2004-10-06_REVISION - M1988044 - Laserfiche WebLink

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Raptor Survey of the Colorado State Land Board's Lowry Range Property, Arapahoe County, CO Brent Bibles, Avian Researcher -Raptors, Colorado Division of Wildlife, Fort Collins, CO The Colorado Division of Wildlife surveyed the riparian bottom of Coal Creek on the State Land Boazd's Lowry Range property on 7 May 2004. Six persons took part in the survey, forming two survey groups. One group surveyed the approximately 6 mile stretch of Coal Creek between County Line Road on the south and Quincy Avenue on the north. The second group surveyed the approximately 3.5 mile stretch from the radio towers along Yale Avenue on the north to Quincy Avenue on the south. Surveys began at azound 08:00 and were completed by azound 13:00. During the surveys, all raptors and nest structures were noted. The survey concentrated on the riparian azea along the creek, the surrounding upland azeas were not surveyed. The following describes the results of these surveys, with narrative concentrating on the stretch of creek between Quincy Avenue and County Line Road (southern stretch). Coal Creek had surface flow for approximately half of its length on the southern stretch. Through this stretch, it consists of a narrow band of riparian forest, mostly cottonwood (Popu/us spp.), in rolling terrain consisting of shortgrass prairie. A gravel operation is prominent on the east bank along about 3 miles of the creek immediately south of Quincy Avenue. There aze numerous oil wells along the creek for about a 2 mile stretch south of the grave] operation. Thirty-one raptors were spotted during the survey, although some of these were probably duplicate sightings. Of these, 12 were Red-tailed Hawks (Buteo jamaicensis), eight were American Kestrels (Falco sparverius), seven were Great Horned Owls (Bubo virginianus), one was a Northern Harrier (Circus cyaneus), and one was a Swainson's Hawk (Buteo swainsoni). Two individuals, an owl and a buteo, were not identified to species. Four stick nests were located. One was an old nest and the remaining three were Red-tailed Hawk nests used in 2004. Table 1 provides location information on all sightings. Figures I and 2 are maps of the surveyed azea indicating the location of the observed individuals and nests. Two of the Red-tailed Hawk nests were active. RTHAl had a female in brooding posture on the nest, and a male was neazby. RTHA3 had a defensive female in the immediate azea, and a male nearby. There was down and fresh greenery on the nest, indicating that young nestlings were present. RTHA2 had recently failed. Both adults were present, but were not vocal, and a lot of down was present on the nest edge. These indicate that the nest probably failed after eggs had hatched. The old stick nest (OLD1) was not used this year. It did not appear to have been constructed by Red-tailed Hawks, appearing more like a nest constructed by Swainson's Hawks or Cooper's Hawks (Accipiter cooperii). However, the azea did not appeaz to be probable Cooper's Hawk habitat. The sightings on the south stretch (County Line Road to Quincy Avenue) probably indicate the presence of three Red-tailed Hawk territories, eight American Kestrel territories, and four Great Homed Owl ten•itories in this stretch. The sightings on the north stretch (north of Quincy Avenue) probably represent two Red-tailed Hawk territories, a Swainson's Hawk territory, and a Great Horned Owl territory. This survey found the raptor species that would be expected to occur in this area. However, I noticed two possible concerns related to the raptor community in the azea. First, raptor activity was noticeably absent in the mile adjacent to the most active portion of the gravel mining activity (Figure 1), and this stretch generally was less diverse than other portions of the azea surveyed. Second, there appeazed to be no cottonwood regeneration along the creek, probably the result of past grazing. All existing cottonwoods are mature, and there is no indication of any replacement except in two small grazing exclosures. The lack of regeneration could have significant impact on future raptor use of this area as the mature trees aze lost.