Morris, P. 1979. Ratsin the diet of the Barn Owl (Tyroalba).J. Zool.Lond. 189:540-545. Morton, M.L., J.L. Horstmann,and C. Carey. 1973. Body weightsand lipidsof summering mountainWhite-crowned Sparrows in California.Auk. 90:83-93. Mugaas,J.N. and J.R. Templeton. 1970. Thermoregulationin the Red-breastedNuthatch. Condor 72:125-132. Nelson,A.L. and A.C. Martin. 1953. Gamebirdweights. J. Wildl. Manage.17:36-42. Palmer, R.S. 1954. The mammal guide. Garden City, NY: Doubledayand Co. 384 pp. Poole,E.L. 1938. Weightsand wing areasin North American birds.Auk 55:511-517. Porter, R.D. and C.M. White. 1973.The PeregrineFalcon in Utah, emphasizingecology and competitionwith the Prairie Falcon. Brigham Young Univ. Sci. Bull. 18:1-74. Robertson,W.B., Jr. 1958. Investigationsof Ring-neckedPheasants in Illinois. Ill. Dept. Conserv.Tech. Bull. 1. 137 pp. Schreiber,R.K. 1973. Bioenergeticsof rodents in the northern Great Basin desert. Ph.D. Thesis.Univ. of Idaho. 133 pp. Seymour,R.S. 1973.Physiological correlates of forcedactivity and burrowing in the spadefoot toad Scaphiopushammondi. Copeia 1973:103-115. Smith,D.G. andJ.R. Murphy. 1973.Breeding ecology of raptorsin the easternGreat Basinof Utah. Brigham Young Univ. Sci. Bull. Biol. Ser. 18:1-76. SouthernH.N. 1954. Tawny Owlsand their prey.Ib/s 96:384-410. Stewart,P.A. 1937. A preliminarylist of bird weights.Auk 54:324-332. Thomsen, L. 1971. Behaviorand ecologyof Burrowing Owls on the Oakland Municipal Airport. Condor73:177-192. Trost, C.H. 1972. Adaptationsof Horned LarksEremophila alpestris to hot environments.Auk 89:506-527. Vermeer, K. 1970. Breeding biologyof California and Ring-billedGulls. Can. Wildl. Serv. Rep. 12.52 pp. Welty,J.C. 1962. The life of birds.Philadelphia: W.B. Lander Co. 546 pp. White, C.M. and T.J. Cade. 1971.Cliff-nesting raptors and ravensalong the ColvilleRiver in Arctic Alaska.Living Bird 10:107-150. Willson,M.F. 1966.Breeding ecology of the Yellow-headedBlackbird. Ecol. Monogr. 36:51-77. Withers,P.C. 1977.Energetic aspects of reproductionby the Cliff Swallow.Auk. 94:718-725.

NEST SITE SELECTION BY PEREGRINE FALCONS by David A. Ponton Los Alamos National Laboratory P.O. Box 1663 Los Alamos, New Mexico 87545

The PeregrineFalcon (Falco peregrinus) is knownto usedifferent nestsites (nest ledges) at a particularcliff, either in successiveyears, or in responseto the lossof a clutch of eggs(Herbert and Herbert, 1965; Porter and White, 1973; Ratcliffe,1980). In GreatBritain, at least4 alternativenest sites are usedat mosteyries, and one had 8 (oneinvolving a repeatclutch) in 9 seasons(Ratcliffe, 1980). A peregrineeyrie in northern New Mexicois unusualin that 10 different nestsites were used in 10 consecutiveseasons. The nestsites are eroded potholes in volcanictuff along1 km of cliff, whereapproximately 150 similar holes are available.

27 Raptor Research17(1):27-28 The large availabilityof suitablesites apparently facilitated non-repetitive selection. In the 1lth and 12th years,the femaleapparently failed to lay eggs.A newfemale appeared in 1976and laid eggsin 1977, 1978,and 1979,continuing the patternof selectingnew nestsites each year. However,two second(repeat) clutches were laid in previouslyused sites. Specifically,the 1978second clutch was laid in the 1977nest site, and the 1979second clutch was laid in the siteused for the first clutchin 1978.This pattern,i.e., the secondchoice of nestsite having been the firstchoice the yearbefore, I have termed the "fall-back-one" behavior. The onlyhistorical event common to both secondclutch sites is egg laying. I suggestthat preferencefor locationof the secondclutch is for a sitewhere egg laying and associatedbehavior have been ritualized in the nearestpast. Previous nestingsuccess at thatsite is incidental. If the "fall-back-one"behavior pattern is, in fact,common in peregrines,it should aid in predictingthe locationof secondclutches. I thankWayne Hanson for locatingnest sites in 1978,and John Hubbard and Wayne Pilz for reviewingearlier drafts.

Literature Cited Herbert, R.A. and K.G.S. Herbert. 1965. Behaviorof PeregrineFalcons in the New York City Region.Auk 82:62-94. Porter, R.D. and C.M. White, 1973. The PeregrineFalcon in Utah, EmphasizingEcology and Competitionwith the Prairie Falcon.BYU ScienceBulletin, Bio. Series,Volume XVIII, No. 1.74 pp. Ratclff•e,D. 1980.The PeregrineFalcon. Buteo Books, USA and T. & A.D. PoyserLtd., Great Britain. 416 pp.

Carnushemapterus NITZSCH FROM SWAINSON'S HAWK

by Richard E. Fitzner Ecological SciencesDepartment Battelle, Pacific Northwest Laboratory Box 999 Richland, WA 99352 and Norman E. Woodley Museum of Comparative Zoology Harvard University Cambridge, MA 02138

The winglessectoparasitic fly (Camushemapterus, Nitzsch) was first reported on North Americanbirds by Bequaert (1942)although in Europe,C. hemapterusseems tobe fairly generallydistributed. Bequaert (1942) identified the fly from 2 birds,a nestlingflicker (Colaptes cafer) collected at PennYann, NewYork and a ScreechOwl (Asiootus) taken in Florida. Capelieand Whiteworth(1973) have since reviewed the distributionofC. hemapterusin North America,siting records for 9 hostspecies, including 3 woodpeckers,starling (Sturnus vulgaris), Black-billed Magpie (Pica pica) and American Kestrel (Falcosparverius). Mainand Wallis (1974i found C. hemapterus onnestling Osprey (Pandion haliaetus) inMassachusetts and Wilson(1977) found PileatedWoodpecker (Dryocopus pileatus) nesting material to containthe parasites.These records, seemto indicatethat Camusis widespreadin the United States.Its distribution,however, will be unclearuntil there is a systematicstudy of bird ectoparasitesin this country. Bequaert(1942) reports the C. hemapterushas been observed on 12 familiesand 26 speciesof birdsin Europe.Seven raptorspecies, White-tailed Eagle (Haliaeetus albicilla), Imperial Eagle (Aquila heliaca), Peregrine Falcon (Falco peregrinus), Kestrel(F. tennunculus),Saker (F. cherrug),Barn Owl (Tytoalba), and Tengmalm'sOwl (Aegoliusfunereus)have been noted as host. In July of 1980,while examining nestling Swainsoh's Hawks (Buteo swainsoni), we found that 12 of the 15 nestlingswe studiedwere parasitized by C. hemapterus.The fliesoccurred in groupsof 3 to 5 andwere found only in the axillaryregion of thehawks. No flieswere attached and on being disturbed they moved from the bare axillary region to nearbyfeathered areas.The exactnature of the dietofC. hemapterusisunknown. Noller (1920) reports that thefly sucksblood from itshost, whileHendel (1928) felt thatCarnus feeds most probably on skinsecretions. We observeddried blood spots on the hawks axillaryregion which is supportive of Noller's(1920) claim. The true diet of the fly is presentlyin question,but the fly couldact as a vectorof certainavian blood parasites. Our findingsare of interest,since few records have been reported for C. hemapterusin non-cavity nesting birds or from long-distancemigrants like the Swainsoh'sHawk. Our report is alsothe first recordof this dipteran parasiteon the Swainsoh's Hawk.

Raptor Research17(1):28-29 28