title: Testosterone elevation and response to gonadotropin-releasing hormone challenge by male northern cardinals (Cardinalis cardinalis) following aggressive behavior.
abstract: There is much discrepancy about the relationship between testosterone (T) and male aggressive behavior. For example, in birds, males of many species significantly elevate T levels during inter-male conflict. However, this is not universal, and in species where males typically do not elevate T during aggressive interactions, concentrations of the hormone are often assumed to be circulating at maximum levels. We examined if male northern cardinals (Cardinalis cardinalis) significantly elevated T during simulated territorial intrusions (STIs). We also examined if individuals had the capacity to further elevate T levels in response to gonadotropin-releasing hormone (GnRH) injections immediately after an aggressive encounter. Our results indicate that male cardinals do not significantly elevate T levels in response to STIs, but have the physiological capacity to significantly elevate T in response to GnRH injections following aggressive interactions. This implies that T levels of individuals captured during STIs were not at maximum concentrations. However, additional findings in this study also suggest the possibility that prolonged social instability could elicit significant elevations in T in males of this species, warranting further investigation.
authors.affiliation: Department of Biological Sciences, The University of Southern Mississippi, 118 College Drive # 5018, Hattiesburg, MS 39406, USA. Margaret.Devries@eagles.usm.edu
authors.forename: M Susan
authors.initials: MS
authors.lastname: DeVries
authors.forename: Caitlin P
authors.initials: CP
authors.lastname: Winters
authors.forename: Jodie M
authors.initials: JM
authors.lastname: Jawor
mesh_terms: D000374:Aggression / Q000187:drug effects* / Q000502:physiology*; D000818:Animals; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology / Q000502:physiology*; D008297:Male; D046109:Passeriformes / Q000097:blood / Q000502:physiology*; D013731:Territoriality; D013739:Testosterone / Q000097:blood* / Q000502:physiology
chemical_list: D007987:Gonadotropin-Releasing Hormone; D013739:Testosterone