House Sparrow madness

The annual Christmas Bird Count (CBC) season is nearly upon us. The count in which I have participated the longest is the Detroit River MI/ON CBC, because the city of Dearborn is within the count circle. In 1995, RRBO started coordinating the Dearborn portion of the count, so there is intensive coverage in the city, and I keep a separate tally of the numbers in Dearborn before they are added into the count totals.

The CBC issue of American Birds, published by National Audubon, contains summary information and various analyses of CBC data. One standard article is the summary of highest counts of individuals for the U.S. Last year, the Detroit River count had a highest number of House Sparrows -- 4537 -- of any of the 1673 counts held in the U.S.

A quick look at my numbers showed that 77% of those House Sparrows were counted in Dearborn, and 3255 of them (72%) were counted in the various sunflower/wildflower fields planted by Ford -- 2400 in a single field, as I noted in my blog post last year. The Detroit River count also had the highest number of House Sparrows in the 2006-2007 count (5168), of which 57% were from Dearborn.

Does this mean that Dearborn, or the metro Detroit area, has the highest concentration of House Sparrows in the country? Hardly. Over the years, I've given some thought to the accuracy of counts of very common species considered "trash" by most birders, particularly House Sparrows, European Starlings, and Rock Pigeons. Let's face it: most people participate in CBCs and other bird counts in order to see what "goodies" might be found, not to spend the time it takes to get accurate counts of House Sparrows. I usually see numbers of mundane species coming into compilations as ballparked figures, especially in urban areas where counting these species can be tedious.

There is great value in being meticulous about counting very common species of birds. For nearly 20 years, I've conducted a Winter Bird Population Survey. I'm sure glad I took the time to count American Crows the first ten years or so (and there were often hundreds), because since West Nile virus hit town, numbers plummeted and have not recovered.

Despite whether you care about or like House Sparrows or other common birds, take the time to get reliable numbers on the various counts you participate in. These citizen science projects are some of the best sources of long-term population data we have, and their integrity may be jeopardized by "garbage in, garbage out."

In 2003, I co-authored a paper published in Ontario Birds summarizing the first 25 years of the Detroit River CBC. You can download a PDF copy here.

Thanks to Diane Newbery for publishing this House Sparrow photo under a Creative Commons license.

RRBO bird banding video

This video was produced in 2001. Although I enjoy having people see me so much younger and thinner, it could use an update as it was shot on film and the digital conversion isn't very high resolution. Nonetheless, it gives you an idea of how and why we band birds. We use this to introduce students, program participants, and visitors to the banding process.

Banding at RRBO from Julie Craves on Vimeo.

"Look what the cat dragged in"

Only about 1% of banded small songbirds are ever recovered away from the place they were banded (much of the value of focused banding studies is in initial captures and within-season recaptures). So when a bander receives notice that one of their banded birds has been found somewhere else, it's a pretty notable event. Especially remarkable is when a migrant bird is banded on its wintering grounds and recovered where it breeds (or vice versa).

Thus it was astounding to learn that a Bobolink banded in Bolivia by the Vermont Center for Ecostudies was recovered three years later in Vermont, just miles from the bander's home, 4300 miles away! This was the first time a Bobolink banded on its wintering grounds had been recovered on its breeding grounds (or vice versa).

Tempering that news was the fact that this bird, having managed to have survived at least three migratory journeys totaling 35,000 miles in flight, was delivered dead to a homeowner by a house cat.

Often, banders do not know the exact cause of death of a reported bird...usually the report is only coded "found dead." Sometimes the person who finds the bird is more specific. Out of the last 40 or so birds we have banded here at RRBO for which we have received reports, only around 30% were found alive. The majority of those found dead did not specify a reason. Of those that did, nearly 40% were coded "caught by or due to cat." They included these birds:

• A White-throated Sparrow banded on 26 October 1992 "caught by or due to cat" 5 May 1993 in Columbus, OH.
• A Song Sparrow banded on 3 April 1995 "caught by or due to cat" 17 Jun 1995 just south of North Bay, Ontario.
• An American Goldfinch banded on 10 May 2001 "caught by or due to cat" 12 May 2002 in Berea, KY.

(You can view a map and list of our out-of-state recoveries of banded birds here.)

The huge problem to birds and wildlife posed by outdoor cats is one that sparks a great deal of emotion. In fact, the blog post about the Bobolink pussy-footed around the issue to avoid the controversy. The bander pointed out that the fact that a cat brought home a dead bird is not concrete evidence that it killed the bird. However, it is generally believed that items brought home by cats are indeed prey killed by that cat, and numerous peer-reviewed scientific studies have used this behaviorial trait of cats to determine composition of prey items (see Barratt 1998, Churcher and Lawton 1987, and Woods et al. 2003 and the scores of references therein).

Don't get me wrong -- I love cats! I have two of my own, but they never go outdoors. Please, if you own a cat, keep it indoors. It is better for wildlife, and it is better for your cat.

For more information, you can see RRBO's keep cats indoors page, or visit the American Bird Conservancy's Cats Indoors! campaign web site.


Barratt, D. G. 1998. Predation by house cats, Felis catus (L.) in Canberra, Australia. I. Prey composition and preference, Wildl. Res. 24:263–277.

Churcher, P. B., and J.H. Lawton 1987. Predation by domestic cats in an English village, J. Zool. (London) 212:439–455.

Woods, M., R.A. McDonald, and S. Harris. 2003. Predation of wildlife by domestic cats Felis catus in Great Britain, Mammal Rev. 33:174–188.

Fall 2009 banding summary

I've posted a summary of the fall 2009 banding season at the RRBO web site. You'll find all the summary stats, a weather summary, top ten species banded, some commentary on deviations in numbers from previous averages, and notable within-season and between-year recaptures. There is also a brief explanation of how we calculate our capture rate, and our weather policy.

I've also updated our lists of the most commonly banded species. For the first time in RRBO history, American Robin unseated Gray Catbird at the top of the list.

Coming up, some results from our diet study.

An amazing white-breasted robin finishes the season

This stunning and unusual American Robin with a white breast was the highlight of our final day of banding for the fall 2009 season today. Our short, final week was not particularly notable; I'll be posting a season summary in a few days. Meanwhile, let's check out this very cool robin!

American Robins with abnormal plumage are not terribly uncommon. There was the funky orange-faced bird I banded a couple of weeks ago. I band robins with one or a few white feathers at least once a season. In October 2007 I banded an adult female in which nearly all the gray feathers had a frosted appearance. I have found photos of quite a few robins that were the "opposite" of our bird, with pale backs but normal breasts (in Minnesota, Saskatchewan, Iowa, Pennsylvania, and Utah). However, I have never encountered or heard of a robin that had a completely white breast with a normal back, wings, and head like the bird we banded today.

Most of the gray plumage on this robin, which was a hatching-year bird (born this year), was normally-colored. It did have a few partially white feathers on each wing. Most of these feathers were short and/or deformed. On the left wing there was one slightly brittle short feather with a bit of white, and one mostly white feather next to it.

On the right wing, one primary was half white, stunted, and growing in this weird direction. About half of the tail feathers were also "messy" looking, due to some brittleness and twisting to them.

The only hint of orange pigment was on a few feathers under each wing.

This condition is usually called "leucism," which is an abnormal reduction in the deposition of pigment in the feathers. Some leucistic birds appear entirely washed out or pale if the reduction of pigment is roughly equal in all feathers (some authors now call this "hypomelanism"). More often, pigment is absent in only some feathers, and this is known as pied leucism, or "partial amelanism." Both the grayish-brown and orange/rust feathers on robins are colored by various types of melanin pigments.

There are a number of causes for this type of plumage abnormality. Some are environmental, including injury, disease, or malnutrition. Others are genetic. In the dozens of pied leucistic birds that I have handled, I have never noted the white or pale feathers being deformed in any way. This tends to make me believe that this robin's problems were genetic in some way. The bird appeared healthy otherwise.

This was the last robin -- the 391st -- of the season, and a pretty cool way to wrap up fall 2009.