“Angry Birds” are perhaps the best known species among electronic bird-watchers these days, but we should never forget that real birds are amazing creatures. Incredibly diverse (think ostrich to hummingbird to penguin), they continue to fascinate scientists and laymen. Here are some recent science stories about our feathered friends.
- Hunting in the dark: Most seabirds hunt during the day, but the common murre often hunts at night, finding its prey underwater in near total darkness. How do they do it? Writing in PLoS One,1 a trio of Canadian scientists watched murres exercise their unique night-hunting ability. They found murres hunting as deep as 580 feet at light levels covering 13 orders of magnitude (103 to 10-10 watts per square meter). Hunting in the near-complete darkness of starlight was less frequent, but the birds were observed diving in both ambient moonlight and starlight. The scientists are not sure if the birds catch prey by random search in the deepest darkness or use some kind of non-visual cues. “This research … raises questions about the strategies and mechanisms birds use to find prey under very low light conditions,” they said.
The researchers said very little about evolution, referring backhandedly to “the evolution of” this or that a couple of times in the first paragraph, then stating, “To maximize foraging opportunity, many deep diving marine predators have evolved large, sensitive, dark adapted eyes.” But dark-adapted eyes often work less well in bright light, so they seemed puzzled how the common murre’s eyes could have evolved to be good at both. “Murres dived through a broad range of light levels – from sunlit to starlit – as they foraged throughout the day and night,” they noted. “This is perplexing since it seems unlikely that their eyes could be adapted for visually guided foraging across all conditions.” Last sentence: “Though the physiological mechanisms behind the murres’ ability to hunt through wide-ranging light conditions have yet to be understood, their ability to function through such conditions is a testament to their adaptability.”
- Tool use: A brief news item in Nature (27 Oct 2011, p. 431) claimed that “The ability to use tools is not always a sign, or a driver, of intelligence – certainly not in some Galapagos finches.” A researcher gave a kind of IQ test to finches that use twigs to pry out food (mimicking tool use) and other finches that do not. Neither group scored higher. “The findings show that physical and cognitive abilities do not always evolve hand-in-hand,”Nature claimed, begging questions whether either ability evolved in the first place. Still, any animal handy with a twig is a pretty clever bird.
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