Effects of physiological and social challenges in different seasons on fecal testosterone and corticosterone in male domestic geese ( Anser domesticus )

Abstract

We investigated the reliability of the non-invasive approach of measuring steroid hormones from feces in the domestic goose (Anser domesticus), a mainly herbivorous bird with a short gut passage time (2-3 h). Groups of eight outdoor-housed male domestic geese were subjected to three different experiments, injection of either GnRH analogue or ACTH, or "social stimulation" by confrontation with two alien males or females. These experiments were replicated in three different seasons, in spring, during peak reproductive activity, in summer, during long-day photorefractoriness and postnuptial molt, and in fall, during sexual reactivation. GnRH stimulation resulted in significant increases of mean response and peak fecal testosterone metabolites (TM) in spring and fall. Response TM concentrations excreted in spring were generally higher than in summer and fall. Social confrontation with two females, but not with two males, increased mean and peak TM in all seasons. In general, ACTH treatment resulted in a proportionally higher increase of fecal corticosterone metabolites (BM) than GnRH did in fecal TM (80-to 140-fold vs 6-to 8-fold). ACTH significantly increased mean and peak BM in all seasons. Social confrontation with two males significantly increased fecal BM in spring, but confrontation with two females increased fecal BM in fall. Our results indicate that determining steroids from feces is a generally valid approach. However, the sensitivity of the method may vary between different hormones and results may differ between seasons. BM results seemed more sensitive and seasonally robust than did TM.

Experimentally elevated testosterone increases status signalling in male Greylag geese (Anser anser)

“…However, in agreement with other studies (Bishop and Hall 1991;Cockrem and Rounce 1994;Palme et al 1996), experiments with domestic geese showed deterministic relationships between plasma steroids and metabolites in the faeces (Hirschenhauser et al 2000a;Kotrschal et al 2000). Therefore, we are confident that our faecal BM and TM levels are representative for plasma corticosterone and T within 2-3 h before defecation.…”

“…The system was probably saturated at the receptors' level and additional T did not produce any further effect (Hutchison 1976;Beletsky et al 1990;Groothuis and Meeuwissen 1992). This is even more remarkable, as steroid excretion seems to be more efficient in spring than in autumn (Kotrschal et al 2000). We assume that there may also have been more carrier protein, which could have buffered additional T and would have made circulating T inert to inactivation and excretion.…”

“…The time span corresponds to the expected peak of steroid excretion following a physiological or behavioural challenge in geese (Krawany 1996;Hirschenhauser et al 2000a;Kotrschal et al 2000). Sampling was timed to avoid the early morning peaks of adrenal activity (Schütz et al 1997;Rich and Romero 2001;Carere et al 2003).…”

Heart rate modulation in bystanding geese watching social and non-social events

“…In group-living animals, social interactions may have pronounced effects on individuals' subsequent behaviour (de Waal & Yoshihara 1983;Black & Owen 1989;Briffa & Elwood 2001) and physiology ( Hack 1997;Otten et al 1997;Kotrschal et al 2000;Briffa & Elwood 2005). Social interactions affect not only individuals actively involved but also individuals that observe an interaction (bystanders).…”

Early social influence on nestling development in Waldrapp ibis (Geronticus eremita)

“…One week before and 1 week after the nestlings were placed together, fecal samples were collected daily from individuals to determine excreted corticosterone metabolites by enzyme-immunoassay (EIA). Corticosterone metabolites were analyzed by EIA, as described by Kotrschal et al [1998] and evaluated by Hirschenhauser et al [2000] and Kotrschal et al [2000].…”