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The Endangered Species Act is a 1966 federal law designed to prevent species from passing into extinction. An extinct species is an animal or plant species that has died out everywhere in the world. An endangered species is one that is in danger of extinction throughout all or a significant portion of its range. A threatened species is one whose numbers are low or declining. A threatened species is not in immediate danger of extinction, but is likely to become endangered if it is not protected. Howelia has been placed on the endangered species list and can be found in only a few places on the Ridgefield National Wildlife Refuge. Howelia is a rare native plant that is only found in only a few sites in Washington, Idaho, and Montana. Howelia grows in small lakes and in the bottom of ponds. Small aquatic insects and their egg masses can be found in the leaves and stems of the plant. Howelia was first discovered in Oregon, but has not been sighted since the1970's. It has also disappeared from California. The preservation of wetlands and lakes is very important to the recovery of endangered plants such as Howelia. Although once endangered, the bald eagle is now considered a threatened species. 
When Europeans first arrived on the North American continent, there were between one-quarter to one-half million bald eagles. Bald eagle populations declined dramatically as they lost their nesting habitat to development and were killed by settlers. In 1940, Congress passed the Bald Eagle Protection Act, but the increasing use of pesticides, especially DDT, caused nesting failures. In 1967, bald eagles were listed as endangered under the Endangered Species Preservation Act. In 1972, the Environmental Protection Agency banned the use of DDT in the United States. These intense recovery programs resulted in increasing populations, and in 1999, the bald eagle was reduced to a threatened species. Adult bald eagles are readily identified by a white head and tail and huge yellow bill. Immature bald eagles are mostly dark brown. The refuge hosts several species of concern, including the dusky Canada goose and the Oregon white oak. Dusky Canada Goose 
One of the primary goals for creating the Ridgefield National Wildlife Refuge was to provide a wintering area for waterfowl, with a special emphasis on dusky Canada geese. The only place the dusky Canada goose spends its winters is along the lower Columbia River and in the Willamette River Valley of Oregon. To ensure that the geese had secure wintering areas, the Ridgefield National Wildlife Refuge was established in 1965, along with three other refuges in the Willamette Valley. Dusky Canada geese are one of seven subspecies of Canada geese found on the refuge, identified by their chocolate brown breast. Oregon White Oak 
In
the state of Washington, the Oregon white oak is a habitat of concern.
The Oregon white oak is Washington's only native oak. The Oregon
white oak habitat is found on the basalt bluffs above the Columbia
River floodplain where it is dry. Harvesting of oak trees, urban development, forest succession, cattle grazing, and fire suppression have contributed to the decline of the Oregon white oaks. In the refuge, an aggressive program of blackberry vine removal will help regenerate growth of young Oregon white oak trees. Invasive plants are introduced through human activity, and compete with native plant and animal species. Wildlife refuges are intensely managed to benefit fish and wildlife. Wildlife biologists and refuge managers work collectively to devise management plans to protect and conserve wildlife refuges. Invasive and non-native species are paid special attention on refuges. Refuge managers restore habitats to native vegetation where suitable. Managing habitats may include mowing blackberry brambles as well as disking up wetlands and fields that are filled with reed canarygrass. Native grasses and wetland plants are then planted in the place of these invasive plants Himalayan Blackberry Vines 
Himalayan blackberry
vines have invaded woodland areas of the Ridgefield National Wildlife
Refuge. The Himalayan blackberry is the most common blackberry species
in the Pacific Northwest. Originally from India, it was brought
to the United States from England. The rapidly spreading Himalayan blackberry is very aggressive, covering the ground and climbing high into branches of trees, creating walls of vines thickly armed with spines. Himalayan blackberry vines smother young plants, and can be seen surrounding some of the Oregon white oak trees on the refuge. Removal is difficult, and requires cutting of the vines, and spraying of new leaves to kill the roots. Reed Canarygrass 
Reed canarygrass, a marsh grass introduced early in this century, has invaded many of the wetlands in the Pacific Northwest, including those on the refuge. This plant is an aggressive invader, outcompeting most of the natural vegetative communities in which it becomes established. A perennial grass, reed canarygrass grows into stands so dense that wildlife cannot use it. In the spring it collapses to the ground, making it poor nesting cover. The small seeds, although numerous, are an insignificant portion of waterfowl's diet. Although it is nearly impossible to eliminate, mowing the canarygrass during late summer and early fall does provide short, green vegetation preferred by Canada geese and wigeon ducks when they arrive in the fall. Try these classroom and field trip activities to learn more about endangered and invasive species. Habitat
Crisscross: Print out this crisscross puzzle, then answer the
clues. Click on the glossary button at the top of this page if you
need help. top of page Learn more about endangered, threatened, and invasive species! Washington Birds and Mammals of Special Concern National Invasive Species Program Habitat and Endangered Species Maps for Ridgefield National Wildlife Refuge Clark County Endangered Species Act Program Visit the other learning stations in the Refuge Habitats field trip. |
