0 0 1 0 1 0 0 1 0 1 0 0

? ? ? ? ? ? ? ? 0 ? ? ? 0 ? ? ?

0 1 1 1 0 0 0 1 0 1 1 0 1 0 1 0 1 0 0 1 0 1 0 0

? ? 1 ? ? ? ? ? 0 ? 0 ? 0 0 0 0 ? ? 1 ? ? ? ? ? 0 ? ? ? 0 ? ? ?

0 1 0 0 0 0 0 1 0 1 1 0 1 0 1 0 1 0 0 1 0 1 0 0 0 1 0 0 0 0 0 1 0 1 1 0 1 0 1 0 1 0 0 1 0 1 0 0

Giraffidae Okapi johnstoni Giraffa camelopardalis

0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 1 1 0 0 0 0 0 1 0 0 0 0 0 0

1 0 0 1 0 1 1 0 1 1 1 0 0 0 0 1 1 1 0 1 0 0 1 1 1 0 1 0 0 0 1 0 0 1 0 0 0 0 0 1 0 1 0 1 0 0 1 1

Moschidae Moschus chrysogaster

1 0 ? 0 ? 0 1 0 0 1 1 0 0 0 0 0

0 1 0 0 0 0 0 0 0 1 1 0 1 0 0 1 1 0 0 1 0 0 1 1 (continued )

223

ANIMAL BEHAVIOUR, 67, 2

Table A1. Continued

M. M. M. M.

leucogaster fuscus berezovskii moschiferus

Cervidae Hydropotes inermis Elaphodus cephalophus Muntiacus atherodes M. reevesi M. feae M. gongshanensis M. crinifrons M. muntjak Megamuntiacus vuqangensis Dama dama Axis axis A. porcinus A. kuhlii A. calamianensis Cervus unicolour C. timorensis C. mariannus C. alfredi C. duvaucelii C. eldii C. nippon C. albirostris C. elaphus Odocoileus hemionus O. virginianus Blastoceros dichotomus Ozotoceros bezoarticus Hippocamelus antisensis H. bisulcus Mazama americana M. gouazoubira M. rufina M. chunyi Pudu mephistophiles P. pudu Alces alces Rangifer tarandus Capreolus capreolus C. pygargus

Independent variables Large body size Small body size Spotted adults Striped adults Dark legs White legs Dark tail White tail White rump Grasslands/scrublands Dense forest Desert Rocky Tundra Swamp Open environment Solitary Intermediate groups Large groups Hiders Followers Hunted by aerial predators Hunted by stalkers Hunted by coursers

Dependent variables

Snort Whistle Foot stamp Tail flick Tail flag Bound/leap/stott Zigzag/tack Prance Inspection Freeze Refuge in cliffs/burrows Enters water Attack Scatter Bunch Group attack

224

1 1 1 1

0 0 0 0

0 0 0 0

? ? ? ?

0 0 0 0

? ? ? ?

0 0 0 0

1 1 1 1

0 0 0 0

0 0 0 0

1 1 1 1

1 1 1 1

0 0 0 0

0 0 0 0

0 0 0 0

0 0 0 0

0 0 0 0

1 1 1 1

0 0 0 1

0 0 0 0

0 0 0 0

0 0 0 0

0 0 0 0

0 0 0 0

1 0 0 0

1 1 1 1

1 1 1 1

0 0 0 0

0 1 0 1

0 0 0 0

0 0 0 0

1 0 0 0

1 1 1 1

0 0 0 0

0 0 0 0

1 1 1 1

0 0 0 0

0 0 0 0

1 1 1 1

1 1 1 1

1 0 0 0 1 1 0 0 0 0 0 1 0 0 0 0

0 1 0 0 0 0 0 0 0 1 0 0 0 0 1 1 1 0 0 1 0 ? ? ?

1 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0

1 0 0 0 0 0 1 1 0 0 1 0 0 0 0 0 1 0 0 1 0 0 1 1

1 0 0 1 0 ? 0 0 0 1 0 0 1 0 0 0

1 0 0 0 0 0 1 1 0 1 1 0 0 0 0 0 1 0 0 1 0 0 1 1

1 1 1 1 1 ?

0 0 0 0 0 ?

0 0 0 0 0 ?

1 1 1 1 1 ?

0 0 0 0 0 ?

? ? ? ? ? ?

0 0 0 0 0 ?

0 0 0 0 0 ?

0 0 0 0 0 0

1 1 1 1 1 ?

0 0 0 0 0 ?

0 0 0 0 0 ?

1 1 1 1 1 0

0 0 0 0 0 ?

0 0 0 0 0 ?

0 0 0 0 0 ?

1 1 1 1 1 1

0 0 0 0 0 0

0 0 0 0 0 0

0 0 0 0 0 0

0 0 0 0 0 0

0 0 0 1 0 0

1 1 ? 1 1 ?

1 1 ? 1 1 1

0 0 ? 0 0 0

1 1 1 1 1 0

1 1 1 1 1 1

0 0 0 0 0 0

0 0 0 0 0 0

0 0 0 0 0 0

0 0 0 0 0 0

0 0 0 0 0 0

1 1 1 1 1 1

0 0 0 0 0 0

0 0 0 0 0 0

1 1 1 1 1 1

0 0 0 0 0 0

0 0 0 0 0 ?

1 1 1 1 1 ?

1 1 1 1 1 ?

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

0 ? ? ? ? 0 0 0 0 0 0 1 0 0 0

1 1 0 0 0 1 0 0 0 0 0 0 0 0 0

? 1 0 0 0 0 0 0 0 0 0 0 0 0 0

1 1 1 1 1 1 0 1 1 1 1 1 1 1 1

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

? 0 0 0 0 0 0 0 0 0 0 0 0 0 0

? 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

? 1 0 0 0 1 0 0 0 0 0 1 0 0 0

? 0 0 0 0 0 0 0 0 0 0 0 1 0 0

? 1 1 1 1 1 1 1 1 1 1 1 1 1 1

0 0 0 0 0 1 0 0 0 0 0 0 0 0 1

? 0 1 0 0 0 0 0 0 0 0 0 0 0 0

1 1 0 0 0 1 0 0 0 0 0 0 0 0 0

? 0 0 0 0 0 0 0 0 0 0 0 0 0 0

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

1 1 1 0 0 0 0 1 1 1 1 1 0 0 0

1 1 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 1 0 0 0 0 0 0 0 0 0 0 0

1 1 1 1 1 1 1 0 0 1 0 1 0 1 1

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

1 0 0 0 0 1 1 0 0 0 0 1 1 1 1

1 1 1 1 1 1 1 1 0 1 1 1 1 1 1

1 1 0 0 0 1 1 1 1 0 1 1 1 1 0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 1

0 0 0 0 0 0 0 0 1 0 0 0 0 0 1

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 1 1 0 0 0 1 0 1 1 1 0 1 0

0 1 1 1 1 1 1 0 0 1 1 1 1 1 1

0 0 1 1 0 0 0 ? ? 0 0 0 0 0 0

1 1 1 0 1 1 1 ? ? 1 1 1 1 1 1

0 1 0 0 0 0 1 ? ? 1 1 0 0 1 0

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

1 1 0 0 0 1 0 0 0 1 0 1 0 1 1

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

1 0 0 0 1 1 0 0 0 1 0 1 1 0 0 0 0 0 0 0 ? ? 0 0 0 0 0 ? 0 0 0 0

1 0 0 0 0 0 1 1 1 1 0 1 0 0 1 1 0 1 0 1 0 0 0 1 1 0 0 0 1 0 0 0 0 1 1 0 0 0 1 1 0 1 0 0 1 0 1 1

0 0 0 0 1 1 0 0 0 1 0 1 0 0 0 0

1 0 0 0 0 0 1 1 0 1 0 0 0 0 0 1 1 0 0 1 0 0 0 1

0 0 0 0 1 1 0 0 0 0 0 1 0 0 0 0

1 0 0 0 1 0 1 1 0 1 0 0 1 0 0 1 0 1 0 1 0 0 1 1

0 0 0 0 1 1 0 0 0 0 0 1 0 0 0 0 1 ? 1 0 0 0 0 0 0 1 0 0 0 0 0 0

1 0 0 0 1 0 0 0 0 1 1 0 1 0 0 0 1 0 0 1 0 0 1 1 0 1 0 0 0 0 0 1 0 1 1 0 0 0 1 1 1 0 0 1 0 1 1 1

0 0 0 0

0 0 0 0

0 0 0 1

? ? ? ?

0 0 0 0

0 0 0 0

0 0 0 0

0 0 0 ?

0 0 0 0

0 0 0 0

1 1 1 1

0 0 0 0

0 0 0 0

0 0 0 0

0 0 0 0

0 0 0 0

0 0 0 0

1 1 1 1

0 0 0 0

0 0 0 0

0 0 0 0

0 0 0 0

0 0 0 0

1 1 1 0

0 0 0 0

1 1 0 1

1 1 1 1

0 0 0 0

0 0 0 0

0 0 0 0

1 0 0 0

1 1 0 1

1 1 1 1

0 0 0 0

0 0 0 0

1 1 1 1

0 0 0 0

1 1 1 1

1 1 1 1

1 1 1 1

0 ? 1 0 0 0 1 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 1 0 1 1 1 1 0 0 0 0 1 0 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 1 1 1 0 0 0 0 1 0 1 1 0 1 0 0 1 0 1 0 1 1 0 1 0 1 1

1 0 1 0 0 1 0 0 0 1 ? ? 0 0 1 ?

1 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 1 1 1 1 0 1 1 1

1 0 1 0 0 1 0 0 0 1 ? ? 0 0 1 ?

1 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 1 1 1 1 0 1 1 1

REVIEWS

Table A1. Continued

Large body size Small body size Spotted adults Striped adults Dark legs White legs Dark tail White tail White rump Grasslands/scrublands Dense forest Desert Rocky Tundra Swamp Open environment Solitary Intermediate groups Large groups Hiders Followers Hunted by aerial predators Hunted by stalkers Hunted by coursers

Bovidae Tragelaphus buxtoni T. spekeii T. angasii T. scriptus T. strepsiceros T. imberbis T. eurycerus Taurotragus oryx T. derbianus Boselaphus tragocamelus Tetracerus quadricornis Bubalus mindorensis B. depressicornis B. quarlesi Syncerus caffer Bos sauveli B. javanicus B. guarus B. grunniens Bison bison Cephalophus adersi C. natalensis C. harveyi C. nigrifrons C. rufilatus C. rubidus C. leucogaster C. ogilbyi C. callipygus C. weynsi C. niger C. spadix C. sylvicultor C. jentinki C. dorsalis C. zebra C. monticola C. maxwelli Sylvicapra grimmia Kobus ellipsiprymnus K. megaceros K. leche

Independent variables

Snort Whistle Foot stamp Tail flick Tail flag Bound/leap/stott Zigzag/tack Prance Inspection Freeze Refuge in cliffs/burrows Enters water Attack Scatter Bunch Group attack Antilocapridae Antilocapra americana

Dependent variables

1 0 0 0 1 1 0 0 1 0 0 0 1 0 0 0

1 0 0 0 0 0 1 1 1 1 0 1 0 0 0 1 0 1 1 1 0 0 1 1

0 0 1 0 1 1 0 1 0 1 0 0 0 0 0 0

1 0 1 1 0 1 1 1 0 1 1 0 0 0 1 1 1 1 1 1 0 0 1 1

1 1 1 1 1 1 1

1 1 1 1 1 1 1

0 0 0 0 0 0 0

1 1 1 1 1 1 1

0 0 0 0 0 0 0

1 1 1 1 1 1 1

1 1 1 1 1 1 1

0 0 0 0 0 0 0

1 1 1 1 1 1 1

0 0 0 0 0 0 0

1 1 1 1 1 1 1

0 0 0 0 0 0 0

1 0 1 1 0 0 0

0 0 0 0 0 0 0

0 0 0 ? 0 0 0

0 0 0 0 0 0 1

0 0 0 0 0 0 1

0 0 0 0 0 0 0

1 1 1 0 0 0 0

1 1 1 1 1 1 1

0 0 0 0 1 1 0

1 1 1 1 1 1 1

1 1 1 1 1 1 1

1 1 1 1 1 1 0

0 0 0 0 0 0 0

1 1 1 1 1 1 1

0 0 0 0 0 1 0

0 0 0 0 0 0 1

0 0 0 1 0 0 0

0 0 0 0 0 0 0

1 1 1 0 1 0 0

1 1 0 1 0 0 1

1 0 1 0 0 0 0

1 1 0 1 1 1 1

0 1 0 0 0 0 1

1 1 1 1 1 1 1

0 0 0 0 0 0 0

0 0 0 0 0 0 0

1 1 1 1 1 1 1

1 1 1 1 1 1 1

1 0 1 0 1 1 0 1 0 1 0 0 0 0 0 ? ? ? ? 0 1 0 0 0 0 0 0 ? 1 0 1 0

1 0 0 1 1 1 1 0 0 1 0 0 0 0 0 1 0 1 1 1 0 0 1 1 1 0 0 0 0 1 1 1 0 1 1 0 0 0 0 1 0 1 0 1 0 0 1 1

1 0 ? 0 0 0 0 0 0 0 0 ? 0 0 1 0

0 1 0 0 1 1 0 1 0 0 0 0 1 0 1 0 1 0 0 ?

? ? ? 0 0 0 0 0 0 0 0 0 0 0 1 0

1 0 0 0 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 1 ? ? ?

? ? ? 0 0 1 0 0 0 0 0 ? 0 0 1 0 ? ? ? 0 0 1 0 0 0 0 0 ? 0 0 1 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 1 1

1 0 0 0 0 1 0 0 0 0 1 0 0 0 1 0 1 0 0 0 1 ? ? ? 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 ? ? ? 1 0 0 0 1 0 1 1 0 1 1 0 0 0 0 1 0 1 1 0 1 0 1 1

0 1 1 1 ? 0

0 0 0 0 ? 1

? 0 ? 0 0 0

0 0 0 0 0 0

1 1 1 1 1 0

0 0 1 0 0 1

0 0 0 0 0 0

0 0 0 0 0 0

0 0 0 0 0 0

0 0 0 0 0 1

0 0 0 0 0 0

0 0 0 0 0 0

0 0 1 0 1 0

0 0 0 0 0 0

1 1 1 1 1 0

0 0 0 0 0 0

1 1 1 1 1 0

0 0 0 0 0 1

0 0 0 0 0 1

0 0 0 0 0 0

0 0 0 0 0 0

1 1 1 0 0 1

0 1 0 0 0 0

0 0 0 0 0 1

0 1 0 0 0 1

1 1 1 0 1 1

1 1 1 0 1 1

0 0 0 1 0 0

0 0 0 0 0 0

0 0 0 1 0 0

0 0 0 0 0 0

1 1 1 1 1 0

0 0 0 0 0 1

1 1 1 1 1 0

0 0 0 1 1 0

0 0 0 0 0 1

1 1 1 1 1 0

0 0 0 0 0 1

0 0 0 0 0 1

1 1 1 1 1 0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ?

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ?

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 0

1 1 1 1 1 1 1 1 1 1 0 0 0 1 1 1 1 1

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0

0 0 1 1 1 1 1 1 1 1 0 0 0 0 1 1 0 0

0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1 1

1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 1 0 1

1 1 1 1 0 1 0 1 1 1 0 1 1 1 1 1 1 1

0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 1 0

1 1 0 0 1 1 0 1 0 0 1 1 1 1 0 1 1 1

1 1 1 1 0 1 1 1 1 1 1 1 1 1 1 1 1 0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

1 1 1 1 0 0 0 0 0 0 1 1 0 0 0 1 0 0

0 0 0 0 0 0 0 0 0 0 0 1 0 1 0 0 1 1

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1

? ? ?

1 0 1 0 0 1 1 1 0 0 0 1 0 ? 0 0

1 0 0 0 1 1 1 1 1 1 0 0 0 0 1 1 0 1 1 1 0 0 1 1

1 1 1 0 0 1 0 0 0 0 0 ? 0 1 0 0 1 1 1 0 0 1 0 0 0 0 0 1 0 1 0 0

1 0 0 0 1 1 1 1 0 1 0 0 0 0 1 1 0 1 1 1 0 0 1 1 1 0 0 0 1 0 1 1 1 1 0 0 0 0 1 1 0 1 1 1 0 1 1 1 (continued )

225

ANIMAL BEHAVIOUR, 67, 2

Table A1. Continued Independent variables Large body size Small body size Spotted adults Striped adults Dark legs White legs Dark tail White tail White rump Grasslands/scrublands Dense forest Desert Rocky Tundra Swamp Open environment Solitary Intermediate groups Large groups Hiders Followers Hunted by aerial predators Hunted by stalkers Hunted by coursers

K. kob K. vardonii Redunca arundinum R. redunca R. fulvorufula Pelea capreolus Hippotragus equinus H. niger Oryx dammah O. gazella Addax nasomaculatus Damaliscus hunteri D. pygargus D. lunatus Alcelaphus buselaphus Sigmoceros lichtensteinii Connochaetes gnou C. taurinus Oreotragus oreotragus Ourebia ourebi Raphicerus campestris R. melanotis R. sharpei Neotragus pygmaeus N. batesi N. moschatus Madoqua saltiana M. piacentinii M. guentheri M. kirkii Dorcatragus megalotis Antilope cervicapra Aepyceros melampus Ammodorcas clarkei Litocranius walleri Gazella dorcas G. bennettii

Dependent variables

Snort Whistle Foot stamp Tail flick Tail flag Bound/leap/stott Zigzag/tack Prance Inspection Freeze Refuge in cliffs/burrows Enters water Attack Scatter Bunch Group attack

226

1 1 1 1 1 1 0 0 0 0 0 1 0 ? 0 0 0 1 1 0 ? 1 0 0 0 0 0 ? 0 ? 0 0 0 1 1 0 1 1 0 0 0 1 0 0 0 0 0 0

1 0 0 0 1 0 0 1 1 1 0 0 0 0 1 1 0 1 1 1 0 0 1 1 1 0 0 0 1 1 0 1 0 1 0 0 0 0 1 1 0 1 1 1 0 0 1 1 1 0 0 0 0 1 0 1 0 1 0 0 0 0 1 1 1 1 0 1 0 0 1 1

0 0 1 1

1 1 1 1

1 1 0 0

1 1 1 1

0 0 0 0

1 1 1 0

1 1 1 1

0 0 0 0

0 0 0 0

0 0 0 0

1 1 1 0

0 0 0 0

0 0 0 0

0 0 0 0

0 0 0 1

0 0 1 0

0 0 0 0

0 0 0 0

0 0 0 0

0 0 0 0

1 1 1 0

0 1 0 0

0 0 0 1

1 1 1 0

0 0 0 0

1 1 1 1

0 0 0 0

0 0 0 0

0 1 1 0

0 0 0 0

1 1 0 0

1 1 1 1

1 1 0 0

1 1 1 1

0 0 0 1

1 1 1 1

0 0 0 0

0 0 0 0

1 1 1 1

1 1 1 1

1 0 1 0 0 1 0 0 0 0 0 1 1 0 0 0 1 0 ? ? ? 1 0 0 0 0 0 0 0 0 0 ?

1 0 0 0 0 0 1 0 1 0 0 0 0 0 0 0 0 1 1 1 0 0 1 1 1 0 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 1 1 1 0 0 1 1

1 0 1 1 0 1 0 0 0 0 0 ? 1 0 0 1 1 0 1 1 ? 1 0 0 0 0 0 0 1 0 0 0

1 0 0 0 1 1 1 0 1 1 0 1 1 0 0 1 0 1 1 1 0 0 1 1 1 0 0 0 1 1 0 1 1 0 0 1 1 0 0 1 0 1 1 1 0 0 1 1

1 0 1 1 0 1 0 0 1 0 0 0 0 0 1 0

1 0 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 1 0 1 0 1 1

1 0 1 1 0 1 0 0 1 0 0 0 0 0 1 1 1 0 1 1 0 1 1 1 1 0 0 0 0 0 1 1 1 0 1 1 0 1 1 1 1 0 0 0 0 0 1 ?

1 0 0 0 0 1 1 1 1 1 0 0 0 0 0 1 0 1 1 0 1 0 1 1 1 0 0 0 0 0 1 0 0 1 0 0 0 0 0 1 0 1 1 1 1 0 1 1 1 0 0 0 1 0 1 1 1 1 0 1 0 0 0 1 0 1 1 1 0 0 1 1

1 0 1 0 0 1 0 0 1 0 0 0 0 0 1 ?

1 0 0 0 1 0 1 1 1 1 0 0 0 0 1 1 0 1 1 1 0 0 1 1

1 0 1 1 0 1 0 1 1 0 0 0 0 0 1 ?

1 0 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 1 0 1 0 1 1

1 0 1 0 0 1 1 1 1 0 0 0 0 0 1 ? 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 0

1 0 0 1 0 1 1 0 0 1 0 0 0 0 0 1 0 1 1 0 1 0 1 1 0 1 0 0 0 0 0 1 0 0 0 0 1 0 0 1 1 1 0 1 0 0 1 1

0 1 1 0 1 1 0 0 0 1 0 0 0 0 0 0

0 1 0 0 1 0 1 0 0 1 0 0 0 0 0 1 1 1 0 1 0 0 1 1

1 0 1 0 0 1 1 0 0 1 1 0 0 0 0 0

0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 1 1 0 0 1 0 0 1 1

1 ? 1 0 0 1 0 0 0 1 1 0 0 0 0 0 1 ? 1 0 0 1 0 0 0 1 1 0 0 0 0 0 1 ? 1 0 0 1 0 0 0 1 0 0 0 0 0 0

0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 0 0 1 0 1 0 0 0 0 0 0 1 1 0 0 1 0 0 1 1 0 0 1 0 0 0 1 0 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 0 1 1 1

1 ? 1 0 0 1 0 0 0 1 0 0 0 0 0 0 1 ? 1 0 0 1 0 0 0 1 0 0 0 0 0 0 0 1 1 0 0 1 1 0 0 1 0 0 0 0 0 0

0 1 0 0 1 1 1 1 0 1 1 0 0 0 0 1 1 0 0 1 0 1 1 1 0 1 0 0 1 0 1 1 0 1 1 0 0 0 1 0 1 1 0 1 0 1 1 1 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 1

0 0 0 1

0 0 0 0

1 1 1 ?

1 1 1 1

0 0 0 0

0 0 0 0

1 1 1 1

1 1 1 0

0 0 0 0

0 0 0 0

1 1 1 1

0 0 0 0

0 0 0 0

0 0 0 0

0 0 0 0

0 0 0 0

0 0 0 0

1 1 1 1

0 0 0 0

0 0 0 0

0 0 0 0

0 0 0 0

0 0 0 0

0 0 0 1

0 0 1 0

1 1 1 0

0 0 0 0

1 1 1 0

0 0 1 1

0 0 0 0

0 0 0 0

1 1 1 1

1 1 1 1

1 1 1 1

0 0 0 0

1 1 1 1

0 0 0 0

1 1 1 0

1 1 1 0

1 1 1 1

1 0 1 0 1 1 0 0 0 0 0 0 1 0 1 0

1 0 0 0 0 0 0 1 1 1 0 1 0 0 0 1 0 1 1 1 0 1 1 1

1 0 1 0 0 1 1 0 0 0 0 0 0 1 0 0

1 0 0 0 0 0 1 1 0 1 0 1 0 0 0 1 0 1 1 1 1 1 1 1

1 ? 0 0 1 1 0 0 0 1 0 0 0 0 0 0

1 0 0 0 1 0 1 0 1 1 0 1 0 0 0 1 1 1 0 1 0 0 1 1

1 0 1 0 0 1 0 0 0 1 0 0 0 0 0 0

1 0 0 0 0 0 1 1 0 1 0 0 0 0 0 1 1 1 0 1 0 0 1 1

1 0 1 0 0 1 0 0 0 0 0 0 0 ? ? 0

1 0 0 0 0 0 1 0 1 1 0 1 1 0 0 1 0 1 1 1 0 1 1 1

1 0 1 0 0 1 0 0 0 0 0 0 0 ? ? 0

1 0 0 0 1 0 1 1 1 0 0 1 1 0 0 1 0 1 1 1 0 1 1 1

REVIEWS

Table A1. Continued

Large body size Small body size Spotted adults Striped adults Dark legs White legs Dark tail White tail White rump Grasslands/scrublands Dense forest Desert Rocky Tundra Swamp Open environment Solitary Intermediate groups Large groups Hiders Followers Hunted by aerial predators Hunted by stalkers Hunted by coursers

G. gazella G. spekei G. cuvieri G. rufifrons G. thomsonii G. subgutturosa G. leptoceros G. dama G. soemmerringii G. granti Antidorcas marsupialis Procapra picticaudata P. przewalskii P. gutturosa Pantholops hodgsonii Saiga tatarica Pseudoryx nghetinhensis Capricornis sumatraensis C. swinhoei C. crispus Naemorhedus caudatus N. goral Oreamnos americanus Rupicapra pyrenaica R. rupicapra Budorcas taxicolour Ovibos moschatus Hemitragus jemlahicus H. jayakari H. hylocrius Capra aegagrus C. ibex C. walie C. caucasica C. cylindricornis C. pyrenaica C. falconeri Pseudois nayaur P. schaeferi Ammotragus lervia

Independent variables

Snort Whistle Foot stamp Tail flick Tail flag Bound/leap/stott Zigzag/tack Prance Inspection Freeze Refuge in cliffs/burrows Enters water Attack Scatter Bunch Group attack

Dependent variables

1 1 1 1 0 1 1 1 1 1 1

1 1 1 1 1 1 1 1 1 1 1

0 0 0 0 0 0 0 0 0 0 0

1 1 1 1 1 1 1 1 1 1 1

0 0 0 0 0 0 0 0 0 0 0

1 0 0 0 0 0 0 0 0 0 1

1 1 1 1 1 1 1 1 1 1 1

0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 1 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0

? ? ? ? ? ? ? ? ? ? 1

? ? ? ? ? ? ? ? ? 1 0

0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0

1 1 1 1 0 0 0 1 0 0 0

0 0 0 0 1 1 0 0 0 0 0

1 1 1 1 1 1 1 1 1 1 1

0 0 0 0 0 1 0 1 1 1 1

1 1 1 1 1 1 1 1 1 1 1

1 1 1 1 1 1 0 1 1 1 1

0 0 0 0 0 0 0 0 0 0 0

1 1 1 1 0 1 1 1 0 1 0

1 1 1 0 0 1 0 0 1 0 0

0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0

1 1 1 1 1 1 1 1 1 1 1

0 0 0 0 0 0 1 0 0 0 0

1 1 1 1 1 1 1 1 1 1 1

1 0 0 1 1 1 0 1 1 1 1

1 1 1 1 1 1 1 1 1 1 1

0 0 0 0 0 0 0 0 0 0 0

1 1 1 1 1 1 1 1 1 0 0

1 1 1 1 1 1 1 1 1 1 1

1 1 1 1 1 1 1 1 1 1 1

1 ? 1 0 0 1 0 0 0 0 0 0 0 0 0 0

1 0 0 0 1 0 1 1 1 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1

1 ? 1 0 0 1 0 0 0 0 0 0 0 0 0 0 1 ? 1 0 0 1 0 0 0 0 1 0 0 0 0 0 ? ? ? ? ? ? ? ? 0 1 1 ? 0 ? ? ?

1 0 0 0 0 0 1 1 1 1 0 1 0 0 0 1 0 1 1 1 0 ? ? ? 1 0 0 0 0 0 1 1 1 1 0 1 0 0 0 1 0 1 1 1 0 1 1 1 1 0 0 0 1 0 0 1 1 1 0 1 0 0 0 1 0 1 0 0 1 0 1 1

0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0

1 0 0 0 1 0 0 1 1 1 0 1 0 0 0 1 0 1 1 0 1 1 1 1

1 ? ? ? ? ? ? ? 0 ? ? 1 1 ? ? 0

1 0 0 0 1 1 1 0 1 0 1 0 0 0 0 0 1 1 0 ?

1 ? ? ? ? ? ? ? 0 ? ? ? 0 ? ? ?

1 0 0 0 0 0 0 0 0 1 1 0 1 0 0 0 1 1 0 0 1 1 1 1

1 ? ? ? ? ? ? ? 0 ? ? ? 0 ? ? ? 1 ? ? ? ? ? ? ? 0 ? ? ? 0 ? ? ? 1 0 1 0 0 1 0 0 0 0 1 0 0 0 0 0

1 0 0 0 0 0 0 0 0 1 1 0 1 0 0 0 1 1 0 0 1 1 1 1 1 0 0 0 0 0 0 0 0 1 1 0 1 0 0 0 1 1 0 0 1 1 1 1 1 0 0 0 0 1 0 0 0 0 1 0 1 0 0 0 0 1 0 0 1 0 1 0

1 0 1 0 0 1 0 0 0 0 1 0 0 0 0 0 1 0 1 0 1 1 0 0 0 0 1 0 1 0 1 0

1 0 0 0 0 1 1 0 0 0 1 0 1 0 0 0 0 1 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 0 0 1 1 0 1 0 1 1 0 1 1 1 1

0 1 1 0 0 1 0 0 0 0 1 0 0 0 0 0

1 0 0 0 0 0 1 0 1 1 1 0 1 0 0 1 0 1 0 0 1 1 1 1

0 1 1 0 0 1 0 0 0 0 1 0 0 0 0 0 1 1 0 0 0 1 0 0 0 1 1 0 0 0 0 0

1 0 0 0 0 0 1 0 1 1 1 0 1 0 0 1 0 1 0 0 1 1 1 1 1 0 0 0 0 0 1 0 0 1 1 0 1 0 0 1 0 1 1 0 1 0 1 1

1 ? 0 0 0 1 0 0 0 0 1 0 0 0 1 1

1 0 0 0 0 1 0 0 0 1 0 0 0 1 1 1 0 1 1 0 1 0 1 1

1 ? 1 0 0 1 0 0 0 0 1 0 0 0 1 0

1 0 0 0 0 0 0 0 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 0

1 0 1 0 1 1 0 0 0 0 1 0 0 0 1 0 1 ? 1 0 0 1 0 0 0 0 1 0 0 0 1 0 1 0 0 0 1 1 0 0 0 0 1 0 0 0 1 0

1 0 0 0 1 0 0 0 0 0 0 0 1 0 0 1 1 1 0 0 1 0 1 0 1 0 0 0 1 0 0 0 1 1 0 0 1 0 0 1 0 1 1 0 1 0 1 1 1 0 0 0 1 0 1 0 1 1 1 0 1 0 0 1 0 1 1 0 1 1 1 1

0 0 1 1 0 1 0

1 1 1 1 1 1 1

? ? ? ? 1 0 1

0 ? ? 0 0 0 1

0 0 0 0 0 0 0

0 0 0 0 0 0 1

1 1 1 1 1 1 1

0 0 0 0 0 0 0

0 0 0 0 0 0 0

0 0 0 0 0 0 0

0 0 0 0 0 0 1

1 1 1 1 1 1 1

0 0 0 0 0 0 0

1 0 0 0 0 0 0

1 1 1 0 0 0 0

1 0 0 0 0 1 1

0 0 0 0 0 0 0

0 1 1 0 1 1 0 0 0 1 1 0 0 0 1 0 ? ? ? 0 1 ? 0 0 0 1 1 0 0 1 ? 0

0 0 0 0 0 0 0

0 0 0 0 0 0 0

0 0 0 0 0 0 0

1 1 1 1 1 1 0

1 1 0 0 1 1 1

1 1 1 1 1 1 1

0 0 0 0 0 0 1

1 0 1 1 1 1 1

1 0 1 1 1 1 1

0 0 1 1 1 0 0

1 0 0 0 0 0 0

1 1 1 1 1 1 1

0 0 0 0 0 0 0

0 0 0 0 0 0 0

1 1 1 1 1 1 1

0 0 0 0 0 0 1

1 1 1 1 1 1 1

1 0 1 1 0 1 1

0 0 0 0 0 0 0

0 0 1

1 1 1 1 1 1 1

1 1 1 1 1 0 1

1 1 1 1 0 1 1

1 1 1 1 1 1 1

1 0 0 0 0 1 1 1 1 1 0 0 1 0 0 1 0 1 1 0 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 1 1 0 0 1 1 1 0 0 1 0 1 0 (continued )

227

ANIMAL BEHAVIOUR, 67, 2

Table A1. Continued

Ovis orientalis O. vignei O. ammon O. nivicola O. dalli O. canadensis

Independent variables Large body size Small body size Spotted adults Striped adults Dark legs White legs Dark tail White tail White rump Grasslands/scrublands Dense forest Desert Rocky Tundra Swamp Open environment Solitary Intermediate groups Large groups Hiders Followers Hunted by aerial predators Hunted by stalkers Hunted by coursers

Dependent variables

Snort Whistle Foot stamp Tail flick Tail flag Bound/leap/stott Zigzag/tack Prance Inspection Freeze Refuge in cliffs/burrows Enters water Attack Scatter Bunch Group attack

228

? 1 0 ? ? ?

1 1 1 1 1 1

? ? 1 ? ? ?

1 1 ? ? ? 1

0 0 0 0 0 0

? ? ? ? ? ?

? 1 ? ? ? 1

? ? ? ? ? ?

0 ? ? ? ? ?

0 0 0 0 0 0

? ? ? ? ? ?

1 ? 1 ? 1 ?

0 ? ? ? ? ?

0 0 0 0 1 1

? ? ? ? ? 0

? 1 ? ? ? 1

? ? ? ? ? 1

0 0 0 0 0 0

0 0 0 0 0 0

0 0 0 0 0 0

1 1 0 0 1 0

1 1 1 0 1 1

1 1 1 1 1 1

1 1 1 0 0 0

1 1 1 1 1 1

1 0 1 1 1 1

0 0 0 0 0 0

1 1 1 0 0 1

0 0 0 1 1 1

0 0 0 1 1 0

0 0 0 0 0 0

1 1 1 1 1 1

0 0 0 0 0 0

1 1 1 1 1 1

1 1 1 1 1 1

0 0 0 0 0 0

1 1 1 1 1 1

1 0 0 0 1 1

1 ? 1 1 1 1

1 ? 1 1 1 1

Sources of data on antipredator behaviour: Flerox (1952); Guiguet & Cowan (1965); Spinage (1968, 1982); Van Wormer (1969); Hornocker (1970); Knight (1970); Dagg (1971); Ralls (1973); Holmes (1974); Kitchen (1974); von Richter (1974); Sokolov (1974); Chapman & Chapman (1975); Hoffman & Rideout (1975); Dagg & Foster (1976); Schaller (1977, 1998); O’Gara (1978); Feldhamer (1980); Gray & Simpson (1980); Mech & Nelson (1981); Valdez (1982); Beck & Wemmer (1983); Chadwick (1983); Grall et al. (1983); Johnsingh (1983); Johnson & Lockard (1983); Anderson & Wallmo (1984); Kranz & Lumpkin (1984); Sowls (1984, 1997); Strahan (1984); Walther (1984); Armstrong et al. (1985); Shackleton (1985, 1999); Dekker (1986); Mayer & Wetzel (1986, 1987); Bunnell (1987); Hoffman & Neas (1987); Hoffman & Wang (1987); Huntingford & Turner (1987); Jackson (1987); Barker et al. (1988); Lent (1988); Stuart (1988); Heptner et al. (1989); Mead (1989); Grzimek (1990); Estes (1991, 1993); Grosse & Pinder (1991); Ko¨hler-Rollefson (1991); Smith (1991); Bodmer & Rabb (1992); Wood (1992); Nabhan (1993); Binyuan & Schaller (1994); Mungall & Sheffield (1994); Danilkin (1995, 1996); Groves et al. (1995a, b); Danilkin et al. (1996); Blank & Kingswood (1996); Custodio et al. (1996); Kingswood & Kumamoto (1996, 1997); Irschick et al. (1997); Luschekina & Sokolov (1997); Shrestha (1997); Gese (1999); Krausman & Valdez (1999); Lindsey et al. (1999); Nowak (1999); Wilson (2000). Sources of morphological, ecological and behavioural information for each species: Spinage (1968, 1982); Van Wormer (1969); Whitehead (1972, 1993); Holmes (1974); von Richter (1974); Dagg & Foster (1976); Schaller (1977, 1998); Cloudsley-Thompson (1980); Kingdon (1982, 1997); Valdez (1982); Chadwick (1983); Johnson & Lockard (1983); Walther et al. (1983); MacDonald (1984); Sowls (1984, 1997); Strahan (1984); Walther (1984); Hoefs (1985); Jones et al. (1985); Payne & Francis (1985); Shackleton (1985, 1999); Huntingford & Turner (1987); Prior (1987); Soma (1987); Putman (1988); Wemmer (1987); Grzimek (1990); Estes (1991, 1993); Agbelusi (1992); Karami & Groves (1992); Perrin & Allen-Rowlandson (1992); Perrin & Everett (1992); Perrin et al. (1992); Sellami & Bouredjili (1992); Vincent & Bideau (1992); Kaji et al. (1993); Miura et al. (1993); Nabhan (1993); Oliver (1993); Stuart & Stuart (1993, 1997); Wang et al. (1993); Clark (1994); Mungall & Sheffield (1994); Bauer (1995); Danilkin (1996); Shrestha (1997); Lindsey et al. (1999); Nowak (1999); Valdez & Krausman (1999); Wilson (2000).