PARENT SESSION
Poster Session #43: Avian Ecology.
Thursday, August 9, 2001. Presentation from 3:30 PM to 5:00 PM. Exhibition Hall

Birds and hedgerows at two spatial scales in an agricultural landscape of Guanajuato, Mexico.

Zuria, Iriana¹, Gates, Edward¹, ¹

ABSTRACT- Hedgerows and other vegetated field margins represent one of the last vestiges of wildlife habitat within regions devoted to row-crop production; however, their value to wildlife has been poorly documented. The importance of these field margins as habitat for resident and Neotropical migratory birds was investigated during the breeding and winter seasons of 1999 and 2000 in an agricultural landscape of Guanajuato, Mexico. Bird species richness and abundance were determined twice each season along 40 transects located in vegetated field margins. Two different spatial scales were taken into consideration. At a local scale we found that field margin height, width, vertical complexity, and number of trees and tree species positively influenced bird species richness and abundance. In some cases a non-linear relationship was evident, suggesting that bird diversity increased until reaching a maximum at an optimum value of the explanatory variable. We used aerial photographs and a Geographic Information System to obtain the landscape scale variables. The most important variables that affected bird species richness and abundance were the distance to natural vegetation patches (arid tropical scrub) and the proximity to human habitation. Proportionally, more migratory birds used vegetated field margins, while more resident species used the natural vegetation. The vegetated field margins were used for perching, foraging, nesting, and cover. The implications for conservation and management are considerable.

KEY WORDS: landscape ecology, geographic information systems, neotropical migratory birds, hedgerows