Continent-scale patterns in temporal dynamics of avian assemblages

A common method of characterizing the bird assemblages of sites in landscape ecological research is to conduct a series of snapshot-type surveys, often over less than one year (Maron et al. 2005). However, highly mobile taxa such as birds show substantial interannual variability in species richness and community composition (e.g. Holmes et al. 1986), and this may have implications for the veracity of snapshot-derived patterns. The environmental correlates of inter-annual variability in bird assemblages are not well known, although it seems likely that more climatically stable regions support less dynamic avian assemblages (Jarvinen 1979). We conducted a continent-scale study to investigate associations between environmental factors and annual bird assemblage turnover rates in Australia. Correlates of inter-annual bird assemblage variability have rarely been investigated at this scale as long-term data from across a broad area are required. However, the availability of long-term, large-scale databases from volunteer-based monitoring initiatives provides opportunities for comparisons across large areas. For example, data from the North American Breeding Bird Survey revealed increased annual turnover in landscapes with smaller forest patches (Boulinier et al. 2001)