Species richness and community composition of passerine birds in suburban Perth: is predation by pet cats the most important factor?
Jacky Grayson, Michael Calver, Alan Lymbery, 2007. "Species richness and community composition of passerine birds in suburban Perth: is predation by pet cats the most important factor?", Pest or Guest: The Zoology of Overabundance, Daniel Lunney, Peggy Eby, Pat Hutchings, Shelley Burgin
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Using data from 57 sites across suburban Perth we tested the influence of Cat Density on species richness and community composition of passerine birds as well as on the presence/absence of 15 common passerine species. Cat Density was not a significant predictor of any of the dependent variables. Instead, passerine species richness declined with increasing Distance to Bushland and with increasing Housing Density, but increased proportionately with the Size of, Nearest Bushland > 5ha. Together, these predictors explained approximately half the variability in bird species richness (adjusted R2 for the complete data set = 0.414). Passerine community composition was significantly affected by Housing Density, Distance to, and Size of, Nearest Bushland >5ha. These environmental variables, especially Housing Density, appeared to act principally by their effect on the number of small and medium sized insectivores. Attempts to predict the presence/absence of 15 common passerines did not yield clear results, although Housing Density appeared the most likely predictor. While cat predation might be significant adjacent to remnant bushland or other areas of conservation significance, blaming cats for bird conservation issues in long-established suburbs may be a scapegoat for high residential densities, inappropriate landscaping at a range of scales or poor conservation of remnant bushland.