Amazing Bird Tricks
“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.
- Birds of a feather flock: We’ve all seen the nature shows with scenes of birds taking off in huge swarms, so thick one wonders how they avoid collisions. Flocks of starlings can contain 10 million individuals (be amazed at this BBC video). Perhaps one of your local bird species puts on similar shows, darting this way and that in unison, executing aerial acrobatics no fighter pilot squad could hope to imitate. “Watching thousands of birds fly in a highly coordinated, yet leaderless, flock can be utterly baffling to humans,” PhysOrg reported. “Now, new research is peeling back the layers of mystery to show how exactly they do it – and why it might be advantageous to fly right.” Charlotte Hemelrijk of the University of Groningen (Netherlands) has shown in computer models that an individual bird only needs to keep track of about seven neighbors to stay in formation. Still, it is not clear why the birds do it. Fun? Exercise? Social birds learn quickly from each other, and humans could learn from flocking birds, finding ways to improve formation flying in aircraft.
- Woodpecker helmets: Speaking of learning from birds, designers of helmets should pay attention to woodpeckers. Their heads have to endure decelerations of 6 or 7 meters per second without sustaining brain injury. According to PhysOrg, a team in China filmed woodpeckers, analyzed the forces involved, and then tried to figure out what factors in the birds’ skulls prevent injury. “The researchers conclude that the shock absorption system is not based on a single factor, but is a result of the combined effect of a number of different morphological features,” the team concluded. The sponginess of the bone, the structure of the beak, and the shape of the cranium were some factors that work in concert to protect the little bird brain. “This combination may be useful in guiding design for new protective gear.”
- Back on the perch: After the discovery of another Archaeopteryx specimen recently (10/19/2011), some will be comforted to hear that the world’s most famous fossil has been returned to the bird category. Dr Michael Lee [South Australian Museum] responded to claims earlier this year that put Archaeopteryx into phylogenetic confusion, raising fear among evolutionists that creationists would spin the announcement to their advantage (7/28/2011). Lee’s team claims the earlier announcement had weak support; their more detailed analysis shows that Archaeopteryx was, in fact, a bird. Team member Trevor Worthy said, “In our work, Mike Lee has shown quite clearly that methodology is highly significant and that before a paradigm is overturned data needs to be rigorously examined.” They used a combination of methods to establish the bird’s identity. How this helps the story of the origin and evolution of birds, though, was not explained.
1. Regular PM, Hedd A, Montevecchi WA, 2011 Fishing in the Dark: A Pursuit-Diving Seabird Modifies Foraging Behaviour in Response to Nocturnal Light Levels. PLoS ONE 6(10): e26763. doi:10.1371/journal.pone.0026763.
The CEH Law applies: the more detail in the observations, the less talk about evolution. We should never take any living thing for granted. There is more wonder in a bacterium than we can imagine; how much more in multicellular creatures that can fly, swim, see in near darkness, swarm in tens of thousands while flying in unison, use tools, and teach us how to make helmets. Take a closer look at the birds in your vicinity today.
The woodpecker’s head’s deceleration is incorrect. The PhysOrg article says the speed decreases by about 6 to 7 m/s, but does not mention how long it takes for that speed change to occur. Therefore, we can’t determine the deceleration. To illustrate how the deceleration might be computed let’s suppose it takes one thousandth of a second (a ballpark figure) for the speed to change. Dividing the speed change by the time gives the average deceleration of 6000 to 7000 m/s/s which is roughly 700 g (700 times the acceleration due to gravity). An article in the Journal of Zoology has suggested decelerations as high as 10000 m/s/s or 1000 g, so our rough calculation here isn’t too far off.