Dominant-subordinate status emerges from agonistic encounters. The weakly electric fish, Gymnotus omarorum, displays a clear-cut example of non-breeding territorial aggression. The asymmetry in the behavior of dominants and subordinates is outstanding. Dominants are highly aggressive and subordinates signal submission in a precise sequence of locomotor and electric traits: retreating, decreasin...

In zones of sympatry between closely related species, species recognition errors in a competitive context can cause character displacement in agonistic signals and competitor recognition functions, just as species recognition errors in a mating context can cause character displacement in mating signals and mate recognition. These two processes are difficult to distinguish because the same trait...

Male golden-collared manakins gather on leks and perform an acrobatic display to attract females. In temperate breeding species, testosterone (T) activation of courtship displays has been well studied. Few studies have examined T activation of displays in tropical species; even fewer have explored the activational role of T in elaborate courtship displays such as in the manakin. In some tropica...

OBJECTIVE To evaluate the effect of high- and low-protein diets with or without tryptophan supplementation on behavior of dogs with dominance aggression, territorial aggression, and hyperactivity. DESIGN Prospective crossover study. ANIMALS 11 dogs with dominance aggression, 11 dogs with territorial aggression, and 11 dogs with hyperactivity. PROCEDURE In each group, 4 diets were fed for ...

During the breeding season, birds establish territories and aggressively defend them against intruders. In general, conspecific intruders elicit greater behavioral responses than heterospecific because heterospecifics are not usually competing for the same resources. Interference competition, through aggressive interactions between species, has the potential to affect community structure [1]. I...

Arctic breeding birds arrive on their nesting grounds in spring when weather conditions may still be extreme (low temperature, snow). The brief Arctic summer requires that they begin breeding as early as possible to take advantage of the ephemeral abundance of food to feed young. Failure to adjust to the local phenology results in drastically reduced reproductive success. Hormone-behavior adapt...

Asymmetries in competitive ability can determine the outcome of social interactions in animals and are often expressed through differences in sexual traits. Competitive ability (resource holding potential, RHP), trait expression and ultimately reproductive success may vary with an individual's age or experience. In some species, reproductively mature males delay acquisition of some adult traits...

Territorial aggression influences fitness and, in monogamous pairs, the behavior of both individuals could impact reproductive success. Moreover, territorial aggression is particularly important in the context of interspecific competition. Tree swallows and eastern bluebirds are highly aggressive, secondary cavity-nesting birds that compete for limited nesting sites. We studied eastern bluebird...

Testosterone promotes aggressive behaviour in male vertebrates during the breeding season, but the importance of testosterone in female aggression remains unclear. Testosterone has both beneficial and detrimental effects on behaviour and physiology, prompting the hypothesis that selection favours an association between aggression and testosterone only in certain contexts in which intense or per...

The homologous neuropeptides vasotocin (VT) and vasopressin (VP) influence agonistic behaviours across many taxa, but peptide-behaviour relationships are complex and purportedly species-specific. Putative species-specific effects in songbirds are confounded with context, however, such that territorial species have been tested only in resident-intruder paradigms and gregarious species have been ...