

Female feeding baby

This study suggests, the benefit for the falcon is the thermoregulation.ExFmem wrote: 1. the equivalent of a doberman pincher protecting the premises: They allow one of their nests to be occupied by a bird of prey in exchange for its ability to attack and kill predators. This designated nest is conspicuous by the presence of a white substance at its entryway. This is the excrement of the Pygmy Falcon.
There is also a present study at Tswalu: http://weavers.adu.org.za/newstable.php?id=205though there is as yet no evidence that Pygmy Falcons are able successfully to deter snakes