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Social organization of the Gunnison's prairie dog, Cynomys gunnisoni, was studied in two populations in south-central Colorado. Gunnison's prairie dogs live in complex, interactive societies fitting current definitions of highly social ground squirrels. Members of harems (‘coteries’) cooperatively use and defend a common territory. Spatial overlap is extensive between the adult male(s) and adult females, and among adult females within the harem through the active season. Amicable behavioral interactions are frequent within the harem, whereas interactions between members of different harems are primarily agonistic and spatial overlap is minimal. Although their behavioral repertoire is more limited, social organization...
We studied patterns of paternity in 840 nestling bobolinks (Dolichonyx oryzivorus) from 191 pairbonded adults and the chicks they reared in west central New York, USA, during 19831986, using allozyme data (4 variable loci). Thirty-six (4.3%) nestlings exhibited genotypes that excluded a putative parent as a genetic parent. Using the method of Westneat et al. (1987) we estimated that 14.6% of the nestlings were sired by extrapair copulations and that 28% of the nests contained = 1 nestling resulting from extra-pair fertilizations (EPFs). Rates of EPFs did not appear to be related to population density among our bobolink populations. Younger males and older females were more likely to have young in their nests sired...
Summary We tested the hypothesis that the alpha and beta songs of male bobolinks (Dolichonyx oryzivorus) have separate intrasexual and intersexual functions by presenting caged males and caged females on the territories of male bobolinks. Although all males in our study population share both alpha and beta songs, we found no evidence for a specialized intersexual function of alpha song or a specialized intrasexual function of beta song. Territorial males increased their singing rate of both alpha and beta songs during both the male presentations and the female presentations. The proportions of the two song types did not change between control and experimental periods for either male or female presentations. We found...
Long-billed curlews (Numenius americanus) appear unique among scolopacid shorebirds so far studied in possessing a significant sex bias in natal philopatry. We resighted 9 curlews at least attempting to breed that were color-banded as chicks; 8 of these were males. Male curlews also cooperate extensively with neighbors in mobbing potential chick predators. This mutualistic behavior may have evolved through kin selection among philopatric males. If so, we would expect such an evolutionary consequence to lead to a similar sex bias in breeding area fidelity. Yet our resightings of colorbanded adults over 4 consecutive years indicate that males and females were equally likely to return to previous nesting territories....
The ontogeny of sibling recognition behavior was studied in the laboratory in tadpoles of the western toad (Bufo boreas boreas) to test the hypothesis that Bufo tadpoles associate with siblings and to compare this behavior with two species of anurans previously studied. Tadpoles reared exclusively with sibs demonstrated a preference to associate with sibs over non-sibs both early and late in development but tadpoles reared with sibs and non-sibs (mixed rearing groups) exhibited no preference. Larvae that developed a preference for sibs after being reared with them for 75 days lost this preference following exposure to a mixed group for 2 to 6 days. Additionally, larvae reared in a mixed group did not develop a preference...
Few studies have experimentally tested the resource dispersion hypothesis (RDH). In this study, I tested whether space use and social organization of Gunnison’s prairie dog responded to changes in the dispersion and abundance of resources. Food manipulations were carried out during the reproductive and nonreproductive seasons across 2 years. Gunnison’s prairie dog adults responded to the experiments by decreasing territory size as food became patchier in space and time. Both males and females modified their home ranges, with no detectable difference between sexes, either prior to or during the experiments. As food became patchier in space and time, the spatial overlap of adults increased, whereas it decreased...
Summary This study examines the effect of moonlight intensity on deermouse (Peromyscus maniculatus) vulnerability to predation by short-eared owls (Asio flammeus). Three nocturnal light intensities, labeled new moon, quarter moon, and full moon, were simulated in a flight chamber. Deermouse activity was observed and measured by an index of tracking intensity in the chamber's sand floor. The mice were then exposed to predation by a short-eared owl in each light intensity and search time, chase time, capture time, and the number of escapes/chase were measured. The results reveal the adaptive significance of deermouse activity suppression in full moon light as an anti-predator response. The deermice reduced activity...
Few studies have experimentally tested the resource dispersion hypothesis (RDH). In this study, I tested whether space use and social organization of Gunnison?s prairie dog responded to changes in the dispersion and abundance of resources. Food manipulations were carried out during the reproductive and nonreproductive seasons across 2 years. Gunnison?s prairie dog adults responded to the experiments by decreasing territory size as food became patchier in space and time. Both males and females modified their home ranges, with no detectable difference between sexes, either prior to or during the experiments. As food became patchier in space and time, the spatial overlap of adults increased, whereas it decreased as...
Few studies have experimentally tested the resource dispersion hypothesis (RDH). In this study, I tested whether space use and social organization of Gunnison?s prairie dog responded to changes in the dispersion and abundance of resources. Food manipulations were carried out during the reproductive and nonreproductive seasons across 2 years. Gunnison?s prairie dog adults responded to the experiments by decreasing territory size as food became patchier in space and time. Both males and females modified their home ranges, with no detectable difference between sexes, either prior to or during the experiments. As food became patchier in space and time, the spatial overlap of adults increased, whereas it decreased as...


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