Thursday, December 15, 2005

Small Canada Geese

In 2004, the 45th Supplement to the American Ornithologists’ Union Check-list of North American Birds split Canada Goose into two separate species: the larger forms remain Canada Goose (Branta canadensis) while most of the smaller forms are now Cackling Goose (Branta hutchinsii).  The Cackling Goose form most likely to be seen in Michigan is the former Canada Goose race B. c. hutchinsii, or Richardson’s Goose. The other small former Canada Geese are western birds that would be considered very rare in the east.  An excellent report on this is on the Ontario Field Ornithologists’ web site.  David Sibley’s website also provides great information.  In particular, read the information on neck size and voice, which from his discussion appear not to be as conclusive as some have been implying. There’s also a nice map indicating which races breed where.  The Ocean Wanderers web page, by Angus Wilson, includes photos, links to specific individuals being debated, and extensive literature citations.

What follows is some information on the identification of Canada Geese found in Dearborn, focusing on an interesting case of a “runt” Canada Goose from Canada.

The most common subspecies of Canada Goose in Dearborn is the Giant Canada Goose, or B.c. maxima.  This largest of the races was extinct in much of eastern North America, and in Michigan, at the turn of the 20th century, wiped out by hunting and habitat destruction.  Aggressive reintroduction campaigns resulted in the surplus of these big, non-migratory geese we see today.  This is the subspecies that nests in Dearborn.

During spring and (especially) fall migration, Giants are joined by the slightly smaller, somewhat darker-breasted migrant race B.c. interior.  Around the UM-Dearborn campus, many geese wearing orange neck collars can be found in the fall.  These birds have been banded on Akimiski Island, Nunavut, in James Bay (while closest to Ontario, all islands in James Bay belong to Nunavut, formerly Northwest Territories).  One neck-collared goose was seen by us in the fall of 1995 and again in the fall of 1998.  It was originally banded in 1990 on Akimiski.

There are other even smaller races of Canada Goose than  B.c. interior. An example is this goose, photographed by Jim Fowler, Jr. at Greenfield Village on 25 Oct 93.  Notice the pale breast, and small size compared to the nearby Giants.  This was probably B.c. hutchinsii (a.k.a. “Richardson’s Goose”), the smallest of the pale-breasted races.  They nest in the northern portion of Hudson Bay.

Next, look at this little dingy-breasted goose below, shown in these two pictures with one of  her two B.c. interior buddies that she hung around with from late September until early October 1998 on the UM-Dearborn campus.  This goose had a regular leg band and a colored leg band.  As it turns out, she was banded as a young female not yet able to fly on 15 Jul 98 on…Akimiski Island!  Since none of the small, dark-breasted races are known to nest in this part of Canada, I contacted the person who bands on Akimiski, Jim Leafloor of the Ontario Ministry of Natural Resources, for more information.

Dr. Leafloor explained to me that all the geese breeding on the island are considered B.c. interior.  This goose was banded on the north shore of the island, where the geese are smaller than other interiors due to low food availability.  The habitat has been degraded over the last two decades by high densities of nesting Canadas (seven times higher than on the nearby mainland and up to 300 times higher on the north coast of the island), use by migrant Brants (another type of goose), and especially increasing numbers of migrant and nesting Snow Geese.  Eggs of these birds when raised in captivity grow to “normal” size like their mainland counterparts.  Therefore, one should use caution assigning subspecies to varying sizes of Canada Goose seen in this region.

For more information on this very interesting phenomena, please see a paper Leafloor and his colleagues  published in the  journal The Auk:

Leafloor, J.O., C.D. Ankey, and D.H. Rusch.  1998. Environmental effects on body size of Canada Geese. Auk 115:26-33.

UPDATE: David Sibley has a post and photos on his site regarding recent research and evidence of hybridization between small (Cackling) Geese and larger Canada Geese. Please see Cackling-ish Geese; here is the paper he refers to:

Leafloor, J.O., J.A. Moore and K.T. Scribner. 2013. A hybrid zone between Canada Geese (Branta canadensis) and Cackling Geese (B. hutchinsii). Auk 130: 487-500.

Sunday, May 15, 2005

Ruby-crowned Kinglet from Toronto

A (but not the) Ruby-crowned Kinglet
banded by RRBO
On 22 April 2005, I captured a banded Ruby-crowned Kinglet.  I was amazed to see that it was not a bird that I had previously banded.  The rule of thumb is that fewer than 1% of small songbirds are ever encountered away from the place they are banded.  And kinglets are one of the smallest songbirds, weighing in at around 6 or 7 grams, or the same weight as an American nickel and a dime.  They are so tiny, in fact, that properly-sized bands have only been made since 1993.  Prior to that time, the smallest band size had to be modified to fit them, and many banders released kinglets without banding them at all.

On 2 May, I received acknowledgment from the U.S. Bird Banding Lab that this kinglet was originally banded as a hatching-year bird (born the same year it was banded) on 10 Oct 2003 outside of Toronto, about 216 miles east-northeast of Dearborn.

In The Canadian Atlas of Bird Banding, I looked up the number of encounters of Ruby-crowned Kinglets, an encounter being a subsequent observation of a banded bird, dead or alive.  Between 1921 and 1995, with over 48,000 banded in Canada between 1955-1995 alone, the number of Ruby-crowned Kinglets encountered was only ten.  The Atlas noted this is one of the lowest encounter rates of any species.  While the U.S. has no similar publication, they do provide  simple tallies of numbers banded and encountered.  Although 127 Ruby-crowned Kinglets sounded more substantial, the encounter rate was actually only 0.03%.  What a special event this was!

The only other foreign encounters I’ve had here at RRBO were an American Goldfinch and a Sharp-shinned Hawk. Both were originally banded within 25 miles of here, and were caught by me within four months of the banding date.  Figuring this kinglet, too, was from nearby, I contacted other regional banders, but nobody could claim this diminutive traveler. Finally, I tracked down the original bander.

The location was Tommy Thompson Park (a.k.a. Leslie Street Spit),  man-made peninsula constructed from dredge and fill which juts out 3 miles into Lake Ontario from the Toronto shoreline. The kinglet was banded by the Tommy Thompson Park Bird Research Station (TTPBRS), a partnership between Toronto and Region Conservation and the Toronto Bird Observatory. The station began operation in 2003. Here is a great map showing the location of the station.

Kinglets, especially Ruby-crowned, are a  bread-and-butter bird for TTPBRS, making up 30% of all birds banded over fall 2003-2004.  This is not surprising. Other lower Great Lakes banding sites located along the shores of Lakes Erie and Ontario also band hundreds or thousands of kinglets: Long Point Bird Observatory, Prince Edward Point Bird Observatory, Braddock Bay Bird Observatory, and Haldimand Bird Observatory, for example.  At our inland site, we don’t even SEE as many kinglets as these stations band in a typical fall season. This seems to provide evidence that these little mites prefer to travel along shorelines rather than over water during their journeys between their nesting areas in northern spruce-fir forests and their wintering areas in the southern U.S., Mexico, and Central America.

The capture of this one bird provides only a single data point, and while it is a notably rare event, in itself it doesn’t deliver a big scientific wallop.  But this encounter is valuable in other ways.  Ruby-crowned Kinglet number 2310-75634  has provided a special connection between two bird research stations studying urban bird ecology — an underappreciated focus that often struggles for acknowledgment and recognition.  And it provides an opportunity for us all to marvel at the resilience of such a small creature, and how much we still don’t know about this common bird that flits among us, just passing by.

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.