Thanks to Steve for this fascinating review of Brant population distribution. The suggestion that the Chatfield birds are from the “high Arctic” population is interesting and seems to make sense given the migration patterns of other high arctic Branta species, such as Richardson’s Cackling Goose. I noticed that Robb Hinds and Glenn Walbek’s photos of the Chatfield birds show wings extending slightly beyond the tail. My photos of Eastern Low Arctic Brant wintering in Rhode Island show tail extending beyond the wing-tips. The long wings of the high Arctic birds are consistent with longer-distance migration, relative to the migration distance required for low-Arctic Brant. I wonder if this difference is discussed in the Brant literature (I admit I have not done my homework on this question). So, if pale Eastern birds winter in Ireland, and darker Western birds winter in the Pacific Northwest, what about the paler western birds that Steve refers to. Do pale ones ever show up in the Pacific Northwest? Do birds of the Irish wintering-population ever show up in the USA in winter?
Nick Komar Fort Collins CO From: Steven Mlodinow Sent: Saturday, December 03, 2011 3:11 PM To: cobirds@googlegroups.com Subject: [cobirds] Brant Split Greetings All, I am probably not up-to-date on the very most recent Brant stuff, but from what I do know, I doubt that the Brant will be split really soon, and what lines they'll be split along. In reality there are 5 populations: 1- Black Brant. Breeds in AK and Siberia (and I am too lazy to dig this up, but probably westernmost Canada), and winter along North American Pacific Coast from BC to Baja 2- Western High Arctic Brant. AKA Gray-bellied Brant. Limited to islands in w. Canada's Arctic. Winter mostly in Washington's Puget Sound, with a goodly number of Black Brant. 3- Eastern High Arctic Brant. These are part of "Atlantic Brant" and winter mainly in and around Ireland. The breed in e. Canadian Arctic. 4- Eastern Low Arctic Brant (I forget the official name for this population). They winter on the North American Atlantic Coast and breed along Hudson Bay and nearby areas. 5- Black-bellied Brent Goose. Breed in Siberia and winter primarily in Europe Black Brant have recently extended their range westward in Siberia, and were they meet Black-bellied Brent Goose, they interbreed with some frequency (or so is my understanding). Notably, Black Brant from these colonies have been banded and found along the North American Pacific Coast. There are a couple records of apparent hybrid Black Brant x Black-bellied Brent Geese along the Pacific Coast of North America as well Gray-bellied Brant. Their mtDNA fits in with Eastern High Arctic Brant, but I am not certain if they've been compared with the "other" Atlantic Brant. Notably, nuclear DNA shows a clear infusion of Black Brant genes (the females tend to loyally return to the breeding grounds with mate in tow; the male might be from a totally different population). I am unclear if there has been any genetic comparison between Eastern High Arctic and Eastern Low Arctic Brant. Habitat wise, Eastern High Arctic and Western High Arctic Brant are very similar to each other and somewhat different from the other Brant populations. Visually, there is nearly complete overlap between the two populations of Atlantic Brant and Gray-bellied Brant with the darkest Eastern High Arctic Brant falling about mid-range in the phenotypic spectrum of Western High Arctic Brant, and the palest Western High Arctic Brant (Gray-bellied) matching the palest Atlantic Brant. Confused? It is confusing. There are 5 populations. Interbreeding between 4 likely occurs, with only the Eastern Low Arctic population being isolated. Black Brant and Western High Arctic Brant (Gray-bellied) overwinter together Black-bellied Brent Goose and Eastern High Arctic Brant overlap in their wintering grounds. Black-bellied Brent Goose and Black Brant interbreed where their breeding ranges meet. Thus, for all of the pairings above, it seems that some degree of interbreeding occurs. How much is unclear. However, it makes for a very muddled picture, and if these will be split is not known, and if they are split, how they will be split is another question. Remember, Gray-bellied Brant has yet to be formally named in the scientific literature. Rather than being similar to the Canada/Cackling Goose picture, the Brant picture actually is rather like that of Greater White-fronted Goose, with 2-3 subspecies in North America (one of which extends into Siberia), a European subspecies, and one in Greenland. Not sure if all this esoteria is of interest to anyone, but there is the picture as I understand it (Based mainly on info about 5 years old). The goose biologists I talked to seemed skeptical of splitting into separate species at that time. Which does not make the Brant at Chatfield less interesting. They are almost certainly from one of the High Arctic populations, and definitely not of our usual sort here in CO Cheers Steven Mlodinow Longmont CO -- You received this message because you are subscribed to the Google Groups "Colorado Birds" group. To post to this group, send email to cobirds@googlegroups.com. To unsubscribe from this group, send email to cobirds+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/cobirds?hl=en. -- You received this message because you are subscribed to the Google Groups "Colorado Birds" group. To post to this group, send email to cobirds@googlegroups.com. To unsubscribe from this group, send email to cobirds+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/cobirds?hl=en.
