IBRC 19-B-10

IDAHO BIRD RECORDS COMMITTEE
RARE BIRD REPORT FORM

SPECIES: Cackling Goose (Branta hutchinsii)
HOW MANY: 19 - “Taverner’s” (B.h. taverneri)

REPORTER: Doug Ward 8362 Selkirk Ct Hayden, ID 80835
REPORTER EMAIL: ward@revettminerals.com
OTHER OBSERVERS: None.

DATE REPORT PREPARED: 2/3/2010
DATE SIGHTING OCCURRED: 24 January 2010

LOCALITY OF OBSERVATION: Cougar Bay (BLM Access), Lake Coeur d’Alene; Kootenai County, Idaho
HABITAT: Ice covered and open water bay; mudflat beach.
CONDITIONS: Birds were scattered over a large area of ice between 75 & 200m from observation point on the beach. Observed between 3:30 – 4:15pm using both 8X40 binoculars and a 15-40X spotting scope (15-25X during observation). Lighting was cloudy, bright overcast with sun at my back.

DID YOU TAKE NOTES?: Yes, later the same day
DID YOU CONSULT FIELD GUIDE OR OTHER REFERENCES?: Yes, another day after the observation
WHAT GUIDE(S) OR REFERENCE(S) DID YOU CONSULT?:
1)“Distribution and Identification of Cackling Goose (Branta hutchinsii) Subspecies”; Mlodinow etal; North American Birds (pp 344-360 Vol.62; 2008)
2)“Complete Birds of North America”; National Geographic; 2005
3) Various internet site to review photographs

DESCRIPTION: “Taverner’s” (B.h. taverneri) – small medium brown goose with black neck, white cheek patch and pale brown chest; colored similarly to “Lesser” Canada Geese (B. canadensis ssp.) they were associating with. Size & Structure: Larger than nearby Ridgway’s Cackling (B.h. minima); slightly smaller than “Lesser”, and much smaller than “Greater” Canadas present. Generally shorter legged than “Lesser” Canadas with shorter, thicker neck (near diameter of head). Bill was short (~¾ head length) and thick at base giving a triangular profile; not “shoveled” like nearby “Lessers”. Head shape was distinctive with high (vertical) forehead, short, flat crown, and very rounded back of head which curved straight into the rear neck (see attached sketch). Culman made sharp angle with forehead. Wing tips reached to, or slightly beyond tail. Plumage: Head & neck black, sharply demarcated from pale breast; no white collar. Triangular white cheek/throat patch extended to below the eye, then angled back toward ear, then up behind and slightly above the eye (see attached sketch). At least two individuals showed a black stripe from chin to throat separating the cheek patch. Back, sides, and belly medium brown lightly scalloped with paler brown. Chest was pale brown. Rump & undertail coverts white; tail black.
BEHAVIOR: Gathering and feeding on ice in a large, loose grouping of Canada Geese (~750 total; ~500 “Greater” ssp. & ~250 “Lesser” ssp.). The Cackling Geese generally stayed associated with each other in groups of 2-5 scattered in the central portion of the larger flock. Cackling Geese could be heard calling amongst the Canada’s (B. canadensis); generally shorter, higher pitched “honks”.

HOW AND WHEN DID YOU POSITIVELY IDENTIFY THE BIRD, AND WHAT CLINCHED THE IDENTIFICATION FOR YOU? Heard Cackling Geese calling as I approached the beach to scope the bay. Fist noticed a distinctive pair of “Ridgway’s” Cackling Geese(B.h. minima; see separate report) then as I scanned the flock, I came across a couple of "short, stocky, triangular shape billed geese" similar in coloration to some nearby "Lesser" Canada Geese (B. canadensis ssp.). My initial thoughts were "Richardson's" Cackling Goose (B.h. hutchinsii) based on my experience with this subspecies in Colorado and New Mexico. After reviewing my reference materials, however, Idecided to change my subspecific identification to "Taverner's" Cackling Goose; see notes under Similar Species.
HOW DID YOU ELIMINATE SIMILAR SPECIES, AND WHAT WERE THEY?
As these were black necked, white cheeked geese without additional white on the face, only Canada Goose (Branta canadensis) was considered to be addressed.
“Greater” Canada Goose (B. canadensis ssp.) is eliminated by the size differential of all the birds considered in direct comparison; these were all ½ the size or smaller than the “Greaters” present.
“Lesser” Canada Geese (B. canadensis ssp.) were much more problematic. Fortunately there were numerous individuals available for direct comparison not only in size, but more importantly head and bill structure. Generally the Cackling Geese (Branta hutchinsii) could be picked out by their shorter, thicker necks, high foreheads which accentuated the bird’s triangular profiled, short bills. The “Taverner’s” (B.h. taverneri), however, were more difficult as they approached the size of some of the “Lessers”. While their plumage was similar to most with their pale chests, you could fairly easily pick out the “Taverner’s” by their shorter legs and particularly their thicker necks which were nearly the diameter of their heads. In addition, their high foreheads made the bill shape noticeably different. All of the “Lessers” present exhibited a low forehead profile which accentuated their longer (~¾ - 1 head length), narrower bill; more of a “shovel” shaped profile. Another point noted was that the folded wingtip of the “Taverner’s” extended to at least the end of the tail though not exaggerated when compared to the “Lessers”; not sure how important a mark this is.
Subspecies Discussion: Notes above made before consulting reference material. Subspecific identification based largely on a recent article in North American Birds (see References) as well as a review of photographs from various sources on the internet.
The most likely identification for the “larger, pale chested” Cackling Geese out there that day was the “Taverner’s” Cackling Goose (B.h. taverneri) subspecies. My initial thought was these were “Richardson’s” Cackling Geese (B.h. hutchinsii) based on my familiarity with this superficially similar subspecies from eastern Colorado where they are fairly regular. After reviewing the documentation, however, I decided on “Taverner’s” verses “Richardson’s” for the following reasons:

1)Location (west slope of Rockies in northern Idaho): Much closer to a portion of “Taverner’s” normal wintering range in central Washington State than that of the closest “Richardson’s” east of the Rocky Mountains in southeastern Colorado. Better explanation for relatively large number of individuals seen; at least 19.
2)Size: Many of these birds were not much smaller than the “Lesser” Canadas present; “Taverner’s” is apparently the largest of the Cackling Geese. “Richardson’s” typically noticeably smaller than “Lesser” Canadas when compared directly.
3)Bill Structure: The base of the bill on the majority of the birds studied was relatively thick with an either straight or even slightly convex (“humped”) culman profile giving a “chunky” look to the bill and head. “Richardson’s” apparently show a rather thin, daintier looking bill.
4)Head Shape: One of the reason’s I thought these may be “Richardson’s” was due to the flat topped head many showed. However, all exhibited a very rounded back of the head and did not show a noticeable “double peaked” look which seems to be prevalent on many “Richardson’s”.
5)Cheek Patch Shape: Many of the birds out there that day seemed to show what I’d considered a characteristic “Richardson’s” cheek patch shape with the front edge “notched” around the eye. After reviewing available photographs, however, it seems all of the subspecies can show this feature though not as regularly as the “Richardson’s”; not sure this is as diagnostic a field mark as I previously thought.

EXPERIENCE WITH THIS SPECIES (AND SIMILAR SPECIES): This is the first time I've seen the "Taverner's" subspecies of Cackling Goose. I'm fairly familiar with “Richardson’s” Cackling Goose (B.h. hutchinsii), pre-split, from Colorado and New Mexico, and have seen "Ridgway's" Cackling Goose (B.h. minima) previously a couple of times.
GENERAL BIRDING EXPERIENCE: I've been birding for 37 years and consider myself an "advanced" birder.

WERE PHOTO(S), VIDEO, AND/OR AUDIO OBTAINED BY YOU?: None

NOTE: The label on the lower sketch, the one that says "19 seen", should read B. h. taverneri, not B. h. hutchinsii.

This sketch was resized by the webmaster.  To view original click the image.