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Age-related differences in dominance ability and the effect of prior residence on age-related dominance were investigated in captive male dark-eyed juncos, Junco hyemalis. To determine if adults and first-winter birdsnext term differed in their intrinsic dominance ability, pairs of adult and first-winter previous termbirdsnext term of equal body size and winning experience were established. Because plumage influences status, young previous termbirdsnext term were experimentally darkened to match their older cage-mates. Adult and first-winter males became dominant with equal frequency. Because of this result and the fact that adults are usually dominant in the field, the effect of prior residence on age-related dominance...
Piñon jays (Gymnorhinus cyanocephalus) distinguished accurately between good and bad seeds of piñon pines (Pinus edulis). This was investigated in captives of three age groups: wild-caught adults, hand-reared yearlings, and hand-reared juveniles. All appeared to use visual, tactile (apparently weight) and auditory (‘bill-clicking’) cues. Discrimination improved with practice. Bad seeds weighted with lead shot caused only temporary confusion. Inexperienced piñon jays demonstrated an immediate preference for piñon seeds over other objects. Distinguishing good seeds from bad was learned. ‘Bill-clicking’ apparently is unlearned, as it appears in young birds in a variety of contexts. The relationship between...
Isolated male red-winged blackbirds develop abnormal songs. Some normal components are delivered with abnormal order and timing. Two males deafened at about 10 days of age develop highly abnormal songs, although they retain more structure than other early-deafened songbirds. In masking noise from 8 to 330 days, one individual sings like a deaf bird.next term With reduced periods of masking singing is more like that of intact previous termbirds.next term Playback of normal song results in imitation. Individual isolates are unselective in learning both conspecific and Baltimore oriole song. Grouped males are more selective. New songs are added in the second year. Improvisation is important in redwing song development...
The impact of sex and age on the nature of dominance hierarchies in black-billed magpies. Pica pica, was investigated. Dominance hierarchies were looked for in 11 unisexual groups each with 10 captive magpies, and 32 mixed-sex groups each with five captive magpies. Strongly linear hierarchies were found in all nine unisexual groups of 10 males. Of the two groups of 10 females observed, one was not linear and the other only marginally so. The occurrence of dominance reversals was 25 times greater in female than in male groups. The difference in dominance relationships between the sexes is discussed in relation to differences in the roles that the two sexes play in the breeding biology of magpies. In all 32 groups...
Vocalizations and associated behaviour of six mated pairs of captive pinon jays (Gymnorhinus cyanocephalus) were recorded under various conditions in an effort to understand functions of the calls. One vocalization, the near, was analysed for components that would allow for individual recognition by pinon jays. Fifteen vocalizations are recognized and most are described quantitatively. Much gradation occurs within and between calls, which may allow for a subtle and complex system of communication in this highly social species. Wild flocks of pinon jays also were observed to corroborate the conclusions reached. Published in Animal Behaviour, volume 25, issue 3, on pages 567 - 584, in 1977.
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Previous investigations have demonstrated the importance of predator diet in chemically mediated antipredator behaviour. However, there are few data on responses to life-stage-specific predator diets, which could be important for animals like amphibians that undergo metamorphosis and must respond to different suites of predators at different life-history stages. In laboratory choice tests, we investigated the chemically mediated avoidance response of juvenile western toads, Bufo boreas, to four different chemical stimuli: (1) live conspecific juveniles; (2) live earthworms; (3) snakes fed juvenile conspecifics; and (4) snakes fed larval conspecifics (tadpoles). Juvenile toads avoided chemical cues from snakes that...
Wolf, Canis lupus, recolonization of the Greater Yellowstone Ecosystem provides a rare opportunity to identify behaviours facilitating coexistence between sympatric canids. We investigated interactions between coyotes, Canis latrans, and recolonizing wolves at ungulate carcasses in Montana's Madison Range. We used a field-experimental study design consisting of a two-level carcass treatment (wolf presence, wolf absence) to assess factors influencing coyote risk assessment, carrion consumption and aggressive encounters with wolves. Socially dominant coyotes (alphas and betas) responded to wolf presence by increasing the proportion of time spent vigilant while scavenging. Vigilance behaviour was more pronounced when...
Age-related differences in dominance ability and the effect of prior residence on age-related dominance were investigated in captive male dark-eyed juncos, Junco hyemalis. To determine if adults and first-winter birdsnext term differed in their intrinsic dominance ability, pairs of adult and first-winter previous termbirdsnext term of equal body size and winning experience were established. Because plumage influences status, young previous termbirdsnext term were experimentally darkened to match their older cage-mates. Adult and first-winter males became dominant with equal frequency. Because of this result and the fact that adults are usually dominant in the field, the effect of prior residence on age-related dominance...
The hypothesis that a late spring arrival and a dull nuptial plumage can aid yearling male passerines in avoiding aggression from territorial adult males was tested. Adult male black-headed grosbeaks, Pheucticus melanocephalus, were presented with three types of conspecific models: (1) adult male, (2) yearling male with bright plumage, and (3) yearling male with dull plumage. Models were associated with a song playback and were presented at (1) the time of adult male arrival and territory establishment, and (2) 2 weeks later at the time of yearling arrival and settlement. Test males were more aggressive toward all model types during early presentations than during late presentations. In addition, adult models elicited...
Data were collected, for 20 consecutive days, on activity patterns in Merino wethers in an outdoor experiment conducted in early summer. A bimodal frequency distribution was found in respect to the activity pattern. Eating and drinking were the principal activities apart from walking between the food and water sources which were 3�2 km apart. Long periods of each day were devoted to idling. Onset of activity was found to be highly correlated with sunrise but cessation of activity showed no relationship with sunset. The relation of these observations to behaviour of free-ranging sheep is discussed. Published in Animal Behaviour, volume 19, issue 4, on pages 3 - 3, in 1971.
A female can usually obtain enough sperm to fertilize all her eggs from a single insemination, and copulation involves certain costs such as increased exposure to diseases and parasites. Why, then, do females of so many species routinely copulate with more than one male? A 7-year study of marked individuals provides an answer for 239 female Gunnison's prairie dogs (Sciuridae:Cynomys gunnisoni) living under natural conditions. The probability of pregnancy and parturition was 92% for females that copulated with only one or two males, but was 100% for females that copulated with at least three males. Further, litter size at weaning varied directly with the mother's number of sexual partners. Published in Animal Behaviour,...
Animals assess many factors when choosing how aggressively to behave during interspecific competitive interactions. Aggressive behaviour can help win resources, but it can also be costly. Here we tested how context such as competitor familiarity, habitat type and resource value affect competitive behaviour using two ant species, Formica xerophila and F. integroides. We found that competitive encounters within an individual's territory yielded more aggressive interactions than encounters in a neutral arena, and aggression towards competitors increased with resource value. Using a recently developed design combining behaviour assays between live ant dyads and ants paired with glass beads chemically resembling competitors,...
Socially learned vocalizations, such as the songs of many songbirds, commonly show repertoires and geographical variation or dialects, but we have only a limited understanding of the cultural evolutionary processes that produce these patterns. In this paper we describe the singing behaviour of populations of black-capped chickadees in Fort Collins, Colorado that represents the apparent evolution of a repertoire of song types. In contrast to most black-capped chickadee singing behaviour, which consists of a single song type that is remarkably invariant across North America, chickadees throughout Fort Collins sing three acoustically distinct song types. Individual males have an average repertoire of 2.8 song types...
Many animals benefit from the presence of conspecifics by reducing their rate of scanning for predators while increasing their time spent foraging. This group size effect could arise from a decreased perception of individual risk (dilution hypothesis) and/or an increased ability to detect predators (detection hypothesis). We compared individual and group vigilance of Rocky Mountain elk, Cervus elaphus, in three regions of Yellowstone National Park, Wyoming, U.S.A. that varied in their encounter frequency with coyote, Canis latrans, grizzly bear, Ursus arctos, and grey wolf,Canis lupus , predators. Adult females without calves increased scanning and decreased foraging with high encounter risk and small herd size....
The temporal and spatial distribution of above-ground activith in Merriam's kangaroo rats, Dipodomys merriami, radio-tracked during 10 winters varied in relation to phases of the moon. At the full moon, animals were more likely to be found in their day burrows at scheduled hourly radio fixes, and when they emerged, they stayed closer to home. At partial moon phases, above-ground activity was preferentially allocated to hours when the moon was down. As predicted from an extension of Rosenzweig's (1974, J. Mammal., 55, 193–199) model of optimal above-ground activity, the suppression of nocturnal activity at the full moon was partially offset by relatively great activity at dusk and dawn, and losses to nocturnal...
The social system of round-tailed ground squirrels, Spermophilus tereticaudus, is quantitatively described in terms of seasonal changes in interaction rates, the effect of age and sex on type and frequency of interaction, the differential response to kin and non-kin, the determinants of dominance, including territoriality, the associations between classes of individuals, and the dispersion of home ranges and core areas. From January to March, the adult squirrels were sociable and nonterritorial. Following copulation in March, they were unsociable and territorial. In May and June, juveniles lived mainly within their mothers' territories. Those juveniles that did not disperse from the study area in late June established...
Five hypotheses of cache recovery behaviour in Clark's nutcracker (Nucifraga columbiana) were examined experimentally. Most caches were made in soil within 5 cm of conspicuous large objects. Both seed-caching and non-seed-caching nutcrackers were able to locate caches. Seed-caching nutcrackers relocated caches using large objects as remembered visual cues. Soil microtopography and small (<2 cm diameter) objects may be used as cues to facilitate cache recovery but are not essential. Non-seed-caching nutcrackers located caches by using soil disturbances at cache sites as visual cues and by searching preferentially near objects where caches were concentrated. Success rates of seed-caching nutcrackers ranged from 52...
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In field-based choice experiments, we examined sex recognition and mate choice in male western toads,Bufo boreas. When given a simultaneous choice between a male and a female of equal size, males did not discriminate between the sexes and attempted to amplex a male or a female with equal frequency. When a test male clasped a stimulus male, the stimulus male uttered a release call that caused the test male to release the stimulus male. Male?male amplexus never lasted more than 3 s, but male?female amplexus was tenacious and prolonged. Furthermore, males discriminated between gravid females that differed in body size, choosing larger gravid females over smaller ones, but they did not discriminate between gravid females...
At a colony of Gunnison's prairie dogs, Sciuridae:Cynomys gunnisoni, containing marked individuals of known genetic relationships, anti-predator calling was investigated in response to moving, stuffed specimens of a natural predator, the American badger,Taxidea taxus. Females with kin in the home territory called more often than females without nearby kin, and females with nearby offspring were especially likely to call. Male gunnisons commonly gave anti-predator calls as well, but male calling was unrelated to kinship of nearby listeners. 1996 The Association for the Study of Animal Behaviour Published in Animal Behaviour, volume 51, issue 4, on pages 871 - 880, in 1996.
This work quantifies the geographic variation (dialects) in the vocalizations of southern Rocky Mountain pikas and presents data on the vocal responses of pikas to playback of recorded vocalizations of two dialects. Pika vocalizations were tape-recorded in twenty-six locations in Wyoming, Colorado, Utahnext term and New Mexico. Two dialects (based on duration of note and frequency of fundamental) were found in short calls. One dialect was north of the Colorado River (dialect A), and the other was south of the Colorado River (dialect B). There was seasonal variation in the incidence of vocalizations with a peak of songs in late spring and a peak of short calls in late summer. Results of this study indicate that acoustic...
map background search result map search result map Juvenile western toads, Bufo boreas, avoid chemical cues of snakes fed juvenile, but not larval, conspecifics Sex recognition and mate choice by male western toads, Bufo boreas Sex recognition and mate choice by male western toads, Bufo boreas Juvenile western toads, Bufo boreas, avoid chemical cues of snakes fed juvenile, but not larval, conspecifics