Cool Bird Tricks
Evidence continues to mount that a lot of capability is packed into a little bird’s brain. We should use the phrase bird-brain to honor smart animals.
- I C U: Mockingbirds can recognize individual humans. Disturb a mockingbird nest, and the parents will single you out from a crowd and go into attack mode, researchers at Duke University found. They observed bird behavior with student subjects at Duke and published their findings in PNAS.1 “These results demonstrate a remarkable ability of a passerine bird to distinguish one human from thousands of others,” they said. “Also, mockingbirds learned to identify individual humans extraordinarily quickly: after only 2 30-s[econd] exposures of the human at the nest.” PhysOrg summarized the paper. It should be noted that this ability is in addition to the mockingbird’s remarkable repertoire of songs.
- Native composers: Zebra finches raised in captivity learn their favorite song without ever hearing it. Science Daily reported on finches raised in complete isolation from their parents and other members of the species. The birds seemed to babble and experiment at first. Their offspring learned the “arrhythmic” song from their tutors, but gradually approached the native song heard in the wild. “What is remarkable about this result is that even though we started out with an isolated bird that had never heard the wild-type, cultured song, that’s what we ended up with after generations,” commented Partha Mitra [Cold Spring Harbor Laboratory]. “So in a sense, the cultured song was already there in the genome of the bird. It just took multiple generations for it to be shaped and come about.”
- Bobble heads: Ever wonder why birds bob their heads when they walk? There’s a reason: it stabilizes their gaze (see 04/12/2005), so that the eyes can remain fixed on a target for the maximum time while the bird moves forward. A new Quick Guide in Current Biology discussed how well this mechanism works.2 “Stabilization of the head occurs in all three axes of space and for both translation and rotation around these axes,” wrote Barrie J. Frost [Queen’s University, Ontario]. “For a walking pigeon the small amount of motion during the hold or stabilization phase is less than 0.5 mm.” This ability involves a complex interaction between the retina, neurons, visual cortex, accessory optic system, vestibular balance system, and the flexible muscles of the neck and the gait of the legs.
The birds with the most remarkable stabilization may live right in your garden. “Humming birds, hovering in front of a flower while feeding show an amazing ability to keep their head stabilized while their body makes considerably larger movement produced by their wing beats and perturbation by the wind,” he said. “Kestrels and kingfishers, while hovering in mid-air before diving to catch their prey, also show remarkable stabilization of the head relative to the much larger movements of their bodies.” Even the heavy flying birds, like geese and swans, do pretty well. “Films and videos … show that while there is an upward thrust of their bodies produced with each downward wing-beat their heads maintain a nearly perfect level path.”
- Goggle eyes: The amazing ability of animals to navigate is a source of ongoing study and experimentation. James L. Gould [Princeton} started his Dispatch in Current Biology3 with the following expression of wonder:
Of all the wonderful things animals can do, the ability of certain species to judge their location on the planet is perhaps the most astonishing. A homing pigeon transported in darkness 200 km in a direction it has never before been and released far further from the loft than it had previously ventured, will typically circle and then set off in roughly the correct direction. A migrating bird, captured near the northern end of its annual journey south and carried in the hold of a plane 5000 km east, sets off southwest toward the goal of its migration, rather than either northwest to its natal area or west for the capture point. The accuracy of this navigation is startling: pigeons fitted with frosted goggles (which eliminate form vision) return to within a couple of kilometers of their loft. How is any of this possible?
The fact is, we don’t fully know. Is it magnetic fields they sense? Odors? Positional cues? Gould discussed primarily how a popular olfactory hypothesis has been falsified. Most likely magnetic field gradients are a factor, but work continues to try to understand how any of this is possible.
1. Levey et al, “Urban mockingbirds quickly learn to identify individual humans,” Proceedings of the National Academy of Sciences USA, published online May 18, 2009, doi: 10.1073/pnas.0811422106.
2. Barrie J. Frost, “Bird head stabilization,” Current Biology, Volume 19, Issue 8, 28 April 2009, Pages R315-R316, doi:10.1016/j.cub.2009.02.002.
3. James L. Gould, “Animal Navigation: A Wake-Up Call for Homing,” Current Biology, Volume 19, Issue 8, 28 April 2009, Pages R338-R339, doi:10.1016/j.cub.2009.03.001.
These are all good reasons to become a bird watcher. Students might like to experiment with the camcorder at the hummingbird feeder or watch pigeons bobbing their heads in the park. Maybe a home schooling family could raise homing pigeons for a science project. Don’t pester the mockingbirds, though. Take an interest in your feathered friends and the other amazing living things around you. Their abilities are more remarkable than you can imagine.