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Home , Buteogallus, Common buzzard, Dark chanting goshawk, Melierax

July1984] ShortCommunications 615 the Spot-wingedFalconet may not benefitthe Monk HoY, G. 1980. Notas nidobio16gicasdel noroestear- Parakeet in such a manner. gentino. II. Physis (Buenos Aires), Secc. C, 39 We are grateful to A. G6mez Dur&n and J. C. Vera (96): 63-66. (INTA) for grantingus the useof the fieldwork areas, MACLEAN,G.L. 1973. The SociableWeaver, part 4: to N. Arguello and M. Nores for their assistancein predators, parasites and symbionts. Ostrich 44: the identification of food remains, and to J. Navarro 241-253. for his help in the field. This work wassupported by STRANECK,R., & G. VASINA. 1982. Unusual behav- a grant from the Subsecretariade Ciencia y Tecno- iour of the Spot-winged Falconet (Spiziapteryx logla (SUBCYT) of Argentina. circumcinctus).Raptor Res. 16: 25-26.

LITERATURE CITED Received7 July 1983, accepted21 February1984. DEAN, A. 1971. Notes on Spiziapteryxcircumcinctus. Ibis 113: 101-102.

The Use of Green Plant Material in Nests to Avoid Ectoparasites

PETER H. WIMBERGER 1 ZoologyDivision, Washington State Museum DB-10, Universityof Washington, Seattle,Washington 98105 USA

Certain characteristicallyplace green plant causesnestling mortality in and nest desertion by material in their nests.This greenery is not part of birds (Webster 1944, Neff 1945, Fitch et al. 1946, Moss the nest structureproper but is placed haphazardly and Camin 1970, Feare 1976,Wheelwright and Boers- around the edges or inside the nest. The birds re- ma 1979).In general,the increasedmortality due to plenishthe spraysof greenmaterial, often daily, dur- ectoparasitesis causedby the loss of blood, which ing incubation and the nestling period (Brown and weakens the host, by viral disease, or by disease Amadon 1968, Beebe1976, pers. obs.). causedby noxiousendoparasites for which arthro- I hypothesize that the plants are placed in the nests pod parasitesare vectors(Herman 1955).The groups to repel or actuallykill avian ectoparasites.Plant ma- of ectoparasitesmost responsiblefor mortality are terial may repel or kill ectoparasitesbecause of the dipterans,fleas, ticks, and mites (Herman 1955). secondarycompounds it contains. Secondary com- Three predictionsfollow from the hypothesisthat pounds often function as repellents in plants the use of nest greenery evolved to inhibit infesta- (Levin 1971). The compoundswork as olfactory re- tions of ectoparasites.(1) Birds that reuse their nests pellents, toxins, or juvenile hormone analoguesto over successiveyears should be more prone to the deter .If the parasite-repellenthypothesis is use of foliage than birds that build a new nest each correct,the plant specieschosen should be aromati- year. Nest reuse is implicated becausehippoboscid cally repellent, becauseavian ectoparasitesdo not in- fly larvae overwinter in nestsand emerge about the gest these leaves. time the eggs hatch (Bequaert1953). The larvae are The aromatic compoundsof plants are hydrocar- large relative to their hosts. Thus, it does not take bons, mainly monoterpenesand isoprene (Rasmus- many of them to weaken their host significantly. A sen 1972).In general,trees and long-lived shrubsemit number of endoparasiticdiseases also are transmitted the greatestvolume of volatile compounds,whereas by hippoboscidsand simuliid flies (Herman 1955). annualsemit the lowestvolume of thesecompounds (2) The incidence of foliage use among birds that (Rasmussen 1972). Plant volatiles are used as a de- prey on higher vertebrates (birds and ) fense againstherbivores but are also used by insects should be greater than that among birds that prey to locatetheir hostplant (Freeland1980). It hasbeen on lower vertebrates,because higher vertebratesoften establishedthat volatile plant compoundscan dis- harbor large flea populations,as well as somedipter- rupt olfaction in insectsby masking the particular ans, ticks, and mites. Parasite transmission occurs chemical cue that the insect uses to find a host (Tah- when mammalsare taken by birds; have been vanainen and Root 1972). If this is true of host-plant found infestedwith fleas(Rothschild and Clay location, it may also be true of host- location. 1952). (3) The types of greenery used in the nest If my hypothesisis correct,then nestgreenery would should be high in volatile secondarycompounds. function in these manners. I used the order Falconiformes in order to test the There is evidencethat infestationsof ectoparasites first two predictionsbecause of the variability in greenery use, nesting habits, and food preferences • Presentaddress: Division of Ecologyand System- that membersof this order exhibit. To get the most atics, Cotson Hall, Cornell University, Ithaca, New accurate and consistent data base about relative fre- York 14853 USA. quencyof greenery use for this comparativestudy, I 616 ShortCommunications [Auk, Vol. 101 used the original data slips associatedwith the egg new nests yearly and use no greenery. Among pas- sets of North American raptors housed at the West- serines that reuse their nests, European Starlings ern Foundation of Vertebrate Zoology and at the (Sturnusvulgaris; pers. obs.), Purple Martins (Progne University of WashingtonMuseum. Information on subis;A. S. Gaunt pers. comm.), and American Crows European Falconiformeswas taken from Harrison (Corvusbrachyrhynchos; P. Arcese pers. comm.) have (1975), becauseEuropean egg collectorswere remiss been reported to place fresh greenery or the highly in describing nest contents.Data about food habits aromatic inner bark of western red cedar (Thuja pli- for North American Falconiformes were taken from cata) in their nests. Snyderand Wiley (1976).A comparabledata base does Contrary to Prediction 2, prey type is not correlat- not exist for EuropeanFalconiformes. I could not test ed with greenery use. Of the 15 that use Prediction 3, becausethe egg collectorsoften failed greenery,only 8 have diets consistingof greaterthan to specify on the data slips what type of greenery 25% higher vertebrates, whereas 5 of 8 species that was used. When greenery was identified, however, useno greenery alsohave diets that consistof greater it invariably was either from trees or shrubs,never than 25% higher vertebrates (Fisher Exact P = 0.51). from herbaceousspecies, although highly aromatic This may be because parasite transmission is not herbs exist. Falconiformesthat do not build nests (e.g. common between predator and prey, because the Falco,some Cathartes),were not included, becausesuch parasitesthat are transmitted are not virulent to the birds do not make choices about nest material. Nest new host, or becausegreenery volatiles are not ef- reusedenotes a regular tendency for a speciesto reuse fective against the relevant ectoparasites. their nest and should not be construed as a clear-cut Greenery usevaries geographically within a species. either / or situation. For instance,greenery was mentioned by collectors An immediateproblem was determiningwhich egg of Red-tailedHawk (Buteojamaicensis) eggs in 10%of collectorswere likely to mention the presence of the nests in the Pacific Northwest (n = 10), in 65% of greenery in nests.Some collectorsleft only meager the nests in the Southwest (n = 23), in 67% of the notes about nest materials and contents. I used the nests in the Northeast (n = 20), in 23% of the nests data from those collectorswho mentioned greenery in Missouri (n = 30), and in 62% of the nests in Cal- at least once to calculate the frequency of greenery ifornia (n = 55). F. W. Preston (pers. comm.) has ob- use by each species.Species that were noted to use served that all of the nests that he has looked greeneryon 50%of the data slipsqualified as green- at in the Northeast contain nest greenery. This dis- ery users.Cooper's (Accipitercooperii) and Bald crepancy is probably due to the patchy data collec- (Haliaeetus leucocephalus) were the only excep- tion of the oologists. The regional differences also tions to this rule. J. McNutt (pers. comm.) observed may be related to the availability of suitable plant that 29 of the 32 Cooper's nestshe watched in species,time of leating, or regional abundancesof the San Juan Islands contained green conifer sprigs ectoparasites.The low incidence of greenery use in that were often replenished. F. W. Preston (pers. the Northwest is evidence that the availability of comm.) has also found that Cooper's Hawks use suitableplant speciesand time of leating make little greenery.Newton (1979)and A. Hanson(pers. comm.) difference in whether or not greenery is used, be- detail extensive use of decorative nest greenery by cause conifers are the predominant trees in the Bald Eagles.Neither of thesespecies was recordedto Northwest. They are aromatic and used in other parts use greenery by 50% of the egg collectors.This sug- of the country where they are available. gests that egg collectorswere likely to overlook The ectoparasite-repellent-greenery hypothesis greenery use in their notes. Thus, my decision to provides the most compelling and generalizable ex- categorizebirds as greenery usersis a conservative planation for the widespreaduse of greenery in bird's one. nests.A number of other hypotheseshave been pos- I chosespecies as the unit under investigation,be- tulated. (1) Greenery serves as a means of nest sani- causethe multispecificgenera usually containspecies tation by covering debris in the nest. (2) It advertises representingall of the behaviorsbeing correlated. nest occupancy.(3) It helps maintain humidity in the This demonstratesthat phylogenetic history doesnot nest. (4) It serves to shade the nestlings (Bush and constraingreenery use and that speciescan be con- Gehlbach 1979). Newton (1979) discusses the first sideredas independent units for the purposesof this three possibilities. study.Significance was determinedusing the Fisher The sanitation hypothesisfails to explain why the 2 x 2 Contingency Test and the Chi-square statistic. material used is invariably green, is brought to the Greenery use is significantly correlatedwith nest nest before the nest is soiled, and is often placed reuse in North American and European Falconi- haphazardly around the nest rim. The use of green- formes, a correlation that supportsthe first predic- ery to indicate nest occupancydoes not explain why tion. Of the 28 speciesthat use greenery, 22 reuse it is still brought after there are eggs or nestlings their nests,whereas only 8 of 20 speciesthat use no present. The nest-occupancyhypothesis may apply greeneryalso reuse their nests(X 2 = 8.281,P < 0.005). to Golden Eagles (Aquila chrysaetos),which place The trend becomes even more striking when one greenery in all the nests within their territory considersthe largenumber of Passeriformesthat build throughout the year in Washington (they maintain July1984] ShortCommunications 617

TABLE1. Tabulationof traitsused in testingpredictions: nest reuse, nest-greenery use, and diet composition (highervertebrates refers to birds and mammals). Taxonomic order after Morony et al. (1975).

Diet >25% higher Species Nestreuse Greeneryuse vertebrates Osprey (Pandionhaliaetus) Honey (Perhis apivorus) American Swallow-tailed Kite (Elanoidesforficatus) White-tailed Kite (Elanusleucurus) Black-shouldered Kite (E. caeruleus) Snail Kite (Rostrhamussociabilis) MississippiKite (Ictiniamississippiensis) (Milvus migrans) (M. milvus) Pallas'sSea- ( Haliaeetusleucoryphus) + + (H. leucocephalus) + + - White-tailed Eagle(H. albicilla) + + EgyptianVulture (Neophronpercnopterus) + - Lammergeier(Gypaetus barbatus) + - Lappet-facedVulture (Torgostracheliotus) CinereousVulture (Aegypiusmonachus) + + Short-toedEagle (Circaetus gallicus) - + Marsh Harrier (Circusaeruginosus) Northern Harrier (C. cyaneus) Pallid Harrier ( C. macrourus) Montagu's Harrier (C. pygargus) Dark ChantingGoshawk ( metabates) ( gentills) + + + EuropeanSparrowhawk (A. nisus) - + Sharp-shinnedHawk (A. striatus) Levant Sparrowhawk (A. brevipes) - + Shikra (A. badius) - + Cooper'sHawk (A. cooperil) + + + CommonBlack-Hawk ( anthracinus) + + - Harris' Hawk (Parabuteounicinctus) + + + (Buteonitidus) + + + Red-shouldered Hawk (B. lineatus) + + - Broad-wingedHawk (B. platypterus) + + - Short-tailed Hawk (B. brachyurus) + + + Swainson's Hawk (B. swainsoni) + + - White-tailed Hawk (B. albicaudatus) Zone-tailed Hawk (B. albonotatus) + + + Red-tailed Hawk (B. jamaicensis) + + + (B. buteo) + + Rough-leggedHawk (B. lagopus) + - + Long-leggedBuzzard (B. rufinus) + - FerruginousHawk (B. regalis) + - + LesserSpotted Eagle ( pomarina) + + Greater SpottedEagle (A. clanga) + + (A. rapax) Imperial Eagle (A. heliaca) + (A. chrysaetos) + + + Bonelli'sEagle (Hieraaetusfasciatus) + + BootedEagle (H. pennatus) + +

alternative nests on a territory; N. V. Marr pers. The humidity-maintenancetheory does not ex- comm.).Resident birds may usegreenery to keepec- plain the factthat the behavioris ascommon in rain- toparasitepopulations low yearround. Further sup- forestsand maritime climatesas it is in dry ones. The portfor the territory-occupancyhypothesis would be shadehypothesis does not explainthe presenceof the observationof greeneryplaced on the nestby greeneryin cavitynests or in thenests of forestbirds migratoryspecies after territory establishmentand nestingbeneath the canopyor why thematerial used before egg laying. to shadeshould be green.There is no indicationof 618 ShortCommunications [Auk,Vol. 101

fresh spraysbeing positioned in the nests of open- FEARE,C. J. 1976. Desertion and abnormal devel- dwelling birds in a manner that would shade eggs opment in a colonyof SootyTerns, Sternafuscata, or nestlingsduring the hottestpart of the day, when infested by infected ticks. Ibis 118: 112- the behavior would be most beneficial. All of the 115. abovehypotheses lack the generality sufficientto ex- FITCH, H. S., F. SWENSON, & D. F. TILLOTSON. 1946. plain the widespread occurrenceof the trait in the Behavior and food habits of the Red-tailed Hawk. variety of climates,habitats, and circumstanceswhere Condor 48: 205-237. it appears,unless greenery is usedfor many different FREELAND,W. J. 1980. Insect flight times and at- reasonsby different species. mospherichydrocarbons. Amer. Natur. 116:736- This indirect test is weak supportfor the hypoth- 742. esis that birds place greenery around their nests to HARRISON,C. 1975. A field guide to nests,eggs and lower the incidence of ectoparasitesto which they nestlingsof British and Europeanbirds. Boston, are host, and it should be interpreted cautiously. Massachusetts, Demeter Press Inc. Clearly, field testsare neededto demonstrateconclu- HERMAN,C. M. 1955. Diseasesof birds.Pp. 450-467 sively whether or not greeneryactually repels or kills in Recent studiesin avian biology (A. Wolfson, ectoparasites.In order to test the hypothesis,one Ed.). Urbana, Illinois, Univ. Illinois Press. could manipulate greenery presence experimentally LEVIN,D. A. 1971. Plant phenolics: an ecological and then compare fledging successfrom the two perspective.Amer. Natur. 105: 157-181. treatments.Simply countingectoparasites in the nest MORONY,J. J., JR.,W. J. BOCK,& J. FARRAND,JR. 1975. and on the nestlings may be meaningless,because Reference list of the birds of the world. New flying insectsmay accountfor a significant portion York, Amer. Mus. Nat. Hist. of the mortality incurred by the young birds from Moss, W. W., • J. H. CAMIN. 1970. Nest parasitism, the ectoparasites. productivity, and clutch size in Purple Martins. I thank D. Boersma, G. Butcher, D. H. Janzen, D. Science 168: 1000-1002. Paulson, F. W. Preston, R. and V. Rausch, D. Rhoades, NEFF,J. A. 1945. Maggot infestation of nestling S. Rohwer, and N. Wheelwright for discussion,com- Mourning Doves. Condor 47: 73-76. menting on earlier drafts of the paper, or providing NEWTON,I. 1979. Population of raptors. me with valuable information. Data were collected Vermillion, South Dakota, Buteo Books. at the WesternFoundation of VertebrateZoology with RASMUSSEN,R. A. 1972. What do the hydrocarbons the help of L. Kiff and at the University of Washing- from trees contribute to air pollution? J. Air Pol- ton StateMuseum. This projectwas supportedin part lution Control Assoc. 22: 537-543. by a JosselynVan Tyne Memorial Award from the ROTHSCHILD, M., & t. CLAY. 1952. Fleas, flukes and American Ornithologists' Union. cuckoos.New York, PhilosophicalLibrary. SNYDER,N. F. R., & J. W. WILEY. 1976. Sexual size LITERATURE CITED dimorphism in hawks and owls of North Amer- ica. Ornithol. Monogr. 20: 1-96. BEEBE,F. L. 1976. Hawks, and . TAHVANAINEN,J. O., & R. B. ROOT. 1972. The influ- Saanichton, British Columbia, Hancock House enceof vegetationaldiversity on the population Publ. Ltd. ecology of a specialized herbivore Phyllotreta BEQUEART,J. C. 1953. The Hippoboscidaeor louse- cruciferae(Coleoptera: Chrysomelidae). Oeco- flies (Diptera) of mammals and birds, part 1. logia 10: 321-346. Entomol. Amer. 32: 1-209. WEBSTER,H. 1944. A survey of the Prairie in BROWN,L., & A. AMADON. 1968. Eagles,hawks and Colorado. Auk 61: 609-616. falcons of the world. New York, McGraw-Hill WHEELWRIGHT,N. T., & P. D. BOERSMA.1979. Egg Book Co. chilling and the thermal environment of the BUSH,M. E., & F. R. GEHLBACH.1979. Broad-winged Fork-tailed Storm Petrel, Oceanodromafurcata, Hawk nest in central Texas:geographic record nest. Physiol. Zool. 52: 231-239. and novel aspectsof reproduction.Texas Orni- thol. Soc. 11: 41-43. Received5 July 1983,accepted 28 February1984.