Effects of visiting black brant nests on egg and nest survival

Journal of Wildlife Management
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Abstract

I used 2 methods to evaluate the effect of visiting black brant (Branta bernicla nigricans) nests on survival of whole nests and eggs in a single colony on the Yukon-Kuskokwim Delta, Alaska. The first technique regressed survival of nests or eggs during a time interval against interval length. Departure of the y-intercept from 1.0 estimated the short-term effect of the visit at the beginning of the interval. The y-intercepts (±95% CI) for whole nests and eggs during the egg laying period were 1.11 ± 0.31 and 1.06 ± 0.31, respectively. During incubation the same 2 parameters were 0.66 ± 0.31 and 0.66 ± 0.33. The regression method was, thus, imprecise and failed to discriminate among widely varying potential impacts of visitors. The second method involved visiting nests and then immediately revisiting them after pairs had returned to their territories. This method estimated loss of eggs as a result of displacement of territorial pairs during the first visit. Only 1 of 50 eggs was lost (n = 27 nests) as a result of visits during egg laying, whereas no eggs were lost (n = 225 eggs and 55 nests) owing to visits during the incubation period. I conclude that the regression approach is an imprecise tool for estimating visitor impact, but results from both methods indicate little effect of nest visitation under conditions existing on the colony I studied.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Effects of visiting black brant nests on egg and nest survival
Series title Journal of Wildlife Management
DOI 10.2307/3809655
Volume 54
Issue 3
Year Published 1990
Language English
Publisher Wiley
Contributing office(s) Alaska Science Center
Description 7 p.
First page 437
Last page 443
Country United States
State Alaska
Other Geospatial Tutakoke River, Yukon-Kuskokwim Delta