Large flocks of Pacific brant depend on a few key areas, especially Izembek Lagoon. (Photo by Heather Wilson/USFWS)

Refuge Notebook: The outlook for Pacific brant

After a multiweek weather delay, Biologist/Pilot Heather Wilson and I took off from Kenai just before noon, Jan. 31, in a Cessna 206 on amphibious floats, and flew southwest to Cold Bay, a tiny village 560 miles to the southwest at the end of the Alaska Peninsula.

Our objective was a “census” of brant wintering among eelgrass beds in Izembek Lagoon, in several other lesser estuaries and in a small archipelago called Sanak Islands about 30 miles offshore in the Pacific.

We monitor populations of birds to ensure they are not overhunted or otherwise in jeopardy from human activities. Since each species and population is unique, and none of the birds are motivated to fully cooperate in the process, the job can get very challenging.

Targeting a “weather window” with high-confidence forecasts adequate to get there and conduct four half-day aerial surveys within two weeks is the biggest challenge of this annual project. The former name of Cold Bay’s only store/bar/hotel, “The Weathered Inn,” tells you all you need to know about its climate.

Trying to fly surveys at Izembek National Widlife Refuge reminded me of the old Maytag ads where the repairman spent most of his time thrumming his fingers and waiting for the phone to ring. But this time we lucked out and completed our surveys over eight days, sandwiched between several brief but powerful storms.

That I, a biologist/pilot retired since 2013, am still invited to participate in projects like this is an artifact of the way waterfowl survey work has evolved. Most waterfowl are scattered widely during nesting and rearing young, but spend the winter and shoulder seasons aggregated in large flocks.

In rare situations we’re able to photograph all flocks and count accurately from the images, but for most we have to visually estimate and record flock size, and use the results for management data.

The estimates include many variables, such as weather, water chop, sun glare and bird behavior, but one of the trickiest is observer bias — each observer’s individual skill and experience.

The best way to hedge against that bias is to use the same observer year after year, and for this survey I am the observer with the longest tenure, and easy to talk into such adventures.

Our 2021 Izembek survey brant estimate was 56,563 — the highest at the end of a significant increasing trend since 1981. Through the same period the Mexico winter count decreased slightly, and the much smaller population in other Pacific Coast wintering areas has remained relatively stable.

Also during that time average winter temperatures have risen gradually at Izembek, reducing ice coverage over the lagoon, improving the birds’ access to eelgrass over time (brant live almost exclusively on a diet of eelgrass), thus making it more and more attractive as a wintering area.

At first we assumed that an increasing number of birds made the choice to cancel the journey south and back again. But, when you figure that they leave before winter really sets in, and they don’t have internet access for weather data, it is unlikely they could know about weather and food conditions along their migration route.

The more likely explanation is that the small number of birds who wintered at Izembek gained an advantage for winter survival and reproduction compared to their migrating peers, so they are simply overtaking them in growth rate and population size.

There are indications that eelgrass abundance may be decreasing in other parts of the brant’s wintering range, and other environmental factors may be affecting brant health and survival, which may account for the drop in winter estimates there.

So this species, though it has the disadvantage of extreme food specialization, may weather the early stages of climate change thanks to the existence of Izembek Lagoon, a keystone resource in just the right place and time.

The other big question is the continued stability of the Pacific brant’s extensive breeding range. Climate warming is happening faster in the Arctic than elsewhere in the Northern Hemisphere, but the net impacts of that and human factors on brant and other species are difficult to predict.

The Yukon-Kuskokwim Delta coast hosts the largest Pacific brant breeding population. Nesting colonies there have declined slightly since 1992. It’s expected that rising sea levels and storm severity will continue to increase, potentially causing widespread reproductive failure.

Next in importance is the Alaska North Slope. The core brant nesting area is along the Beaufort Coast between Utqiagvik (Barrow) and Deadhorse.

Warming trends are predicted to improve forage abundance there for brant and other geese in the near term, but increased oil and gas activity and other human factors will increase disturbance and may support higher predator populations, which could negatively impact breeding success.

A major portion of arctic-breeding brant also use the Kasegaluk Lagoon, located on the Chukchi Coast south of Utqiagvik, for molting in late summer. That area may become at risk of oil transportation mishaps, especially if Chukchi offshore oil development occurs.

Smaller Pacific brant populations also breed in eastern arctic Russia and the arctic Canadian Islands, which will soon see big changes from warming, with unknown consequences to brant.

Pacific brant are just one species among millions (including us!) that will attempt to adapt to a changing environment, but I find it a fascinating example to illustrate some of the coming complex and unpredictable challenges. The big take-home message from the brant example is how critical it is to protect as much diversity of species and habitats as possible.

This brings to mind a quote from Aldo Leopold: “If the biota, in the course of aeons, has built something we like but do not understand, then who but a fool would discard seemingly useless parts? To keep every cog and wheel is the first precaution of intelligent tinkering.”

Bill Larned is a retired biologist/pilot whose 40 year career has consisted mainly of developing and conducting aerial wildlife population and distribution surveys in many parts of the U.S, Canada and Mexico, along with various other biological work for State and Federal agencies. He has lived in Soldotna since 1984. Find more Refuge Notebook articles (1999–present) at https://www.fws.gov/refuge/Kenai/community/refuge_notebook.html.


By BILL LARNED

Refuge Notebook


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