Nick Davies and Justin Welbergen report a novel form of Batesian mimicry: in this case the breast barring that is shared by Common Cuckoo (Cuculus canorus) and Sparrowhawk (Accipiter nisus). Rather than an harmless species mimicking a harmful one, here the indirectly harmful species (the brood parasite cuckoo) gains easier access to host Reed Warbler (Acrocephalus scirpaceus) nests by resembling the more direct threat, the predatory raptor.
(Summary by The Economist.)