title: The hormonal control of begging and early aggressive behavior: experiments in black-headed gull chicks.
abstract: The hormonal control of begging and sibling competition is largely unknown, but recent evidence suggests a role for steroid hormones. We tested the influence of the aromatizable androgen testosterone (T), the non-aromatizable androgen 5alpha-dihydrotestosterone (DHT), and 17beta-estradiol (E) on both begging behavior and aggressive behavior in black-headed gull chicks (Larus ridibundus). Chicks of this species have a conspicuous begging display, while their frequently performed early aggressive behavior is facilitated by testosterone and important for territorial defense. Hormone treatment was applied by implants between days 6 and 16 after hatching. Behavior was tested by means of standard stimulus tests. The results were validated in a second experiment under semi-natural conditions. Begging was suppressed by T and DHT and not affected by E. Aggressive Pecking was strongly facilitated by T. The erect threat posture, characteristic for older chicks, was facilitated by T, DHT, and E and the nest-oriented threat display, typical for young chicks, only by T and DHT. Growth was suppressed in the T group. The results indicate that androgen production, needed for territorial defense, has costs in terms of a suppression of begging and growth. It is discussed to what extent older chicks may avoid these costs by converting testosterone to estrogen and why pre-natal and post-natal exposure to androgens differ in their effect on begging behavior.
authors.affiliation: Department of Behavioural Biology, Biological Centre, University of Groningen, Kerklaan 30, 9750 AA Haren, The Netherlands. t.groothuis@biol.rug.nl
authors.forename: Ton G G
authors.initials: TG
authors.lastname: Groothuis
authors.forename: Albert F H
authors.initials: AF
authors.lastname: Ros
mesh_terms: D000374:Aggression / Q000502:physiology*; D000375:Aging / Q000523:psychology; D000818:Animals; D001717:Birds / Q000502:physiology*; D001835:Body Weight / Q000187:drug effects; D013196:Dihydrotestosterone / Q000008:administration & dosage / Q000494:pharmacology; D004343:Drug Implants; D004967:Estrogens / Q000008:administration & dosage / Q000494:pharmacology; D005247:Feeding Behavior / Q000502:physiology*; D005260:Female; D006128:Growth / Q000187:drug effects / Q000502:physiology; D006728:Hormones / Q000502:physiology*; D008297:Male; D011863:Radioimmunoassay; D012727:Sex Characteristics; D012919:Social Behavior; D012931:Social Environment; D013739:Testosterone / Q000008:administration & dosage / Q000494:pharmacology
chemical_list: D004343:Drug Implants; D004967:Estrogens; D006728:Hormones; D013196:Dihydrotestosterone; D013739:Testosterone