Q I saw the weirdest thing recently: A sparrow flew out of one of our feeders into a bush, and then started sharpening his beak on a branch. Is this unusual, and why did he do this?
A You observed a sparrow practicing good hygiene by wiping its beak clean of any debris or food it picked up at your feeder. This is something that all songbirds do quite often, after drinking, eating or taking a bath. Birds’ beaks continue to grow throughout their lives, so birds also need to hone them from time to time to keep them in shape for eating and grooming.

Triple play
Q I think my cardinal pair raised three batches of babies this summer. Is that even possible?
A Yes, it is possible for cardinals to raise more than two broods, if the weather cooperates. Remember, spring started very early this year, and autumn has been quite warm, providing perfect conditions for squeezing in a third batch of nestlings. I saw evidence of this in my own back yard this fall: At dusk there could be as many as eight young cardinals at the platform feeder, and it was very obvious that they had reached different stages of maturity. Some had a nearly full coat of red feathers and a reddish beak, some had a few red feathers and a still-dark beak and two were brown from head to tail.

Jays vs. cardinals?
Q We’ve always enjoyed having many cardinals at our feeders, but have never had much luck with blue jays. However, this fall there have been blue jays in abundance. Are they likely to push the cardinals out?
A I don’t think you need to worry, since these birds generally live in close proximity and occupy different habitat niches, so aren’t really in competition for resources. Blue jays are aggressive birds and at times may drive all other birds from bird feeders, but the departed soon return. And cardinals are able to see at low light levels, so they can feed earlier in the morning and later in the evening than blue jays can. If you’re suddenly seeing many blue jays, they’re probably migrants, passing through the neighborhood on their way south.

Kojak cardinals
Q A male cardinal visiting our feeders looked like he was wearing a black skullcap, lacking the red peaked feathers all the other males have. Was this a genetic mutation or could he have been sick?
A Late summer and fall is the time when people begin reporting bald cardinals and blue jays in the neighborhood. A number of cardinals may suddenly show up with no head feathers, revealing the black skin underneath. There are two theories about the cause of bird baldness: One school of thought says that some birds drop their head feathers all at once before molting new ones, while the other says that baldness is the result of a feather mite infestation, causing birds to scratch themselves bald.
A reader recently sent in a photo of bald blue jays, taken by a motion camera set up in her feeder. I shared the image with a wildlife veterinarian and she noted tiny pinfeathers visible on the birds’ heads, leading her to line up with the sudden-molt theory for the jays (if the baldness had been caused by parasites, the feathers wouldn’t grow back so quickly). Although some people think birds are infested with parasites, the truth is that they’re very clean and only have a high number of parasites when they’re sick or have immune system problems.

Family dynamics
Q A pair of sandhill cranes nests right near our rural property and they seem almost tame, coming in to eat the crabapples, etc. They have one only chick with them. Is it true that sandhills allow other chicks to starve, in order to raise only one?
A I researched this interesting question and found that while sandhill cranes almost invariably lay two eggs, they tend to have only one chick in their care after the first few months. Many things lead to chick mortality, including predators like coyotes and gulls, as well as collisions with cars, lack of food and other causes.
Usually one chick hatches some hours before the other one and is genetically programmed to be very aggressive toward its sibling. It will push the young bird out of the way when a parent comes in with food, and may even injure its sibling with beak pecks and wing flaps. Quite often it’s this sibling aggression that leads to the death of the younger chick in a sandhill family. However, in years where food is abundant, both chicks may survive.

Finches feasting
Q I was interested in the recent item about goldfinches eating lettuce and chard, because the finches in my back yard are stripping the petals off the coneflowers. I guess I need to plant flowers that don’t attract finches.
A Goldfinches are tearing into people’s gardens all around the metro area, it seems, but I hadn’t heard of them pulling off those pretty pink petals before. One thought occurred to me: I have many coneflowers in the back yard and many finches, with no damage to the flowers. It’s possible this could be at least partly due to the fact that there are two finch feeders near the flower beds. The feeders are filled with a mix of nyger seed and small pieces of sunflower seed and the goldfinches feed on this all day long. If you’re not providing seed now, it might be worth a try.

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.