Brown-headed Cowbird
Molothrus ater
Synopsis: Breeds throughout the state in a wide range of habitats, wherever it can parasitize other species by laying eggs in their nest. In 1940 it was considered "not common anywhere in Oregon" and was restricted to farmlands east of the Cascades (Gabrielson and Jewett 1940). But it began breeding west of the Cascades in the 1950's and today is widespread.

Habitat Associations:
strongest
Aspen Groves (22267 acres)
Salt Desert Scrub Shrubland (571910 acres)
Coastal Headland Grass & Shrubland (2285 acres)
Urban/Residential (619139 acres)
Edges of Cropland/Pasture/Orchard (6423869 acres)
Western Oregon Riverine Woodland (27749 acres)
Streamside/Wetland Shrubland (2171 acres)
strong
Sitka Spruce-W. Hemlock Maritime Forest (402570 acres)
Ponderosa Pine-dominant Mixed Conifer Forest (427287 acres)
Ponderosa Pine Forest/Woodland (4743791 acres)
W. Juniper Woodland (3774399 acres)
Red Alder (125162 acres)
Mixed Conifer/Mixed Deciduous Forest (1403632 acres)
Siskiyou Mtns Mixed Deciduous Forest (188698 acres)
White Oak Forest (115577 acres)
South coast Mixed Forest (2888 acres)
Siskiyou Mtns Shrubland on Serpentine Bedrock (16045 acres)
Mountain Mahogany Shrubland (1378 acres)
Sagebrush Steppe (5209944 acres)
Low-Dwarf Sagebrush (429366 acres)
Big Sagebrush Shrubland (12294958 acres)
Northeast Canyon Grass & Shrubland (399563 acres)
Grassland & Fir-Ponderosa Interspersed (382728 acres)
Northeast Modified Grassland (849373 acres)
Wet Montane Meadow (2910 acres)
Seasonally Wet Playa (125408 acres)
Coastal Dunes & Ponds with Widely Scattered Shrubs/Trees (43358 acres)
Lake/Pond Shoreline & Islands (734668 acres)
Edges of Freshwater Marsh (19950 acres)
some
Douglas Fir-W. Hemlock-W. Red Cedar Forest (5696694 acres)
Douglas Fir-White Fir/Tanoak-Madrone Mixed Forest (934526 acres)
Douglas Fir/White Oak Forest (196681 acres)
Douglas Fir dominant - Mixed Conifer Forest (2010492 acres)
Ponderosa-Lodgepole Pine on Pumice (1502766 acres)
Manzanita-dominant Shrubland (15410 acres)
Bitterbrush-Big Sagebrush Shrubland (153185 acres)
Edges of Recently Cutover/Burnt Forest (1616407 acres)
lesser
Whitebark-Lodgepole Pine Montane Forest (1323 acres)
Northeast Mixed Conifer Forest (3097610 acres)
Jeffery Pine Forest/Woodland (40119 acres)
Conifer Woodland on Serpentine Bedrock (46296 acres)
Lodgepole Pine Forest/Woodland (256439 acres)
Coastal Lodgepole Forest (757 acres)
Douglas Fir-Port Orford Cedar Forest (157277 acres)
Douglas Fir-Mixed Deciduous Forest (2934 acres)
Ponderosa Pine/White Oak Forest & Woodland (163195 acres)
Ponderosa Pine-W. Juniper Woodland (201479 acres)

Relative Detectability: Easy to detect by sight and song, and fairly easy to confirm breeding.

Challenge: Determine if this species breeds more widely than shown in the Siskiyou Mountains and west slope of the Cascades.