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.

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