A Study of Grassland Bird Nest Success Rates on Small Family Farm Hayfields

• Activity Number: 254
• Type: Contributed
• Date/Time: Monday, August 4, 2014 : 2:00 PM to 3:50 PM
• Sponsor: Section on Statistics and the Environment
• Author(s): Ivan Ramler*+ and Susan Willson and Caitlin Ward
• Companies: St. Lawrence University and St. Lawrence University and St. Lawrence University
• Keywords: Applied Statistics ; Ecology ; Ornithology ; Small Sample Size ; Statistical Modeling

Abstract

Industrial agricultural practices demand earlier and more frequent mowing of hay fields, which creates a poor habitat for grassland-nesting birds and is a major contributor to significant population declines in New York State. Nest success rates (NSR) for grassland birds on intensively managed farms have been reported at 0%, but no studies have assessed the effects of small farm mowing practices on grassland birds. To address this, we conducted a small study from 2010 - 2012 in the agricultural landscape on grassland plots typically hayed via small tractor or horse power in Northern New York. We provide a novel modeling approach that makes use of a sliding temporal scale to estimate NSR based on the date of haying. Based on the model, we provide suggestions for haying dates that would minimize avian nestling mortality; in particular, we recommend that farmers avoid haying in June, when most grassland birds will have active nests. As many farmers hay twice over a summer, we suggest an early hay in May, and a second hay after late July. While any haying generally increases nestling mortality, keeping to these guidelines helps keep their impact as small as possible.