Cardinals are unlikely nest robbers

Q: After hearing some birds shrieking, I went to investigate and found a male and female cardinal chasing house sparrows away from a nest in a thick vine. The sparrows kept trying to come back but the male chased them off. Have you ever heard of cardinals taking over a sparrow nest?

A: There are a couple of possible explanations for the bird battle you observed, and I suspect the shoe was on the other foot in this situation. I have never heard of cardinals harming the eggs or nests of other birds so you can probably rule this out. Cardinals build their nests in the open, in shrubs or trees, while sparrows nest inside a cavity, such as a tree hole or nest box. This sounds like all the activity was occurring near an outside nest, which suggests that it belonged to the cardinals and the sparrows were interfering. The sparrows may have been trying to steal some material for their own nest.

Q: I thought juncos only fed on the ground, but during the spring-that-never-came I saw them feeding at my tube feeders and suet cage. Is this common or is it due to the strange weather?

A: You're right, juncos are primarily ground feeders, scrabbling on open ground under trees and feeders for morsels of food. But they've had to "think outside the box" during our prolonged, cold pre-spring. Many readers reported seeing juncos clinging to their feeders, especially those filled with suet, for life-sustaining calories. These resilient little birds saw other birds doing this and decided to give it a try.

Q: I was at the cabin and saw a bald eagle soaring overhead, then it was joined by what I think was an albino eagle. The second bird was pure white with black wing tips. What do you think?

A: Whenever I hear about an all-white bird with black tips on its wings I immediately think of a white pelican. This may seem like an odd diagnosis, but pelicans are about eagle sized (actually, they're larger, but this bird may have been soaring above the eagle and looked smaller), and they're white except for those characteristic black wing tips. An albino eagle is a rarity and such a bird would have no color in any of its feathers.

Q: I fretted about all the birds that showed up in late April, like the loons and the herons. I guess they've survived many seasons without me having to worry about them, but I did feel concerned, especially for hummingbirds. Your thoughts?

A: I'd bet that we humans were more discouraged by spring's tardiness than the birds were. Great blue herons return when there's enough open water along ponds, lakes and rivers to serve their aquatic diet. Loons, too, fly in only after some water has opened up, allowing them to swim and dive for food. They leave for their nesting sites as lakes and ponds open up in the north.

As for hummingbirds, they may be tiny, but they're some of the hardiest birds in the avian world. They invariably arrive at our latitude before flowers are in bloom to provide nectar. They tide themselves over by drinking tree sap. Sometimes the sap flows naturally out of wounds in tree bark, but more often the hummingbirds help themselves to sap wells drilled by yellow-bellied sapsuckers.

Q: Do any raptors migrate in flocks?

A: The hawk that's found most frequently migrating in groups is the broad-winged hawk, a medium-sized cousin of the red-tailed hawk. Few of us ever see broad-winged hawks because they're birds of the forest. Two other raptors found in our region, the turkey vulture and the Swainson's hawk, remain together for days or weeks during migration. Most other raptors may find themselves in large groupings of birds of prey on migration, as they soar together in rising hot air for some minutes or an hour. These aren't flocks but instead I've seen them described as bird traffic jams as they travel through an area.

Q: How do I stop the little brown birds from making nests in my bluebird houses?

A: Those little brown birds are almost surely house sparrows, and bluebirds and house sparrows are a toxic mix. Sparrows compete fiercely for nest boxes since they, like bluebirds, are cavity nesters. Sparrows try to drive off nest-box occupants, and they'll even pierce eggshells or kill a female bird on the nest in order to take it over. It's important to evict the sparrows each and every time they attempt to nest, and do whatever else is needed to deter them, such as not offering seed on the ground. (Sparrows are not a native species, so are not protected by laws designed to protect migratory birds.) Here's a link to a fact sheet with some excellent tips for discouraging sparrows: www.michiganbluebirds.org/problem-solving. Good luck with this. Sparrows can be very persistent but they can be thwarted.

Tip from readers: We've heard from several readers with a tip about making those big, lumpy blocks of suet from the meat counter fit the suet feeder. Before freezing the suet block, cut it into smaller chunks, then store these in the freezer to use as needed.

St. Paul resident Val Cunningham, who leads bird hikes for the St. Paul Audubon Society and writes about nature for local and regional newspapers and magazines, can be reached at valwrites@comcast.net.