HI:
Field ID of Canada Goose species isn't going to be easy!

--
Ian Paulsen
Bainbridge Island, WA, USA
A.K.A.: "Birdbooker"
"Rallidae all the way!"

---------- Forwarded message ----------
Date: Fri, 23 Jul 2004 11:42:57 -0300
From: Ian Mclaren <iamclar at DAL.CA>
To: BIRDWG01 at LISTSERV.ARIZONA.EDU
Subject: [BIRDWG01] Small Canada and Cackling Goose (longish)

All:

I have been beavering away (in true Canuck fashion) for some time on this
issue in the context of occurrences in Atlantic Canada and n.e. US of
various CAGO subspecies/species. One issue, echoed by Phil Davis and
forwarded by Ian Paulson, is the putative intergradation (as opposed to
undoubted casual hybridization) of the small species with the smallest
"large" Canada Goose, _parvipes. This is captured by Phil Davis referring
to _parvipes_ and _taverneri_ forming parts of a "Lesser complex.

I have
snipped out here a part of my gropings on the subject. Don't know where
this is going, but I would appreciate any comments, corrections,
additions, disputes that might be forthcoming, either hear, or on the
List.

_Parvipes_ is recognized by wildlife biologists as a morpholopgical
mess, and field discrimination of a small _parvipes_ from a large
_hutchinsii_ or a dark _parvipes_ from a _taverneri_ is another matter.
Also, as noted by Kevin McGowan, the occurrence of environemntally small
(and darkened) individuals among (large) Canada Goose may be a problem. (I
have addressed this in my nascent MS, but it gets tedious).

Here is a snip from my survey so far.

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MacInnes's (1966) studies of a body-size cline in a putative
"hutchinsii-parvipes complex" along the w. coast of Hudson Bay to
Southampton I. was one basis for assuming widespread interbreeding between
the two subspecies. Also, Macpherson and Manning (1959) designated the
geese of Adelaide Peninsula (at ~95 W) as parvipes, but measurements
(their p. 11) clearly fit hutchinsii. It is now believed that the small,
tundra-breeding geese along the west coast of Hudson Bay are hutchinsii
(e.g. Hines et al. 2000), and that large-bodied tundra- nesting geese
north of Manitoba are interior (Kim Scribner, pers. comm.). With the
exception of one (questionable?) report from West Greenland (Fox et al.
1996), there appear to be no confirmed nestings of parvipes east of
Amundsen Gulf, at about 100 W, exclusively (?) within the treeline (Hines
et al. 2000). Nevertheless, the long-distance migrations of the Shortgrass
and Tallgrass Populations (Dickson 2000) should occasion eastward vagrancy
of this subspecies.

[Snip, snip . .]

The frequent assumption (e.g. Mowbray et al. 2002) that, despite their
genetic distinctiveness, parvipes intergrades extensively with hutchinsii
seems to be based in part on mistaken attribution of the former to a
parvipes-hutchinsii cline in western mainland Nunavut (see above).
Delacour (1951, 1954) suggested that taverneri intergrades with minima,
occidentalis and parvipes in Alaska. Hansen (1962), however, felt "the
likelihood of an overlap in range and intergradation of fulva with B. c.
moffitti is as remote as the possibility between occidentalis and
taverneri farther north, and for the same reason, physiogeographical
isolation." Breeding-ground specimens for genetic studies of taverneri
(Shields and Wilson 1987; Wagner and Baker 1990; Pearce et al. 2000;
Scribner et al. 2003c) have revealed no mtDNA from large-bodied
subspecies. Baker and Marshall (1997) found that one of two specimens from
the wintering grounds had parvipes mtDNA, for which they stated,
"misidentification of subspecies is another possibility."

Eastern limits of breeding taverneri are uncertain. Sinclair et al.
(2003) cite Salter et al (1980) as indicating that [Yukon] "North Slope
birds appeared to be B. c. parvipes." Salter et al. (1980) actually refer
to fall migrants along the Beaufort Sea coast, and merely state:
"According to AOU (1957) Canada Geese along the Beaufort Sea were B. c.
parvipes; we noted that individuals were medium-sized and fairly light in
colouration, but did not make subspecific identification." AOU (1957) did
not, however, include taverneri. The assumed geographical intergradation
between taverneri and parvipes seems to rest largely on perceived
intermediates on wintering grounds. Mowbray et al. (2002), in summing up,
conservatively wrote only of "potential intergrades with B. c. parvipes
eastward in the interior of Alaska."

The western limit of breeding hutchinsii, which shares tundra nesting and
a more recent ancestry with taverneri, is also uncertain. Although Mowbray
et al. (2002) and others have hutchinsii breeding west to the Mackenzie
River Delta, I have found no explicit records of this. Some assumptions
may result from earlier nomenclatural confusion between leucopareia and
hutchinsii (AOU 1957, footnote p. 62). Aldrich (1946) from limited
specimens largely from n.w. Canada stated that "parvipes is the interior,
pale representative of leucopareia" and that "leucopareia intergrades with
parvipes in western Mackenzie." If some of Aldrich's "leucopareia" were in
fact hutchinsii, does this imply a cline in plumage darkness of the latter
from east to west? If so, how would one distinguish in the field a
dark-breasted hutchinsii (like those claimed by Batty and Lowe 2001, plate
3, and Batty et al. 2001, Plate5) from a small- billed taverneri? Do
broad, black gular stripes, certainly characteristic of the Aleutian
leucopareia (Delacour 1954), and shown in claimed taverneri vagrants, also
occur in western hutchinsii? Potentially overlapping breeding ranges of
hutchinsii and taverneri in n.w. Canada clearly need further study; true
intergradation might be looked for in these tundra-nesting, small- bodied
forms.

Aldrich, J.W. 1946. Speciation in the white-cheeked geese. Wilson Bulletin
58: 94-103.

AOU. 1957. Checklist of North American Birds. 5th ed. American
Ornithologist's Union, Baltimore, MD.

Batty, C., and T. Lowe. 2001. Vagrant Canada Geese in Britain and Ireland.
Birding World 14: 57-61.

Batty, C., P. Hackett, and T. Lowe. 2001. Vagrant Canada Geese in Britain
and Ireland: autumn 2001. Birding World 14: 515-519.

Delacour, J. 1951. Preliminary note on the taxonomy of Canada Geese,
Branta canadensis. American Museum Novitates, No. 1537.

Delacour, J. 1954. The Waterfowl of the World. Country Life Ltd., London.

Dickson, K.M. 2000. The diversity of Canada Geese. Pp. 11-24. In Dickson,
K.M. (ed.). Towards Conservation of the Diversity of Canada Geese (Branta
canadensis). Canadian Wildlife Service Occasional Paper 103.

Fox, A.D., C. Gladher, C.R. Mitchell, D.S. Stroud, H. Boyd, and J. Frikke.
1996. North American Canada Geese (Branta canadensis) in West Greenland.
Auk 113: 231-233.

Hansen, H.A. 1962. Canada Geese of coastal Alaska. Transactions of the
North American Wildlife and Natural Resources Conference. 27: 301-320.

Hestbeck, J.R., and M.C. Bateman. Breeding, migration, and wintering
affinities in Canada Geese marked in the Atlantic Provinces. Pp. 73-83. In
Dickson, K.M. (ed.). Towards Conservation of the Diversity of Canada Geese
(Branta canadensis). Canadian Wildlife Service Occasional Paper 103.

Irving, L. 1960. Birds of Anaktuvok Pass, Kobuk and Old Crow, A study in
arctic adaptation. US National Museum Bulletin 217.

MacInnes, C. D. 1966. Population behavior of eastern arctic Canada Geese.
Journal of Willdlife Management 30: 536-553.

Madge, S., and H. Burns. 1988. Waterfowl. An Identification Guide to the
Ducks, Geese and Swans of the World. Houghton Miflin Company, Boston, MA

Mowbray, T.B., C.R. Ely, S.J. Sedinger, and R.E. Trost. 2002. Canada Goose
(Branta canadensis). In The Birds of North America, No. 682 (A. Poole and
F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PS.

Pearce, J.M., B.J. Pierson, S.L. Talbot, D.V. Dickerson, D. Kraege, and
K.T. Schribner. 2000. A genetic evaluation of morphology used to identify
harvested Canada Geese. J. Wildlife Management 64: 863-874.

Sinclair, P.H., W.A. Nixon, C.D. Eckert, and N.L. Hughes. 2003. Birds of
the Yukon Territory. UBC Press, Vancouver, BC.

Scribner, K.T., S.L. Talbot, J.M. Pearce, B.J. Parsons, K.S. Bollinger,
and D.V. Derkson. 2003. Phylogeography of Canada Geese (Branta canadensis)
in western North America. Auk 120: 889-907.

Shields, G.F., and A.C. Wilson. 1987. Subspecies of Canada Goose (Branta
canadensis) have distinct mitochondrial DNA's. Evolution 41: 662-666.

Van Wagner, C.E., and A.J. Baker.1990. Association between mitochondrial
DNA and morphological evolution in Canada Geese. Journal of Molecular
Biology 31: 373-382.
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Ian A. McLaren
Professor Emeritus
Biology Department
Dalhousie University
Halifax, NS B3H 4J1