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Six female desert tortoises, Gopherus agassizii, were observed to consume the soil of a ‘limelayer’ on an exposed site, or to excavate through the overburden where the layer was not exposed. The calcium content of soil from the layer mined was significantly higher than that of adjacent surface soil. All geophagous episodes involved reproductively mature females during the nesting season, a period in which the females were in potential calcium stress. To our knowledge this is the first report of mining and long-term exploitation of natural mineral deposits by a lower vertebrate and may represent behaviour at least as complicated as that seen in many ungulates. Published in Animal Behaviour, volume 30, issue 2,...
An evaluation of Maynard Smith's models of sexual strategies, credited to Oberdieck, Fernando, published in 1978. Published in Animal Behaviour, volume 26, issue 2, on pages 1 - 1, in 1978.
One foraging strategy that scavengers can employ to discover unpredictable food sources is to associate directly with predators who inadvertently provide food. The common raven, a well known feeding generalist, is also a prominent scavenger of wolves' kills and is found to be in close association with this predator. We tested the hypothesis that ravens preferentially associate with wolves in winter as a kleptoparasitic foraging strategy. The presence, absence and behaviour of ravens was documented during winter observations of wolves, coyotes, Canis latrans, and elk, Cervus elaphus, as well as the landscape in the absence of these three species. Ravens were found to be in close association with wolves when they...
Gunnison's prairie dogs, Cynomys gunnisoni, are colonial social rodents that give alarm calls upon the approach of a predator. Field experiments at two natural colonies showed that the prairie dogs are able to encode information into their alarm calls about the colour of clothes and general shape of individual humans eliciting alarm calls. This shows that the prairie dogs are able to incorporate information about the characteristic features of individuals within a given predator category. Published in Animal Behaviour, volume 42, issue 5, on pages 713 - 719, in 1991.
Kin selection and helpers at the nest: Effects of paternity and biparental care, credited to Charnov, Eric L, published in 1981. Published in Animal Behaviour, volume 29, issue 2, on pages 1 - 1, in 1981.
Little is known of the mating system of the swift fox or how it compares to other socially monogamous mammals. In a 4-year study of 188 swift foxes, we used microsatellite analysis at 11 loci along with spatial observations to investigate swift fox mating strategies. The mating strategies used by swift foxes were highly diverse. Previous field observations have indicated that the swift fox is socially monogamous. However, we found that extrapair mating was a common breeding strategy; 52% of offspring were sired by a male that was not the mate of their mother. There was also variation in the structure of social groups. Of 59 social groups, the most common consisted of a male and female pair (93% of social groups);...
Daily time-budgets of adult and immature yellow-eyed juncos, Junco phaeonotus, were examined over the course of the breeding season to compare the relative severity of time constraints among breeding adults and between breeding adults and their offspring. No significant differences in time allocation between males and females were found at any stage of the breeding cycle. Adults feeding nestlings spent substantially more time foraging and flying than females engaged in incubation and the males paired to such females. The allocation of time to foraging peaked after the young left the nest and, among adults, parents caring for recently fledged young faced the most severe time constraints. The allocation of time to...
Male Great Plains toads, Bufo cognatus, exhibit two mating tactics. At any time, most males give advertisement calls to attract females, while other males, ?satellites?, remain silent and station themselves near callers in an attempt to intercept females. Females are usually capable of moving through choruses undetected by males. Those females detected by males can avoid being clasped by quickly darting away; but if clasped, can detach the male by inflating. Females initiated amplexus with callers; subsequently calling males mated with 92% of the females and satellites mated with the remaining 8%. Toads employing the satellite tactic associated with males that had longer calls and that were larger, although call...
The effect of body temperature on the learning of Lashley mazes I and II was studied with the desert iguana, Dipsosaurus dorsalis. Indices of learning were error scores, number of trials to criterion, and running time. Four temperature groups were studied. Lizards trained at 22 �C did not exceed chance levels after 125 trials. A 27 �C and a 32 �C group successfully learned both mazes with fewer errors and less trials in the higher temperature group. Temperature coefficients for these two temperature groups were 3�1 on maze I and 2�3 on maze II. A second 32 �C group trained only on maze II did not differ significantly in trials and error scores from the 32 �C group experienced on maze I. However, variability within...
Although plasticity in signal production is well recognized as a means for animals to modify their communication systems, modifying responsiveness to signals could be equally important. We examined plasticity of responsiveness to social signals that mediate group formation and cohesion in red crossbills. The red crossbill is composed of several ecologically diverged forms, defined by variation in morphology, ecological specialization and vocal behaviour; each form is associated with a distinct variant of the species ?contact call.? To understand how plasticity in response to signal variants may influence social dynamics, we examined the response of red crossbills to distinct call variants before and after experimental...
We studied the effects of prior residence on contests for status within dominance hierarchies of captive male dark-eyed juncos (Junco hyemalis) to test predictions of a game-theory model of contest behaviour (Maynard Smith & Parker 1976; Hammerstein 1981). Several predictions of the model were supported. (1) Encounters between birdsnext term that were equally matched in size, age, experience, and prior residence were more aggressive than those involving residents and non-residents of equal size, age, and experience. (2) Residents usually dominated non-residents when the contestants were equally matched in size, age, and experience. (3) In a few cases, residents dominated non-residents that may have been slightly...
Songbirds undergo a sensitive period in which exposure to adult song is necessary for normal vocal development. During this period, a template is formed and later used as a model for comparison via auditory feedback. In montane white-crowned sparrows, Zonotrichia leucophrys oriantha, whose song typically consists of four to five distinct segments (phrases), exposure to syntactically overlapping phrase pairs during the sensitive period provides the minimum sufficient information for song assembly; exposure to isolated phrases is insufficient. This suggests that a template representing phrase-pair information is sufficient for guiding normal song production. However, birds may also store and use the additional information...