Sunday, January 16, 2005

Gyrfalcon in Dearborn, 2005

The Gyrfalcon (Falco rusticolus) is the world’s largest falcon, nearly the size of a Red-tailed Hawk.  This Arctic-nesting bird is rarely seen in the United States.  When populations of ptarmigan, chicken-like tundra birds that are a main prey item of Gyrfalcons, fall below certain levels, some Gyrfalcons move into southern Canada and the United States in the winter.  When one is found, many birders will rush to see it.

According to The Birds of Michigan, 40% of the state’s records are from Sault Ste. Marie, 20% from Whitefish Point in the U.P., and 10% from the Muskegon area. As of 2005, there were only eight published records from southeast Michigan:
  • A questionable record from Washtenaw Co., 1974.
  • A questionable record from Jackson Co., 1997.
  • Three records for Wayne Co.: Nov 9, 1995 at Lake Erie Metropark (not Oct 9, as has been published elsewhere); Nov 9, 1997 at Point Mouille headquarters (perhaps another bird at Lake Erie Metropark); and Nov 19, 1999 at Lake Erie Metropark.
  • Three records from Pointe Mouille SGA in Monroe Co.  One from the 1970s; one from 12 to 27 March 1994 (this bird also crossed into Wayne Co. on occasion); and one from 6 to 15 March 2003, also at Pointe Mouillee.
Thus it was sensational when Kim Hall, Julie Craves, and Darrin O’Brien located a subadult (first year) Gyrfalcon at a Dearborn office complex while participating in the annual Detroit River Christmas Bird Count on 1 Jan 2005. The Rouge River Bird Observatory coordinates the Dearborn portion of the count.

Initially, the bird puzzled the observers. The possibility of Gyrfalcon seemed so outrageous that they watched the bird move from a small woodlot to various trees, light posts, and buildings in the Parklane Towers office complex for some time while they convinced themselves they were actually looking at this species, a first for Dearborn.  The Parklane Towers are large concrete structures that are among the tallest in the immediate area. Their cliff-like appearance may have made the falcon feel at home.

They quickly got the word out via cell phone and the Internet, and by the end of the afternoon over 20 birders had ignored their hangovers, abandoned the Rose Bowl, or otherwise dropped their New Year’s Day plans to see this rare visitor. Gyrfalcons come in three color types, or morphs: white, gray, or dark.  This bird is a dark morph. In the Arctic, Gyrfalcons feed on large birds and small mammals.  Here, this bird likely fed on rabbits, squirrels, pigeons, and ducks. It was last seen on 4 Jan 2005.

Saturday, January 15, 2005

Michigan’s first Virginia’s Warbler

On the morning of 13 May 1993, an unusual bird was removed from the mist nets of the Rouge River Bird Observatory on the UM-Dearborn campus.  Initially, the bird appeared to be a strangely-plumaged Nashville Warbler (Oreothlypis [Vermivora] ruficapilla).

The bird was primarily grayish, with little or no contrast between the color of the head and that of the back and wings; the back and wings were not olive-colored like a Nashville Warbler. There was a restricted amount of yellow on the upper breast and undertail coverts with much of the breast and belly grayish, rather than the uniform yellow of a Nashville. Like a Nashville, the bird had a complete, pale gray eye ring, and a small concealed rufous crown patch. We had an unbelievable hunch about what it was, and after going through a series of photographic references and technical references, we confirmed that this bird was not a Nashville Warbler, but rather the closely related Virginia’s Warbler (Oreothlypis [Vermivora] virginiae).

This capture represented the first record of Virginia’s Warbler for Michigan. In summer, this species is normally found in the Rocky Mountain southwest. It winters mostly in mountainous regions of Mexico, and also California.

Virginia's Warbler and Julie Craves
The typical breeding habitat for Virginia’s Warbler is dense shrubs, Ponderosa pine and pinion-juniper forests at 7500 to 8000 feet elevation.
This Virginia’s Warbler had a great deal of body fat, and weighed 9.1 gr. After it was banded and photos and other measurements taken, it was released. It was not resighted.
Prior to this 1993 record, there were very few records of Virginia’s Warbler east of the Mississippi. They were:
  • 16 May 1958, Point Pelee National Park, Ontario. Male, collected.
  • 6 October 1962, banded at Island Beach State Park, Ocean Co., New Jersey.
  • 9 to 11 May 1974, photographed at Point Pelee National Park, Ontario.
  • 5 May 1975, Point Pelee National Park, Ontario.
  • 6 May 1979, Evanston, Illinois.
Since the RRBO record, there have been two others in Michigan. One 20 to 21 May 1997 in Chippewa County, and the other a bird banded 25 June 2006 in Kalamazoo County.