Experimental Design
Omnivorous migratory songbirds undergo endurance flights biannually and many species switch to eating mostly berries that are rich in fats and antioxidants during their fall (post-breeding) migration (Alan et al. 2013, Bolser et al. 2013); thus, they are an ideal natural system to study how the endogenous antioxidant system responds to flight training, dietary antioxidants, and dietary fat. We used European Starlings (Sturnus vulgaris ) as representative songbirds for this study because they are abundant in the New World and Old World, are omnivorous and acclimate well to captivity and new diets, and have been successfully trained and flown in wind tunnels in other studies (Nebel et al. 2012, Hall et al. 2014, Casagrande et al. 2020, McWilliams et al. 2020). Hatch year European starlings were caught at a dairy farm 20 km north of the Advanced Facility for Avian Research (AFAR), University of Western Ontario, London, Ontario prior to fall migration in 2015 (August 19-23). Starlings from this southern Canada wild population are considered to be partial migrants as inferred by banding records (Cabe 1993). Starlings were housed in one of four large indoor aviaries at AFAR (two 2.4m x 3.7m x 3.1m and two 2.4m x 2.3m x 3.5m). On August 24th we measured morphological characteristics, body mass, and molt score (0 – 5; (Ginn and Melville 1983)) for each individual. Birds were then randomly sorted into four groups (Figure 1) with roughly equal distributions of body size and molt score. We maintained aviaries at 21°C on a natural light cycle from capture until the start of the experiment on September 21st when we fixed the light schedule at 11:13 L:D (day length on this date in London, Ontario). Upon capture and until the start of the experiment each week we weighed and inspected all birds to assess their health. All birds were cared for under animal care protocols for University of Western Ontario (2010-216) and the University of Rhode Island (AN11-12-009).