For about the last month, geese have been honking about in the
morning, as if making ready for a road trip. A little early it seems
to me. Maybe not, next week is the first week that one can put their
studded snow tires on.
But brants seemed to be more decisive...per article in our Anchorage
Daily News this morning...
Warmer Alaska winters let geese skip trip south
By DAN JOLING / Associated Press Writer
ANCHORAGE, Alaska - A small Pacific sea goose is finding Alaska
winters more to its liking, and a federal study suggests it's due to
Until recently, 90 percent of the Pacific brant population wintered in
Mexico. A U.S. Geological Survey study found that up to 30 percent of
the geese now forgo warmer regions of the Pacific coast to spend
winters in snowy, icy Alaska, trading a long migration for an
abundance of food formerly unavailable because it was covered with
coastal sea ice.
"It's a general trend that's occurring in the northern hemisphere
anyway, that birds are moving north, shifting their distributions,"
said lead author David Ward of the USGS Alaska Science Center. "In
this case, it was a shift in winter distribution."
Brant are herbivores. The shift appears related to changes in the
availability of eelgrass, which grows in shallow bays and coves and is
their primary food when not breeding. Higher air and water
temperatures have reduced Alaska coastal sea ice and made eelgrass
accessible for more winter days.
A previous study indicated brant could spend fat reserves on migration
or an Alaska winter as long as they had undisturbed access to
sufficient amounts of eelgrass, Ward said. That may not have been the
case a few decades ago.
Fewer than 3,000 brant were detected wintering in Alaska before 1977.
That has jumped to as many as 40,000 birds.
The study looked at brant numbers from the mid-1960s to 2005.
Researchers looked at brant numbers collected in annual Christmas bird
counts plus federal waterfowl surveys that started in the 1980s. Data
collected after 2005 corroborates the trend, Ward said. Alaska now has
the second highest winter concentration of brant after Mexico.
The Alaska brant are mostly found in Izembeck Lagoon and adjacent bays
on the Alaska Peninsula, the 500-mile tongue of mainland that juts
toward the Aleutian Islands.
Mean surface air temperature during winter at the end of the Alaska
Peninsula increased about 1 degree Celsius between 1963 and 2004. That
resulted in a 23 percent reduction in freezing degree days and a 34
percent decline in the number of days when ice kept brant from
Conditions on the peninsula are fairly harsh, Ward said. A cold snap
in the wet conditions can ice up a brant's wings, preventing it from
There are benefits, however, to the birds sitting out a flight as long
as 3,500 miles to Baja California, which they sometimes do nonstop.
Eelgrass in northern latitudes has higher protein value. The geese
stay closer to breeding grounds in Alaska and can gauge weather and
time breeding to the disappearance of snow. Goslings hatched early in
Arctic "green-up" have a better chance at survival.
"These birds grow faster, they grow bigger, stronger, and they have
higher survival than birds that come late to the breeding grounds,"
Another climate factor likely figures in the migration decision, Ward
said. Low pressure systems that sent storms sweeping across the Gulf
of Alaska have moved north. The storms provided a kick-start to brant
migration in the form of a tail wind.
"The birds have fewer times that they can get these tail winds," Ward
Wintering in Alaska comes with risk, however. A sudden, severe cold
snap could put a significant portion of the brant population in
During freeze-ups around Izembek Lagoon, the birds can find smaller
feeding areas on nearby islands or perhaps the west side of Kodiak.
But after that, it's a 1,200-mile flight to food in British Columbia's
Queen Charlotte Islands.