Above left,right: Malheur Lake near Malheur NWR HQ. Center Great Blue Heron near HQ.
Malheur National Wildlife Refuge HQ at 4223 elevation, 43.15.49 North | 118.50.35 West.
Left: Antelope north of Malheur NWR. Center:Vegetation near HQ. Right: North of Malheur Lake.
Left: Patrol Road. Center: Basalt Colums next to Highway 205. Right: Blitzen Valley.
Above columar basalt on Highway 205 at 3964 feet elevation, 43.00.32 North | 118.53.09 West.
Left: NWR boundary marker. Center and Right: Buena Vista Overlook.
Buena Vista Overlook at 4076 feet elevation, 43.03.49 North | 118.52.03 West.
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OWESA geographic model: geomorphology | climate
| vegetation | wildlife
|human settlement|
Geomorphology
Climate (references)
Annual precipitation in Harney Basin varies from over 19" over the
upland watershed of the Silvies River to less than 10" over the alluvial
basins. (Mc Dowell 1992) At Burns and Malheur National Wildlife Headquarters,
the climatic regime is arid, while in the uplands it is semiarid. Mean annual
precipitation at Burns is 7.8 inches and mean annual temperature is 46.4
Farenheight. Two different precipitation mechanisms are present, creating
a bimodal distribution during the year. Like most of the Pacific Northwest,
the received winter storms result from large-scale low pressure centers
steered by the westerlies . A second precipitation mechanism at Burns is
thunderstorms occurring during the late spring and early summer. May and
June is a relative wet time for Harney Basin. (Mc Dowell 1992, Sellers 1968)
Annual precipitation varies 8-9 inches at Malheur National Wildlife Refuge
headquarters to over 70 inches in surrounding mountains. About one-third
falls as snow, but snow depths rarely exceed 6 inches on the refuge. Thunderstorms
occasionally produce hail in the summer months and storms from late July
through mid-September, usually having little precipitation, but do produce
lightening strikes which often cause spectacular range fires and reduced
visibility. (Littlefield 1990)
Malheur Lake is actually a vast inland marsh which contains abundant
submerged and emergent vegetation. The submerged vegetation is dominated
by sago pondweed, which is food plant of great importance to waterfowl.
Other submerged species include horned pondweed, water milfoil, and coontail.
In deep water the emergent vegetation is dominated by hard stem bulrush
and cattail is common. The uplands adjacent to the playas are dominated
by big sagebrush, rabbitbrush, and greasewool, interspersed with grasses,
including giant wild rye and desert saltgrass. (Greenspan 1985, Feldhamer
1979)
"The variety of habitats on Malheur NWR account for the large number
of bird species which have been recorded. In a region characterized by shrub-steppe
desert, the key to this avian diversity is water." (Littlefield 1990)
Marsh dwellers in this water vegetation include Snowy egrets, White-faced
Ibis, Black-necked Stilt, and Franklin's Gull, and Black-throated Sparrow.
These wetland like habitats found on the refuge interspersed with deep marshes,
saline flats, wet meadows, grass-shrub uplands, riparian zones help produce
the contrast necessary for the large assortment of birds which occur supported
in twelve major vegetative communities on the refuge. (Littlefield 1990)
The Harney Basin supports a rich and varied fauna. Large game animals
include mule deer, antelope, and mountain sheep. Carnivores include bobcat,
mountain lion, coyote, red fox, raccoon, river otter. Lagomorphs include
white and black-tailed jackrabbits, Nuttall's cottontail, and pygmy rabbit.
A wide variety of rodents includes chipmunks and squirrels, western pocket
gophers, and various rats and mice, porcupine, muskrat, lizards, frogs,
toads, and fish, (Greenspan 1985).
During spring migration over 25,000 ducks, 125,000 geese, and 6,000 Lesser
Sandhill Cranes may use this habitat simultaneously. In addition, nearly
25,000 duck pairs, 2,000 Canada Goose pairs, 1,500 Long-billed Curlews,
and hundreds of other shore birds, marshbirds, and songbirds remain throughout
the summer to nest. In the deeper marshes, gulls, terns, ibises, herons,
egrets, and cormorants usually find ideal nesting habitats. (Littlefield
1990) Although much of the area on the north shore of Lake Malheur is privately
owned, the federally owned Malheur National Wildlife Refuge is the regional
center for species diversity, abundance, and refuge. See the Oregon
Wildlife Viewing Guide (1994) for important additional details on
wildlife description, viewing information, and directions to wildlife viewing
sites.
alluvial - (Alluvium) General descriptive term for clay, silt, and sand
transported by running water and deposited in sorted or semisorted sediment
on a flood plain, delta, or in a stream bed.
regime - A ruling system.
bimodal - Occurring twice.
low pressure -At a particular location, atmospheric pressure varies primarily
as a result of the migration of large systems of high and low pressure.
Pressure falls slowly; then rises as systems passes. Reifsnyder, W.F., 1980.
Weathering The Wilderness . Sierra Club Books, San Francisco.
McDowell, P., 1992. An Overview of Harney Basin Geomorphic History Climate
and Hydrology. Land and Life At Malheur Lake . (Eds. Raven, C., and
Elston, R.G., 13-14. Intermountain Research, Silver City, Nevada.
Sellers, W.D., 1968. Climatology of Monthly Precipitation Patterns In
The Western United States, 1931-1966 . Monthly Weather Review , 96,
585-595.
Littlefield, C.D., 1990. Birds of Malheur National Wildlife Refuge ,
Oregon . Oregon State University Press, Corvallis.
playas - A shallow lake basin in a desert region intermittently filled with
water that evaporates in a short period of time.
Greenspan, R.L., 1985. Fish and Fishing In Northern Great Basin Prehistory
. Dissertation, Department of Anthropology, University of Oregon.
Feldhamer, G.F., 1979. Vegetative and Edaphic Factors Affecting Abundance
and Distribution of Mammals in Southeast Oregon. The Great Basin Naturalist
. 39, 207-218.
Littlefield, C.D., 1990. Birds of Malheur National Wildlife Refuge
,Oregon. Oregon State University Press, Corvallis.
variety of habitats - three images (Malheur blue to lavender, vegetation
at HQ, Krumbo Reservoir (ephemeral)
avian -Relating to, or derived from birds.
birds - Blitzen River marsh area, mid-way between Malheur Lake and Frenchglen.
(audio file)
Return to vegetation.
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fauna - Animal life.
Littlefield, C.D., 1990. Birds Of Malheur National Wildlife Refuge ,
Oregon . Oregon State University Press, Corvallis.
Copyright
Phil Kessinger, 1997
Eugene,Oregon USA
All Rights Reserved
phil_k
at
efn.org
Revised December 2002