Samplings: October 2008

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Günther’s dik-dik

White-bellied go-away bird

Daniel Blumstein

A number of animals eavesdrop on warnings sounded by other species: if a predator is afoot, everyone wants to hear the news. Most prey species known to heed “second-language” alarm calls are social creatures with large vocal repertoires of their own—good indicators of intelligence. But Günther’s dik-diks don’t fit that pattern. Mated pairs of the miniature antelopes live by themselves on multi-acre territories on the East African savanna, and they make only a few quiet little calls, including just one alarm: the breathy “zik-zik” behind their name. So when local lore that dik-diks heed the alarms of white-bellied go-away birds reached Amanda J. Lea, two fellow undergraduates at the University of California, Los Angeles, and their advisor, Daniel T. Blumstein, they pricked up their own ears. Go-away birds announce incoming predators from their treetop perches for all to hear. When the researchers played recorded go-away-bird alarm calls, dik-diks usually assumed a vigilant stance or stopped foraging and headed for cover, whereas they all but ignored broadcasts of unalarming birdsong. Dik-diks can’t afford to miss out on a warning: more than twenty predators include dik-dik in their diets. Lea and Blumstein expect that interspecies eavesdropping is much more common than biologists now appreciate among vulnerable animals—regardless of how social, vocal, or intelligent they are. (Behavioral Ecology)