Estimating regional population size and annual harvest intensity of the sooty shearwater in New Zealand |
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Authors: | Jamie Newman Darren Scott Corey Bragg Sam McKechnie Henrik Moller David Fletcher |
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Affiliation: | 1. Centre for the Study of Agriculture, Food and Environment , University of Otago , PO Box 56, Dunedin, 9054, New Zealand;2. 30 Hill Road Purakanui, Dunedin, 9081, New Zealand;3. Centre for the Study of Agriculture, Food and Environment , University of Otago , PO Box 56, Dunedin, 9054, New Zealand E-mail: henrik.moller@otago.ac.nz;4. Department of Mathematics and Statistics , University of Otago , PO Box 56, Dunedin, 9054, New Zealand |
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Abstract: | Abstract Recent comprehensive survey data from multiple New Zealand offshore islands were combined with demographic population models to produce the first formal estimate of the total population of sooty shearwaters within New Zealand territory. We estimated the total population over 1994–2005 to be 21.3 (19.0–23.6) million individual birds in the New Zealand region. This population consisted of 12.8 (12.0–13.6) million adults, 2.8 (2.5–3.1) million chicks, and 4.4 (4.2–4.7) million breeding pairs. Breeding sooty shearwaters were concentrated primarily around the southern islands of New Zealand, with 53% breeding in the Titi Islands surrounding Rakiura (Stewart Island). Rakiura Maori muttonbirders were estimated to harvest 360 000 (320 000–400 000) sooty shearwaters per year, equivalent to 18% of the chicks produced in the harvested areas and 13% of chicks in the New Zealand region. Overall, 11% of the chicks within the Titi Islands live on unharvested ground. Systematic and widespread surveys of breeding colonies in South America are needed before a reliable global sooty shearwater population estimate can be calculated. |
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Keywords: | harvest intensity population size population structure sooty shearwater sustainability |
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