![]() ![]() ![]() Because of this, female cuckoos are quick and stealthy when they lay their eggs-aside from the chuckle call. They also “monitor cuckoo activity in the vicinity of their nest and vary these defenses in relation to local parasitism risk,” write York and Davies. They mob adult cuckoos and sometimes reject host eggs in their nests by kicking them out or abandoning the nests altogether. Host birds like reed warblers are wise to the possibility of cuckoo parasitism. But, write York and Davies, “manipulation by imperfect mimicry is frequent in the natural world, and resemblance to hawk calls in some key features might be sufficient to trick hosts.” The way to find out is to determine whether the call seems to be effective in freaking out the host birds. Has the female common cuckoo evolved a cry that imitates a hawk? Both the cuckoo chuckle and the sparrowhawk cry consist of a rapid series of notes with a similar pitch and a similar rhythm. Cuckoos seem to be a fan of that tactic: some cuckoo species look quite a bit like hawks, and this seems to protect them from mobbing by other birds. For instance, the wasp beetle mimics a stinging wasp, causing predators to steer away. Plenty of species have evolved to mimic predators, often for their own protection. York and Davies’ paper in Nature Ecology & Evolution this week provides evidence that the cuckoo chuckle does indeed seem to distract host birds by making them fear a sparrowhawk attack. But it does have similarities to the call of the sparrowhawk, which led researchers Jenny York and Nicholas Davies to wonder whether the call might be a purposeful deceit-a ruse to distract the hapless host birds while their nest is being violated. That chuckle doesn’t sound at all like the male cuckoo call. That’s a strange thing for them to do, because host birds aren’t too fond of cuckoos. ![]() Yet female cuckoos have a tendency to make a bubbly, chuckling call while they’re laying their eggs. That means they lay eggs in the nests of other birds, which then put the effort into raising the chicks. Per Harald Olsen / Wikimedia Commons reader comments 10 withĬuckoos are nest parasites. ![]()
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