Affiliation:
1. Z.B. Lockyer, D.J. Delehanty Department of Biological Sciences, Idaho State University, Pocatello, Idaho 83201
2. P.S. Coates, M.L. Casazza U.S. Geological Survey, Western Ecological Research Center, 6924 Tremont Road, Dixon, California 95620
3. S. Espinosa Nevada Department of Wildlife, Reno, Nevada 89512
4. Present address of Z.B. Lockyer: Idaho Department of Fish and Game, 1345 Barton Road, Pocatello, Idaho 83204
Abstract
Abstract
Greater sage-grouse Centrocercus urophasianus, hereafter sage-grouse, populations have declined across their range due to the loss, degradation, and fragmentation of habitat. Habitat alterations can lead not only to vegetative changes but also to shifts in animal behavior and predator composition that may influence population vital rates, such as nest success. For example, common ravens Corvus corax are sage-grouse nest predators, and common raven abundance is positively associated with human-caused habitat alterations. Because nest success is a central component to sage-grouse population persistence, research that identifies factors influencing nest success will better inform conservation efforts. We used videography to unequivocally identify sage-grouse nest predators within the Virginia Mountains of northwestern Nevada, USA, from 2009 to 2011 and used maximum likelihood to calculate daily probability of nest survival. In the Virginia Mountains, fires, energy exploration, and other anthropogenic activities have altered historic sage-grouse habitat. We monitored 71 sage-grouse nests during the study, placing video cameras at 39 nests. Cumulative nest survival for all nests was 22.4% (95% CI, 13.0–33.4%), a survival rate that was significantly lower than other published results for sage-grouse in the Great Basin. Depredation was the primary cause for nest failure in our study (82.5%), and common ravens were the most frequent sage-grouse nest predator, accounting for 46.7% of nest depredations. We also successfully documented a suite of mammalian and reptilian species depredating sage-grouse nests, including some predators never previously confirmed in the literature to be sage-grouse nest predators (i.e., bobcats Lynx rufus and long-tailed weasels Mephitis frenata). Within the high elevation, disturbed habitat of the Virginia Mountains, low sage-grouse nest success may be limiting sage-grouse population growth. These results suggest that management actions that restore habitat in the Virginia Mountains and decrease anthropogenic subsidies of ravens will benefit sage-grouse.
Publisher
U.S. Fish and Wildlife Service
Subject
Nature and Landscape Conservation,Animal Science and Zoology,Ecology,Ecology, Evolution, Behavior and Systematics
Cited by
29 articles.
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