Abstract
Caribou (Rangifer tarandus) are nonindigenous to all but the eastern-most island of the Aleutian archipelago of Alaska. In 1958–1959, caribou were intentionally introduced to Adak Island in the central archipelago, and the population has at least tripled in recent years subsequent to the closure of a naval air facility. Although dispersal of caribou to adjacent islands has been suspected, no historical documentation has occurred to date. Herein, we report consistent detections of caribou sign on the adjacent island of Kagalaska over 2 summer field seasons (2010–2011), and visual detection of caribou on that island during the summer of 2011. Ecological impacts of caribou on Kagalaska are not strongly apparent at the present time and we do not know how many animals permanently occupy the island. However, establishment of a reproductively viable resident population on Kagalaska is worrisome and could set the stage for a step-wise invasion of additional nearby islands.
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Acknowledgments
This study was funded by the USFWS—Invasives with Volunteers Program (D. Jerry), with in-kind support from the USGS Western Ecological Research Center. Biologists with the USFWS Alaska Maritime National Wildlife provided invaluable logistical support and expert knowledge, especially L. Spitler and S. Ebbert. We thank K. Ramey for outstanding field work in 2010, and J. Estes and T. Tinker for granting use of their Boston Whaler. Discussions with D. van Vuren were particularly helpful. We thank K. Miles, and two anonymous referees for helpful reviews on previous manuscript drafts. Mention of trade names does not imply endorsement by the US Government.
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Ricca, M.A., Weckerly, F.W., Duarte, A. et al. Range expansion of nonindigenous caribou in the Aleutian archipelago of Alaska. Biol Invasions 14, 1779–1784 (2012). https://doi.org/10.1007/s10530-012-0195-z
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DOI: https://doi.org/10.1007/s10530-012-0195-z