Natal and Breeding Dispersal of Razorbills (Alca torda) in Eastern North America

• Main Authors: Lavers, JL, Jones, IL, Diamond, AW
• Format: Article in Journal/Newspaper
• Language: English
• Published: Waterbird Soc 2007
• Subjects: Biological Sciences; Ecology; Ecology not elsewhere classified; Canada; Digges; Gannet Islands; Nunavut; Alca torda; Razorbill
• Online Access: https://doi.org/10.1675/1524-4695(2007)030[0588:NABDOR]2.0.CO;2; http://ecite.utas.edu.au/77907

Until recently, our understanding of the role of movement in animal populations was limited due toa prevalence of studies on single local populations. Here we report on local and regional movement patterns of Razorbill(Alca torda), the least numerous Atlantic alcid, through the use of multi-site capture-mark-recapture/resightfor five breeding locations spanning their entire North American breeding range. Razorbill philopatry and breedingsite fidelity rates for the Gannet Islands, Labrador were high with 83% of young birds (N = 340) and 97% of adults(N = 149) returning to the same colony to breed. The distance moved between the natal colony and the colonywhere an individual later bred was significantly greater for birds banded as chicks, both between colonies on thesame island and within islands in the Gannet Islands cluster.Regional movements of 40 banded individuals wererecorded during 2003-2006, including seven birds that were confirmed breeding at a location different from theirnatal colony. Emigration distances among colonies in North America ranged from 57 to 1,737 km, providing an unexpectedlyhigh rate of movement of birds between breeding colonies that has not been previously reported for anyauk species. One bird, banded as a chick on Digges Island, Nunavut in 1982 was recaptured 24 years later as a breederon the Gannet Islands (1,737 km away). A chick banded on Handa Island, Scotland in 1971 was seen four timesin 2004 at the Gannet Islands (3,210 km away). Despite exhibiting low productivity and survivorship, Razorbill populationsat some Atlantic Canada breeding sites have been increasing. We conclude that the dispersal and recruitmentof individuals into new colonies that are characteristic of other seabird species may also partly explain patternsof population dynamics at North American Razorbill colonies.Received 27 February 2007, accepted 09 October 2007.