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*P and J. Smith Ecological Consultants, 44 Hawkins Parade, Blaxland, New South Wales, Australia 2774.

An assessment was made of historical change in the native bird fauna of the Western Division of New South Wales. Change has been more extensive than is generally recognized. It was concluded that 103 native bird species and subspecies (35% of the total) have decreased since European settlement and 83 (29%) have increased, while 105 (36%) have shown no consistent overall trend. The most pronounced changes have involved 20 decreasers and eight increasers, including six species that are now presumed extinct in the Division, five species that now occur only as rare vagrants, and four recent colonists. Overall, more birds have decreased in the semi-arid zone of the Division than in the arid zone, and more in mallee scrub and eucalypt woodland than in other vegetation types, due largely to the pattern of vegetation clearing in the Division. Other factors (overgrazing, introduced predators and, for some species, reduced prey populations) are implicated in the major declines and these have been more evenly distributed in relation to climatic zones and vegetation types. Marked features of the decreasers are an over-representation of Australian endemics, residents, woodland and scrub birds, tree and shrub nesters, and birds with a clutch size of only one or two. Specific features of the major decreasers are an over-representation of non-passerines, birds restricted to a single vegetation type, ground foragers and ground nesters. The increasers include many wetland birds that have benefitted from the creation of additional permanent wetlands in the Division. Among the terrestrial increasers, there is an over-representation of birds of open vegetation, ground foragers and regular drinkers. Factors responsible for past avifaunal change continue to operate, and new threats have arisen. Effective conservation of the bird fauna will require not only further reserves, but also active management both on and off reserves. Prerequisites for success are a better understanding of the processes of change, and greater co-operation among land managers.

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