Effects of land-based light pollution on two species of burrow-nesting seabirds in Newfoundland and Labrador, Canada

This study examines the occurrence and underlying factors of onshore strandings of two species of seabirds breeding in Newfoundland and Labrador, Canada. Atlantic Puffins (Fratercula arctica) are found stranded in coastal communities bordering the Witless Bay Ecological Reserve in artificially lit areas. Between 2011 and 2020, 3845 recently fledged puffins were found during nightly searches. Counts of puffins found per night were related to the phase of the moon, with the fewest birds found around the full moon. Mean annual body mass of pufflings was positively associated with annual recovery rates, providing a non-intrusive approach to monitor inter-annual productivity at the colony. Using two approaches to estimate population impacts of strandings, we estimate that < 0.2% of fledging chicks were attracted to lights emitted from coastal communities. Despite bordering two of the largest Leach's Storm-Petrel (Oceanodroma leucorhoa) colonies in Newfoundland, this species was rarely observed stranded in the Witless Bay area. Rather, most of the 1903 stranded storm-petrels reported in 2018 and 2019 were found on industrial properties bordering, or inland of, Conception Bay, at minimal distances of 25 km inland from the Witless Bay Ecological Reserve. Most storm-petrels were recently fledged juveniles. Strandings were less likely to occur around the full moon. Neither strong nor persistent winds were observed during nights of large stranding events, however, these nights tended to have winds coming from the north, suggesting that stranded storm-petrels fledged from Baccalieu Island, located at the mouth of Conception Bay and hosting the largest colony in the world. Stronger mitigation measures to avoid and minimize light emittance, as well as research investigating light characteristics to reduce attraction, are urgently needed to decrease unnecessary strandings, particularly for the Leach's Storm-Petrel, recently assessed as Threatened by the Committee on the Status of Endangered Wildlife in Canada