“…As such, social costs should be considered in future studies examining trade-offs between ornamentation and fecundity (Fitzpatrick et al, 1995) because, as my results show, social costs of possessing ornamental traits may also lower female reproductive success. Whether such costs translate into lower offspring quality remains to be tested, but correlative studies in tree swallows suggest that females that are more ornamented, and presumably of higher quality Bentz and Siefferman, 2013), produce offspring of lower quality (Coady, 2011;Bentz and Siefferman, 2013). Moreover, interactions with conspecifics may increase social instability resulting in elevated levels of the stress hormone corticosterone (Haller et al, 1999), which may also explain why more ornamented female tree swallows have greater levels of nest parasitism, poorer immune defences, and lower hematocrit levels (Coady, 2011;Bentz and Siefferman, 2013).…”