What makes cardinals so red?

Q: I've heard that cardinals get their red color from the food they eat, but there's not much red food available in winter, so how do they stay red?

A: You're right, cardinal feathers get their red pigment from the foods the birds eat, and the color is deposited before the birds molt new feathers in the fall. This is a time when food is abundant in the natural world, including fruits like grapes and berries, as well as seeds and insects, all of which can contribute to feather color. Once a feather appears on the bird, it holds its color without needing any new pigments from the bird's diet.

Q: Mourning doves are monopolizing our platform feeder, sitting in it for an hour at a time, or longer. This keeps the other birds away, so even though we like the doves, we feel we need to chase them away. Do you have any suggestions for stopping them from taking over the feeder?

A: This sounds like mourning doves being mourning doves — they seem to like to adopt a spot and sit in it for extended periods. In my backyard, they show up about a half-hour before sunset and sit on the rim of the birdbath, sometimes drinking but mostly sitting, which deters other birds from getting a last-of-the-evening drink. In your case, they have the perfect setup, with food close by and a good perch for surveying the surrounding area. Doves have a bad habit, though: They'll poop right in the food tray.

I think a good solution would be to purchase a feeder with an adjustable dome. You could then lower the dome so birds as tall as cardinals and blue jays can feed in the tray, but exclude larger birds like mourning doves.

Q: A recent column suggested that there aren't many birds in Loring Park in Minneapolis. I walk through the park every day and am happy to report that it is filled with birds — one just has to listen and look. There are chickadees, nuthatches, goldfinches and woodpeckers, and a pair of hawks nested in the park last year. These are random, unscientific observations but they do attest to a healthy mix of birds in a big city park.

A: Thank you for the excellent report, which counters an earlier correspondent's lament of not seeing many birds in this urban park. With its pond and many trees, Loring Park should be an attractant for many kinds of birds, and your steady visits and powers of observation show that it is.

A: I wish I had not included kinglets, meaning golden-crowned kinglets, on the list of birds that could be seen in our backyards in the winter. While golden-crowned kinglets can be around all winter, they're generally found in forests, where they hunt relentlessly for tiny insects. They'd almost never be around bird feeders, unless they'd discovered the energy provided by suet.

Q: Do birds converse in winter? It seems to me that they must peep or caw or utter some other sound.

A: That's a good question, and you're right, birds aren't totally silent in the winter. But with few exceptions, they don't sing outside breeding season, so winter is a much quieter time. However, birds need to warn if a predator is in the area, or alert members of their feeding flock to a good source of food, as well as several other communication needs. Birds make calls, such as the sparrow's "peep," the crow's "caw," and the cardinal's chip note to talk to each other. Beginning in January, cardinals switch over to their "wha-cheer" courtship and territorial song, and chickadees do the same with their sweet "fee-bee" sounds. And then, in May, the floodgates open as all the songbirds begin singing to attract a mate and firm up a breeding territory.

Q: I'm looking for real hummingbird's nest, one made and used by a hummingbird. The reason is my lady friend is obsessed with birds and collects their nests. I'm looking to propose and had the idea of placing the ring inside a hummingbird nest, if that's possible.

A: You have a sweet idea, but the Migratory Bird Treaty Act, in place for more than 100 years, makes it illegal to have a bird's nest in your possession. The law was put in place at a time when many bird species were being hunted to near-extinction to provide feathers and nests for women's hats and other accessories. It was made illegal to possess migratory birds, their feathers, eggs and nests, and this law has served birds well for a century. In a quick search of the internet, I discovered a company selling a small glass jewelry box shaped like a hummingbird at her nest, and this might be just the thing for your proposal.