Characteristics of fields used by birds in winter in New York

Abstract

Populations of birds utilizing open fields have been declining for decades in North America. Research has primarily focused on these species during the breeding season, however, while wintering distribution and habitat selection are understudied. Research during the nonbreeding season may be especially important in northeastern North America where reforestation is reducing the amount of open-field habitat. In this study, we examined how the abundance of Snow Buntings (Plectrophenax nivalis) and Horned Larks (Eremophila alpestris) varied between agricultural fields of different cover types and sizes during the nonbreeding season. We conducted repeated transect surveys in 9 fields with different crop residues (stubble), a one-time rapid survey of 99 fields of varying sizes and agricultural uses, and an analysis of eBird data examining the presence or absence of our focal species across New York State. The repeated transect surveys revealed that both Snow Buntings and Horned Larks were more likely to be detected in corn stubble fields compared to pasture and hay fields. The rapid survey revealed no difference in the detection of Snow Buntings related to cover types or field size, although no buntings were detected in fields <8 acres (3.24 ha). More Horned Larks were detected in corn and soy fields than in all types of grass fields, and more were detected in larger fields than in smaller fields. The analysis of eBird data revealed that likelihood of occurrence for both species increases with the increasing percentage of open habitat in the surrounding landscape (500 m radius). This study highlights the importance large field complexes where corn and other agricultural stubbles provide habitat and presumably greater food resources for open-field birds in winter.