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Julie Craves explains Red-breasted Nuthatch irruptions and whether pennies deter algae in birdbaths

Red-breasted Nuthatch by May Haga

In the column “Since You Asked” in every issue of BirdWatching, Contributing Editor Julie Craves answers readers’ questions about birds and bird behavior. Here are questions from our August 2015 issue:

I live in northern Massachusetts and see many White-breasted Nuthatches at the feeder but few Red-breasted Nuthatches. Is this too far north for them, or is something happening to the population? — Vahe Bedian, Ashburnham, Massachusetts

Red-breasted Nuthatches are permanent residents in much of New England and farther north into Canada, and they nest across Massachusetts. They favor habitats with conifers; spruce and fir are the most important tree species, although hemlock, pine, and other evergreens are also used. In eastern North America, forests inhabited by Red-breasted Nuthatches may contain more hardwoods than in the west.

Some northern populations migrate south in winter. In years in which cone production in breeding areas is poor, non-migratory populations of Red-breasted Nuthatch may move south in great numbers, a phenomenon known as an irruption. Irruptions in the species tend to occur in a two- or three-year cycle. The winter of 2014-15 saw relatively few nuthatches move south, so be on the lookout for them this winter.

Migratory populations tend to fly south in late summer. At feeding stations, they are especially fond of peanut chips, black-oil sunflower seeds, and suet.


It could be that your immediate area does not have enough conifers to attract Red-breasted Nuthatches, even in winter. I have found that during irruption years, they are far more common at backyard feeders in neighborhoods with conifers than they are in larger deciduous woodlots just a few miles away.

A number of other northern-breeding species also stage irruptions, particularly Pine Siskin, Purple Finch, redpolls, and crossbills. Each fall, the Ontario Field Ornithologists posts a prediction about which species might be expected to move.

Copper treatments are used in ponds to deter algae. A friend told me he throws a few pennies in his birdbath to help keep it clean. Does this work, and is it harmful to birds? — Wiley Berry, Jacksonville, Florida


A few pennies in the birdbath probably won’t do much harm and may help a bit, as long as the pennies are dated prior to 1982. Since then, pennies have been made of zinc that is merely coated with copper.

The water in a birdbath can become fouled quickly by droppings, food, and whatever else birds might introduce. For that reason, the water needs to be changed every day or so. The amount of copper that leaches into the water from pennies over such a short time is quite small, and it may not be enough to deter algae growth. If you change the water frequently and give the surface of the bath a quick scrub with a brush, algae, mosquitoes, scum, and dirt shouldn’t become a problem.

About Julie Craves

Julie-Craves-120Julie is supervisor of avian research at the Rouge River Bird Observatory at the University of Michigan Dearborn and a research associate at the university’s Environmental Interpretive Center. She writes about her research on the blog Net Results, and she maintains the website Coffee & Conservation, a thorough resource on where coffee comes from and its impact on wild birds.

Read other questions that Julie has answered in “Since You Asked.”

If you have a question about birds for Julie, send it to [email protected] or visit our Contact page


A version of this article was published in the August 2015 issue of BirdWatching. Subscribe.

Originally Published

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