Intraspecific variation in detection of bird-habitat relationships: declining birds in southern Australian woodlands

Abstract

An understanding of the responses of declining bird species to habitat loss, fragmentation and degradation is essential for their conservation. However, species' relationships with particular threatening processes may vary in different systems, and long-term variability in bird communities and differences in sampling protocols may cause different real or apparent habitat relationships to be detected in the same system at different times. We investigated temporal variation in detection of relationships between habitat remnant size, isolation and degradation and the presence of several bird species that are known to be declining in southern Australia. Habitat relationships detected for these species were compared with a) those detected for the same species in the same remnants in surveys undertaken seven years previously, and b) those reported from other fragmented, southern Australian systems. Most of the relationships displayed by the study species in other landscapes were not apparent in this system, and there were temporal differences in the detected landscape and habitat relationships of several species. These findings indicate that the effects of habitat fragmentation can appear to vary in their impact on a species among landscapes, as well as through time, which complicates considerably the task of conservation managers. Correlative relationships between species' presence and habitat characteristics can be misleading if the mechanisms through which the habitat factors influence species are not understood.