Understanding Waterfowl
By Bruce Batt, Ph.D.
Back from the Brink
Once on the verge of extinction, the Aleutian goose has now surpassed population goals
One of the great conservation stories of the 20th century is the restoration of the Aleutian cackling goose from no more than a few hundred birds in 1967 to a healthy population estimated at 114,000 birds in early 2008. Although not widely known, this recovery nicely illustrates several basic principles that biologists must address in the management of all waterfowl populations.
The small Aleutian goose may be the handsomest of all the white-cheeked geese. A large gander will weigh only about 5 pounds. The only smaller white-cheeked goose is the true cackling goose, which weighs in at 3 1/2 pounds. The Aleutian is dark brown with the typical black neck and white cheek patch, and most have a prominent white neck ring.
Their namesake and breeding range are a number of the Aleutian Islands, which extend west from southwest Alaska toward Russia. These islands separate the Bering Sea from the North Pacific Ocean. The story of the Aleutian goose starts with Danish-born Vitus Bering’s discovery of the Aleutian Islands for Russia in 1741. Bering lost his life during the expedition, but survivors made their way back home and reported on the fabulous richness of the fur-bearing resources they saw on the islands and in the ocean around them. Undoubtedly, the quality of the region’s furs results from the extreme weather these animals must endure.
Soon to follow was a near “gold rush” of trappers to harvest the bounty of the land and sea. Both arctic and red foxes were especially sought after, but on many islands, trappers found neither species. By 1750, they started to transplant foxes to unoccupied islands to establish new populations for their enterprise. By the 1930s, foxes had been released on about 190 islands. This proved a deadly change for the geese, which until that time had been nesting in a relatively predator-free environment—probably for centuries.
Foxes are efficient predators. While they gladly steal eggs to eat, feed their young, or cache for future use, their main goal is to capture the nesting hens, which are a much larger bundle of groceries. The loss of the female not only eliminates the immediate season’s production but also her potential production from all future seasons within her normal lifespan.
At the same time breeding birds were being decimated, other factors along the flyway further aggravated the situation. Habitat loss on migration and wintering areas had occurred, and hunting was continuing to take a toll. Hunting is seldom an overriding factor that negatively affects waterfowl populations, but it can be when extremely low numbers occur. And it can be especially important for long-lived geese, which have generally low adult mortality.
Aleutian geese were declared a federally endangered species in 1967. Biologists in the Pacific Flyway worked with the U.S. Fish and Wildlife Service to develop a recovery plan that directly addressed low recruitment rates from the islands and survival of young and adults throughout the year.
The most significant step was removal of all the foxes on several islands by trapping. This kind of management makes sense on an island when a one-time effort can remove animals that were not part of the native fauna, and replacements cannot simply move in from surrounding habitats to fill the void. Geese from captive flocks were then released, and families of wild geese were transplanted from Buldir Island, the largest island that still had breeding Aleutians. The release of captive birds was discontinued after a few years because their survival rates were low and the wild transplanted families were doing so much better. Other management actions for Aleutian geese included complete protection from hunting and the restoration and protection of key staging and wintering habitats.
The population started recovering within a few years, and Aleutian geese were upgraded from endangered to threatened in 1990. They were removed completely from the threatened and endangered species list in 2001. By the winter of 2007-2008, the population was about 114,000 birds and sustaining an extraordinary growth rate of about 14 percent per year, far surpassing the 60,000-bird population goal of the Pacific Flyway Aleutian goose management plan.
Managers now face new problems as the geese are causing damage to spring grazing pastures for cattle in northern California and Oregon. In response, both California and Oregon have relatively liberal hunting seasons. For example, California hunters enjoy a six-bird “small” Canada goose limit, which can include both cackling geese and Aleutians. The season is open until March 10, the federally mandated closing date under the Migratory Bird Treaty between the United States, Canada, and Mexico. The late season is focused on keeping the birds off private lands where the damage to forage occurs. The complicated challenge for managers is to achieve harvest rates that will get the population to a level near the 60,000 goal to sustain harvest opportunity while at the same time protecting forage crops.
Dr. Bruce Batt recently retired after serving a lengthy tenure as chief biologist at DU’s national headquarters in Memphis.