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This rare mustard grows on barren white outcrops exposed along drainages by erosion from <br />downcutting of streams in the Picaence Basin in Rio Blanco County, Colorado. The bladderpod <br />is the rarer than the Dudley bluffs twinpod; its entire range is limited to within 10 miles of the <br />original type locality. The bladderpod grows on the top and sides of level outcrops where the <br />white shale is exposed. <br />Dudley Bluffs twinpod <br />The Dudley Bluffs twinpod (Physaria obcordata), is a rare member of the Brassicaceae <br />(mustard) family. Dudley Bluffs twinpod is 4.8 to 7.2 inches tall with oblanceolate, entire leaves <br />0.4 to 0.6 inches wide and 1.6 to 3.8 inches long, with a silvery sheen due to a dense covering of <br />overlapping, dish - shaped trichomes. The species' scientific name refers to the hear- shaped silique <br />or fruit. Flowers are yellow, and typically present in May and June. <br />This rare mustard grows on barren white outcrops exposed along drainages by erosion from <br />downcutting of streams in the Picaence Basin in Rio Blanco County, Colorado. The range of <br />Dudley Bluffs twinpod is slightly broader, with some occurrences separated by as much as 23 <br />miles. The twinpod grows on steep sideslopes. <br />Candidates <br />Greater sage - grouse <br />The Greater sage - grouse (Centrocercus urophasianus), is the largest grouse in North America. <br />Males often weigh in excess of 4 -5 pounds and hens weigh in at 2 -3 pounds. On the ground and <br />in flight they appear almost black, and their long pointed tail is approximately half the length of <br />their body. Both sexes have narrow, pointed tail feathers, feathering to the base of the toes, and a <br />variegated pattern of grayish brown, buff and black on the upper parts, with paler flanks and a <br />diffuse black pattern on the abdomen. Adult males have blackish -brown throat feathers which are <br />separated by a narrow band of white from a dark V- shaped pattern on the neck. White breast <br />feathers conceal 2 large, skin sacs (used in courtship displays) which are yellow -green in color. <br />Males also have yellow eyecombs (obvious in the spring during courtship displays). Female sage <br />grouse lack the specialized structures used for courtship displays but generally resemble males in <br />coloration. However, in comparison to males, their throats are buffy with blackish markings and <br />the lower throat and breast are barred which presents a blackish -brown appearance. Immature <br />birds (less than 1 yr. of age) can be distinguished from adults by their light yellowish green toes <br />(adults have dark green toes). The birds are found at elevations ranging from 4,000 to over 9,000 <br />feet and are highly dependent on sagebrush for cover and food. <br />Yellow -billed cuckoo <br />The Yellow - billed cuckoo (Coccyzus americanus), is a medium sized bird (12 inches in length) <br />with grey -brown above and white below plumage, with rusty colored flight feathers. The <br />underside of the tail has pairs of large white spots. This bird has a slightly down - curved bill, <br />which the upper mandible of the bill is black and the lower mandible is yellow. This species <br />occupies tall riparian habitat consisting of cottonwood (Populus deltoids) over story and an <br />Page 9 <br />