Evaluating the role of caretaker-rated personality traits for reproductive outcomes in a highly endangered Hawaiian corvid

Personality studies are increasingly relevant and applicable to a broad range of conservation issues, including a role for selecting compatible mates in conservation breeding programs (CBPs). Choosing compatible breeding pairs is essential for maximizing reproductive success in CBPs, which provide assurance populations for species facing extinction and candidates for translocation to support wild populations. We investigated the value of caretaker-assessed personality ratings of the critically endangered ‘Alalā (Hawaiian Crow, Corvus hawaiiensis) in predicting reproductive outcomes: nest quality, fertile egg production, and hatchability in the ‘Alalā CBP. Caretakers used well-defined operational definitions to rate 22 personality traits for 69 male and 59 female ‘Alalā, achieving high inter-rater agreement (ICC ≥ 0.85) for 8 traits – aggressive, bold/fearless, fearful, imprinted/abnormal, inept, submissive, territorial, and tendency to feather pluck (a stereotypic behavior) – used in a principal components analysis to distill intercorrelated variables into three principal components. While we did not find that personality influences nest quality or hatchability (based on limiting inferences to fixed effects with high relative importance scores; ≥0.8), we found some evidence that pairs with males that were more territorial/aggressive and fearful than their mates had a higher probability of egg fertilization, but there was substantial variability in this relationship, with confidence intervals overlapping zero. These personality traits may influence pair dynamics, enhancing compatibility, may predict better pair coordination on the nest, or both. Our results highlight the ability of caretakers to successfully identify ‘Alalā personality traits and provide some support for integrating personality into the pairing process; however, further research is needed to understand the value of ‘Alalā personality as a mate selection tool. The application of similar approaches to enhance CBP performance in other taxa is promising, but will require overcoming methodological challenges surrounding the complexity of data collection and interpretation of consistency among raters.