Satellite-tracking provides first description of migration in Tasmanian Boobooks Ninox leucopsis

Avian migration exposes birds to a suite of threats across breeding and non-breeding grounds and within migratory corridors. Consequently, research describing migratory behaviours, including phenology and spatial patterns, has important implications for wildlife management and conservation. Tasmanian Boobooks Ninox leucopsis are widely speculated to be partial migrants, with a subset of the population thought to winter in mainland Australia. Despite strong circumstantial evidence, including apparent staging on headlands in Victoria prior to anticipated southward migration, large-scale movement in this species remains unconfirmed. We reviewed occurrence records of Tasmanian Boobooks from mainland Australia to demonstrate a pattern of seasonal occurrence, with all verifiable records (n = 140) occurring predominantly in winter. We then captured five Tasmanian Boobooks on Victorian headlands, verified their species identity through molecular screening, and used satellite- and GPS-tracking to demonstrate their migration. Three of these birds were tracked for the entirety of their journey across Bass Strait. Migration journeys were each completed in an overnight, direct flight. GPS tracks showed that these owls settled around Tasmania’s central highlands, and point to a possible altitudinal element to their migration, with relatively harsh climatic conditions in montane regions (>450 m altitude) during winter as a possible driver. This evidence from tracking and genetic sampling indicates that Tasmanian Boobooks are partial migrants. Our results have direct implications for understanding a key avian flyway across Bass Strait. These findings underscore an urgent need to better understand this flyway, given anthropogenic modifications to this system, including impending development of offshore wind infrastructure.