Partial migration pays off in black-faced cormorants: insights from post-breeding GPS tracking

• Published in: Marine biology 2024-11, Vol.171 (11), p.213, Article 213
• Main Authors: Cansse, Thomas, Lens, Luc, Orben, Rachael A., Sutton, Grace J., Botha, Jonathan A., Arnould, John P.Y.
• Format: Article
• Language: English
• Subjects: Animal breeding; Availability; Banding; Biomedical and Life Sciences; Bird migration; Birds; Breeding; Coasts; Data loggers; Environmental conditions; Food; Food availability; Food supply; Foraging; Foraging behavior; Foraging habitats; Freshwater & Marine Ecology; Global positioning systems; GPS; Habitat selection; Habitat utilization; Habitats; Life Sciences; Marine & Freshwater Sciences; Marine biology; Microbiology; Migrations; Ocean floor; Oceanography; Original Paper; Population studies; Populations; Prey; Seabirds; Seasonal variation; Seasonal variations; Spatial data; Weather patterns; Zoology
• ISSN: 0025-3162; 1432-1793
• DOI: 10.1007/s00227-024-04541-z

Seasonal variation in food availability or adverse weather patterns can create challenging conditions for year-round survival. Birds experiencing such fluctuations may migrate to locations with better food availability in the non-breeding period. While some species are obligate migrants, others are facultative migrants where various post-breeding strategies exist within populations. Several cormorant and shag species are facultative migrants with a range of post-breeding movement strategies within populations. Currently, most of the information available on cormorant post-breeding strategies originates from banding studies and little is known about their movements, time budget or habitat use during the non-breeding period. In the present study, Australian endemic black-faced cormorants ( Phalacrocorax fuscescens ), breeding on Notch Island, Victoria, were tracked with GPS data loggers during the non-breeding period. Different post-breeding strategies were observed. Individuals were either resident ( N  = 36, 69%), remaining within a short distance of the colony (16.7 ± 2.2 km) or migratory ( N  = 16, 31%), travelling greater distances (250.7 ± 24.4 km) to establish a new central place foraging location. Data from individuals which covered the entire non-breeding period indicated that, across strategies, individual birds had one area of residency during the non-breeding period. Migratory individuals were found to have lower daily activity levels, spending less time flying and foraging, than resident individuals during the early non-breeding period, possibly indicating that they had access to greater prey resources. Regardless of the post-breeding strategy, individuals utilised foraging locations that were of similar seabed depths year-round suggesting individual specialisation in prey resources or foraging habitats.