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PSemo to: Arnold Ruskin, Claremont Engineering Company From: Roland L. Redmond and William 0. Wirtz, II, Ph.D. Subject: Cliff nesting raptors on the Logan Wash Site, Garfield Co. Colorado. Date: 15 June 1976 Between 3 May and 17 May 1__976, nineteen raptor nesting sites were located at the Logan Wash Site (Figure 1 and Table 1). Three active Golden Eagle eyries (SZ, 510, S 3), one active American Kestrel eyrie (C 1), and one active Turkey Vul~ure eyrie (S B) were located. During twelve days spent on [he study area not a single Prairie or Peregrine Falcon was sighted. According to Dr. James F.nderson (pers.~comm.), the first weeks in hfay are a difficult time to locate nesting pairs of falcons. Females are incubating eggs or brooding young and are very reluctant to leave the eyrie. Pfales spend much of the day hunting for themselves and their mates. Unless a male is near- by one might approach quite close to an active eyrie and not know it. At this time one must rely on a spotting scope to locate tell-tale patches of "white-wash" beneath eyrie sites. The best time to arouse warning calls from adult Prairie Falcons is during the first week of June when both parents are busiest supplying food to their young (Enderson, pers. comm.). Smith Gulch was searched most thoroughly. Observations were carried out from every accessible vantage point on top, and the lower, sandstone cliffs were scanned from below. We consider it unlikely that an active falcon eyrie exists in Smith Gulch. Given the number of hours spent searching, were a pair present, [he male should certainly have been sighted at least once. Fifteen different stick nests (indicated by S on map) were located on the cliffs. It was not possible to ascertain whether these were all of Golden Eagle construction. Most were of comparable size and in similar rock formations. 55 is particularly large and deep; S7 is quite shallow and contained a fresh evergreen bough in the cup. The propensity of Golden Eagles to maintain alternate nests is well docu- mented in the literature (see Dixon, 1937; Watson, 1957; Lockie and Ratcliffe, 1964; PicGahan, 1968; Boeker and Ray, 1971; and Beecham and Kochert, 1975). According [o McGal~an (1968:4): "Many pairs of eagles build more than one nest. They generally use the same nest through consecutive nesting seasons, even though they repair the supernumerary nests and attend them regularly until the eggs are laid. Supernumerary nests were found for 20 nesting pairs or 56 percent of 36 occupied nests visited from 1961 to 1965. One pair attended eight nests, no two of them farther apart than 0.3 mile."