Meeting Abstract
Mistletoebirds (Dicaeum hirundinaceum, family Dicaeidae) are the primary dispersers of mistletoe seeds in Australia and are mistletoe fruit specialists, but are also known to ingest other fruits, nectar, and invertebrates. We used stable isotopes of carbon (δ13C) in breath, blood and feathers and nitrogen (δ15N) in blood and feathers from mistletoebirds to detect potential changes in diet through time and to investigate the proportional contribution of arthropods vs. fruit to their diet. Mistletoebirds were mist-netted and sampled and diet sources (i.e. arthropods and mistletoe fruit) sampled at three sites in south-west Western Australia when ripe mistletoe fruit was available at each site. Sampling occurred during the austral autumn, winter and summer months. We found that mistletoebirds appear to change their diet over time, as indicated by the significant differences in δ13C values of breath and feathers (tissues that have significantly different turnover rates) from birds at two of the three sites. We also found that the contribution of arthropods to the diet of mistletoebirds varies depending on the time of year, or between sites, ranging from 45% to 67%. This could be associated with increased protein requirements during breeding and moulting or differences in availability of food sources between the sites occupied at these times.
