Factors influencing nest survival and productivity of Red-throated Loons (Gavia stellata) in Alaska

The Condor
By: , and 

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Abstract

Red-throated Loon (Gavia stellata) numbers in Alaska have fluctuated dramatically over the past 3 decades; however, the demographic processes contributing to these population dynamics are poorly understood. To examine spatial and temporal variation in productivity, we estimated breeding parameters at 5 sites in Alaska: at Cape Espenberg and the Copper River Delta we estimated nest survival, and at 3 sites within the Yukon-Kuskokwim Delta we estimated nest survival and productivity. Nest survival varied broadly among sites and years; annual estimates (lower, upper 95% confidence interval) ranged from 0.09 (0.03, 0.29) at Cape Espenberg in 2001 to 0.93 (0.76, 0.99) at the Copper River Delta in 2002. Annual variation among sites was not concordant, suggesting that site-scale factors had a strong influence on nest survival. Models of nest survival indicated that visits to monitor nests had a negative effect on nest daily survival probability, which if not accounted for biased nest survival strongly downward. The sensitivity of breeding Red-throated Loons to nest monitoring suggests other sources of disturbance that cause incubating birds to flush from their nests may also reduce nest survival. Nest daily survival probability at the Yukon-Kuskokwim Delta was negatively associated with an annual index of fox occurrence. Survival through the incubation and chick-rearing periods on the Yukon-Kuskokwim Delta ranged from 0.09 (0.001, 0.493) to 0.50 (0.04, 0.77). Daily survival probability during the chick-rearing period was lower for chicks that had a sibling in 2 of 3 years, consistent with the hypothesis that food availability was limited. Estimates of annual productivity on the Yukon-Kuskokwim Delta ranged from 0.17 to 1.0 chicks per pair. Productivity was not sufficient to maintain population stability in 2 of 3 years, indicating that nest depredation by foxes and poor foraging conditions during chick rearing can have important effects on productivity.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Factors influencing nest survival and productivity of Red-throated Loons (Gavia stellata) in Alaska
Series title The Condor
DOI 10.1650/CONDOR-14-25.1
Volume 116
Issue 4
Year Published 2014
Language English
Publisher Cooper Ornithological Society
Contributing office(s) Alaska Science Center Biology WTEB
Description 14 p.
First page 574
Last page 587
Country United States
State Alaska
Other Geospatial Cape Espenberg, Copper River Delta, Yukon-Kuskokwim Delta
Online Only (Y/N) N
Additional Online Files (Y/N) N
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