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

Abstract

Testosterone modulates male vertebrates' sexual and social behaviour. We experimentally investigated the testosterone-sensitive behaviours in male greylag geese (Anser anser) by implanting silastic tubes containing crystalline testosterone during the mating season (February; 5 implanted and 5 control males) and in the early winter (November; 7 and 7). Focal animals were part of a semi-tame, unrestrained flock with fully intact social relationships. Excreted testosterone and corticosterone immunoreactive metabolites (TM, BM) were determined by enzyme immunoassay. Individual faecal samples and behavioural protocols were collected daily over a period of 5 weeks, including 1 control week before implantation. In February, no significant behavioural effects of the supplemental testosterone were observed, which may be due to the naturally occurring high systemic androgen levels in spring. In November, however, implanted males had higher TM excretion rates and performed status signalling behaviour ("beak up") more frequently than control males. No differences between implanted and control males were found with respect to BM, agonistic interactions or vigilance behaviour. Furthermore, during the second week after implantation, TM positively correlated with the frequency of "beak up" of implanted males, whilst their female partners were attacked with lower latency by other members of the flock than the females of control males. Hence, status signalling in greylag ganders seems to be testosterone-sensitive year-long and "inappropriate" status signalling of males may draw attacks towards their females.

Comparison of different enzymeimmunoassays for assessment of adrenocortical activity in primates based on fecal analysis

“…However, the suitability of the assays for monitoring adrenocortical activity varied among species, and no one assay was applicable to all species. Specifically, whereas a cortisol assay is useful for tracking changes in glucocorticoid output in primates that excrete cortisol in clearly detectable amounts into the feces, our data also indicate that in species in which cortisol is nearly absent in the feces, group-specific assays provide a better option because they show a stronger signal response to treatment and thus have a higher biological sensitivity for detecting changes in glucocorticoid production [c.f., Frigerio et al, 2004;Möstl et al, 2005]. Since the group-specific assays also performed well in the other cercopithecoid and hominoid primate species tested, our data suggest that, at least in Old World primates, assays utilizing group-specific GC antibodies have a higher potential for cross-species application than more specific assays using antibodies designed to measure cortisol.…”

Social and environmental factors modulate leucocyte profiles in free-living Greylag geese (Anser anser)

“…Social context is known to be among the strongest modulators of the physiological stress responses in greylag geese (e.g., Wascher, Scheiber & Kotrschal, 2008; Wascher, Arnold & Kotrschal, 2008; Wascher et al , 2009; Kralj-Fiser et al, 2010), which in turn are alleviated via emotional social support by partners (Frigerio, et al , 2003; Scheiber et al , 2005; Scheiber, Kotrschal & Weiß, 2009; Wascher et al, 2012). Across seasons, males and females are faced with different demands (Kotrschal, Scheiber & Hirschenhauser, 2010); consequently, physiological changes, such as levels of corticosterone, co-vary with seasonal variation in behaviour (Hirschenhauser, Moestl & Kotrschal, 1999a; Hirschenhauser, Moestl & Kotrschal, 1999b; Frigerio et al, 2004a). The reproductive season of greylag geese starts in January.…”

Synthesis of Measuring Steroid Metabolites in Goose Feces

“…For example, the annual cycles of fecal sex steroids in greylag geese25,27 generally matched those of plasma in barheaded geese ( A. indicus ),28 and the seasonal patterns of fecal corticosterone were associated with social status and behavioral interactions 24,26. Also, androgen metabolite levels in males were affected by the winning of interactions and pair‐bond challenges during the breeding season,26 as predicted by the “challenge hypothesis.”29 And finally, implants of exogenous testosterone resulted in higher levels of androgen metabolites in the feces of adult males 30. Meanwhile, we have done more detailed analyses of short‐term hormonal responses to behavior and changes in the social environment 31–34.…”

“…29 And finally, implants of exogenous testosterone resulted in higher levels of androgen metabolites in the feces of adult males. 30 Meanwhile, we have done more detailed analyses of short-term hormonal responses to behavior and changes in the social environment. [31][32][33][34] Here, we aim to present a synthesis of the technical aspects of measuring steroids (particularly androgens and glucocorticoids) in goose feces.…”