Give a Hoot: evaluating population augmentation efforts of the Western Burrowing Owl (Athene cunicularia hypugeae) in Canada

Abstract

Migratory animals are a growing conservation concern and present unique challenges to population augmentation programs. Quantitatively evaluating and monitoring augmentation efforts is critical for conservation success. My research formally evaluated the success of two Western Burrowing Owl (Athene cunicularia hypugaea) population augmentation programs in Manitoba and British Columbia using survival, recruitment, and reproduction. Manitoba’s headstarting program holds hatching year (HY) owls overwinter taken from the nests of previous captive-released pairs. After being overwintered in human care, the HY owls are released in pairs as second year (SY) owls. British Columbia has a breeding and release program where owls are bred in facilities; their offspring are then held overwinter, paired and soft-released in the spring. Both programs soft-release SY pairs that lay clutches in the wild and young are referred to as “wild-hatched owls”. In British Columbia, wild-hatched owls returned significantly more than captive-released (ß = 1.05±0.29, p < 0.001). Holding animals overwinter may hinder accurate migratory behaviour. Fewer owls returned to release sites with more cropland (p = 0.049). Releases should be prioritized at sites with low percentages of cropland. Interestingly, individuals who returned from migration to form pairs and breed had significantly higher reproductive success than captive-released pairs (p < 0.001), suggesting effects of survivor-bias or mate choice. My thesis has identified opportunities to implement research with a priori hypotheses and data-driven management directions for the conservation of Burrowing Owls in Canada.