Pileated woodpeckers sometimes venture into cities

Q: I had never seen a pileated woodpecker before, but then suddenly one appeared on my neighbor's ash tree. Is this unusual?

A: These large, crow-sized woodpeckers prefer to spend their time in the woods, but occasionally one will venture out into the city, most often into areas with mature trees, to search for insects hidden beneath the bark. I hope this doesn't mean that the woodpecker detected emerald ash borers burrowing in your neighbor's tree. I recently read that city foresters had discovered two new infestations of ash borers in St. Paul, and woodpeckers led them to the sites.

Q: I was out in the woods today and was lucky enough to see two great horned owls, but they looked exactly the same. Is there any way to tell the two sexes apart?

A: You really can't tell great horned owls apart by their plumage, since males and females look exactly alike. The best indicator is size: Females are larger than males. Unless you see two owls together, however, it's tough to tell which is bigger.

Q: It was my understanding that owls swallowed their food whole, but how could they do that with something as large as a heron or a woodchuck, as you recently wrote about?

A: You're so right, owls typically swallow prey such as mice and voles whole, and then later cough up a pellet containing the indigestible bits. But great horned owls will hunt larger animals, even those too large to eat all at once and too heavy to carry off, such as rabbits and woodchucks. In such cases, they use their razor-sharp talons to slice off the head of their prey, which has the most nutrition value, and fly off to eat it out of sight.

Q: There were at least 15 cardinals at my feeders and in the trees this morning. Do cardinals travel as a group to feed in winter, or do they just happen to meet up at the feeders?

A: Cardinals are very territorial during breeding season, so we never see them in flocks from early spring to late fall. But as their hormones subside and the temperature falls, cardinals become much more tolerant of each other. We begin to see small groups of cardinals, usually a family, in late fall. In the deep of winter, when the birds need more calories to survive each day, it's beneficial to have more eyes searching for food and watching out for predators, so the flock grows. Membership in a flock varies at different times of day, in different habitats and over the course of the winter. It's also possible that more than one flock may meet up at feeders at the heaviest feeding times for cardinals, at dawn and dusk. So the flock you see around your feeders probably traveled there as a group as they foraged. Soon, though, cardinals will begin singing their territorial songs, and the flock will break up.

Q: This isn't a bird-related question, but could I really have seen an opossum under the bird feeders the other day?

A: Yes, it's not at all unlikely for our back yards to attract a Virginia opossum. These marsupials used to be confined to the South, but have been pushing their way northward. Possums are primarily nocturnal but sometimes are out foraging during the day. With their scanty coats and unfurred ears and tail, they're vulnerable to cold snaps. Possums scoop up dropped seed and often visit compost piles.

Q: I've been feeding birds for many years, but this is the first time I've seen mourning doves under the feeders. Is this odd?

A: It's not all that unusual to find mourning doves around our feeders in winter. These cousins of the pigeon eat seeds and grain, so they're especially drawn to cracked corn and seeds like millet. We've hosted them in the back yard for many years, most often at dusk, when a crowd gathers at the heated birdbath, seemingly warming up in the steam before heading to their nighttime roost. They're fairly nomadic and haven't appeared for the past couple of years.

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