Breeding Biology of Grassland Birds in Western New York: Conservation and Management Implications

Declining grassland breeding bird populations have led to increased efforts to assess habitat quality, typically by estimating density or relative abundance. Because some grassland habitats may function as ecological traps, a more appropriate metric for determining quality may be breeding success. Between 1994 and 2003 we gathered data on the nest fates of Eastern Meadowlarks (Sturnella magna), Bobolinks (Dolichonyx oryzivorous), and Savannah Sparrows (Passerculus sandwichensis) in a series of fallow fields and pastures/hayfields in western New York State. We calculated daily survival probabilities using the Mayfield method, and used the logistic-exposure method to model effects of predictor variables on nest success. Nest survival probabilities were 0.464 for Eastern Meadowlarks (n = 26), 0.483 for Bobolinks (n = 91), and 0.585 for Savannah Sparrows (n = 152). Fledge dates for first clutches ranged between 14 June and 23 July. Only one obligate grassland bird nest was parasitized by Brown-headed Cowbirds (Molothrus ater), for an overall brood parasitism rate of 0.004. Logistic-exposure models indicated that daily nest survival probabilities were higher in pastures/hayfields than in fallow fields. Our results, and those from other studies in the Northeast, suggest that properly managed cool season grassland habitats in the region may not act as ecological traps, and that obligate grassland birds in the region may have greater nest survival probabilities, and lower rates of Brown-headed Cowbird parasitism, than in many parts of the Midwest.

View of the library at the New York Trade School

This photograph shows several empty tables and a few shelves in the library at the New York Trade School. Black and white photograph.

View of Air Conditioning and Refrigeration classroom at the New York Trade School

This black and white photograph shows classroom space of the Air Conditioning/Refrigeration Dept. empty of students. Black and white photograph.

Section of Television Laboratory at the New York Trade School

Several students are shown working in a section of the Television Laboratory at the New York Trade School. Black and white photograph with some damage due to writing in red ink along the long edges.

Class of Electrical Students at the New York Trade School

A class of electrical students at the New York Trade School are pictured at workbenches. Black and white photograph.

View of the library at the New York Trade School (2)

This is a view of the library at the New York Trade School, which was taken at a slightly different time than Photo73 as shown by the different wall hangings, namely the addition of a stuffed deer on the wall. Photograph is black and white and slightly fading.

A group of Litho students at the New York Trade School

A group of students from the New York Trade School studying lithography pose for a group photo. Black and white photograph mounted on paper.

View of Lithography Lab at the New York Trade School

Part of a lithography lab at the New York Trade School is depicted in this photograph. To the right sample prints are hung on a board, while other prints can be seen on the table, possibly drying. Black and white photograph.