Dominance, aggression, and glucocorticoid levels in social carnivores
In social animals, reproductive success is often related to social dominance. In cooperatively breeding birds and mammals, reproductive rates are usually lower for social subordinates than for dominants, and it is common for reproduction in subordinates to be completely suppressed. Early research with captive animals showed that losing fights can increase glucocorticoid (GC) secretion, a […]
Communal nesting is unrelated to burrow availability in the common warthog
Warthogs, Phacochoerus africanus, are an unusual ungulate. They are facultative cooperative breeders where females within the same population display both solitary and cooperative reproductive strategies. Warthogs require burrows for sleeping and rearing their young, yet they are unable to dig their own burrows and rely on aardvark excavations. Studies of warthogs have failed to show […]
Nest attendants in parakeet auklets
Abstract 10.1002/zoo.1027.abs Breeding behaviors in a captive population of parakeet auklets (Cyclorrhynchus psittacula) were observed to determine whether a third bird present at the entrances to nest tunnels was a helper or competitor. Comparisons were made between focal pairs of nesting birds, two with and two without attendants. Pairs with attendants spent more time feeding […]
Trade-offs between social learning and individual innovativeness in common marmosets, Callithrix jacchus
Social learning and innovation are two different ways to acquire novel behaviours, and the form of the relationship between these two processes strongly affects cultural evolution. Whereas modelling results suggest a negative correlation between the two processes within a species, comparative data show, and the cultural intelligence hypothesis predicts, positive covariation across species. Thus, there […]
Onset of plural cooperative breeding in common marmoset families following replacement of the breeding male
Common marmosets, Callithrix jacchus, are usually characterized as singular cooperative breeders, with only a single, dominant female reproducing in each group. Anecdotal reports, however, have described two females breeding concurrently when an unrelated male joins their group. We tested the hypothesis that incorporation of an unrelated adult male into a family systematically leads to the […]
Elevated prolactin levels immediately precede decisions to babysit by male meerkat helpers
Recent studies suggest that decisions to care for the offspring of others in societies of cooperative vertebrates may have a hormonal basis. The crucial question of whether changes in hormone levels immediately precede or merely follow bouts of offspring care, however, remains largely unanswered. Here, we show that in wild groups of cooperatively breeding meerkats, […]
Social suppression of female reproductive maturation and infanticidal behavior in cooperatively breeding Mongolian gerbils
In several cooperatively breeding species, reproductively suppressed, nonbreeding females are attracted to infants and routinely provide alloparental care, while breeding females may attack or kill other females’ infants. The mechanisms underlying the transition from alloparental to infanticidal behavior are unknown. In this study, we tested the hypothesis that this transition is associated with cessation of […]
Fitness Consequences of Maternal Rearing Strategies in Warthogs: Influence of Group Size and Composition
Cooperatively breeding species are defined by the presence of individuals who help in rearing the offspring of others. This seemingly altruistic behaviour has been difficult to define and the help provided has not always resulted in a reproductive advantage to the recipient. We examine maternal rearing strategies in the common warthog, Phacochoerus africanus, a facultative, […]
Division of labour within cooperatively breeding groups
Within cooperative societies, group members share in caring for offspring. Although division of labour among group members has been relatively well studied in insects, less is known about vertebrates. Most studies of avian helping focus solely on the extent to which helpers provision the offspring, however, helpers can participate in everything from nest building to […]
Testosterone-dependency of male solo song in a duetting songbird — Evidence from females
For male songbirds of the temperate zone there is a tight link between seasonal song behaviour and circulating testosterone levels. Such a relationship does not seem to hold for tropical species where singing can occur year-round and breeding seasons are often extended. White-browed sparrow weavers (Plocepasser mahali) are cooperatively breeding songbirds with a dominant breeding […]