Winter bird assemblages across an aridity gradient in south-west Western Australia

D.T. Bell, R.C. Bell, William A. Loneragan

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Abstract

Avian assemblages of eight sites located along a 625km gradient across south-west WesternAustralia were recorded during the winters of 2004 and 2006. The total number of species observedwas 92, with 10 sighted only in 2004, 14 sighted only in 2006, with the remaining 68 sighted duringboth survey periods. Measures of site species richness, diversity and evenness were determined foreach site and for each sampling year and the turnover rates of avifauna species categorized aseither sedentary or locally nomadic versus either migratory or nomadic between years weredetermined. The similarity between avifauna assemblages was determined by DetrendedCorrespondence Analysis and related to environmental data by correlation analysis and analysis ofvariance. Assemblage similarity between years at each site was greater than similarity betweenadjacent sites in the same year. However, avifauna similarity was related more to average annualprecipitation than geographic proximity and was secondarily influenced by the presence offlowering trees and shrubs. There was no relationship between position on the geographic gradientand bird assemblage richness, diversity, evenness or dominance. Turnover rates between years ofsampling of the regionally-nomadic and migratory species were significantly higher than sedentaryand locally-nomadic species. A number of species showed discontinuous distributions in the centralWheatbelt, further documenting the impact of clearing on the avifauna of southwestern WesternAustralia.
Original languageEnglish
Pages (from-to)219-227
JournalRoyal Society of Western Australia, Journal
Volume90
Publication statusPublished - 2007

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