Q: I love having goldfinches around and really would like some of them to raise their families in my backyard. What kind of birdhouse should I buy?
A: It would be futile to buy a house for goldfinches because they will not use it. This is a hard and fast rule in the bird world: If birds build their nests in cavities, there’s a good chance they’ll use a nest box (aka a birdhouse). But most birds are not used to exploring dark, enclosed spaces, and will only use nests they build themselves in shrubs or trees, and this includes goldfinches. Only about 10% of birds are cavity nesters/birdhouse users, and these include chickadees, bluebirds, tree swallows and house wrens.

Balcony pests
Q: I live in a downtown condo and have a big problem with pigeons who want to nest on my balcony. I like pigeons and find them beautiful and calming to watch, but they’re too messy. We’ve tried shiny streamers, but they don’t seem to work, although a fake owl works better. Any suggestions?
A: Pigeons are pretty cool, but they’re their own worst enemy in confined spaces, since they poop a great deal and leave a big mess. I looked online to see what might be worth a try, and came across many different kinds of bird spikes. These could be installed on your balcony to deter pigeons from landing there. Many cities use spikes to discourage pigeons and other birds from nesting on public buildings. The spikes don’t harm birds but do keep them from landing.
Readers: Any other suggestions?

Wide open spaces
Q: A large flock of geese spent most of a windy day on our iced-over lake in late winter. I wonder what appealed to them out there?
A: If you’ve ever seen a fox or coyote try to sneak up on a group of waterbirds, you’ve seen how well this out-in-the-open-strategy works for geese. Sitting on ice far from shore, they can see the approach of predators and have plenty of time to escape into flight. When they become hungry, they’ll head inland to feed.
Hawks and their prey
Q: I sometimes see both a Cooper’s hawk and a sharp-shinned hawk hunting the birds in my backyard in the same week. Are they hunting for the same birds?