On the Wing: Preening is practical for birds

Q We often see birds preening, using their bills to arrange and smooth feathers. It has to be something other than ego, right?

A Yes. Without a mirror, ego is not a factor. It's a maintenance issue. Feathers are fragile. The zipper-like edges of feathers pull apart. Feathers become disarranged. Some break.

And then there are dust, dirt and parasites. The most common external parasite is the bird mite, sometimes called lice. Mites are common among parasite species, but uncommon in number of birds affected. Mites feed on blood. The nest environment can be ideal for propagation; a nest might hold tens of thousands of mites.

They will bite humans (although they can't live on us). So it's a good idea to clean bird nest boxes with care, using gloves and a tool, and definitely stand upwind. Mites and dirt are removed as the bird slides the feather through its bill. Proper feather arrangement is accomplished, and oftentimes oil from a special gland beneath the tail is applied as waterproofing.

Nightjar's name Q Whippoorwills are part of a family called nightjars. What is the origin of such an unusual name?

A Whippoorwills are a bird you often can hear in Minnesota and Wisconsin wooded areas with brushy interludes. They have an onomatopoeic name; it is taken directly from our interpretation of the sound the bird makes. Whippoorwills during courtship season will repeat their name for hours at night. It's a loud call that carries a good distance. One calling near your cabin will soon become a big nuisance. Now nightjar: Night is obvious. It's when this family of birds -- 78 members worldwide, eight breeding in the United States-- are active. How did the word jar get added? Google sources kept telling me that it referred to the harsh sound the birds make. That didn't make sense. Finally, I found a reference to the bird's extremely large mouth. That makes sense. With the bird's mouth closed you see only the tight lips of a stubborn child (note: birds do not have lips). Open, however, the mouth gapes; it's huge. It is an insect vacuum cleaner. In flight, an insect is seen, scooped up in the wide-mouthed "jar," and swallowed.

Bird cannibalism Q Will birds eat others of their species? Do they practice cannibalism?

A Yes, but it isn't gratuitous. Nest-bound birds sometimes are eaten by the parents or siblings when there are too many young for the parents to care for and successfully fledge. It's a practical solution: Waste not, want not.

If food is in short supply, and one of the nestlings is not doing well, it might be eaten. This will aid survival of the remaining baby bird(s). Survival, after all, is the name of the game.

Gulls, birds that will eat almost anything, will eat the young of other gull species, and sick or injured gulls of their own species. In Alaska, I saw a herring gull pulling feathers from a dying Bonaparte's gull in preparation, I assumed, for lunch. I don't know if the attacking bird killed or injured its prey or was taking advantage of a wounded or sick bird.

Discouraging grackles Q Any day now a large flock of grackles will fill the trees in our yard, then rapidly empty the four tube feeders we have hanging there. Can I make them go away?

A The birds have flocked up for migration. They see your feeders as a fueling stop. Take the feeders down temporarily. No food, no stopover. I've also removed the trays from tube feeders, and replaced the manufacturer's perches with much shorter perches. This makes it difficult for the grackles to sit on the feeders.

Light bones aid flight Q Why are bird bones hollow?

A Hollow bones weigh less. Solid bones, much heavier, would make flight impossible.

Marshes vs. swamps Q Some birds live in marshes, others in swamps. How can you tell the difference in habitat?

A Swamps have trees or other woody vegetation. Marshes don't.

Territoriality is seasonal Q Why do I have no more than three or four cardinals at my feeders spring, summer and fall, but up to a dozen in the winter?

A It's a territorial thing. During nesting season, birds stake out feeding territories that they defend with vigor. In the winter, the competition for food lessens, so the birds are more willing to share.

Birdseed values Q Birdseed varies in price. The bags of seed at the grocery store seem to be better buys than the seed the bird store offers. Is this true?

A Like just about everything else, you get what you pay for. Seed is cheap because it has less value to the retailer, the packager and the birds. The energy content of the more expensive seeds is higher. Black oil sunflower seed, for example, is an excellent source of nourishment for birds. It's good for you, too, because you'll see more birds at your feeders.

Nest re-use Q Do birds re-use nests?

A Large birds like hawks and eagles will use a nest year after year, often refurbishing it or adding on before a new nesting season. Cavities will be re-used. But birds that build nests in trees, shrubs or grass start from scratch each spring. If you have nest boxes, clean out the old nests before birds return in the spring.

Lifelong birder Jim Williams can be reached at woodduck38@gmail.com. Join his conversation about birds at www.startribune.com/wingnut.