Bird and Bat Diversity and Abundance in Agroecosystems in Relation to Drainage Hedgerow and Landscape Structure

Abstract

Hedgerows are common semi-natural linear features along agricultural drainages in temperate agroecosystems. Two important variables likely to affect diversity within hedgerows include hedgerow structure and landscape structure. I hypothesized that hedgerows that are taller, wider, and more variable in height, and landscapes with smaller fields and higher forest amount, will support higher diversity within drainage hedgerows by providing more habitat. I used point counts of forest and shrub-edge-associated birds and ultrasonic recordings of bats along drainage hedgerows in eastern Ontario to test my hypotheses. Overall, I found that drainage hedgerow height was positively associated with higher biodiversity for birds and bats. Width and variation in height were also important depending on the response considered. With respect to landscape structure, edge-associated species generally responded positively to smaller field sizes. My results show that structurally complex drainage hedgerows and smaller fields provide valuable habitats for birds and bats in agroecosystems.