Agonistic behavior and feeding competition in the largest piranha species, Pygocentrus piraya, in a zoo
In the wild, piranhas are thought to feed in groups. Previous studies on piranhas in aquariums have variously observed either social attraction or aggressive dominance. The Rio São Francisco piranha (Pygocentrus piraya) is the largest species of piranha. It is rare in aquarium collections and its social and feeding behaviors have never been studied. To […]
Tank cleaning temporarily increases stress and decreases affiliative behavior in zebrafish
Small, tropical fish are popular companion animals and constitute a major proportion of the vertebrates used in scientific research, but little is known about how they are affected by routine husbandry practices. Manual tank cleanings are a common and potentially stressful maintenance procedure that involves siphoning out a substantial volume of tank water, ‘vacuuming’ the […]
Behavioral interactions and glucocorticoid production of Somali wild ass (Equus africanus somaliensis) mothers and foals
Somali wild ass (Equus africanus somaliensis) are the most endangered species of wild equid, and little is known about their reproductive biology. Here, we describe social interactions and glucocorticoid production of five pairs of Somali wild ass females and their foals, which were born within a two-month period at the Saint Louis Zoo. Behavioral data […]
Aggressive and Affiliative Behavior in Green Monkeys With Differing Housing Complexity
Eleven green monkeys (Cercopithecus aethiops) were combined into three social groups (two heterosexual, one all-male) in enclosures with similar volume but different levels of environmental complexity (two or four compartments). Agonistic and affiliative interactions were recorded over a 21-week period. The two heterosexual groups had their environmental complexity reduced (number of compartments reduced by one-half […]
Within-group social relationships among females and adult males in wild western lowland gorillas (Gorilla gorilla gorilla)
Within-group female relationships, and relationships between females and adult males have not been described for wild western lowland gorillas. New data are presented here from Mbeli Bai in the Nouabale´-Ndoki National Park, Republic of Congo. Nine groups were observed over a continuous 2-year period, and affiliative and agonistic interactions, as well as time spent by […]
Fighting dynamics of male copperheads,Agkistrodon contortrix (Serpentes, Viperidae): Stress-induced inhibition of sexual behavior in losers
Abstract 10.1002/(SICI)1098-2361(1996)15:33.3.CO;2-E Adult male copperheads (Agkistrodon contortrix) fight for priority of access to females during the mating periods in spring and late summer. During fights, one male abruptly quits and retreats, and the other chases in pursuit. One male thus emerges as the winner and the other as the loser. Reversal of this outcome does […]
Female crickets are driven to fight by the male courting and calling songs
Crickets have traditional sex roles, where males compete aggressively for access to selective polyandrous females. However, in a laboratory experiment, we found that normally nonaggressive female Gryllus campestris fought each other vigorously in the presence of a courting male, resulting in a dominant female that gained a greater probability of receiving the spermatophore. Female-female fights […]
Male morphs in tree lizards have different testosterone responses to elevated levels of corticosterone
Changes in circulating glucocorticoid and androgen levels mediate agonistic behaviors in many vertebrates. Individual variation in the magnitude of the glucocorticoid response to stressful stimuli, the negative effects of elevated glucocorticoid levels on androgen levels, or both could mediate individual differences in subsequent agonistic behavior. In a series of previous studies, we found that both […]
Grooming and coalitions in Japanese macaques (Macaca fuscata): Partner choice and the time frame reciprocation
Evidence of a reciprocal exchange of grooming and agonistic support in primates is mixed. In this study, the authors analyzed a large database of grooming and coalitions in captive female Japanese macaques (Macaca fuscata) to investigate their within-group distribution and temporal relations. Macaques groomed preferentially those individuals that groomed them most and supported preferentially those […]
Female meadow voles (Microtus pennsylvanicus) demonstrate same-sex partner preferences
Female meadow voles (Microtus pennsylvanicus) are territorial during warm months but demonstrate social tolerance under low temperatures. In spring, females nest together and some pairs participate in communal nursing and rearing of young. Because communal nursing involves significant cooperation, selective pair-bonds may develop between 2 nestmates. Using a choice apparatus, the authors determined that (a) […]