Bird assemblages of a fragmented agricultural landscape and the relative importance of vegetation structure and landscape pattern

Many of the world's agricultural areas have greatly reduced levels of natural vegetation. This results in highly fragmented mosaic landscapes with multiple land- use types. We examined the importance of vegetation and landscape pattern by comparing the bird assemblages of riparian zones, non- riparian forest patches, and pasture in a fragmented agricultural landscape in south- eastern Australia. Bird surveys were conducted every four weeks at 27 sites in the Goldfields region of central Victoria for one year. The landscape context ( position and shape of patches) and vegetation attributes were measured for each site. We found that bird assemblages strongly differed among these landscape elements. Mean abundance was significantly greater at forested patches, and there was a three- fold reduction in species richness at pasture sites. Bird assemblage structure was influenced substantially more by vegetation than by the landscape context of sites. Our results indicate that riparian vegetation is a key element for avian diversity, even in massively altered landscapes. The restoration of riparian vegetation and its connectivity with adjacent forest types would greatly benefit bird assemblages in agricultural areas.