Experience modulates both aromatase activity and the sensitivity of agonistic behaviour to testosterone in black-headed gulls.

University of Groningen Experience modulates both aromatase activity and the sensitivity of agonistic behaviour to testosterone in black-headed gulls

Agonistic acts as possible indicator of food anticipatory activity (FAA) in rainbow trou (Oncorhynchus mykiss)

Food anticipatory activity (FAA) was assessed in rainbow trout ( Oncorhynchus mykiss ) in two small raceways using demand-feeding (T2) and hand-feeding (t2). The fish of both raceways were subjected to restricted feeding (RF) at two times in two places and the fish distribution and/or trigger actuation, total agonistic behaviour between fish, and swimming speed were measured. Food anticipatory ...

Agonistic behaviour of juvenile gulls, a neuroethological study.

The results relating to agonistic behaviour obtained during an exploration of the brain of juvenile herring and lesser black-backed gulls (Larus argentatus andfuscus) with electrical stimulation are reported. As an introduction the normal agonistic behaviour of immature gulls is described. While the flight and aggressive behaviour is largely unritualized the threat behaviour is more stereotyped...

The relation among gonadal steroids, immunocompetence, body mass, and behavior in young black-headed gulls (Larus ridibundus).

We experimentally examined the effect of testosterone on the antibody response to a single immunization with sheep red blood cells in young black-headed gulls. This species performs a number of testosterone-mediated elaborate postural displays in social interactions and breeds in dense colonies in which there is a high likelihood of infectious diseases. In young chicks, only one-third were capa...

Maternal yolk androgens stimulate territorial behaviour in black-headed gull chicks.

Avian eggs contain substantial amounts of maternal androgens. The concentrations of these yolk androgens are affected by the maternal environment, such as the level of social competition, parasite exposure or food conditions. Since yolk androgens have been shown to affect a wide array of offspring traits, they may adjust the chicks to the expected post-hatching environment, but experimental evi...