Q Why do some people get upset when they find out I welcome house sparrows to my bird feeder?

A House sparrows aren't native to North America. They're European birds, imported long ago.

Here, they tip the balance of our natural order. They nest in cavities, thus providing unfair competition for our native cavity nesters -- Eastern bluebirds, in particular. House sparrows will enter a nest box or other cavity being used by bluebirds and kill the occupants and/or poke holes in eggs.

Some people feed them because they love all bird species, or because their location limits avian visitors to house sparrows.

Your hospitality is understandable, but you're doing native birds no favors. Try black oil sunflower seeds in your feeder. Sparrows are grain eaters. Sunflower seeds appeal to many of our native back-yard birds.

Eye injuries

Q We have a one-eyed blue jay visiting our feeder. The bad eye is milky. Will the bird survive with only one eye?

A Yes, unless infection sets in soon after the injury. In that case, if possible, the bird should be taken to the Wildlife Rehabilitation Center of Minnesota, 2350 Dale St., Roseville. Call first at 651-486-9453. Birds sometimes lose an eye. Fights, predators or misjudged flight into a thicket, among other things, can cause the damage. Many of the injured adapt to monocular vision without problem.

Birds can bleed

Q Do birds bleed?

A Yes. They have blood, hearts, veins, arteries, the whole works. Most dead birds we see died of blunt-force injuries (flying into a window, getting hit by a car), which don't necessarily produce blood. But it's there.

Splattering of evidence

Q Bird droppings are not hard to find. Urine leaves no evidence. Do birds urinate?

A Birds efficiently combine both feces and urine in one liquidy squirt that has amazing adhesive qualities.

Name change

Q My older bird book identifies a species of duck as oldsquaw. My new book calls this bird long-tailed duck. What happened?

A The new name is politically correct and anatomically more precise. Oldsquaw referred to the sound a flock of these birds make while on the water. Some observers said the ducks seemed to murmur to each other, i.e. gossip. Male long-tailed ducks do indeed have long tails, an adornment for courtship.

Deterring blackbirds

Q Is there any way to avoid the hordes of blackbirds and grackles that descend on our yard each fall? They are expensive to feed.

A Use safflower seed in your feeders during that migration period. Blackbirds love sunflower seeds, but have smaller appetites for safflower, or so we understand. Remove large feeders with large perches or feeders with trays that catch seed. Don't put seed in platform or fly-through feeders. You might limit your feeding to one small tube feeder with short perches. Prayer doesn't seem to work.

Crows and ravens

Q Are crows and ravens related?

A Yes, both are members of the corvid family, along with jays and magpies. Ravens are larger than crows, have heavier bills, and have more neck feathers that can have almost a ruff-like appearance. The easiest way to distinguish them is to check the tail. A raven's tail has a bit of a taper to it, coming to a broad point. The tails of crows are evenly rounded.

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