POST BY: Andrew Alba
I have been fortunate to work closely with some of the best zoos in the country. I recently completed a Master’s thesis at the University of Missouri, during which I collaborated with 21 zoos and 2 conservation breeding facilities. The commitment to animal care and welfare, wildlife conservation, and scientific research I have observed at these facilities has been both encouraging and inspiring.
In particular, using science to monitor and enhance animal welfare, or the physiological and psychological well-being of animals, is a priority in many zoos1. A number of zoos have or are developing research programs or will partner with universities to scientifically evaluate animal welfare. Welfare monitoring can take many forms, but usually the most effective studies incorporate multiple parameters, including behavioral observations, endocrinology, environmental monitoring, and measures of reproductive success, among others.
A common strategy for evaluating animal welfare involves measuring glucocorticoid hormones as a proxy for stress2. Animals (and humans) have coping mechanisms that allow them to be challenged with short-term stress, but the biological cost of chronic stress can be considerable3. The stress response, which is mediated by the release of glucocorticoids4, can suppress reproduction, growth, and immune function if activated persistently5. Left unchecked, chronic stress can compromise animal welfare and preclude the establishment of self-sustaining populations3,6.
Welfare monitoring can be especially important for individuals of endangered species that are intended for reintroduction. For my Master’s project, I set out to determine if chronic stress is a contributor to challenges faced by the Guam kingfisher (Todiramphus cinnamominus) breeding program. Currently, several zoos are tirelessly committed to improving the conservation situation of the Guam kingfisher. This critically endangered species once occurred on Guam but now survives only in zoos and breeding facilities7, like the one pictured below. During World War II, the introduction of the brown tree snake (Boiga irregularis) devastated much of Guam’s avifauna8. As a last resort, 29 Guam kingfishers were captured to establish a founder population for breeding in the 1980s9. The program was initially successful, but high mortality and inconsistent reproduction began to impede population growth in the 1990s10.
My intent was to identify environmental conditions associated with stress in this species and use that information to guide management updates. I developed a noninvasive protocol to monitor corticosterone, the major glucocorticoid hormone of the avian stress response4, and related corticosterone with environmental conditions at each facility housing the birds. As an added facet, I also investigated breeding success in relation to stress. Once analyses are complete, I hope to identify best practices (i.e., those associated with stress levels of wild congeneric birds and high reproductive success) among the 23 facilities, and distribute results and recommendations to all facilities managing the birds. Implementation of stress-reducing techniques may enhance welfare of Guam kingfishers, leading to population growth and encouraging reintroduction success.
- Orban D, Freeman H, Wheaton C, Mellen J, Soltis J, Leighty K. 2015. Use of science to enhance animal welfare at Disney’s Animal Kingdom. World Association of Zoos and Aquariums Magazine 16:18–21.
- Sheriff MJ, Dantzer B, Delehanty B, Palme R, Boonstra R. 2011. Measuring stress in wildlife: Techniques for quantifying glucocorticoids. Oecologia 166:869–887.
- Moberg GP. 2000. Biological responses to stress: Implications for animal welfare. In: GP Moberg, JA Mench, editors. The biology of animal stress: Basic principles and implications for animal welfare. Wallingford, UK: CAB International. p. 1–21.
- Romero LM, Butler LK. 2007. Endocrinology of stress. Int J Comp Psychol 20:89–95.
- Charmandari E, Tsigos C, Chrousos G. 2005. Endocrinology of the stress response. Annu Rev Physiol 67:259–284.
- Ballou JD, Lees C, Faust LJ, Long S, Lynch C, Foose TJ. 2010. Demographic and genetic management of captive populations. In: Kleiman DG, Thompson K, Kirk-Baer C, editors. Wild mammals in captivity: Principles and techniques for zoo management. 2nd Edition. Chicago, IL: University of Chicago Press. p 219–252.
- Bahner B, Baltz A, Diebold E, editors. 1998. Micronesian kingfisher SSP husbandry manual. Philadelphia, PA: Zoological Society of Philadelphia. 54 p.
- Wiles GJ, Bart J, Beck REJ, Aguon CF. 2003. Impacts of the brown tree snake: Patterns of decline and species persistence in Guam’s avifauna. Conserv Biol 17(5):1350–1360.
- Haig SM, Ballou JD. 1995. Genetic diversity in two avian species formally endemic to Guam. Auk 112(2):445–455.
- Baltz AP. 1998. The assessment of reproductive potential in Micronesian kingfisher pairs. Zoo Biol 17:425–432.