[Tweeters] Snow Geese Movements

[Michael Price]

Hey tweets

In Vancouver BC there's a similar question about goose movements, not just
Snow Geese, but also Canada Geese (*Branta canadensis*), complicated by the
addition of three non-migratory CAGO races intentionally imported from
southern Ontario and Alberta by hunting groups into the Fraser Valley in
the 1950's and 1960's (*B.c. moffitti, B.c. maximus, *and* B.c. interior*).
Moved right in and overstayed their welcome. Good paper on this, Introduced
Canada Geese in the Fraser Estuary, by Dominic Janus, 2022.


Reason I bring this up and why it may shed some light on local northbound
SNGO movements is that we have the problem of local resident movements vs.
those of the original Pacific Flyway birds (*B.c fulva, taverneri, minima*
etc.) I suggest the key difference is altitude. Our local residents,
whether on their way to a forage site or molt-lake/pond rarely move above
100m/238 ft. Migrants come in *high*, about 300m/1000 ft to 600m/2000 ft.
in the direction of migration. So I suggest, as a very rough rule-of-thumb,
low altitude indicates a local intention; high altitude, a migrational one.

best, m
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