Sea Ice Influences Habitat Type Use by Great Black-Backed Gulls (Larus marinus) in Coastal Newfoundland, Canada

Abstract

The influence of an unusual concentration of sea ice and breeding failure on the foraging movement patterns and habitat use of Great Black-backed Gulls (Larus marinus) was investigated. GPS loggers were deployed on three incubating females when multi-year sea ice moved into foraging ranges, dividing the tracking period (1–23 June 2017) into ice-free (5–10 days) and ice-present periods (11–12 days). Foraging trip parameters (e.g., distance, duration) differed among individuals but not with ice conditions. Great Black-backed Gulls decreased use of islands when ice was present (0.05 ± 0.08 locations/trip) relative to absent (5.9 ± 0.5 locations/trip), but increased use of marine habitat when ice was present (9.4 ± 0.2 locations/trip) relative to absent (2.9 ± 0.2 locations/trip). Great Black-backed Gulls also moved at higher speeds in areas of 91–100% ice cover relative to < 50% ice cover, suggesting that low percent cover sea ice acts as important at-sea foraging/roosting sites. Additionally, two Great Black-backed Gulls that were continuously tracked during post-breeding failure repeatedly visited the colony throughout July-August, suggesting some advantage to maintaining a presence at nest sites.