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Predators of Dusky Canada Goose goslings and the effect of transmitters on gosling survival

Journal of Field Ornithology

By:
, , , and
DOI: 10.1111/j.1557-9263.2008.00191.x

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Abstract

The population of Dusky Canada Geese (Branta canadensis occidentalis) has been in long-term decline, likely due to reduced breeding productivity. To identify causes of mortality, we monitored goslings marked with radio transmitters on the western Copper River Delta, Alaska, from 1997 to 1999. Almost all gosling mortality (96%; 81 of 84) was due to predation, with mink (Mustela vison) and Bald Eagles (Haliaeetus leucocephalus) the most important predators. Bald Eagles are also major nest predators and, thus, appear to play a key role in limiting the breeding productivity of Dusky Canada Geese. Daily survival rate for goslings to 28 d of age was lower (0.011; 95% CI 0.002-0.024) for those with transmitters than for those without, but did not differ for older goslings (29-45 d). Although finer resolution in the timing of the transmitter effect within the first 28 d was not possible, we found that, by limiting our sample to goslings that survived until after 2-3 d posthatching, support for a transmitter effect was much reduced. Younger, smaller birds are inherently more vulnerable than older birds to transmitter effects. In addition, the process of radio-marking may have delayed the departure of goslings from nests and increased their risk of mortality shortly after hatching. Although radio transmitters may often be the only practical means for determining causes of mortality for young waterfowl, we suggest caution in using transmitters because of their potential negative effects, particularly during the first few days after hatching. ?? 2008 Association of Field Ornithologists.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Predators of Dusky Canada Goose goslings and the effect of transmitters on gosling survival
Series title:
Journal of Field Ornithology
DOI:
10.1111/j.1557-9263.2008.00191.x
Volume
79
Issue:
4
Year Published:
2008
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Field Ornithology
First page:
399
Last page:
407
Number of Pages:
9