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Mulga bird communities. I. Species composition and predictability across Australia
Author(s) -
CODY MARTIN L.
Publication year - 1994
Publication title -
australian journal of ecology
Language(s) - English
Resource type - Journals
eISSN - 1442-9993
pISSN - 0307-692X
DOI - 10.1111/j.1442-9993.1994.tb00484.x
Subject(s) - ecology , insectivore , geography , foraging , species diversity , woodland , habitat , biology
Data are presented from bird censuses at 20 mulga ( Acacia aneura ) sites across Australia. Null (binomial) models show that community composition is far more consistent among censuses than is expected by a random drawing from all candidate species. By denning and using the designations ‘core species’, ‘peripheral species’, and ‘casual species’, it was shown that 32% of the total 81 bird species censused constituted core species and core niches that account for nearly 75% of the bird density in mulga bird communities countrywide. A minor proportion of the variation in the mulga censuses was attributable to geographic variation in vegetation structure, related to the β‐component of diversity. Some mulga niches have regional replacements that contribute to a species turnover among sites and to the γ‐diversity of the species set; other species of sporadic occurrence are attributable to the geographic position of the mulga site in terms of adjacent habitats (mostly eucalypt woodland and mixed acacia scrub), a ‘spillover’ effect. Regional variations in the composition of some specific guilds, namely ‘crows’, ‘wrens’, ‘butcherbirds’, foliage insectivores, ground‐foraging insectivores, perch‐and‐pounce foragers and mid‐sized, ground‐foraging omnivores, are analysed in some detail to illustrate factors that contribute to a large species total in mulga, despite the predominance of core species.