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 .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 (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, (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 (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 Literature Cited

Bequaert,J. 1942. hemapterus Nitzsch, an ectoparasiticfly of birds, New to America (Diptera).Bull. BrooklinEnt. Soc. 37:140-149. Capell,K.J., and T.L. Whiteworth.1973. The distributionand avianhosts ofCarnus hemapterus (Diptera:milichiidae) in North America.J. Med. Ent. 10:525-526. Hendel,F. 1928.Zweiflfigler order Diptera.II. AllgemeinerTeil. in F. Dahl, Die Tierwelt Deutschlands,XI, Dipt., Pt. 2, pp. 1-135. Main, A.J., and R.C. Wallis.1974. Primary records of twovertebrate ectoparasites in New England(Acarina:Argasidae and Diptera:Milichiidae).Proc. Entomol. Soc. Washington 76:427. Noller,W. 1920.Die Ergebnisseder Hemoptroteus-Forschung.Zugleich vorlfufige Mitteilung fiber Zfichtungsversuche an einigenanderen Trypanosomen. Arch. F. Protistenk.,41:149-168. Wilson,N. 1977.Ectoparasites found in the nestcavities of PileatedWoodpeckers in Oregon.Bird-Banding 48:171-173.

THREE ADULT BALD EAGLES AT AN ACTIVE NEST 1 by JamesD. Fraser2 L.D. Frenzel Department of Entomology,Fisheries, and Wildlife, University of Minnesota, St. Paul, MN 55108 John E. Mathisen Chippewa National Forest Cass Lake, MN 56633 and Mark E. Shough Bemidji Aviation Inc. Bemidji, MN 56601

AlthoughBald Eagle (Haliaeetus leucocephalus) trios have been observed at nestsin Alaska(Sherrod et al. 1976,Heglund and Reiswig1980), we are unawareof similarreports in the coterminousUnited States.Here we describe4 observations of 3 adult eaglesat a neston the ChippewaNational Forest,north central Minnesota.The nestwas observed 93 times betweenMarch and Octoberin 1976-1978.All observationswere made from fixed-wingaircraft. On 7 April 1976,an adult eagle was observed in thenest in incubatingposture; 2 others,I in adultplumage and 1 with an off-whitehead similar to Southern's(1967) plumage F, wereperched next to the nest.On 22June 1977,an adultwith a nearly white head was in the nestwith 2 nestlings,another adult was in the nesttree, and a third adult wasin a tree approximately100 m to the south.On 7 April 1978,an adultwas in incubatingposture while 2 otherswere perched togetherin the nesttree. On 30June 1978,2 adultsand 1 nestlingwere in the nestand a third adultwas perched 200-300 m to the north. One fledglingwas produced in 1976,2 in 1977,and 1 in 1978.Because our observationswere brief, we wereunable to determine the natureof interactionsamong the eaglesinvolved. It isnot clear to us,therefore, what role, if any, the 3rd adult playedin the nestingeffort. Sherrodet al. (1976)reported 3 sitesoccupied by trioson AmchitkaIsland, Alaska. Three Amchitkanests were also occupiedby triosin 1980 and one of thesecontained 4 eggs(Heglund and Reiswig1980). Both Herrick (1934:106) and Bent(1937:325) reported 4-egg clutches for the BaldEagle, and Bentsuggested that the eggsmay have been produced by more than I female. The datasuggest that Bald Eagles are occasionally polygynous. Detailed behavioral observations of triosare required to testthis hypothesis, however. The Amchitkapopulation apparently has not experiencedthe level of reproductivefailure reported for eagle populationselsewhere (Sprunt et al. 1973,Sherrod et al. 1976)and the Chippewapopulation appears to be recovering rapidly from effectsof contamination(Fraser 1981). The 4-eggclutches reported by Herrick (1934) and Bent (1937) werelaid well beforethe earliestreport of widespreadBald Eaglenest failures (Broley 1950). Perhaps trios occur most frequentlyat nestsin healthyBald Eaglepopulations. If so,trios may become more commonin the coterminousstates if Bald Eaglereproduction and survivalimprove.

•PaperNo. 12,049,Scientific Journal Series, Minnesota Agricultural Experiment Station, University of Minnesota,St. Paul, MN 55108 2PresentAddress: Department of Fisheriesand Wildlife Sciences,Virginia PolytechnicInstitute and StateUniversity, Blacksburg,VA 24061.

29 Raptor Research 17(1):29-30