Surprising discoveries in picking a bird’s brain | WHIDBEY BIRDING
By FRANCES WOOD
South Whidbey Record Columnist
February 5, 2013 · Updated 3:30 PM
Most February mornings I begin my cup of coffee before dawn, when the sky offers only a soft whisper of morning light. I often see an Anna’s hummingbird enjoying its first drink at my feeder around the same time. I’m amazed it can negotiate through the darkness from its nighttime roost to my deck.
Years ago I learned that birds possess sharper vision than humans and that they can see in light frequencies, which we can’t, such as ultraviolet. My crack-of-dawn visitor sent me to Google more.
Bird eyes, on average, account for 15 percent of the mass of the bird’s entire head. Human eyes, by contrast, account for less than 2 percent. Evolution in birds has favored visual acuity both for finding food and for seeing predators.
Birds and humans both employ photoreceptive cell rods in the retina to assist vision in low-light conditions. A human eye has 200,000 of these cell rods per square millimeter, whereas owls, for example, have five times the number.
Birds and humans also have photoreceptive cones in the retina. It’s these cones that enable us to see color light. Birds have 12 times more per square millimeter than we humans do.
Even though I’m rather blurry-eyed before my first cup of coffee and limited by darkness, birds have the capability to see without difficulty.
Seeing is one thing, recognizing is another.
Dr. John Marzluff at the University of Washington has for years studied crows’ abilities to recognize faces and found that crows can distinguish individual human facial features. He used masks to shift the “faces” from one body to another during his research, eliminating body size, shape or language as factors.
When one researcher captured a crow for banding the crow remembered that specific person and avoided him.
Also the crows sent word around the flock and other crows also avoided the culprits who had captured them.
I tried to reverse the situation. Could I distinguish between individual crows? Even if a crow flew directly over my head and splatted on my upturned face, I couldn’t pick that individual bird out of a police line up of crow criminals.
A couple of weeks ago I read here in the South Whidbey Record (Jan. 26, “Several solutions considered for Cranberry Lake poop problem”) that the park officials at Deception Pass State Park had closed Cranberry Lake to swimming and other activities because the lake tested significantly above acceptable E. coli bacteria levels. The poop from Canada geese was determined to be the reason.
Understandably, this gaggle of geese needs to be scared away from the area.
Part of the planned solution is to place coyote cutouts around the lake. Birds are pretty dumb, right; surely they won’t notice any difference between a real coyote and a cut out imposer.
Have they read the literature? Or noticed the futility of scarecrows?
If you or I happened to look up and see a coyote cutout, we might be startled for a moment. But even our eyes, with one-tenth the visual capacity of birds, wouldn’t be fooled for long.
Also, the cutouts will be static. I remember seeing a Coopers hawk pursue a robin.
Attempting to veer away from the predator, the robin crashed into a window and fell to the ground, likely dead within seconds of impact.
The hawk landed on a nearby deck railing watching for the robin. Even though the robin was in clear sight, within a few yards of the hawk, the hawk wouldn’t go after it because it was not moving. It was the movement that alerted the hawk to its prey in the first place.
I predict that static, coyote cutouts will fade into the benign environment for those Cranberry Lake geese within hours of their installation.
Birds are excellent visual hunters and survivors. Let’s drop the label of birdbrain, especially in areas where they excel. And admire their visual acuity as well as their more commonly accepted skills at flight and song.
Frances Wood can be reached firstname.lastname@example.org.