The role of temperature and microclimate in the survival of wintering grassland birds

Avian Conservation and Ecology

article

Denis J. Pérez-Ordoñez¹  Mieke Titulaer¹  Maureen D. Correll³  Erin H. Strasser⁴  Fabiola Baeza-Tarin¹  Russell L. Martin⁵  Louis A. Harveson¹ 

[1] Borderlands Research Institute, Sul Ross State University;Universidad Autónoma de Chihuahua;U.S. Fish and Wildlife Service;Bird Conservancy of the Rockies;Texas Parks and Wildlife Department

关键词: Baird's Sparrow;    Chihuahuan Desert;    Grasshopper Sparrow;    thermal refuge;    winter survival;   

DOI  :  10.5751/ACE-02010-170101

学科分类：口腔科学

来源: Resilience Alliance Publications

【 摘 要 】

Over the past 40 years, grassland birds have declined steeply in North America, necessitating the study of limiting factors throughout their full annual cycle to mitigate this decline. Here we explored factors that may influence winter survival of two grassland specialist birds with steep declines; Baird's Sparrow (Centronyx bairdii) and Grasshopper Sparrow (Ammodramus savannarum200 individuals of both species combined, and tracked them daily from mid-December to mid-March. We estimated ground cover in a 5 m radius circular plot for ≥ 20 locations per individual. We also placed temperature loggers at 40 bird points (of both species combined) and 40 random points to measure microclimate used by these birds. We then estimated winter survival probability using logistic-exposure and used general linear models to evaluate the relationship of ambient temperature and habitat covariates with survival. Winter survival over an 85 day period was lower for Grasshopper Sparrow than Baird's Sparrow (three-year mean = 65.92% and 85.54%, respectively), and ranged from 47% to 100% for both species. We found that minimum ambient temperature was the main factor limiting survival of sparrows. Microclimate temperatures were higher in bird locations compared to random locations and were warmer in shrub cover and tall grass than short grass or litter. These results indicate that microclimate may be important to sparrows on the wintering grounds and highlight the value of habitat structure for providing thermal refuges. Our results emphasize the need to maintain vegetative cover for grassland birds to protect against harsh weather conditions that may limit their survival.

【 授权许可】

CC BY