. Brigham Young University science bulletin. Biology -- Periodicals. Fig. 41. Raven'.s nest built upon prairie eyrie (shown in Fig. 40). Photo by R. D. Porter, 1951. nests of other species of raptors and Common Ravens, which suggests that these species ma}' be beneficial to the Prairie Falcon b\' providing additional nesting sites. Table 10 gives the kind of nesting situations used bv Prairie Falcons in Utah. Sometimes these competitors may preempt their old nests from the Prairie Falcon. An oc- Table 10. Percentage use of various categories of eyrie sites bv Prairie Falcons in Utah (see photo
. Brigham Young University science bulletin. Biology -- Periodicals. Fig. 41. Raven'.s nest built upon prairie eyrie (shown in Fig. 40). Photo by R. D. Porter, 1951. nests of other species of raptors and Common Ravens, which suggests that these species ma}' be beneficial to the Prairie Falcon b\' providing additional nesting sites. Table 10 gives the kind of nesting situations used bv Prairie Falcons in Utah. Sometimes these competitors may preempt their old nests from the Prairie Falcon. An oc- Table 10. Percentage use of various categories of eyrie sites bv Prairie Falcons in Utah (see photos by Wolfe,'1928)' Kind of Site Usage n of eyrie types Percent Potholes= 26 Open cliff ledges Crevices 23 7 Stick nests Red-tailed Hawk's on cliff face 16 7 Common Raven's on cliff face' Tree nests Golden Eagle's on cliff face 5 2 1 Unknown species of hawk Totals 1 72 'From unpuliHshed data of authors, ficldnotcs of R. G. Bw. A B, Boyle, ana R. J. Envin, and from ornithological literature for the stale. ^Five or 6,9 percent of the eyries were in old ravens' nests lo (ated witliiii potholes. 'IncliidinB the five that were in old ravens' nests within pot holes, a total of 10 or percent were in old ravens' nests. currence of this kind took place at an eyrie in Weber County observed by Porter and Erwin. The falcons were using an old raven's nest which apparentlv had been occupied for many vears bv falcons, since it was almost entirely buried in excrement (Fig. 40). Without the old raven's nest as a base, a falcon's eyrie would have been impossible. When fir'st located on 5 June 1950, five fully grown young were present in the nest. The following year the eyrie contained three. fresh eggs on 7 April. When it was next visited on 8 Mav, a raven flushed from the eyrie site, exposing six raven eggs in a newlv constructed stick nest over the old prairie eyrie (Fig. 41). The whereabouts of the previous tenants was not de- termined. Peregrin
Size: 1662px × 1504px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorbrighamyounguniversity, bookcentury1900, bookcollectio
