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DECEMBER
2005 BIRD OF THE MONTH |
Your Christmas Goose: Canada or Cackling?
By Linda DeKort
CLICK HERE FOR .PDF VERSION
One of the most significant changes for birders in the 2004 supplement of the American Ornithologist
Union checklist, according to Sibley, was the split of Canada Goose into two species. “The former
broad Canada Goose species has been divided into a large-bodied, interior- and southern-breeding
species, and a small-bodied tundra-breeding subspecies. The large-bodied group is still known as Canada
Goose (Branta canadensis) while the small-bodied group takes the name Cackling Goose (Branta
hutchinsii). Cackling Goose includes the subspecies hutchinsii, asiatica (probably extinct),
leucopareia,
taverneri, and minima. Canada Goose now includes the subspecies canadensis, interior, maxima, moffitti,
parvipes, fulva, and occidentalis.”
Distinguishing between all of these subspecies is
challenging, since some of their field marks overlap. In
general, cackling geese subspecies are smaller, have a
relatively shorter bill, are relatively darker on the
back and the breast, and have high-pitched squeaky
voices or barks, hence the name “cackling.” According to
Dan Casey, they also have an overall squared shape of
the head, and in a relaxed posture the
neck is noticeably shorter than larger Canada Goose
subspecies. The black stocking of the neck often ends in
a diffuse border between the black and whitish feathers
of the breast. Also in body form and posture, the
Cackling Geese look a bit short-legged, due to tarsus
length in relationship to body mass when compared to
Canada Goose subspecies. Harry Krueger warns that
“because of intergrades, human assisted transplants,
changing environmental factors, and a still developing understanding of each
of these races and their interactions with each other, it will often be impossible for even the most skilled
and well-informed field observer to identify each goose they encounter.” Despite the challenges, there
has been much reporting recently of cackling geese sighted by Montana Online Birders. Bob Rost reported
last week that he had found 6 Cackling Geese on the Polson Golf Course. He reported that “they
were with a large flock of Canadas in the little pond and that they all forage the grass in herds. These little
guys are very small, very dark on the breast with stubby bills. They always feed in a tight group, even in
body contact most of the time.” Barb Jaquith, of Red Lodge, also reported earlier in November that
“among a huge number of Canada Geese on Cooney Dam we found a few small individuals. At the time
we were thinking that they were RICHARDSON'S CACKLING. Today, …we are not sure that they weren't
LESSER CANADA. That seems to be the only flyway through this area. Mike Schwitters agrees that
“the identification of Cackling Goose in Montana is a very tough problem. This is particularly the case
when trying to distinguish between the smallest of the Canada subspecies, Branta canadensis parvipes,
aka Lesser Canada Goose and the largest of the Cackling Geese, Branta hutchinsii hutchinsii. Both
forms can be found in Montana but B. c. parvipes seems to far outnumber B. h. hutchinsii.”
Dan Casey reports that “Cackling Geese certainly occur here with some level of regularity. I have
seen small flocks of Mallard-sized geese at Church Slough in spring. I have seen 4 Cackling Geese in a
large group of Canadas in Polson that I photographed. I saw another on the Ninepipe CBC last year. We
expect Cackling Geese to show up more in spring than in the fall. Local observers should carefully note
overall size, relative darkness of the back and breast, bill size and voice to help sort out just how frequently
and in what numbers Cackling Geese occur here.”
If you are interested in finding out more specifics about the type of goose you might be sighting
(or cooking) this Christmas season, come to the December program and check out these web sites:
http://www.idahobirds.net/identification/white-cheeked/introduction.html
http://www.sibleyguides.com/canada_cackling.html
http://www.oceanwanderers.com/CAGO.Subspecies.html |
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