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Reboreda, J. C., & Kacelnik, A. (1990). On cooperation, tit-for-tat and mirros. Anim. Behav., 40(6), 1188–1189.
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Cuthill, I. C., Kacelnik, A., Krebs, J. R., Haccou, P., & Iwasa, Y. (1990). Starlings exploiting patches: the effect of recent experience on foraging decisions. Anim. Behav., 40(4), 625–640.
Abstract: Laboratory and field experiments have shown that, as predicted by the marginal value model, starlings, Sturnus vulgaris, stay longer in a food patch when the average travel time between patches is long. A laboratory analogue of a patchy environment was used to investigate how starlings respond to rapidly fluctuating changes in travel time in order to find out the length of experience over which information is integrated. When there was a progressive increase in the amount of work required to obtain successive food items in a patch (experiment 1), birds consistently took more prey after long than after short travel times; travel experience before the most recent had no effect on the number of prey taken. Such behaviour does not maximize the rate of energy intake in this environment. The possibility that this is the result of a simple constraint on crop capacity is rejected as, when successive prey were equally easy to obtain up until a stepwise depletion of the patch (experiment 2), birds took equal numbers of prey per visit after long and short travel times: the rate-maximizing behaviour. A series of models are developed to suggest the possible constraints on optimal behaviour that affect starlings in the type of environment mimicked by experiment 1.
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Kacelnik, A. (1990). R.C. Bolies and M.D. Beecher, Editors, Evolution and Learning, Lawrence Erlbaum, Hillsdale, New Jersey (1988), p. x. Anim. Behav., 40(3), 602–603.
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Cassini, M. H., Kacelnik, A., & Segura, E. T. (1990). The tale of the screaming hairy armadillo, the guinea pig and the marginal value theorem. Anim. Behav., 39(6), 1030–1050.
Abstract: Foraging by screaming hairy armadillos, Chaetophractus vellerosus, and guinea pigs, Cavia porcellus, was studied in the laboratory. The main question was whether patch exploitation varies with overall capture rate as predicted by the marginal value theorem (MVT). Armadillos in experiment I and guinea pigs in experiment II experienced a single travel time between depleting patches of two kinds: good and poor. There were two treatments, which differed in the quality of poor patches. MVT predicts that within a treatment, more prey should be taken from good than from poor patches and between treatments, good patches should be exploited in inverse relation to the quality of poor patches and poor patches should be exploited in direct relation to their own quality. In experiment III, guinea pigs experienced three treatments which differed in the travel requirement, while the two patch types remained the same. MVT predicts that within a treatment more prey should be taken from good than from poor patches and that between treatments more prey should be taken from both patch types as travel requirement increases. The qualitative predictions were supported in the three experiments. The quantitative fit was good but there was a bias towards more severe patch exploitation than predicted. The results indicate that in these species patch exploitation depends on overall food availability as predicted by the MVT when overall food availability differs either because of patch type composition or because of differences in travel requirement between patches.
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BASHORE, T. L., KEIPER, R., TURNER, J. W. J. R., & KIRKPATRICK J. F. (1990). The accuracy of fixed-wing aerial surveys of feral horses on a coastal barrier island. J. coast. res, 6, 53–56.
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Gordon, I. J., & Lindsay, W. K. (1990). Could Mammalian Herbivores “Manage” Their Resources? Oikos, 59(2), 270–280.
Abstract: The concept of resource management has gone hand in hand with group selection arguments. For this reason, it has been cast aside in the era of evolutionary theory which assumes that foraging strategies must have evolved under selection operating to maximise an individual's inclusive fitness. However, results from empirical studies show that under favourable environmental and social circumstances, resource management could be selectively advantageous. Much of the recent literature on plant-herbivore interactions suggest that herbivory can result in changes in the resource base which are assumed to increase the intake and fitness of the herbivore. As a result, a number of authors suggest that herbivores manage their resource utilisation to maximise the flow of nutrients from these resources. Long term territoriality or the exclusive use of a home range are the social systems most likely to favour selection for prudent resource exploitation. This review argues that, in many habitats, resource management strategies are not feasible, as individuals have little control over the way resources are depleted and renewed. Thus far, very little evidence is available showing that herbivorous mammals actively manage the resources which they utilise.
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Dublin, H. T., Sinclair, A. R. E., Boutin, S., Anderson, E., Jago, M., & Arcese, P. (1990). Does competition regulate ungulate populations? Further evidence from Serengeti, Tanzania. Oecologia, 82(2), 283–288.
Abstract: Changes in populations of several ungulate species in the Serengeti-Mara region of East Africa over the past 30 years suggest several hypotheses for their regulation and coexistence. Recent censuses in the 1980s have allowed us to test the hypotheses that: (1) there was competition between wildebeest (Connochaetes taurinus) and Thomson's gazelle (Gazella thomsoni). This predicted that gazelle numbers should have declined in the 1980s when wildebeest were food limited. Census figures show no change in gazelle numbers between 1978 and 1986, a result contrary to the interspecific competition hypothesis; (2) wildebeest and African buffalo (Syncerus caffer) populations were regulated by intraspecific competition for food. Since both populations reached food limitation in the 1970s, the hypothesis predicted that the populations should have been stable in the 1980s. The results confirm these predictions for wildebeest and the buffalo population in the Mara reserve. In the Serengeti the buffalo population declined 41% over the period 1976-1984. The decline was not evenly distributed over the park, some areas showing an 80-90% decline, others no change or an increase in numbers. The decline was associated with proximity to human habitation; (3) an outbreak of the viral disease, rinderpest, in 1982 may have been the cause of the drop in buffalo population. Blood serum samples to measure the prevalence of antibodies were collected from areas of decreasing, stable and increasing populations. If rinderpest was the cause of decrease there should be a negative relationship between the prevalence of rinderpest and the instantaneous rate of increase (r). The results showed no relationship. We conclude that rinderpest was not the major cause of the drop in buffalo numbers. Elephant (Loxodonta africana) numbers dropped 81% in Serengeti in the period 1977-1986. In the Mara there was little change. The evidence suggests that extensive poaching in northern and western Serengeti during 1979-1984 accounted for the drop in both elephant and buffalo numbers.
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Charles T. Snowdon,. (1990). Language capacities of nonhuman animals. American Journal of Physical Anthropology, 33(S11), 215–243.
Abstract: In the last two decades, the study of language parallels in nonhuman animals has generated considerable controversy and excitement. Many have perceived demonstrations of linguistic skills in nonhuman animals as a threat to human uniqueness, whereas others have been uncritical of claims for complex cognitive skills in animals. Two different paradigms for studying linguistic parallels have appeared. One approach teaches great apes linguistic analogues of human language using signs or arbitrary symbol systems; the other seeks to decode communicative complexity in the natural languages of nonhuman animals. This paper reviews the language analogue studies with great apes and cetaceans, examining the utility of the different methods and reviewing the animals' accomplishments. Studies of ontogeny, syntax, referential communication, audience effects, and perception of vocalizations in the natural communication of birds, squirrels, and primates are evaluated. Finally, the brain mechanisms underlying human speech and language are compared with those involved in vocal communication in nonhuman primates. Although chimpanzees and bonobos have accomplished much, they do not threaten human uniqueness with respect to speech and language. Many of the claims for language paralleles in natural communication systems of nonhuman animals are weak, and many can be interpreted without recourse to cognitive constructs. Whereas there exist many similarities between subcortical controls of language and of animal vocalizations, there are no parallels to Broca's and Wernicke's areas in monkeys. However, the critical studies have not been done.
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Pettifor, R. A. (1990). The effects of avian mobbing on a potential predator, the European kestrel, Falco tinnunculus. Anim. Behav., 39(5), 821–827.
Abstract: European kestrels were observed being mobbed by other birds on 63 occasions. Eleven species were involved, and in two instances mobs were composed of more than one species. Both flight-hunting and perch-hunting kestrels flew significantly further between their foraging positions when they were mobbed than when they were not mobbed; on average, mobbing resulted in flight-hunting kestrels moving 6[middle dot]8 times, and perch-hunting kestrels 2[middle dot]7 times, the mean distances moved by non-mobbed birds. The mean strike distance of perch-hunting kestrels attempting to capture birds was significantly less than the distance between perches flown by perch-hunting kestrels when mobbed. These data provide quantitative support for the assumption that mobbing causes a predator to vacate its immediate foraging area. The activity of the kestrels also influenced the frequency that they were mobbed, with kestrels that were flight-hunting being mobbed more than expected compared with ones that were perch-hunting. Kestrels were observed being mobbed throughout the year, and there was no discernible difference in their response to mobbing between seasons. These results are discussed in relation to current ideas on the functions of avian mobbing.
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Thouless, C. R. (1990). Feeding competition between grazing red deer hinds. Anim. Behav., 40(1), 105–111.
Abstract: The effect of social rank on the feeding behaviour of female red deer, Cervus elaphus L., on the Isle of Rhum, Scotland, was investigated. Hinds were less likely to approach and more likely to leave the vicinity of other individuals if these hinds were dominant to them. Movements away by subordinates were more likely to involve a break from feeding. Feeding rate, as measured by bite rate, increased with distance from dominant neighbours, but was unaffected by the distance to subordinates. It appears that aggressive interactions had little direct effect on access to food. Instead, it is suggested that feeding competition in red deer hinds is largely a passive process, operating through the avoidance of conflict by subordinates.
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