Relative abundance of introduced European birds varies with field margin type on arable farms in Canterbury, New Zealand

Abstract

Some introduced passerine species can cause considerable damage to arable crops in New Zealand. These crops are usually surrounded by hedgerows and, in Canterbury, these are commonly Monterey pine (Pinus radiata) and macrocarpa (Cupressus macrocarpa). The present study aimed to determine whether bird abundance and species composition differed among field margins bordered either by hedgerows of common species (pine and macrocarpa), mixed hedgerows (a variety of native and introduced plant species) or bare fence lines (no hedgerow). The numbers and species of birds along line transects traversing field margins were recorded on three different farms during spring and summer 2012. Generally, the same 12 introduced bird species were found along the different margins. However, a greater number of chaffinch (Fringilla coelebs), European goldfinch (Carduelis carduelis), European greenfinch (Carduelis chloris) and, to a lesser extent, house sparrow (Passer domesticus) were recorded in common hedgerows than in mixed species hedgerows and bare fence lines. This study indicates that composition of vegetation at field margins may influence the relative abundance of introduced birds.