Monday, November 23, 2009

"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.

Friday, November 13, 2009

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.

Sunday, November 8, 2009

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.

Wednesday, November 4, 2009

National exposure in E/The Environmental Magazine

The November/December 2009 issue of E/The Environmental Magazine has an article about brownfield restoration called "Strange Sanctuary: Old Factories Offer New Hope for Wildlife." It focuses on the potential for wildlife habitat in industrial settings, highlighting the Detroit River International Wildlife Refuge and work I have performed there as part of RRBO's partnership with the Refuge. The article also mentions the monitoring I've done on various Ford Motor Company properties, including the sighting of a Gyrfalcon in 2005. The Ford surveys are done as part of my regular inventories of birds throughout the city of Dearborn. Urban ecology is not, generally, very glamorous work. But as I was quoted saying in the article, "I have come to really love this juxtaposition of the hyper-urban with resilient nature.”

Monday, November 2, 2009

Fall 2009: Week 11 in review

Things seemed more "normal" this past week, at least in terms of volume. Diversity slacks off this late in the season, with only a smattering of lingering migrants but more winter-type birds.

We banded an Eastern Phoebe on 25 October, a species we don't band too often. This was also the day we banded what will probably be our last Gray Catbird of the season, and when we caught our first Purple Finch of the fall (below).

It's always a treat to band a colorful adult male Purple Finch (the young males are not red and look like females). If the color difference between Purple Finches and House Finches doesn't tip you off, also notice the lack of brown streaking on the sides of the Purple Finch, and how straight the top of the upper bill is -- it is curved on House Finches (a male shown below). Should you have either species in your hand, House Finches are pretty docile, while Purple Finches are known for their biting!

On 29 October we had a nice surprise. We recaptured a Slate-colored Junco banded here as a young (hatching year) bird on 24 Oct 2007. Winter site fidelity is well-known in juncos, but given the number of them here during fall and winter, and the wide area on campus they occupy, it's not very often that we recapture one from a previous year. Also on 29 October, a Rusty Blackbird sang for me in the banding area. We no longer see many of this declining species (although it was the 10,000th bird banded at RRBO), so even though I didn't catch it, I was happy to see and hear it.

I also don't catch many White-breasted Nuthatches, but this one got snagged investigating a chickadee that was fussing in the net.

On 1 November, we broke our record for the most robins banded in a single fall season. We ended the day at 357. Our fall average is 172, and our previous high number was 354. This is only the fourth fall season that we have broken 300.

Will be winding down the fall banding season this week.