Captive management, stress, and reproduction in the Guam kingfisher

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] As a strategy for recovering imperiled species in the wild, captive breeding has achieved measured success. Specifically, captivity often involves sources of stress that can cause unfavorable conditions, including inhibition of growth, immunity, and reproduction. High stress may be a factor in the limited success of the breeding program for Guam kingfishers (Todiramphus cinnamominus). We investigated how stress, as evidenced by corticosterone in feathers, in Guam kingfishers was related to reproduction and captive conditions. Current techniques for measuring corticosterone present challenges and limitations. Therefore, we first developed and validated an alternative protocol for extracting and measuring corticosterone from feathers. We then compared corticosterone of captive birds with that of wild congeneric kingfishers, and we compared corticosterone to breeding success in captive kingfishers. Next, we developed models to examine the effect of captive conditions on corticosterone in Guam kingfishers. Results indicated that corticosterone of captive and wild kingfishers did not differ. Reproductively successful male Guam kingfishers had lower corticosterone than unsuccessful males, but we found no evidence of an effect on breeding in females. Finally, models indicated that variables related to climate and enclosure size affected corticosterone in the birds. Using these results, we provide a discussion of how management might be altered to reduce stress in the kingfishers. We hope that implementation of new techniques will improve breeding.