The conservation value of paddock trees for birds in a variegated landscape in southern New South Wales. 1. Species composition and site occupancy patterns

Abstract

The use of paddock trees by birds was assessed in a grazing landscape in southern New South Wales. Australia. Seventy paddock tree sites were surveyed for 20 min each in the morning, and 36 sites were surveyed again at midday in March 2000. During this time, the presence and abundance of birds was recorded. Several site and landscape variables were measured at each site. These included tree species, a tree size index, a measure of the crown cover density around the site, and proximity to the nearest woodland patch. During formal surveys, 31 bird species, including several woodland species, were observed using paddock trees. Data from bird surveys in woodland patches that were obtained in a separate study in November 1999 were used to compare whether there was a relationship between the abundance of a given bird species in woodland patches and paddock trees. Many birds commonly detected in woodland patches were also common in paddock trees. However, some birds with special habitat requirements were absent from paddock trees although they were common in woodland patches. Site occupancy patterns were modelled for several guilds of birds using logistic regression. Foliageforaging birds were more likely to occupy clumps of trees and sites with a high tree size index. Nectarivores appeared to be more likely to be detected at sites more than 200 m from woodland, although this result was marginally non-significant (P = 0.08). The probability of detecting granivores was higher at sites with a low tree size index. Open country species were most likely to occupy large trees and sites that were located more than 200 m from the nearest woodland patch. The value of paddock trees may have been underestimated in the past because a wide variety of bird species use paddock trees on a regular basis. Ensuring the continued survival of paddock trees should be an important aspect of future conservation and revegetation efforts. Show more