Dusky Canada goose | |
---|---|
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Aves |
Order: | Anseriformes |
Family: | Anatidae |
Genus: | Branta |
Species: | |
Subspecies: | B. c. occidentalis |
Trinomial name | |
Branta canadensis occidentalis (Baird, 1858) |
The dusky Canada goose (Branta canadensis occidentalis) is a subspecies of the Canada goose. They are the darkest variant, similar to the Pacific cackling goose. Tagged dusky geese have red bands with white letters on them attached to their neck. They represent one of the smallest populations of Canada goose in the Pacific Northwest. [2] Due to the species' minimal population and exclusive breeding grounds, the dusky Canada goose is a species of interest to the Pacific Flyway Council and the U.S. Forest Service. [3] The Cordova Ranger District, on the Chugach National Forest, has been working since 1984 to implement a monitoring and restoration program for the geese. [4]
The dusky Canada goose is the darkest of the subspecies of the Canada goose. They have a warm brown breast and body, contrasting the buff breast and gray body of other subspecies. Dusky Canada geese represent one of the smallest populations of Canada goose in North America. [2] The dusky Canada goose weighs approximately 3–12 lb (1.4–5.4 kg) and is 25–45 in (640–1,140 mm) in length. [5] Male and female geese have black heads and necks, white cheeks, and similar voices. [5] Approximately four to six eggs are the size of each clutch, with an average incubation period of four weeks. [6]
The dusky Canada goose is occasionally merged with the Vancouver Canada goose (B. c. fulva), but the latter is larger and largely nonmigratory and found from southern Alaska to northern Vancouver Island, British Columbia. [7] Dusky geese, along with the giant Canada goose, are the most closely related birds to the Hawaiian goose, or nene. Based on the genetic analysis, they settled in Hawaii around 500,000 years ago. [8] However, over sixty years of banding data. suggest that the majority of the dusky population breed on the Copper River Delta, Alaska and winter in the Willamette Valley. [3] Other than a few geese nesting on Middleton Island in the Gulf of Alaska, the Copper River Delta is known as the exclusive breeding grounds for this subspecies. [5] Population estimates indicated that there were approximately 20,000 to 25,000 geese in the 1970s and between 12,000 to 15,000 in the 1990s. [6] This decline prompted the strict conservation efforts by the U.S. Forest Service in 1984.
Dusky Canada geese are often more wary than some of the other subspecies, flying low and inspecting a potential area to land before descending. Their wings molt from around early July to early August. Often, molting individuals will wait in sub-alpine lakes for their feathers to grow back. [9] The dusky Canada goose mainly winters in much of the Willamette Valley and southern Washington and breeds in the southeast Alaskan Copper River Delta and Middleton Island. [3] However, the dusky Canada geese have faced heavy predation through predators such as brown bears (Ursus arctos), coyotes (Canis latrans), and bald eagles (Haliaeetus leucocephalus), with bald eagles acting as the most destructive predator. [6] Studies suggest that bald eagles account for nearly eighty percent of nest predation. [5]
Breeding populations occur on Middleton Island and the Copper River Delta. An earthquake in 1964 lifted the delta by around 4 feet (1.2 meters), damaging usable breeding grounds. Middleton Island contains around 1,500 breeding birds, which is close to the maximum birds the island can handle. [3] New breeding islands have been created to increase the population. However, because the population is in such a limited area, small environmental changes can drastically alter the future outlook of the subspecies. Alaskan predators such as bears and foxes have come in contact with the native breeding population in recent years. Dusky populations have dropped due to this new threat. Since the Great Alaska Earthquake of 1964, measuring in at 9.2 magnitude, caused existing wetlands to dry, predation rates increased in the following years. [6] This phenomenon ultimately led to the 1984 implementation of the dusky conservation program, a joint project led by the U.S. Forest Service that includes the Alaska Department of Fish and Wildlife, Oregon Department of Fish and Wildlife, and Ducks Unlimited Incorporated. [3] The goal of the program has been to promote the reproductive rates of the species to boost their population size. [4] In order to do this, the program has installed artificial nest islands in various ponds across the Copper River Delta to mimic the appearance of natural nest islands and act as useful locations for the geese to nest. [6] Over time, these artificial nest islands have shown to have dusky nest occupancy rate increases from 10% to 50% from 1984 to 2011, and an average annual nest success rate of 63%. [3]
The bald eagle is a bird of prey found in North America. A sea eagle, it has two known subspecies and forms a species pair with the white-tailed eagle, which occupies the same niche as the bald eagle in the Palearctic. Its range includes most of Canada and Alaska, all of the contiguous United States, and northern Mexico. It is found near large bodies of open water with an abundant food supply and old-growth trees for nesting.
The nene, also known as the nēnē or the Hawaiian goose, is a species of bird endemic to the Hawaiian Islands. The nene is exclusively found in the wild on the islands of Oahu, Maui, Kauaʻi, Molokai, and Hawaiʻi. In 1957, it was designated as the official state bird of the state of Hawaiʻi.
The snow goose is a species of goose native to North America. Both white and dark morphs exist, the latter often known as blue goose. Its name derives from the typically white plumage. The species was previously placed in the genus Chen, but is now typically included in the "gray goose" genus Anser.
The double-crested cormorant is a member of the cormorant family of water birds. It is found near rivers and lakes and in coastal areas and is widely distributed across North America, from the Aleutian Islands in Alaska down to Florida and Mexico. Measuring 70–90 cm (28–35 in) in length, it is entirely black except for a bare patch of orange-yellow facial skin and some extra plumage that it exhibits in the breeding season when it grows a double crest in which black feathers are mingled with white. Five subspecies are recognized. It mainly eats fish and hunts by swimming and diving. Its feathers, like all cormorants, are not waterproof, and it must dry them out after spending time in the water. Once threatened by the use of DDT, the numbers of this bird have increased markedly in recent years.
The Canada goose is a large species of goose with a black head and neck, white cheeks, white under its chin, and a brown body. It is native to the arctic and temperate regions of North America, and it is occasionally found during migration across the Atlantic in northern Europe. It has been introduced to France, the United Kingdom, Ireland, Finland, Sweden, Denmark, New Zealand, Japan, Chile, Argentina, and the Falkland Islands. Like most geese, the Canada goose is primarily herbivorous and normally migratory; often found on or close to fresh water, the Canada goose is also common in brackish marshes, estuaries, and lagoons.
Steller's eider is a migrating Arctic diving duck that breeds along the coastlines of eastern Russia and Alaska. It is the rarest, smallest, and fastest flying of the eider species.
The sandhill crane is a species of large crane of North America and extreme northeastern Siberia. The common name of this bird refers to their habitat such as the Platte River, on the edge of Nebraska's Sandhills on the American Great Plains. Sandhill cranes are known to frequent the edges of bodies of water. The central Platte River valley in Nebraska is the most important stopover area for the nominotypical subspecies, the great sandhill crane, with up to 450,000 of these birds migrating through annually.
The Copper River or Ahtna River, Ahtna Athabascan ‘Atna’tuu, "river of the Ahtnas", Tlingit Eeḵhéeni, "river of copper", is a 290-mile (470 km) river in south-central Alaska in the United States. It drains a large region of the Wrangell Mountains and Chugach Mountains into the Gulf of Alaska. It is known for its extensive delta ecosystem, as well as for its prolific runs of wild salmon, which are among the most highly prized stocks in the world. The river is the tenth largest in the United States, as ranked by average discharge volume at its mouth.
The cackling goose is a species of goose found in North America and East Asia.
The brant or brent goose is a small goose of the genus Branta. There are three subspecies, all of which winter along temperate-zone sea-coasts and breed on the high-Arctic tundra.
William L. Finley National Wildlife Refuge is a natural area in the Willamette Valley in Oregon, United States. It was created to provide wintering habitat for dusky Canada geese. Unlike other Canada geese, dusky Canada geese have limited summer and winter ranges. They nest on Alaska's Copper River Delta and winter almost exclusively in the Willamette Valley. Habitat loss, predation, and hunting have caused a decrease in population.
Ankeny National Wildlife Refuge is located in the fertile Willamette Valley of northwestern Oregon, 12 miles (19 km) south of Salem. The valley was once a rich mix of wildlife habitats. Valley wetlands were once extensive, with meandering stream channels and vast seasonal marshes. Today, the valley is a mix of farmland and growing cities, with few areas remaining for wildlife.
Baskett Slough National Wildlife Refuge is in northwestern Oregon, 10 miles (16 km) west of Salem in Polk County. The Refuge consists of 1,173 acres (4.75 km2) of cropland, which provide forage for wintering geese, 300 acres (1.2 km2) of forests, 550 acres (2.2 km2) of grasslands, and 500 acres (2.0 km2) of shallow water seasonal wetlands and 35 acres (0.14 km2) of permanent open water. In 1965, Baskett Slough National Wildlife Refuge was created to help ensure some of the original habitat remained for species preservation. The refuge is managed by the U.S. Fish and Wildlife Service, an agency of the U.S. Department of the Interior.
The Aleutian cackling goose is a small subspecies of the cackling goose averaging 1.7 to 2.1 kg in weight. It was one of 122 species of animals, birds, and fishes first documented for science by the Lewis and Clark Expedition.
The San Luis National Wildlife Refuge Complex is located in the northern San Joaquin Valley, within Merced County and Stanislaus County of California. The complex, with four federal National Wildlife Refuges, is managed by the U.S Fish & Wildlife Service.
McNary National Wildlife Refuge is a wildlife preserve, one of the national wildlife refuges operated by the United States Fish and Wildlife Service. Extending along the east bank of the Columbia River in southeastern Washington, from the confluence of the Snake River to the mouth of the Walla Walla River, and downstream into Oregon, McNary NWR is located in rural Burbank, but very close to the rapid development of the Tri-Cities. In fact, the refuge meets the definition of an "urban refuge." Few areas in North America support waterfowl populations in the extraordinary numbers found here. There are spectacular concentrations of Canada geese, mallards, and other waterfowl. More than half the mallards in the Pacific Flyway overwinter at some time in this portion of the Columbia River Basin.
The Arctic Goose Joint Venture (AGJV) is a conservation partnership established in 1989 between governments, organizations, and conservation groups to coordinate research and monitoring of Arctic, sub-Arctic and boreal nesting goose populations of North America, specifically the cackling goose, Canada goose, emperor goose, greater white-fronted goose, Ross's goose, and snow goose. Executing Arctic research expeditions in collaboration with partners is a primary goal of the venture, so that the logistics of such research can be coordinated efficiently. One of its main activities is to collar geese in Canada, the United States, and other nearby Arctic areas, such as Wrangel Island of Russia.
The giant Canada goose is the largest subspecies of Canada goose, on average weighing in at 5 kg. It is found in central North America. These geese were at one point considered extinct, but were later rediscovered. The giant Canada goose was once kept and bred in captivity for use as hunting decoys and for food.
The Moffitt's Canada goose, also known as the Western Canada goose or Great Basin Canada Goose is a subspecies of the Canada goose. Native to the western interior of North America surrounding the Rocky Mountains, its range has expanded due to introductions to various regions of western North America.
The Vancouver Canada goose is a subspecies of Canada goose, residing in western British Columbia and southern Alaska.
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