possible Taverner's Cackling Goose, Palo Alto, November 2009
I found this small Branta goose today (November 1) among Canada Geese at Byxbee Park in Palo Alto. I think the three most likely IDs are Lesser Canada Goose (B. c. parvipes), Taverner's Cackling Goose (B. h. taverneri) and Aleutian Cackling Goose (B. h. leucopareia). I'm leaning toward Taverner's even though that would be the rarest of the three in this location because:
- Size was clearly smaller than surrounding Canada Geese, but to my eye not as small as Aleutian (admittedly very subjective) - see the comparison shots with Canada Goose in the bottom row; note that Taverner's and Aleutian, and Taverner's and Lesser Canada overlap in size.
- Bill appeared shorter with a steeper culmen than Canada, including Lesser, but not as stubby as Aleutian (also subjective, but see these photos of Aleutian Cackling Goose for comparison).
- Crown appeared rounded or domed; Lesser Canada has a more elongated, oval-shaped crown with a more sloped forehead; the head of Aleutian is blocky with a flatter crown.
- Grayish breast with darker flanks and belly typical of Taverner's; Aleutian tends to be browner, most Lessers have whiter breasts.
- Black gular stripe (separating white cheeks on bottom of head) typical of Aleutian and Taverner's; rarely found in Lesser.
- White neck ring usually found on Aleutian and sometimes on Lesser is absent - Taverner's is the least likely to show a white neck ring.
Reference: Mlodinow, S.G., P.F. Springer, B. Deuel, L.S. Semo, T. Leukering, T. Doug Schonewald, W. Tweit, and J.H. Barry. 2008. Distribution and identification of Cackling Goose (Branta hutchinsii) subspecies. North Amer. Birds 62: 344–360.
Click on the thumbnails for a larger image. Comments/corrections on the ID are welcome. Thanks.