Q: This has puzzled me for a long time: I have wood chip mulch on my garden beds, and many times in the fall I notice pieces of mulch lying on the grass, outside the gardens. I can't imagine what causes this, can you?

A: The same thing happens to the mulch in my garden beds in late September and early October each year. The culprit is a handsome migratory bird that feeds on the ground, the white-throated sparrow.

These chunky little birds forage by kicking through any litter on the ground, hopping forward and scraping back with their feet, to uncover seeds and tasty insects. This action tosses mulch and leaves around.

The way I see it, white-throated sparrows are gorgeous birds with such a sweet song (allaboutbirds.org/guide/White-throated_Sparrow/sounds) that a bit of raking is a small price to pay to have them visit as they pass through.

Playing with food

Q: I recently saw a bird doing something and wondered if it was unusual: A hawk, either a sharp-shinned or a Cooper's, was in the backyard with what I think was a goldfinch carcass. It kept picking it up and throwing it in the air, just as my cat does with her mouse toys. I'm more used to seeing a hawk swoop down to grab its prey, then fly away. Was this its way of killing the bird?

A: I've never seen anything like the behavior you describe, either, but I suspect that this was a young hawk, hatched earlier in the summer. While still in the nest it may have tossed around food pieces that its parents brought back for their brood, and maybe the hawk you saw hadn't quite given up on that behavior yet.

I checked with sources at the Raptor Center, who told me that they've never seen such behavior in this kind of hawk, but that some birds of prey engage in behaviors that don't seem to be directly linked to a successful hunting outcome.

Pigeon problems

Q: We live by a marsh, and blackbirds have been a problem at our feeders. Some time ago we switched to safflower seeds and this keeps most of the grackles and starlings away, but now there's a new problem bird — there can be up to eight pigeons at once on the feeder. I'm not happy about them devouring all the seed.

A: Like you, I'm not a big fan of pigeons at my bird feeders: They eat a lot of seed and they have the bad habit of pooping right in or on the feeder, which can spread diseases to other birds. How about investing in a new feeder, one with a dome that can be raised or lowered? You can set the dome low enough to exclude pigeons but still allow birds like cardinals and woodpeckers to feed.

'Dees and downies

Q: Chickadees and downy woodpeckers visit my suet and peanut feeders, and it often seems that if a chickadee comes in, a downy isn't far behind, or vice versa. Do these birds share some kind of relationship?

A: These two species of birds aren't related, but they do share food preferences, so it's not at all unusual to see them, one after the other, at feeders. Have you noticed how backyard birds tend to feed almost at the same times as we do, in the morning, midday and late afternoon? A good time for one bird to feed often is a good time for others, as well.

Water works

Q: One day in the fall we had a group of eight robins splashing at our birdbath and chasing each other around. This went on for almost 20 minutes, with up to three robins at a time in the bath. Do you have any idea what this interaction was about?

A: Robins are known to be "water babies," eager to bathe anytime, anywhere. I'll bet the birds that suddenly appeared at your birdbath had been part of a group of robins just starting their migration. When one bird spied the water, it dropped down to wash off the dust from its journey, and then was followed by others. They might still be feeling a bit territorial so sometimes engaged in chases to try to dominate the birdbath.

Five in a glide

Q: I was sitting out on my deck about 5 p.m. when five large black birds glided overhead. They were as big as crows but they weren't flapping their wings, just doing a spread-winged glide. Would crows glide like that for a spell and do they migrate in family groups?

A: Yes, crows do glide through the air, if conditions are right — they save energy by not engaging in powered flight for a bit. I'll bet the five birds you saw made up a family group heading to a pre-roost before assembling with many other crows to roost together for the night. As for migration, crows are known as partial migrants, meaning that some head elsewhere in the fall, but many, especially pairs that have established a territory, will stay around all winter.

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