Changing Climate, Changing Patterns: An Occasional Series On The Impacts Of Warming Temperatures

October 12, 2009
Brant geese
A Pacific brant family on the Yukon-Kuskokwim Delta, Alaska. Photo: Jeff Wasley, courtesy U.S. Geological Survey
A Pacific brant family on the Yukon-Kuskokwim Delta, Alaska. Photo: Jeff Wasley, courtesy U.S. Geological Survey

Warming Temperatures Affect Geese Migration

 As Alaska’s climate has warmed over the last four decades, Pacific brant geese have drastically changed their winter migration, according to a recent study in the journal Arctic. Whereas 90 percent of the population recently wintered in Mexico, today about 30 percent of the population —roughly 40,000 birds—are spending their winters in Alaska, according to the U.S. Geological Survey-led study.

“This increase in wintering numbers of brant in Alaska coincides with a general warming of temperatures in the North Pacific and Bering Sea,” said David Ward, the lead author of the study and a USGS researcher at the Alaska Science Center. “This suggests that environmental conditions have changed for one of the northernmost-wintering populations of geese.”

The study found that the migration shift appears related to the changes in availability and abundance of eelgrass, the primary food in the non-breeding season. Release of the study garnered widespread news reports of the impacts a warming climate has on species migration. In Mother Jones, Julia Witty notes that warming temperatures have well-documented effects on the abundance and distribution of many marine species, including walleye Pollock, Pacific cod, northern fur seals, and thick billed murres.

A Polar Field Services Series: Changing Climate, Changing Patterns

The field notes team plans to report a series of stories and interviews with scientists on the real-time impacts climate change has on native populations—both human and animal. The recent article by Ward et al. details the changing patterns in brant outside of the breeding season. To learn more about how climate change is altering the birds during the summer breeding season, we asked Jim Sedinger, professor at the Department of Natural Resources and Environmental Science at the University of Nevada, about his long-term research on breeding strategies of Pacific brant in Alaska, funded by the NSF.

Interview With Jim Sedinger

Polar Field Services (PFS): What makes brant geese an interesting species to study for ornithologists, ecologists, and climate scientists?

Jim Sedinger: The colonial nesting nature of brant makes it possible to study demography (survival, reproductive effort, recruitment into the breeding population, etc.), which is difficult for many other species.  Brant behavior in winter also allows following individuals in winter and spring.  Brant come out of the water following high tide each day to preen and acquire grit.  Investigators can read their uniquely engraved plastic leg bands during these periods.  In some years during the 1990s David Ward’s crews read > 14,000 bands in Mexico during winter.  Individual brant are also observed in large numbers in Humboldt Bay (Jeff Black and students) and the Strait of Georgia (Environment Canada).

Brant on the Pacific coast are dependent on eelgrass in bays and estuaries extending from Alaska to Baja, so they are excellent indicators of environmental conditions along the coast.

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