Data from seasonal and environmental dynamics of avian assemblages at arid zone waterholes
In arid zone environments long-lasting waterholes can provide the only reliable sources of water during prolonged dry periods and hence play an important role in maintaining avian diversity in the longer term. We used camera traps and direct surveys to investigate avian assemblages at six long-lasting waterholes across three sampling seasons (two summers and one winter) within the MacDonnell Ranges Bioregion in central Australia. Compositional differences in avian assemblages over space and time were analysed using a combination of multivariate and non-parametric analyses. We found significant differences in the structure of avian assemblages, particularly between the two summers and the winter season. These were related to migratory and nomadic species and species not normally considered dependent of surface water appearing at waterholes during the summer seasons. There was significant variation in avian assemblages among waterholes, which appeared related to individual species responses to the environmental characteristics of different sites. Distance-based linear models indicated that ground-foraging species such as the Torresian Crow and Common Bronzewing were less frequent visitors at sites with higher canopy and shrub cover. Zebra Finches were observed less frequently at large waterholes (> 300 m2) and White-plumed Honeyeaters were observed more frequently at sites with taller canopies. Our findings, which benefitted from the application of two survey methods, suggest seasonal weather patterns and environmental characteristics are important factors that influence when and where species access long-lasting waterholes. This has potential management implications, for example if there is a loss of tree and shrub cover over time, this may deter visitation by canopy-foraging honeyeaters or increase visitation by opportunistic ground foragers (such as the Torresian Crow), which could negatively impact other species through increased antagonistic interactions such as egg and chick predation. The conservation of diverse waterhole habitats in upland arid zones will ensure they are accessible for a variety of species into the future.