Effects of plant diversity and width of farm shelterbelts on woodland birds and bats

Recent studies in Australia have demonstrated the general importance of farm shelterbelts to native wildlife conservation. These studies are rarely detailed enough, however, to identify specific characteristics needed to enhance wildlife habitat. Nor have they considered the role of pest suppression that an increase in insectivorous vertebrates in shelterbelts might play.  Two major studies of the birds and bats using farm shelterbelts in Australia have contributed to the provision of this information. These studies involved the study of birds in 93 windbreaks from 1993-7 and of birds and bats in 62 shelterbelts from 2004-6, both located in central New South Wales. The studies showed that bird species known to be woodland-dependent were more abundant in wider, more diverse shelterbelts and many individual woodland species showed a positive response to either width or woody plant diversity. The species richness of both insectivorous birds and bats was positively correlated with the species richness of the woody plants in the shelterbelts. Faecal analysis of birds foraging in shelterbelts has provided evidence for several bird species consuming pest arthropods. Beetles, ants and spiders were the dominant prey arthropods in most faecal samples. Manipulating the groundcover of shelterbelts by the addition of nectar- and pollen-rich plants increased the diversity and activity of arthropods, mainly of parasitic wasps. We conclude that well designed shelterbelts can provide quite valuable habitat on farms for vertebrate wildlife and beneficial invertebrates.