5 October 2016
Daniel Natusch, University of Sydney
Let the revels begin. Every summer, crowds of animals gather around trees at the northernmost tip of Australia to enjoy a feast hosted by starling colonies.
Metallic starlings (Aplonis metallica) migrate each year from New Guinea to the tropical rainforests of north-east Australia, where they stay from November to April. The birds return to same patch each season, with up to 1000 individuals nesting communally in the same tree.
As a result, the areas underneath the nesting sites become the most diverse animal hotspots in the world. Mammals, reptiles, amphibians and other birds congregate to feed on seeds scattered by the starlings, as well as fallen eggs and chicks.
Bird droppings enrich the soil, boosting insect populations and root growth, which provide additional food sources.
An eight-year study of 27 starling colony trees on Cape York Peninsula found that they attracted 42 different species during the nesting season. Many species were 100 to 1000 times more abundant under nesting trees than trees elsewhere.
“The hotspots are spectacular,” says Daniel Natusch at the University of Sydney, who led the study. “It is uncommon to have a single resource that attracts such a diverse assemblage of species.”
We know that other bird colonies attract animals, for example, penguins lure in predatory seals, whales and sharks, but Australia’s starling colonies pull in the highest number and diversity of species by far.