Research Article Handling Stress of Female Common Eiders During Avian Cholera Outbreaks E. ISABEL BUTTLER, 1 Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, Canada K1S 5B6 H. GRANT GILCHRIST, National Wildlife Research Centre, Environment Canada, 1125 Colonel By Drive, Raven Road, Carleton University, Ottawa, ON, Canada K1A 0H3 SE ´ BASTIEN DESCAMPS, 2 Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, Canada K1S 5B6 MARK R. FORBES, Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, Canada K1S 5B6 CATHERINE SOOS, Environment Canada, 115 Perimeter Road, Saskatoon, SK, Canada S7N 0X4 ABSTRACT Researchers often consider the importance of minimizing holding time during research activities; however, the long-term costs of such handling stress is rarely measured explicitly. As part of an ongoing study of common eiders (Somateria mollissima) at a breeding colony in East Bay, Southampton Island, Nunavut, we recorded duration of restraint for females captured during avian cholera epizootics (2007 and 2008) and monitored female fates (breeding probability, onset of laying, and survival) relative to holding time. Probability of death increased with holding time in 2007 from an estimated 0.05 for females held 20 min to 0.33 for females held for 150 min. In 2008, we responded by limiting holding time to <90 min and mortality was no longer positively correlated with holding time, although total mortality was greater due to increased severity of avian cholera. In both years, longer restraint durations delayed onset of egg-laying after capture by 0.5 days for each 10 min of additional restraint but did not prevent breeding. This delay of nest initiation did not enhance survival probability. Our results show that prolonged holding time can exacerbate mortality during epizootics and emphasize the importance of minimizing restraint time in wild birds, especially in the presence of diseases. ß 2011 The Wildlife Society. KEY WORDS Arctic, avian cholera, breeding onset, common eider, disease mortality, epizootic, handling stress, Pasteurella multocida, Pasteurellosis, Somateria mollissima. Animal research often requires temporary handling of the study animal, yet handling induces a physiological stress response that increases with duration of each handling episode (e.g., Wingfield et al. 1995). Long-term consequences of this stress are often considered but are rarely quantified (van Oers and Carere 2007). Mounting a stress response is thought to be energetically costly and may lead to a trade-off with other energetically costly functions (Sheldon and Verhulst 1996, Nelson et al. 2002; also see Ra ˚berg et al. 1998). Indeed, stress is known to reduce immune function and is thought to result in suppression of costly behaviors such as breeding (Dhabhar and McEwen 1997, Wingfield et al. 1998, Sapolsky et al. 2000, Nelson et al. 2002). These detrimental effects of stress on physiology and behavior can be long lasting (Sapolsky et al. 2000, van Oers and Carere 2007) and are thought to play an important role in determining dynamics of diseases in the wild (McEwen et al. 1997; see also Botzler 1991). To our knowledge, effects of stress (or quantifiable surrogates) on the survival and fitness of birds in the presence of a disease have not been examined in the wild. One of the most important diseases occurring among North American waterfowl is avian cholera, which is caused by the highly contagious bacterium Pasteurella multocida (Friend 1999; review in Samuel et al. 2007). Even though strains of P. multocida that cause explosive outbreaks are highly virulent, some birds successfully fight infection (Reed and Cousineau 1967, Harper et al. 2006). Common eiders (Somateria mollissima) nesting colonially on a small island in East Bay, Southampton Island, Nunavut, Canada, have experienced confirmed annual avian cholera epizootics since 2005. Due to its immunosuppressive effect, stress caused by handling may augment disease susceptibility and mortality among eiders, particularly among breeding individuals (see also Descamps et al. 2009). The energetic or immunosuppressive cost of a stress episode such as handling may be reduced if it results in a delay of egg-laying that allows females to recover from the stress event (Wingfield et al. 1998, Salvante and Williams 2003). In the presence of a contagious disease, handling stress may even enhance a female’s survival if, in response to hand- ling, she skips breeding and leaves the colony and is thus less exposed to the pathogen (Wingfield et al. 1998; see also Lancaster et al. 2008). Due to annually recurring disease mortality, the East Bay colony constitutes an ideal system to address the question of whether acute stress experienced prior to nest initiation increases the probability of mortality from avian cholera or causes females to delay or curtail breeding. We examined the impact of handling stress on breeding propensity, nest initiation date, and the ability of an indi- vidual female to survive disease exposure over time. We examined whether prolonged handling time caused females Received: 3 April 2009; Accepted: 13 June 2010 1 E-mail: isabel.buttler@gmail.com 2 Present Address: Norwegian Polar Institute, Polar Environmental Center, 9296 Tromsø, Norway. Journal of Wildlife Management 75(2):283–288; 2011; DOI: 10.1002/jwmg.38 Buttler et al.  Effects of Handling on Breeding Female Eiders 283