One of the things I learned from 32 years of teaching biology is that many non-human animals are way smarter than we give them credit for -- and its corollary, which is that we humans are not as far separated from the rest of the natural world as many of us would like to think.
A charming piece of research in Science this week illustrates this point brilliantly. It's about a species of African bird, the Greater Honeyguide (its scientific name, which I swear I'm not making up, is Indicator indicator). It's found in open woodland in most of sub-Saharan Africa, and has a very specialized diet -- it lives on bee eggs, larvae, and wax (it's one of the few known animals that can digest wax).
Because of its diet, local residents have developed a mutualistic relationship with honeyguides, a relationship that is what gives the birds their common name. People living in the region listen for the bird's call and then follow it to find the bees' nests it was attracted to. The people tear open the nests and take the honey -- and the bird gets the larvae and the wax. Many cultures that live in the honeyguides' range have developed specific calls to attract the birds when they're ready to go on a honey hunt.
The study, led by ecologist Claire Spottiswoode of the University of Cambridge, looked at the fact that honeyguides seem to learn the specific calls used by the people they live near. Initially, it was uncertain if the people had figured out what the birds responded to, or if the reverse was true and the birds had learned what noises the people made. So she and her team decided to test it; they used recordings of individuals from two cultures that are known to use honeyguides, the Hadza of Tanzania and the Yao of Malawi and Mozambique. The Hadza employ a complex series of whistles to summon their helpers, while the Yao make a "brrr-huh" sound.
Both signals work just fine, but only in particular regions. When a recording of the Hadza signal is played in Malawi, or a recording of the Yao signal is played in Tanzania, the birds don't respond. The birds have evidently learned to recognize the specific calls of their partners in the region where they live -- and don't "speak the language" used elsewhere.
Spottiswoode's team also found there are two places where the symbiotic relationship is falling apart. In more urban areas, where commercial sugar is widely available, there are fewer people engaged in honey hunting, so the birds have decided they're better off working as free agents. Even more interesting, in some areas in Mozambique, the Yao discovered that if they destroy the wax and the rest of the hive, the honeyguides will stay hungry and look for other nests. But... the birds are learning that their human partners are stiffing them, and they're becoming less likely to respond when called, so the human honey hunters are having less overall success.
So even birds can recognize when they're getting a raw deal, and put a stop to it.
The more we find out about the other life forms with which we share the planet, the more commonality we find. Everything in the natural world exists on a continuum, from our physiology and our genetics to characteristics many thought of as solely human traits, like emotion, empathy, and intelligence.
So be careful when you throw around terms like "bird-brain" -- they're not as far off from us as you might like to believe.
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