Q: I discovered an active oriole nest in a tree on our lakeshore, and was lucky enough to spot the parents bringing food to the nest. But now I'm confused: I thought only female birds fed their young.
A: You'll have a fun time watching those parent orioles rearing their youngsters, a shared behavior that is not unusual in the bird world. While mammal mothers typically handle all of the care of their offspring, it's a different story with birds. As Mary Holland has written on her fascinating website, Naturally Curious, "At least 81 percent of bird species exhibit bi-parental care," adding that while they may not share duties equally, both parents contribute. Robins are a good example: The female incubates the eggs, but once these hatch, both parents feed the chicks and keep the nest clean.
Hammer heads
Q: I've been told that woodpeckers protect their brain when drumming on trees by wrapping their tongue around it to prevent concussion. Is this correct?
A: Woodpeckers' ability to pound on hard surfaces without damage to their brain is amazing, and your informant is partially correct. In truth, though, a woodpecker's skull fits tightly around its brain, preventing movement during pecking sessions, thereby avoiding concussion. In many species of woodpeckers the tongue does wrap around the brain, but this isn't to protect it. Instead, in these species, especially northern flickers and red-bellied woodpeckers, the only place to store their very long tongues (up to 5 inches long in the flicker's case) is to wrap it inside below the jaw and then over the top of the inner skull when not in use.
Northward bound
Q: I saw an odd sight while up at our cabin in early June — large flocks of Canada geese passing overhead on their way north. At times there were several hundred of them. Isn't this early for migration?
A: That's an excellent observation of a phenomenon that occurs in the water bird world. They molt in early summer, losing all their wing feathers at once. This means they're unable to fly until new wing feathers grow in, so in anticipation of this flightless period, the geese head north to find large bodies of water. There they'll be safer from predators for the several weeks it takes to complete their molt.
Vulture aerie?
Q: Several of us were walking through a nature area close to downtown the other day when two turkey vultures suddenly flew up from a spot about 30 feet off the ground. After we passed by they returned to the same place. Is there any chance they might have been nesting?
A: Although turkey vultures prefer to nest far from human activity it's very possible that the pair you encountered were protecting a nest. You mentioned that this park has rocky ledges, and that's exactly the kind of structure that turkey vultures will choose for raising their young. They're also known to nest in caves, thickets, mammal burrows, hollow logs, abandoned buildings and even deer hunting stands.
Flimsy nests?
Q: Bird nests seem to be rather flimsy affairs. If they spent more effort on construction, mightn't they have better success with their offspring?
A: That's a good question, but I can't agree that birds' nests are flimsy. Instead, I'd say that their nests are as sturdy as they need to be for the intense few weeks that birds use them. As an adult bird, most usually the female, builds the structure that will hold her eggs and later offspring, she feels pressured by the need to accomplish the job quickly. Time is limited during breeding season, and spending less time on nest building allows fledglings more of the summer to pick up important life skills.
And yes, young birds sometimes fall out of nests before they're ready to fly, but this usually is due to overcrowding, as the brood grows, or nestlings flapping their wings to build flight muscles. Once young birds leave the nest, they move away and the structure is left to disintegrate through the seasons (although robins sometimes re-use their nests).
St. Paul resident Val Cunningham, who leads bird hikes for the St. Paul Audubon Society and writes about nature for local, regional and national newspapers and magazines, can be reached at valwrites@comcast.net.
