J. Raptor Res. 28(4):232-235 ¸ 1994 The Raptor ResearchFoundation, Inc. ECTOPARASITES OF THE SPOTTED OWL JOHN E. HUNTER, R.J. GUTIERREZ,ALAN B. FRANKLIN1 AND DAVID OLSON Departmentof Wildlife,Humboldt State University,Arcata, CA 95521 U.S.A. ABSTRACT.--Weconducted a surveyof spottedowl (Strix occidentalis)ectoparasite richness by examining live and museumspecimens of the three subspeciesof spottedowl. Sevenectoparasite species from five arthropodorders were collected.A tick (Dermacentoroccidentalis), a mite (Euschoengastiasp.), and a flea (Opisodasysvesperalis) were collected,but were presumedto be accidentalstrays from prey. Strigiphilus lice were found on all the subspeciesof spottedowl, while the louseKurodaia magna was only collected from the northern spottedowl (S. o. caurina).The hippoboscidfly Icostaamericana was found on the Californiaspotted owl (S.o. occidentalis);this species had previouslybeen well documentedin the northern subspecies.The only hippoboscidfly found infestingthe Mexican spottedowl (S. o. lucida)was Ornithoica vicina. KEY WORDS:ectoparasites; Icosta americana; Kurodaia magna;Ornithoica vicina; spotted owl; Strigiphilus syrnii; Strix occidentalis. Ectoparfisitosde Strix occidentalis RESUMEN.--Realizamosun estudiosobre la riquezade ectoparfisitosde tressubespecies de Strix occidentalis, a travgsdel exfimende especimenesvivos y de museo.Se colectaronsiete especiesde ectoparfisitos correspondientesa cinco 6rdenes de artr6podos.Entre las especiesque se colectaronestrin Dermacentor occidentalis,Euschoengastia sp. y Opisodasysvesperalis, aunque presumimos que sonaccidentalmente arras- trados por las presasmayores de S. occidentalis.Strigiphilus se encontr6en todaslas subespeciesde S. occidentalis,mientras que Kurodaiamagna se colect6 solamante en S. o. caurina,la especiedel norte.Icosta americanase encontr6en S. o. occidentalisde California; previamentetambign ha sido bien documentada en la subespeciedel norte. Ornithoicavicina se encontr6infectando a S. o. lucida. [Traducci6n de Ivan Lazo] Ectoparasitesare a potentiallyimportant yet rel- which infect spottedowls (Gutigrrez 1989, Hoberg atively unstudiedaspect of avian biology. Ectopar- et al. 1989, Hoberg et al. 1993, Young et al. 1993). asitescan impair thermoregulatoryability (Boothet We initiated a survey of spottedowl ectoparasite al. 1993), reducenestling body massand survivor- richness,including each of the three subspecies(AOU ship(Moller 1990), influencesexual selection (Clay- 1957). ton 1990a), and transmit endoparasitesand patho- METHODS gens (Baker 1967, Clayton 1990a). Ectoparasites Between 1987 and 1993 approximately1000 spotted and their hostsalso offer unique opportunitiesto owlswere capturedand releasedduring demographic stud- study coevolutionand communityecology, and can ies in northwest Galifornia (Franklin et al. 1990), the help elucidatephylogenetic relationships among re- central Sierra Nevada of Galifornia (Bias and Gutierrez lated bird taxa (Marshall 1981). 1992), and central Arizona. Birds from theseareas rep- The spottedowl (Strix occidentalis)has generated resented the northern (S. o. caurina), Galifornia (S. o. oc- cidentalis),and Mexican (S. o. lucida) subspecies,respec- considerablescientific and political interest (USDI tively. Ectoparasites from these birds were collected 1992). Consequently,all aspectsof its biology are incidentallywhen they were encounteredduring routine potentially important to biologistsand managers. bandingand data collection.Because no systematicmeth- Recent surveyshave describedsome endoparasites odologyor specialequipment were used, we did not at- tempt to quantify the prevalenceor intensity of ectopar- asitesusing data from live owls. During 1993, however, we specificallyexamined 18 live Mexican spottedowls for • Presentaddress: Colorado Cooperative Fish and Wildlife hippoboscids.These birds were examinedfor about 5 min ResearchUnit, 201 Wagar Building, ColoradoState Uni- each, with each body region (front, back, head, wings) versity, Fort Collins, CO 80523 U.S.A. being searchedby lookingat the surfaceand by deflecting 232 DECEMBER 1994 SPOTTED OWL ECTOPARASITES 233 feathers.No magnificationor forcepswere used.We used northern spottedowl. This flea is a commonparasite thesedata to estimateprevalence as the proportionof Mex- of northern flying squirrels(Glaucomys sabrinus) in ican spottedowls infested,and mean intensity as mean the Pacific Northwest (Lewis et al. 1988). True hosts number of hippoboscidsper infestedowl. We also examined 13 northern, 13 California, and 28 for each of theseectoparasite species were listed by Mexican spotted owl museum skins for phthirapteran Forsmanet al. (1984) asspotted owl prey. Accidental chewinglice. Many chewinglice will not abandondead ectoparasitesare of interest becausecolonization of hosts,and will remain attached to feathers after the bird new hostspecies may be a resultof repeatedtransfers has been processedinto a museumspecimen (Marshall 1981). The hostspecificity and high mortality away from from true to accidentalhosts (Marshall 1981, Clay- hostsexhibited by chewinglice (Marshall 1981) reduced ton 1990b). the probabilitythat secondarytransfer occurred between We found lice on five (38.5%) of the northern, museumspecimens. Owl specimensexamined were housed two (15.4%) of the California, and one (3.6%) of the in the Museum of Vertebrate Zoology;Humboldt State UniversityCollection; American Museum of Natural His- Mexican spottedowl museumskins. A possibleex- tory; SmithsonianInstitution, SouthwestForest Science planation for the greater percentageof northern Complex; and the Museum of Northern Arizona. Owl spottedowl museum specimenswith lice was that specimenswere originally collectedat locationsscattered basedon specimenlabels, most of these owls were throughout their respectiveranges, except for northern collectedafter being found deador injured. The sin- spottedowl specimenswhich camesolely from northwest California. Each museumspecimen was searchedwith the gle Mexican spottedowl museumspecimen with lice nakedeye for about20 min by lookingat the surfaceand was found dead, while all the remaining Mexican by deflectingfeathers, and any lice found were removed and California specimenswere apparently healthy with forceps.Estimates of louseprevalence were calculated whenthey were collected.Unhealthy hosts often have using data from museum specimensonly. All ectoparasitescollected were placed in 70% ethyl higher louse loads, presumably as a result of de- alcohol.Representative specimens of eachtaxon were iden- creasedgrooming activity (Marshall 1981). Any ef- tified by cooperatingtaxonomists of the United StatesDe- fect of Phthiraptera on spottedowls is unknown. partment of Agriculture's SystematicEntomology Labo- We collectedStrigiphilus syrnii (Ischnocera:Phil- ratory in Beltsville,Maryland. opteridae)from both live and museumspecimens of northern spottedowls, and Strigiphilussp. lice from RESULTS AND DISCUSSION museum specimensof California spottedowls that Seven speciesfrom five arthropod orders were were collectedin Mariposa County, California, but collected:one tick (Parasitiformes), one mite (Acar- none from live California spottedowls. Strigiphilus iformes),one flea (Siphonaptera),two chewinglice sp. were found on a Mexican spottedowl museum (Phthiraptera),and two hippoboscidflies (Diptera). skin that was collected in the Sacramento Mountains Given the limited scopeof our survey,we are con- of New Mexico. S. syrniiwere foundon live Mexican fident that other ectoparasitetaxa are yet to be col- spottedowls. Northern spottedowls are known hosts lectedfrom spottedowls. of this species(Clayton and Price 1984, Clayton We consideredthree of the sevenectoparasite spe- 1990b). The previouslypublished records of S. syrnii cies as accidentalon spottedowls, probably origi- from spottedowls were from unspecifiedlocations nating from prey items.A larval Dermacentorocci- in California and British Columbia, Canada (Clay- dentalis (Acari: Ixodidae) and a nymphal D. ton and Price 1984). Other known hostsfor S. syrnii occidentaliswere collectedfrom live northernspotted are the great hornedowl (Bubovirginianus), barred owls. Small mammals act as hosts for immature D. owl (Strix varia), greatgray owl (Strix nebulosa),and occidentalisthroughout western California and Or- rufous-leggedowl (Strix rufipes;Clayton and Price egon(Kohls 1937). We also collecteda larval Eus- 1984, Clayton 1990b). choengastiasp. (probablyE. humerosa)mite (Acari: We collectedKurodaia magna (Amblycera: Men- Trombiculidae) from a Mexican spottedowl mu- oponidae)from live andmuseum specimens of north- seumspecimen that was collectedin Phoenix,Ari- ern spottedowls from northwestCalifornia, but none zona.Euschoengastia show a preferencefor rodents; from California or Mexican spottedowls. This spe- E humerosalarvae parasitizea wide variety of bird cies had been previouslycollected from northern and mammal taxa (Wrenn and Loomis 1974). We spottedowls from westernOregon (R.D. Pricepers. observed,but were unable to collect,an unidentified comm.). The great horned owl and the barred owl flea on a live Mexican spottedowl, and we collected are the other known hostsof K. magna (Price and an Opisodasysvesperalis (Ceratophyllidae) from a live Beer 1963). 234 HUNTER ET AL. VOL. 28, NO. 4 Young et al. (1993) describedin somedetail the observedwith severetrauma as a result of hippo- occurrenceof hippoboscidflies on northern spotted boscidinfestation (USDI 1992). owls from northwest California. Seventeenpercent