TREE SHREW, DRONGO and SPARROWHAWK - a beneficial alliance?
by @notrocketscience check it out in full on his fabulous blog
Images: Drongo by Nimesh M
Through the branches of the forest, the tiny Nicobar treeshrew scuttles about searching for insects. They’re followed by the racket-tailed drongo, a small bird that picks off juicy morsels flushed out by the foraging treeshrews. So far, this isn’t unusual - many distantly related animals forage together.
But this alliance has a third, more surprising member - a sparrowhawk. This bird of prey is five times larger than either of the others and can easily kill the treeshrew. But it doesn’t - instead, it feeds on prey that are disturbed by its partners.
Meera Anna Oomen and Kartik Shanker discovered this strange coalition and they suspect that it’s engineered by the drongos. Certainly, sparrowhawks aren’t traditional companions for treeshrews. On their own, these mammals keep their distance from the raptors for their own safety and are extremely vigilant. But with the drongos around, they tolerated the hawks and allowed them to get a couple of metres closer. The hawks, meanwhile, appear to use the drongos as a way of finding treeshrews.
Birds of prey are unusual participants in foraging groups. When they join another species, it’s usually one big enough that it couldn’t be a possible meal. That clearly doesn’t apply on Nicobar Island.
Nonetheless, the hawks, and certainly the drongos, seem to get a good deal out of their partnership. Oomen and Shanker think that they find more food when they follow treeshrews (although the data on this are still limited). Why a bird of prey should stray from its typical hunting technique is unclear, but it may be that the treeshrews simply aren’t a possible target with the drongos around.
Don’t be a bird brain, learn like an Anole
You can teach and Old Dog New Tricks - or at least and Old Macaque