HARDLY bird-brained, the black-capped chickadee has one of the animal kingdom鈥檚 most intricate alarm calls. These palm-sized puffballs vary the number of syllables in their battle cry depending on the predator.
鈥淲e really were surprised at just how sophisticated the alarm call system is and how sophisticated the judgement of predation risk was,鈥� says lead author Christopher Templeton of the University of Washington in Seattle.
Templeton and his colleagues listened to the alarm calls of a flock of six chickadees confronted by 13 bird predators, ranging in size from the 40-centimetre wingspan pygmy owl to the rough-tail hawk with 140-cm wings. They also tested responses to a cat and a weasel.
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After analysing 5000 recorded calls, the team found that the number of 鈥渄ees鈥� in the bird鈥檚 trademark 鈥渃hickadee-dee-dee-dee鈥� call corresponded to the size of the predator. Smaller, more manoeuvrable hunters, which pose the greatest threat, received the most vociferous response (Science, vol 308, p 1934). Chickadees have another predator alarm call, a high-pitched, quiet 鈥渟eet鈥� that warns of dangers flying overhead.
These findings are similar to those from studies of vervet monkeys, which have different calls for 鈥渟nake鈥� and 鈥渓eopard鈥�, for example.
