Individual behavior and housing setup interact to influence markers of welfare in the critically endangered Hawaiian crow

While some stress can be beneficial for survival, identifying drivers of detrimental stress is essential for improving animal welfare and reproductive outcomes in conservation breeding programs. We examined the interaction between housing and behavioral indicators of temperament, both of which may explain variability in markers of positive and negative (stress) welfare in a critically endangered bird, the ‘alalā (Hawaiian crow; Corvus hawaiiensis). During the 2019 breeding season, we collected behavioral data, including markers of negative welfare (e.g. alarm calling and pace flying), positive welfare (e.g. foraging and preening), and four temperament-like traits (aggression, social connectedness, restfulness, and shy/boldness), on 26 mated pairs engaged in varying breeding stages at a conservation breeding center in Hawaiʻi. All pairs were housed in one of two housing setups: 1) a two-compartment, "breeding" aviary (predicted to be less stressful due to relative seclusion and single-pair occupancy) or, 2) a > 2 compartment “holding” aviary, used to house pairs immediately adjacent to other 'alalā (predicted to be more stressful for 'alalā due to the close proximity of others and the territorial nature of the species). Regardless of housing, we observed lower rates (per min) of positive welfare behaviors in incubating and parent-rearing than non-breeding individuals. However, when we examined the interaction of housing and temperament-like traits, the welfare outcomes were more nuanced. Birds in highly compatible pairs (regardless of enclosure) and, surprisingly, birds in more crowded aviaries (regardless of temperament) exhibited higher rates of positive welfare behaviors. Moreover, non-restful birds had higher mean positive welfare rates when housed in holding aviaries. Although not of primary interest in our study, we also found that average positive welfare behaviors increased over time (across repeated observations on each pair), which were largely associated with the presence or absence of rainfall. Following these results, we recommend future studies in which non-restful and highly compatible ‘alalā pairs are relocated to holding aviaries, as this may increase overall welfare of the breeding population. Additionally, where possible, we recommend future studies control for weather when conducting behavioral observations. Overall, our findings underscore the importance of accounting for differences in behavior among individuals when examining the impact of housing on animal welfare in conservation breeding facilities.