- Email: [email protected]
Differences in experimental and natural encounters of black-tailed prairie dogs with snakes
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Animal Behaviour, 35, 5
consumption (Emlen 1966; M a c A r t h u r & Pianka 1966). Along this line it follows that the quality of a prey item, as measured by the net energy reward/ total time expenditure, is devalued as search time increases (Pulliam 1974; Werner & Hall 1974; Charnov 1976). If the probability of finding an active nest is equal to that of finding an inactive nest, then a patch with both active and inactive nests would yield fewer rewards per nest found than a similar patch with all active nests. Active nests placed near empty nests would benefit if the probability of being located is decreased due to the presence of empty nests, or if the probability of exceeding a patch-use threshold before being located is high, M o r e profit may be gained if the probability of location is unequal for old and new nests. Anecdotal observations suggest that, due to vegetational changes around nest sites, old nests are found more readily than active nests. The idea that the choice of certain nesting materials may provide long-term benefits, beyond the bounds of a single season, is intriguing though not fully substantiated. Predator deterrent roles of some supernumerary nests, even if not primary, may serve to offset excessive energy expended for their production. The evidence presented suggests that protection from predation is gained by the presence of empty nests. The degree to which this phenomenon reduces predator success is likely to be a function of the efficiency of finding nests as influenced by the visibility within the habitat, the number and density of inactive nests, and the proportion of nesting pairs which are near inactive nests. I thank G. R. Brooks and C. R. Terman for helpful comments on the manuscript. BRYAN D. WATTS
Department of Biology, College of William and Mary, Williamsburg, VA 23185, U.S.A.
References Bent, A. C. 1968. Order Passeriformcs: Family Fringillidae. Life histories of North American cardinals, grosbeaks, buntings, towhees, finches, sparrows, and allies. U.S. ?Cam. Mus. Bull., 237, 1-15. Best, L. B. I978. Field sparrow reproductive success and nesting ecology. Auk, 95, 9-22. Charnov, E. L. 1976. Optimal foraging: attack strategy of a mantid. Am. Nat., 110, 141 151. Collias, E. C. & Collias, N. E. 1964. The evolution of nestbuilding in the weaverbirds (Ploceidae). Univ. Calif. Pubis Zool., 73, 1 162. Collias, N. E. & Collias, E. C. 1978. Cooperative breeding behavior in the white-browed sparrow weaver. Auk, 95, 557-567.
Conner, R. N., Anderson, M. E. & Dickson, J. G. 1986. Relationships among territory size, habitat, song, and nesting success of northern cardinals. Auk, 103, 23-31. Emlen, J. M. 1966. The role of time and energy in food preference. Am. Nat., 100, 611 617. MacArthur, R. H. & Pianka, E. R. 1966. On the optimal use of a patchy environment. Am. Nat., I00, 603-609. McGahan, J. 1968. Ecology of the golden eagle. Auk, 85, 1-12. Motai, T. 1973. Male behavior and polygamy in Cisticola juneindis. Misc. Rep. Yamashina'sInst. Ornithol. Zool., 7, 87 103. Nice, M. M. 1957. Nesting success in altricial birds. Auk, 74, 305-321. Pulliam, H. R. 1974. On the theory of optimal diets. Am. Nat., 108, 59-74. Verner, J. & Engelsen, G. H. 1970. Territories, multiple nest-building, and polygamy in the long-billed marsh wren. Auk, 87, 557-567. Welty, J. C. 1975. The Life of Birds. New York: Dryden Press. Werner, E. E. & Hall, D. J. 1974. Optimal foraging and the size selection of prey by the bluegill sunfish Lepomis macrochirus. Ecology, 55, 1042-1052.
(Received 17 November 1986; revised 2 March 1987; MS. number: As-434)
Differences in Experimental and Natural Encounters of Black-tailed Prairie Dogs with Snakes Two untested assumptions in most studies of mobbing behaviour have been that experimental presentations of a predator elicit the same behaviour in prey as that observed naturally, and that these encounters generate the same differences between prey individuals as those occurring naturally. In a recent, provocative paper, Knight & Temple (1986) showed that red-winged blackbirds, Agelaius phoeniceus, were sensitive to several aspects of a potential nest predator. The birds treated models differently than a live individual, and treated predators differently depending on subtle features o f the situation (e.g. whether the predator was looking at the nest or in another direction). They concluded by arguing that studies of avian nest defence needed to show more concern in describing experimental protocol. In this paper I demonstrate that black-tailed prairie dogs, Cynomys ludovicianus, treat potential snake predators differently, depending on whether they encounter these snakes naturally or in an experimental situation. Furthermore, I examine natural and experimental encounters to determine whether the same pattern o f differences between individuals emerges in both situations. As part of a study of prairie dog anti-predator behaviour, I presented tethered rattlesnakes, Cro-
Short Communications
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Table I. Three-way ANOVA comparing differences in the behaviour of black-tailed prairie dogs in natural and experimental encounters with snakes Experimental Variable
Fathers
Strikes Swats Barking* Barks/min* Distance]" Snake portion* % SD]" % 2 m]" % Feedt % Time up]" N
3.31 4.97 0.50 5.02 4.08 2.36 65.94 91.28 21.82 99.97 2
Natural
Non-fathers Mothers Non-mothers Fathers 0.32 0.32 0.38 2.42 4.89 2.32 29-55 78.33 50.12 100.00 2
0 0 0.20 1.14 23.35 2.23 24.26 41-69 42.59 94.58 2
0 0 0 0 27.51 1.28 11.18 27.06 42.23 74.46 5
0 0 0 0 4.35 2.87 59.72 92.27 13-95 97.68 2
Non-fathers Mothers Non-Mothers 0 0 0 0 2.70 2.50 53.96 99.71 4.50 100.00 2
0 0 0 0 27-45 2.66 8.99 19.87 64.42 97.35 2
0 0.10 0 0 36.92 2.48 27.44 39.13 48.82 99-27 5
Strikes: strikes by snakes at prairie dogs; Swats: swats by prairie dogs at snakes; Barking: number of bouts of barking by prairie dogs per encounter; Barks/min: rate of barking per min of an encounter; Distance: distance of prairie dogs from snakes (in prairie dog body lengths); Snake portion: portion of snake prairie dogs were closest to (3 = head, 2 = midbody, 1 = tail); %SD: % samples prairie dogs were actively snake-directed; % 2 m: % samples prairie dogs were within 2 m of the snake; % Feed: % samples prairie dogs were feeding; % Time up: % samples prairie dogs were above-ground during an encounter. * For experimental versus natural encounters, P < 0.05, df= 1, 7. "~For males versus females, P < 0.05, df= 1, 7.
talus atrox, and bullsnakes, Pituophis melanoleucus sayi, at various sites within a black-tailed prairie dog colony located on the Muleshoe National Wildlife Refuge, Muleshoe, Texas. Prairie dogs in this colony also encountered free-roaming snakes. Twenty-one natural and 32 experimental encounters between prairie dogs and snakes were recorded on videotape and audio-tape for later analysis. D a t a were decoded from videotapes at 10-s intervals and data on off-camera individuals were obtained from the accompanying narration (see Loughry, in press, for details of methodology). Some of the measured variables are described in Table I (see Loughry, in press, for a complete list). These encounters were of roughly equal duration (ca. 10 rain/encounter). To discover the influence of situation on prairie dog anti-snake behaviour, I identified 12 adult individuals that were present for at least one encounter of each type (average values were used for individuals present more than once for a particular kind of encounter). I then ran a mixed, three-way A N O V A with repeated measures on one factor, using sex, parental status and type of encounter as the three factors (Bruning & Kintz 1977) and using 15 variables obtained from the video records. I had previously found sex and parental (father versus non-father) differences in anti-snake behaviour, and this analysis allowed identification of significant main effects due to
situation. A significant three-way interaction was taken as evidence that the pattern of differences between classes of prairie dogs changes as a function of the type of encounter. The results of this analysis are presented in Table I, which lists those variables for which a significant difference was found. Table I shows that prairie dogs behaved differently towards tethered and freeroaming snakes. Prairie dogs swatted at and elicited strikes from snakes only in experimental encounters. Further, prairie dogs barked at snakes only in experimental encounters, but were more often closest to the snake's head during natural encounters (see data on the portion of the snake prairie dogs were closest to: Table I). No variable, however, showed a significant three-way interaction, indicating that differences between classes of prairie dogs were consistent across situations. F o r example, considerable sex differences in anti-snake behaviour were maintained across situations, although father-non-father differences were most pronounced in experimental encounters (e.g. see %st~ and %Feed; Table I). Prairie dogs performed some activities in only one type of encounter. This can be explained in terms of the constraints afforded by each type of encounter. Natural encounters typically took place in burrow mouths, while experimental encounters took place above ground. During natural encounters I sometimes observed prairie dogs
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kicking dirt into the mouth of the burrow in an apparent attempt to bury the snake (cf. Halpin 1983). This kind of activity is impossible in an encounter above ground and was not observed in experimental encounters. Situational constraints may also explain why prairie dogs attacked and swatted only at experimental snakes. In natural encounters, a snake usually moved away after being discovered. Tethered snakes cannot do this, and there may be a higher probability of either participant escalating the encounter (cf. Maynard Smith 1974). Also, most natural encounters were with rattlesnakes (18 out of 21), and prairie dogs were less likely to swat or attack rattlesnakes (Owings & Loughry 1985; Loughry, unpublished data; see also Halpin 1983). Prairie dogs barked only at experimental snakes. Barking at snakes, however, was common prior to the pups' first emergence from natal burrows, and most natural encounters occurred after pup emergence (18 out of 21). Finally, in natural encounters, snakes usually sat in the mouth of a burrow with their heads facing out. Since I could not see into a burrow to ascertain the snake's position during an encounter, I assumed that the snake's head was the portion of the snake closest to the prairie dog throughout the entire episode. Thus, the difference in the portion of the snake that prairie dogs were closest to (Table I) described here may be a product of imprecise measurement. In sum, most of the differences in the behaviour of prairie dogs in natural versus experimental encounters seems to be explainable in terms of the specific features of each situation. However, these situational differences did not alter the basic pattern of differences between classes of prairie dogs in how they treated snakes. No significant three-way interactions were found, and the patterns of differences between males and females were identical to those previously reported (Loughry, in press). Fathers behaved differently from non-fathers in experimental encounters compared to natural encounters, but small sample sizes make this result preliminary. My results indicate that experimental presentations of predators may be justifiable for determining the pattern of differences between potential prey individuals. However, experimental presentations provide a distorted picture of the behaviour of these individuals. Thus, care should be taken in interpreting the outcome of experimental manipulations, especially when no natural encounters are available for comparison. These results further point to the importance of context in understanding the behaviour of animals confronting a potential predator (see also Hennessy, in press). This work was supported by the Theodore
Roosevelt Memorial Fund, a U.C. Davis Graduate Research Award and Faculty Research Grant D819 to D. H. Owings. Thanks to the editor, R. L. Knight and an anonymous reviewer for many helpful suggestions. W.J, LOUGHRY Animal Behavior Graduate Group, Department of Psychology, University o f California, Davis, CA 95616, U.S.A. References Bruning, J. L. & Kintz, B. L. 1977. Computational Handbook of Statistics. Glenview: Scott, Foresman. Halpin, Z. T. 1983. Naturally-occurring encounters between Mack-tailedprairie dogs (Cynomys ludovicianus) and snakes. Am. Midl. Nat., 109, 5~55. Hennessy, D. F. In press. A format for describing the generative structures of behavioural patterning. In: Levels of Social Behavior: Evolutionary and Genetic Aspects (Ed. by G. Greenberg & E. Tobach). New York: Gordian Press. Knight, R. L. & Temple, S. A. 1986. Methodological problems in studies of avian nest defence. Anita. Behav., 34, 561 566. Loughry, W. J. In press. The dynamics of snake harassment by black-tailed prairie dogs. Behaviour. Maynard Smith, J. 1974. The theory of games and the evolution of animal conflicts. J. theor. Biol., 47, 209 221. Ov)ings, D. H. & Loughry, W. J. 1985. Snake-elicited jump-yipping by black-tailed prairie dogs: ontogeny and snake specificity.Z. Tierpsyehol., 70, 177 200. (Received 12 January 1987,"revised 27 February 1987; MS. number: AS-428) Paternal Care and the Development of Adaptive Variation in Anti-Predator Responses in Sticklebacks Differences in anti-predator responses between local populations have been documented for a number of species (e.g. Curio 1976; Owings & Coss 1977; Glywicz 1986; Magurran 1986) and are often interpreted as an evolved adaptation to local predation conditions. However, this explanation requires that the behavioural variation is at least partially hereditary, and information on this point is sparse and conflicting. Even a single exposure to a predator can modify subsequent responses (Ginetz & Larkin 1976), but in guppies (Poecilia reticulata, Seghers 1974) and in three-spined sticklebacks (Gasterosteus aculeatus, Giles 1984; Tulley 1985) for example, between-population variation in anti-predator behaviour persists in animals reared without exposure to predators.
Animal Behaviour, 35, 5
consumption (Emlen 1966; M a c A r t h u r & Pianka 1966). Along this line it follows that the quality of a prey item, as measured by the net energy reward/ total time expenditure, is devalued as search time increases (Pulliam 1974; Werner & Hall 1974; Charnov 1976). If the probability of finding an active nest is equal to that of finding an inactive nest, then a patch with both active and inactive nests would yield fewer rewards per nest found than a similar patch with all active nests. Active nests placed near empty nests would benefit if the probability of being located is decreased due to the presence of empty nests, or if the probability of exceeding a patch-use threshold before being located is high, M o r e profit may be gained if the probability of location is unequal for old and new nests. Anecdotal observations suggest that, due to vegetational changes around nest sites, old nests are found more readily than active nests. The idea that the choice of certain nesting materials may provide long-term benefits, beyond the bounds of a single season, is intriguing though not fully substantiated. Predator deterrent roles of some supernumerary nests, even if not primary, may serve to offset excessive energy expended for their production. The evidence presented suggests that protection from predation is gained by the presence of empty nests. The degree to which this phenomenon reduces predator success is likely to be a function of the efficiency of finding nests as influenced by the visibility within the habitat, the number and density of inactive nests, and the proportion of nesting pairs which are near inactive nests. I thank G. R. Brooks and C. R. Terman for helpful comments on the manuscript. BRYAN D. WATTS
Department of Biology, College of William and Mary, Williamsburg, VA 23185, U.S.A.
References Bent, A. C. 1968. Order Passeriformcs: Family Fringillidae. Life histories of North American cardinals, grosbeaks, buntings, towhees, finches, sparrows, and allies. U.S. ?Cam. Mus. Bull., 237, 1-15. Best, L. B. I978. Field sparrow reproductive success and nesting ecology. Auk, 95, 9-22. Charnov, E. L. 1976. Optimal foraging: attack strategy of a mantid. Am. Nat., 110, 141 151. Collias, E. C. & Collias, N. E. 1964. The evolution of nestbuilding in the weaverbirds (Ploceidae). Univ. Calif. Pubis Zool., 73, 1 162. Collias, N. E. & Collias, E. C. 1978. Cooperative breeding behavior in the white-browed sparrow weaver. Auk, 95, 557-567.
Conner, R. N., Anderson, M. E. & Dickson, J. G. 1986. Relationships among territory size, habitat, song, and nesting success of northern cardinals. Auk, 103, 23-31. Emlen, J. M. 1966. The role of time and energy in food preference. Am. Nat., 100, 611 617. MacArthur, R. H. & Pianka, E. R. 1966. On the optimal use of a patchy environment. Am. Nat., I00, 603-609. McGahan, J. 1968. Ecology of the golden eagle. Auk, 85, 1-12. Motai, T. 1973. Male behavior and polygamy in Cisticola juneindis. Misc. Rep. Yamashina'sInst. Ornithol. Zool., 7, 87 103. Nice, M. M. 1957. Nesting success in altricial birds. Auk, 74, 305-321. Pulliam, H. R. 1974. On the theory of optimal diets. Am. Nat., 108, 59-74. Verner, J. & Engelsen, G. H. 1970. Territories, multiple nest-building, and polygamy in the long-billed marsh wren. Auk, 87, 557-567. Welty, J. C. 1975. The Life of Birds. New York: Dryden Press. Werner, E. E. & Hall, D. J. 1974. Optimal foraging and the size selection of prey by the bluegill sunfish Lepomis macrochirus. Ecology, 55, 1042-1052.
(Received 17 November 1986; revised 2 March 1987; MS. number: As-434)
Differences in Experimental and Natural Encounters of Black-tailed Prairie Dogs with Snakes Two untested assumptions in most studies of mobbing behaviour have been that experimental presentations of a predator elicit the same behaviour in prey as that observed naturally, and that these encounters generate the same differences between prey individuals as those occurring naturally. In a recent, provocative paper, Knight & Temple (1986) showed that red-winged blackbirds, Agelaius phoeniceus, were sensitive to several aspects of a potential nest predator. The birds treated models differently than a live individual, and treated predators differently depending on subtle features o f the situation (e.g. whether the predator was looking at the nest or in another direction). They concluded by arguing that studies of avian nest defence needed to show more concern in describing experimental protocol. In this paper I demonstrate that black-tailed prairie dogs, Cynomys ludovicianus, treat potential snake predators differently, depending on whether they encounter these snakes naturally or in an experimental situation. Furthermore, I examine natural and experimental encounters to determine whether the same pattern o f differences between individuals emerges in both situations. As part of a study of prairie dog anti-predator behaviour, I presented tethered rattlesnakes, Cro-
Short Communications
1569
Table I. Three-way ANOVA comparing differences in the behaviour of black-tailed prairie dogs in natural and experimental encounters with snakes Experimental Variable
Fathers
Strikes Swats Barking* Barks/min* Distance]" Snake portion* % SD]" % 2 m]" % Feedt % Time up]" N
3.31 4.97 0.50 5.02 4.08 2.36 65.94 91.28 21.82 99.97 2
Natural
Non-fathers Mothers Non-mothers Fathers 0.32 0.32 0.38 2.42 4.89 2.32 29-55 78.33 50.12 100.00 2
0 0 0.20 1.14 23.35 2.23 24.26 41-69 42.59 94.58 2
0 0 0 0 27.51 1.28 11.18 27.06 42.23 74.46 5
0 0 0 0 4.35 2.87 59.72 92.27 13-95 97.68 2
Non-fathers Mothers Non-Mothers 0 0 0 0 2.70 2.50 53.96 99.71 4.50 100.00 2
0 0 0 0 27-45 2.66 8.99 19.87 64.42 97.35 2
0 0.10 0 0 36.92 2.48 27.44 39.13 48.82 99-27 5
Strikes: strikes by snakes at prairie dogs; Swats: swats by prairie dogs at snakes; Barking: number of bouts of barking by prairie dogs per encounter; Barks/min: rate of barking per min of an encounter; Distance: distance of prairie dogs from snakes (in prairie dog body lengths); Snake portion: portion of snake prairie dogs were closest to (3 = head, 2 = midbody, 1 = tail); %SD: % samples prairie dogs were actively snake-directed; % 2 m: % samples prairie dogs were within 2 m of the snake; % Feed: % samples prairie dogs were feeding; % Time up: % samples prairie dogs were above-ground during an encounter. * For experimental versus natural encounters, P < 0.05, df= 1, 7. "~For males versus females, P < 0.05, df= 1, 7.
talus atrox, and bullsnakes, Pituophis melanoleucus sayi, at various sites within a black-tailed prairie dog colony located on the Muleshoe National Wildlife Refuge, Muleshoe, Texas. Prairie dogs in this colony also encountered free-roaming snakes. Twenty-one natural and 32 experimental encounters between prairie dogs and snakes were recorded on videotape and audio-tape for later analysis. D a t a were decoded from videotapes at 10-s intervals and data on off-camera individuals were obtained from the accompanying narration (see Loughry, in press, for details of methodology). Some of the measured variables are described in Table I (see Loughry, in press, for a complete list). These encounters were of roughly equal duration (ca. 10 rain/encounter). To discover the influence of situation on prairie dog anti-snake behaviour, I identified 12 adult individuals that were present for at least one encounter of each type (average values were used for individuals present more than once for a particular kind of encounter). I then ran a mixed, three-way A N O V A with repeated measures on one factor, using sex, parental status and type of encounter as the three factors (Bruning & Kintz 1977) and using 15 variables obtained from the video records. I had previously found sex and parental (father versus non-father) differences in anti-snake behaviour, and this analysis allowed identification of significant main effects due to
situation. A significant three-way interaction was taken as evidence that the pattern of differences between classes of prairie dogs changes as a function of the type of encounter. The results of this analysis are presented in Table I, which lists those variables for which a significant difference was found. Table I shows that prairie dogs behaved differently towards tethered and freeroaming snakes. Prairie dogs swatted at and elicited strikes from snakes only in experimental encounters. Further, prairie dogs barked at snakes only in experimental encounters, but were more often closest to the snake's head during natural encounters (see data on the portion of the snake prairie dogs were closest to: Table I). No variable, however, showed a significant three-way interaction, indicating that differences between classes of prairie dogs were consistent across situations. F o r example, considerable sex differences in anti-snake behaviour were maintained across situations, although father-non-father differences were most pronounced in experimental encounters (e.g. see %st~ and %Feed; Table I). Prairie dogs performed some activities in only one type of encounter. This can be explained in terms of the constraints afforded by each type of encounter. Natural encounters typically took place in burrow mouths, while experimental encounters took place above ground. During natural encounters I sometimes observed prairie dogs
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kicking dirt into the mouth of the burrow in an apparent attempt to bury the snake (cf. Halpin 1983). This kind of activity is impossible in an encounter above ground and was not observed in experimental encounters. Situational constraints may also explain why prairie dogs attacked and swatted only at experimental snakes. In natural encounters, a snake usually moved away after being discovered. Tethered snakes cannot do this, and there may be a higher probability of either participant escalating the encounter (cf. Maynard Smith 1974). Also, most natural encounters were with rattlesnakes (18 out of 21), and prairie dogs were less likely to swat or attack rattlesnakes (Owings & Loughry 1985; Loughry, unpublished data; see also Halpin 1983). Prairie dogs barked only at experimental snakes. Barking at snakes, however, was common prior to the pups' first emergence from natal burrows, and most natural encounters occurred after pup emergence (18 out of 21). Finally, in natural encounters, snakes usually sat in the mouth of a burrow with their heads facing out. Since I could not see into a burrow to ascertain the snake's position during an encounter, I assumed that the snake's head was the portion of the snake closest to the prairie dog throughout the entire episode. Thus, the difference in the portion of the snake that prairie dogs were closest to (Table I) described here may be a product of imprecise measurement. In sum, most of the differences in the behaviour of prairie dogs in natural versus experimental encounters seems to be explainable in terms of the specific features of each situation. However, these situational differences did not alter the basic pattern of differences between classes of prairie dogs in how they treated snakes. No significant three-way interactions were found, and the patterns of differences between males and females were identical to those previously reported (Loughry, in press). Fathers behaved differently from non-fathers in experimental encounters compared to natural encounters, but small sample sizes make this result preliminary. My results indicate that experimental presentations of predators may be justifiable for determining the pattern of differences between potential prey individuals. However, experimental presentations provide a distorted picture of the behaviour of these individuals. Thus, care should be taken in interpreting the outcome of experimental manipulations, especially when no natural encounters are available for comparison. These results further point to the importance of context in understanding the behaviour of animals confronting a potential predator (see also Hennessy, in press). This work was supported by the Theodore
Roosevelt Memorial Fund, a U.C. Davis Graduate Research Award and Faculty Research Grant D819 to D. H. Owings. Thanks to the editor, R. L. Knight and an anonymous reviewer for many helpful suggestions. W.J, LOUGHRY Animal Behavior Graduate Group, Department of Psychology, University o f California, Davis, CA 95616, U.S.A. References Bruning, J. L. & Kintz, B. L. 1977. Computational Handbook of Statistics. Glenview: Scott, Foresman. Halpin, Z. T. 1983. Naturally-occurring encounters between Mack-tailedprairie dogs (Cynomys ludovicianus) and snakes. Am. Midl. Nat., 109, 5~55. Hennessy, D. F. In press. A format for describing the generative structures of behavioural patterning. In: Levels of Social Behavior: Evolutionary and Genetic Aspects (Ed. by G. Greenberg & E. Tobach). New York: Gordian Press. Knight, R. L. & Temple, S. A. 1986. Methodological problems in studies of avian nest defence. Anita. Behav., 34, 561 566. Loughry, W. J. In press. The dynamics of snake harassment by black-tailed prairie dogs. Behaviour. Maynard Smith, J. 1974. The theory of games and the evolution of animal conflicts. J. theor. Biol., 47, 209 221. Ov)ings, D. H. & Loughry, W. J. 1985. Snake-elicited jump-yipping by black-tailed prairie dogs: ontogeny and snake specificity.Z. Tierpsyehol., 70, 177 200. (Received 12 January 1987,"revised 27 February 1987; MS. number: AS-428) Paternal Care and the Development of Adaptive Variation in Anti-Predator Responses in Sticklebacks Differences in anti-predator responses between local populations have been documented for a number of species (e.g. Curio 1976; Owings & Coss 1977; Glywicz 1986; Magurran 1986) and are often interpreted as an evolved adaptation to local predation conditions. However, this explanation requires that the behavioural variation is at least partially hereditary, and information on this point is sparse and conflicting. Even a single exposure to a predator can modify subsequent responses (Ginetz & Larkin 1976), but in guppies (Poecilia reticulata, Seghers 1974) and in three-spined sticklebacks (Gasterosteus aculeatus, Giles 1984; Tulley 1985) for example, between-population variation in anti-predator behaviour persists in animals reared without exposure to predators.