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Answers to questions about phoebe nests, murders of crows, and birds and coffee

An Eastern Phoebe carries moss to her nest at Pike Lake Provincial Park in Saskatchewan. Photo by mayhaga.
An Eastern Phoebe carries moss to her nest at Pike Lake Provincial Park in Saskatchewan. Photo by mayhaga.

Julie Craves answers readers’ questions about birds in every issue of BirdWatching magazine. Here are her three most recent answers:

Last year, a pair of Eastern Phoebes nested on our porch light. While my family and I enjoyed watching them raise their young, we were grossed out by the millions of tiny bugs that came from the nest. What were they, and how do we prevent them (the bugs, not the birds) this year? — Lynn Jack, Albany, New York

Bird nests can be homes to a wide variety of nest parasites. Based on your description, it sounds like the bugs you saw were bird mites in the genera Dermanyssus and Ornithonyssus, common parasites related to spiders. They live on the blood of nestling birds and are encountered by nest-box landlords frequently.

The mites have short life cycles, and their numbers can be substantial, even in the few weeks that birds occupy nests. As long as the baby birds are getting adequate nutrition, they can usually withstand a typical infestation; birds and mites have co-evolved, and birds are adapted to deal with them. Heavy infestations, however, do have the potential to weaken young birds or cause premature fledging.

When birds leave the nest, the mites will sometimes also leave and look for new hosts. They are dependent on birds to reproduce. While mites may bite humans (perhaps causing an itchy rash) and become a nuisance, they are not harmful to us.

Some species can live a while without a blood meal, but most can’t survive for long in low-humidity situations, such as the inside of a house. Nonetheless, the best way to prevent mites from coming indoors is to make sure birds don’t nest close to a doorway, window, or other portal to your home. You might try making your porch light unsuitable for nesting while placing a nesting platform in a spot where mites cannot enter your home (but where you can still observe the birds).

If you need to clean an area that once had a nest or want to clean out a nest box, use a weak bleach solution. Afterward, place diatomaceous earth (a non-toxic dust-like insecticide available in garden centers) in cracks and crevices. Please do not use synthetic pesticides on or near your home or on or in a place where birds may nest in the future. The risks are not worth it.

Why is a group of crows called a “murder”? — Dexter Chrisman, St. Louis, Missouri

I have found several different explanations for the derivation of the collective phrase “a murder of crows.” Here are two of the most common:

The first involves the belief that a group of crows will pass judgment on the bad deeds of a flock member and may kill it.

A simpler and more satisfactory explanation is that crows (and their relatives) are omnivorous. They often scavenge and are associated with road kill, carcasses, and therefore death.

Answers to your questions about birds and coffee:

I appreciate all the positive feedback on The True Cost of Coffee, my article about the connection between coffee and birds. I have answered many of your questions personally and on the magazine’s page on Facebook.

I have a website devoted to raising awareness about coffee called Coffee & Conservation. On it you will find two articles that I wrote to provide answers to common questions. One is Resources for BirdWatching Magazine readers. The other lists brands of coffee to avoid and offers information on the environmental friendliness of many other brands, retailers, and coffee shops: Popular coffee brands: A compilation. Please feel free to leave a comment or ask additional questions.

Julie Craves answers readers’ questions in her column “Since You Asked,” which appears in every issue of BirdWatching magazine. This article appeared in the June 2013 issue. Julie 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.

Send a question about birds to Julie.

  Originally Published

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