Verification of Unusual
Rec. # 2010-12
|Scientific name:||Branta hutchinsii|
|Date:||6 March 2010|
|Length of time observed:||half hour|
|Number:||16 (total of both ssp)|
|Location:||pasture west of road, south of Warren, 0.6mi north of jct of 950 S & 5900 W|
|Elevation:||approx. 4220 feet|
|Distance to bird:||several hundred feet|
|Optical equipment:||Leica 10x42 BN binoculars|
|Weather:||Sunny, hazy clouds|
|Light Conditions:||bright, diffuse due to the hazy cloud/smog cover|
|Description: Size of bird:||very large duck|
|(Description:) Basic Shape:||Branta goose (small head on long neck; plump body; moderately-long legs; short, thick bill)|
|(Description:) Overall Pattern:||brown, with black head & neck & tail, and white cheek patch & undertail|
|(Description:) Bill Type:||short & thick, goose-like|
Field Marks and
There were two obvious subspecies of Cackling geese in a pasture full of Canada
geese (plus some other waterfowl):
1) MINIMA ssp: There were 13 of what I believe are B. h. minima. These were notably darker of breast than the other Branta sp. geese around them. They had no obvious white neck collars. They had tiny, round heads, lacking the elongated, boxy look of the Canada geese next to them. Their bills were so short that they at times seemed almost invisible (an illusion heightened by their conical shape), but at other times one could see that they were very highly conical. These geese were tiny in mass compared to the Canada geese around them, and almost half as tall. Their necks were very short, proportionally to their bodies, compared to those of the Canada geese around them.
2) There were 3 geese I believe to be "Richardson's" Cackling geese (B. h. hutchinsii) with the minimas. These 3 geese were just a little larger than the minimas around them, but much smaller than the Canada geese next to them. They had larger, blockier heads, though much smaller than the heads of the Canadas around them. Their bills were also longer than those of the minimas around them, but clearly shorter & more conical than those of the Canada geese around them. The necks on these geese were similarly short relative to their bodies as their minima group-mates, but perhaps a bit longer.
One can make out the bill shapes, relative body sizes, realtive breast colors, etc, in the admittedly poor photos I am including with this report. I will try to include some comments with the photos.
|Song or call & method of delivery:||none noted for certain with all the other waterfowl calling|
|Behavior:||Very tellingly, the group of Cackling geese stayed in a rather tight group that moved through the Canada geese around them. The Richardson's geese tended to stay together as a subunit within that group of Cacklers. The geese were resting when I first saw them, but when I got out of my car they got up and began moving slowly away, again at a different (faster) rate than the Canada geese around them. At all times, the Cackling geese stayed in a much tighter group than the Canada geese around them, which were dispersed more widely, often in pairs or threes.|
|Habitat:||pasture with short grass around what appears to be remnants of an old riverbed, with oxbows (ponds on which were also found Tundra swans). The pasture was located within a farming community near the lower portions of the Weber river and not too many miles east of the margins of the Great Salt Lake.|
were they eliminated:
Canada geese were eliminated by short, conical bills, short necks, small heads
(round in the case of the minimas), very small body size, and, in the case of
the minimas, dark breasts. The self-sorting behaviour of the group of Cacklers
(BOTH subspecies together!) within the much larger assortment of Canada geese is
also suggestive of a different species, though not definitive.
Brants are eliminated by the white cheek patches.
The subspecies identifications are less certain (and I welcome alternative suggestions). I think the minimas were pretty clearly minimas by the combination of diminutive size, round heads, very short, conical bills and lack of white neck collars (which eliminates the "Aleutian" cackler). The three geese I am calling "Richardson's" cacklers are differentiated from other ssp. as follows:
1) taverneri - has longer bill, but otherwise similar. Head on these 3 geese was blocky, consistent with Richardson's.
2) leucopareia - this ssp. is much too dark and too similar in size to the minima (which were a bit smaller than these three).
this & similar species:
|I have seen both subspecies of Cacklers in coastal Oregon & Washington states, plus the Richardson's a few times in Utah.|
National Geographic "Field Guide to the Birds of North America". Upon returning
from the field, I consulted several websites to confirm the subspecies,
1) "The New Goose", by Mark Stackhouse (http://www.utahbirds.org/RecCom/NewGoose.htm)
2) "Canada Geese"
I've also consulted Cliff Weisse's excellent website for Idaho sightings in the past.
|Description from:||Notes taken at time of sighting|
|Observer:||David S. Wheeler|
|Observer's address:||2196 South 1000 East, Salt Lake City, UT 84106|
|Observer's e-mail address:||email@example.com|
|Other observers who independently identified this bird:||no one but my dog at the time, and he isn't talking|
|Date prepared:||17 March 2010|