[obol] geese and gulls

From: Lars Per Norgren <larspernorgren@xxxxxxxxx>
To: obol@xxxxxxxxxxxxx
Date: Tue, 14 Oct 2014 12:14:52 -0700
    Gulls have long posed an ID challenge. Canada Geese seemed harmless until 
the AOU elevated "Cackling " Goose to full species status. What used to be a 
garden variety is now a constant source of anxiety for America's birders. 
Marlowe's reference to "regular" Cacklers is indicative of the pitffalls posed 
by white-cheeked geese. What constitutes "regular' depends on where you are 
birding, and when. I first learned about Aleutians in a fifth grade Weekly 
Reader. That was 45 years ago and there were about 100 of them in the world. 
They were being captive bred at the USFWS facility in Pawtuxent MD . Your 
chances of seeing one in the wild was next to zero. My best friend lived on SW 
53rd St in Corvallis and his dad kept a good assortment of pinioned geese, 
including "true" Cacklers he'd captured in Alaska. A pair of Aleutians landed 
with this captive flock and stayed for days, allowing photographs and positive 
ID. This was a short bicycle ride from my own house. Rare doesn't mean 
impossible.
     At that time, the late sixties/early seventies, "true" Cacklers wintered 
in the Central Valley. For me, a true Cackler is synonymous with the subspecies 
minima. They nest on the Yukon Delta, weigh about 2 1/2 pounds (like a Mallard 
or BIg Brown Gull) and are an intense, glossy, chocolate brown. This hue 
approaches purple on the breast of some individuals.
I have some recollection that the historic population of true Cacklers exceeded 
200,000.  When I first began birding their numbers were down to about 20,000 
and they were an uncommon sight in Oregon, passing through quickly under 
migration. In the ensuing decades their numbers have rebounded and they now 
winter in Oregon, not California. It is a simple matter to see 10,000 of them 
in a single flock at various places between Sauvie Island and Eugene.
    The Great Backyard Bird Count reported slightly over 1,000 minima for the 
whole state of California two or three years ago. This is a highly informal 
system of census, but I believe extremely methodical counts by the USFWS 
confirm those numbers. True Cacklers are a trash bird in Oregon, but a novelty 
in the Golden State. Meanwhile, about 100,000 Aleutian Cacklers have taken 
their place in the Central Valley. In the sixties the only white-cheeked goose 
one regularly saw in winter in the southern Willamette Valley was the Dusky 
Canada Goose. I remember the utter fascination I felt at seeing a lone 
mofitti(Western Canada Goose) in a flock of Duskies at the Corvallis Airport 
one December afternoon. Hunting was allowed at Finley NWR. Every goose that was 
bagged got examined. The Duskies were checked for age and sex, the rest 
dismissed as "other". This latter category was mainly taverni, whose numbers 
seemed to grow geometrically. There was quite awhile, maybe a decade and a 
half, when  taverni seemed to be the default white-cheek in western Oregon in 
winter. When the AOU split the white-cheeks both taverni and Aleutians were 
assigned to the Cackler species. But "regular" Cackler east of the Rockies 
means the subspecies hutchinsii, and when Cacklers were elevated to full 
species their lantinate binomial became Branta hutchinsii. This midwestern 
subspecies has the common name of Richardson's Cackler.
     The main Washington County library at Dawson Creek Park is a great place 
to examine a variety of white-cheeked geese at close range. Emperor Goose, 
Black Brant, and Greater White-fronted Geese occasionally spice up the salad. 
Stefan Schlick and I were examining an Emperor Goose one October afternoon a 
few years ago and got the inspiring wisdom of a USFWS goose biologist who had 
also been attracted by news of the Emperor. We looked at a pair of geese twice 
the size of the minima and half the size of mofitti, the Western Canada Goose 
that now can be found year round in the Willamette Basin. This pair of 
medium-sized white-cheeks were dull dark brown. The biologist told us they were 
probably Taverner's Cacklers from the south coast of Alaska, much darker than 
the interior taverni. But the Lesser Canada Goose also nests on Cook Inlet, 
where they are much darker than the more familiar interior forms of Lesser. 
This smallest subspecies of Canada Goose overlaps the largest subspecies of 
Cackler in size. To quote the expert, "they are often indistinguishable in the 
hand". Gulls, like geese, have an impressive ability to take advantage of human 
induced changes in the environment. And geese, like gulls, have a reliable 
talent for confounding their human admirers.
     Plastic neck markers are a handy way of alleviating ID insecurity. Red 
with black alpha-numeric codes are installed on Dusky Canada Geese, yellow with 
black for true Cacklers, and green with white for Aleutian Cacklers.  Not every 
flock has members with plastic collars, but they often do. And as a bonus, if 
you get the alpha-numeric code and report it you will soon be notified by email 
as to when and where the goose was tagged, and by whom.   Lars

OBOL archives: www.freelists.org/archive/obol
Manage your account or unsubscribe: //www.freelists.org/list/obol
Contact moderators: obol-moderators@xxxxxxxxxxxxx
[obol] geese and gulls

Other related posts:
