Does landscape water availability influence floodplain woodland bird density?

AbstractIrrigated agriculture in south‐east Australia has increased water availability to native flora and fauna by creating artificial open‐water habitats and raising water tables across the landscape. However, it has also caused loss of floodplain woodlands and reductions in the frequency, extent and duration with which floodplains are inundated, resulting in habitat degradation. The effects of such changes on floodplain fauna such as woodland birds are poorly understood. This paper explores the hypothesis that water availability at landscape scales influences woodland bird density. It examines the density of selected bird species in remnant floodplain woodlands of two contrasting regions within the same drought‐affected catchment and tests two predictions: (1) Increased water availability in the landscape resulting from greater surrounding irrigation land use intensity will be associated with higher bird density in floodplain woodlands and (2) lower flood frequency within a site will be associated with lower bird density in floodplain woodlands. Two contrasting levels of the effect of irrigation land use intensity on woodland bird density were found: firstly, a broad‐scale positive relationship between irrigation water availability and bird density at a regional scale and, secondly, a within‐region negative effect of very high intensity irrigation land use upon bird density. We suggest that these effects are mediated through the influence of water and land use on both food and habitat availability, and research is needed focusing on links between flood regime, vegetation condition and bird density in the absence of intensive irrigation land use to ascertain the importance of flooding to woodland birds. © 2014 Commonwealth of Australia. Ecohydrology © 2014 John Wiley & Sons, Ltd.