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Memo tu: Arnold Ku:;kin, (aarcinou[ h:nginceri.ug Cu. <br />From: William 0. Wirtz, lf, Yh.ll. <br />Date: 31 October 1975 <br />Subject: Potential disturbance of peregrine falcon (Falco Lrrngrinus) at or near <br />nesC sites. <br />I have as yeC been unahl.e Lo contact any recognized :wLhurity on peregrines <br />by phone. I wi.l.l Cry to tall: wiCL Dr. Tom J. Cade, Corncl.l UnivursiLy; 1)r. James <br />II. I:ndcrson, 'Phc Colorado Collcgr; Dr. Clayton 1Jltilc, Iiri.gh.vn Young Univcrs.Ccy. <br />All arc recognized autha'i.ties on peregrines, and currently working ~~rith them, <br />From the literature I have gleaned six particularly significant point.=., as <br />follows: <br />1. 'fherc arc apparently very few peregrine eyries (nesC sites) in C~Lorado <br />at the present (findorsrnt, 1972). <br />2. 1C seems that adu1C morCaliLy is a more imporlaut factor .in pere~rinc <br />population decline than e.itlter decreased productivity or increased nest failure <br />(Young, 1.969). <br />3. Human harassment in the form of disturbance at eyries is a serious factor <br />in some siCUations, particularly in parts of Che West (Snow, 1972). <br />4. Successful eyries may have to be at least one-half mile from the nearest <br />human habitation, unless Che cliff is particularly high and precipitous (}lickey <br />and Anderson, 1969). <br />5. Deterioration of habitat is not the major problem in peregrine pepu.lacion <br />decline (Snota, 1972). <br />6. A definite possibility for habitat management is the resCriction of <br />acCivities around known eyries daring the breeding and nesting season (Snow, 1972). <br />Conclusions: <br />We must find the eyrie and determine if .it is used oath year, without dis- <br />turbing the uccupants (use binoculars and Celescope from valley and topside), and <br />if iC is used deCcrminc wltaC maximum buffer zone might be leCC around Che area <br />while still permitting Che intended mining acCivities. As a pair of peregrines <br />may use more than one ncsCing s.iCC in Che same or dif.fercnC years 'it 'is possible <br />that the Smith site i.s not used every year. It is possible chat .if dumping were <br />begun in Smith before Che breeding season commenced the pair would move Co an <br />alCernaCC site [archer from the disturbance. It is a]so possible that the pro- <br />posed dumping site i.s f.ar enough from [lie existing eyrie that breeding birds <br />would not be disturbed by activity there. <br />