Maternal ‘imprinting’ in goats?

314

ANIMAL

BEHAVIOUR,

in light and all differences are highly significant. The total dependence of algonquin on light for mating was confirmed in the thr& new strains,- as was the nearly complete dependence on light in the additional strains of ‘western-northern’ uthu~uscu and narrugunsett (regarding these two, although non-virginity cannot be excluded as responsible for the few cases of mating detected in ‘dark’ vials, thefe was never any eyidence of non-virginity Fie;) breeding m vlals m which vlrgm females had been -0;r first study (Curtright, unpublished) included seven days’ cohabitations in light and darkness of all possible intergroup combinations of the arhubusca semispecies. There were hizhlv significant reductions of mating in darkness in fo;r corn&nations: ‘eastern A’ females x ‘eastern B’ males, ‘eastern A’ females x ‘westernnothern’ males, and both reciprocal combinations of ‘eastern B’ and ‘western-northern’. Our second series included combinations of uztecu and ‘western-northern’ uthubascu, which are known to mate fairly easily in the laboratory (D. D. Miller, Evolurion, 12, 72-81, 1958) and which contrasted in their ability to mate in darkness. The results are given in Table IB. Mating in the light between ‘wester&northern’ females and azteca m&z occurred about as often as within ‘western-northern’ itself, but the reciprocal combination gave significantly less mating. In darkness there were highly significant reductions of mating in both combinations. Perhaps most noteworthy is the fact that mating in the dark between ‘western-northern’ females and uztecu males took place significantly more often than between ‘western-northern’ females and their own males, suggesting that ‘western-northern’ urhubusca males are deficient in darkness with respect to uzteca males in some element of behaviour needed for mating. These results provide additional support for the generalization of Grossfield (1971 b) that endemic species of Drosophila are light dependent and that sibling species (and divisions of the same species; Grossfield, 1971a) may vary in degree of dependence on light for mating. D. algonquin may be regarded as yet another example of Grossfield’s Class III, in which mating is completely blocked by darkness. ROBERT D. CURTRIGHT DWIGHT D. MILLER

School of Life Sciences, University of Nebraska, Lincoln, Nebraska 68588. (Received

2 August 1978; revised 25 September MS. number: ~~46)

1978;

Maternal ‘Imprinting’ in Goats? Previous research has indicated that maternal attachment in goats is specific, rapidly formed, and fairly stable, somewhat analogous to imprinting in birds. There seems to be a sensitive postpartum period for the formation of maternal attachment (P. H. Klopfer, D. K. Adams & M. S. Klopfer, Proc. Nat. Acad. Sci., 52, 911-914, 1964). Only 5 min of contact with at least one of her kids immediately after birth is sufficient to establish a maternal bond, since a mother will later accept all her kids of that litter but will reject alien young (Klopfer et al. 1964). Presumably, all the kids of her litter share some litterspecific cue(s) for recognition (P. H. Klopfer, Am. Scf., 59,404-407, 1971). However, results of the present study suggest that maternal ‘imprinting’ in goats may not occur as rapidly as previously reported.

27,

1

In February 1976 various mixed-breed and purebred goats of the Irish Hills Goat Dairy, Tipton, Michigan, were exposed to their kid for 5 min shortly after parturition (the birth session). Timing of the 5-min birth session was interrupted if labour indicating the arrival of another kid intervened. Timing resumed upon completion of the second birth. All kids after the firstborn were immediately removed; this did not affect subsequent acceptance or rejection. Immediately after the 5-min birth session the kid was removed for a l-h separation period. During that interval the kid was dried and the mother was prevented from licking or smelling her flanks, her anal region, or the ground. Any remaining fluid or membranes were removed from the pen. At the end of the separation period the own or an alien kid was presented first for a IO-min acceptance-rejection test. Order of kid presentation was counterbalanced. Alien kids were less than 36 h old. The duration of licking of kid and nursing and number of butts and threats were recorded by hand, with the aid of a stopwatch, during the acceptancerejection test. Acceptance involved avid licking of a kid for more than 2 min. Contrary to the previous results mentioned above and totally unexpectedly, 62% (13/21) of the goats accepted both their own kid and the alien, while only 14% (3/21) accepted their own and rejected the alien (Table I, upper section). This difference between the number of goats accepting both kids and those accepting only their own kid (and rejecting the alien) was significant (~2 = 6.25, df = 1, P < 0.02, two-tailed), despite the fact that there was no significant difference between the proportion accepting their own kid (16/21) and the proportion accepting the alien (15/21). These results were obtained with various mixed and purebred goats, while earlier studies employed purebred Toggenburgs. We therefore repeated this study with purebred Toggenburgs born and raised at the Duke University Field Station and obtained the same results: acceptance of both own and alien kids (middle section, Table I), indicating that breed differences do not account for the above findings. In the present study alien kids were less than 36 h old and had been kept with their mother for only 0 to 15 min (Irish Hills and Duke data), while alien kids in previous studies were less than or equal to 3 days old and had been kept with their mothers the whole time. We therefore again applied the same procedure with Toggenburgs but presented aliens that were 8 h to 5 days old and had been kept with their mother the whole time. These results are shown in the lower section of Table I. All goats (6/6) accepted their own kid, while five of these six rejected an alien, thus replicating earlier findings. This difference between acceptance of younger aliens (all 1 h old, N = 4) and rejection of older aliens (mean age = 59.8 h, N = 6) was significant, Fisher’s exact probability = 0.05, two-tailed. The present results suggest that maternal ‘imprinting’ in goats may not occur as rapidly as previously reported, since mothers given 5-min postpartum contact with their own kid generally failed to discriminate later between own and alien young unless aliens had been kept with their own mother for more than 8 h. In the latter case, aliens are rejected. Thus a kid that had no contact with one mother would probably be accepted by another, at least within 1 h after birth. Age of alien rather than amount of time spent with its mother may account for older aliens being rejected. Older aliens may behave differently from younger ones and therefore be rejected by other mothers. Although our

SHORT

COMMUNICATIONS

315

Table L Response of Goats to Own sod Alien Young

Treatment at biih

Response to kids

Comments

S-min contact

Aa? and Acc$;;3,21)* Accept and Reject (3/21)

Alien kids Q 36 h old and kept with own mother for 0 to I5 min. Various mixed and purebred goats

S-min contact

Accept and Accept (4/4)

Alien kids 1 h old and not kept with own mother. Purebred Toggenburgs

5-min contact

Accept and Reject (5/6) Accept and Accept (l/6)

Alien kids 8 h to 5 days old and with own the whole time. Purebred Toggenburgs

mother

the

*Ratio of number of goats showing this behaviour to the number of goats observed shown in parentheses. observations suggest that this is not initially the case, this oossibilitv cannot be ruled out. We tentatively suggest that a mother may ‘label’ her kid directly through licking it and indirectly through the kid’s miik intake. Lickcng may transfer rumen microfauna to the kid’s body surface; while ingestion and digestion of milk and subsequent defaecation may influence mouth, body, and anal odours, respectively. Normal mother goats frequently lick and sniff the kid’s anal region, fa& and body during the first 24 h after birth; while the average latency to first nursing ranges from 30 min to 2 h (P. H. Klopfer & M. S. Klopfer, A&m. Behav., 25, 286291,. 1977). A mother may be concurrently labelling her kid and learning the label(s). The labels may change over time or perhaps be substituted by other features (e.g. vocalizations, appearance, behaviour). Such a labelled kid may than be recognized and accepted by its own mother but rejected by another mother. while any unlabelled kid might still be accep table &thin a fe\; hours after partursion. Some recent preliminary results in which older aliens not kept with their mother (thus presumed unlabelled) were accepted tend to support this labelling hypothesis. However, this hypothesis must remain tentative until we obtain the data necessary to decide between the two most reasonable alternative hypotheses. This research was supported in part by NIMH Grant 04453 to Peter H. Klopfer. DAVID J. GIJESERNICK KATHRYN CORBEAU PETER H. KLOPFER

Zoology Department, Duke University, Durham, North Carolina (Received

9 August MS.

JONES

27706. 1978; reised 24 August number: AS-@)

1978 ;

Mammal Ear mimicry: A Hypothesis on the Bebavioural

Function of Owl ‘Horns Several owl species have feather ‘horns’ or ‘ears’, the function of which seems unknown. We here propose that specific facial structures including the feathered ‘ears’ and facial expressions have been selected for because they simulate mammalian faces during interspecies threat display. ‘Homed’ owls and mammalian oredators might interact in various ways. Eagle owl (Bubo bubo) nests are situated on easily accessible sites in places known to be

freauented bv lvnx fLvnx Iv&. ‘Face to face’ encounters bet&en the iyix and this-great horned owl must therefore often occur. During confrontations it seems probable that a defence-displaying owl, simulating a lynx face with ears. oossiblv aided bv soecialized facial exuressions would m&e the lynx withdiaw, thus decreasing successful predation. Lynx mimicry could also be highly effective towards foxes and martens, which are known to eat eggs and young of eagle owls. The long-eared owl (Asio orus) breeds in old squirrel (Sciurus vulgaris) nests which are also frequently visited by the pine marten (Martes murtes). The pine marten is a highly specialized predator of squirrels, and often rests in squirrel nests. The breeding owl is therefore also exposed to a high frequency of marten encounters. The short-eared owl (Asio flummeus), a ground breeder, probably has a similar relation to ground-searching canids, particularly the Arctic fox (Alopex lagopus) and red fox (Vufpes vulpes). In this owl, facial expressions have been described which are similar to the face of a fox. Figure 1 gives sketches of the three combinations of faces, and as can be seen, there are similarities and nearly equal facial dimensions. The nest site selected by owl-species thus exposes the breeding birds to a high frequency of visits by mammalian predators. In addition to their auditory function, mammalian external ears play an important role as a signal source. Many mammal species turn their ears backwards and down in the later stages of threat, while most species erect the ears and point them towards the opponent in the first stages of such encounters. The feathered ears of owls are situated at corresponding parts of the face and mimic all these positions. Closer approach by the predator might additionally be avoided by beaksnapping and the impression of a larger conspecific, resulting from maximal puffing up by the owl. Coevolution of antagonistic behaviour patterns between avian and mammalian predators using the same habitat offer a reasonable explanation for the development of the ‘eared’ facial structures in owls. IVAR MYSTERUD* HENNING DUNKERS

*Zoological Institute, University of Oslo, Post Box 1050, Blindern, Oslo 3, Norway. t2930 Bagn, Norway. (Received

25 April MS.

1978; revised 13 September number: s-30)

1978 :