II II Incidence of Louse-flies (Hippoboscidae) in Some Alaskan Birds

Jackson S. Whitman Nixon Wilson Alaska Dept. Fish and Game Dept. Biology PO Box 230 Univ. Northern Iowa McGrath AK 99627 Cedar Falls IA 50613

INTRODUCTION

Informationwas gathered on'the incidence of climate is moderatedby maritime influences,with hippoboscidlouse-flies (Diptera, Hippoboscidae) short transitionperiods between seasons. Sum- on passerinebirds in interiorAlaska during 1987. mertemperatures typically rise as highas 300 C. Other authorshave discussedlouse-fly infesta- Thunderstorms occur duringJune and July. The tionsin birds,but alwaysin areas with lesssevere frostfree periodduring 1987 was 92 days, from30 climaticconditions. The hippoboscidspecies found May through29 August. (Omithomyabequaertl} was describedby Maa (1969) as a new species,and few data are avail- Netting and trappingsessions were conducted able on abundance, hosts, or distribution.A total of sporadicallythrough the day. Birdswere removed 429 birdsof 28 specieswas examinedfor louse- from nets or trapswithin 15 min of capture.They flies. This paper documents10 avian hosts,from were immediatelyweighed, banded, examined for five families;eight of those hostsare newlyde- ectoparasites,and released.Hippoboscid flies were scribed.Adult louse-flies were found during a 70- collecteddirectly from the birdsand placedin small day periodfrom 23 Junethrough 29 August1987. plasticvials of 70% ethyl alcoholbefore identifica- tion. Flies that avoided capture were assumed to Rates of ectoparasitismupon avian hosts are be O. bequaertiandwere includedin the totals.No probablyaffected by a varietyof factors,including otherspecies of ectoparasiteswere found.Unless feedingand preeningpractices by potentialhosts. stated otherwise, chi-square tests were used. Birdsthat typicallyconsume airborne insects are potentiallouse-fly predators, probably reducing RESULTS AND DISCUSSION the occurrenceof these parasites.The lack of louse-flieson swallowssupports this theory. During 1987, 429 birds of 28 species were cap- tured a total of 473 times and examined for louse- LOCALITY AND METHODS flies.Louse-fly presence on birdswas firstnoted on 23 June and the last occurrence documented on 31 Avianhosts were captured in the vicinity of McGrath, August,although bird capturesoccurr(Jd during Alaska(latitude 620 58' N, longitude1550 37' W, otherseasons. Because six speciesof birdswere elevation103m) in mistnets or'McCamey chicka- not captured during the period when louse-flies dee traps.Vegetation in the area is dominatedby were found,we will not discussthose species. birch(Betu/a papyrifera), balsam popular (Popu/us balsamifera),and white spruce(Picea glauca), Of 301 individualsof 23 speciescaptured during with willow (Salix spp.) and shrub- dominated the periodin which louse-flies were presem(Table ground cover. 1), 57 birds (19%) had one or more Iouse-,•lies.In contrast,13 birdspecies (represented by 53 indi- Becauseof surrounding mountain ranges, weather viduals)were not found to hostlouse-flies. During in McGrathis typicallythat of the shelteredconti- theseason of louse-fly infestations 57 of248 (23%) nentalinterior. Winter temperatures are cold (to individualsof knownhost species were parasit- -55ø C) andgenerally dry. During summer, the ized.

Vol.17,No.2 NorthAmerican Bird Bander Page6•' During the 70-day period when louse-flywere Black-cappedChickadee (Parus atricapillus),Bo- present, rates of infestationwere not stable. Per- realChickadee (Parus hudsonicus), Arctic Warbler cent frequencyof occurrenceincreased through (Phylloscopus borealis), Wilson's Warbler(Wilsonia Juneand early July, peaked in late July (11-20 July, pusilia), Yellow Warbler (Dendroica petechia), 40%; 21-31 July, 43%), and declinedthereafter NorthernWaterthrush ( Seiurusnovaboracensis), (Figure 1). Other investigatorshave notedsimilar SavannahSparrow ( Passerculussandwichensis), seasonal infestationrates in variousgenera and FoxSparrow (Melospiza iliaca) and Pine Grosbeak species of louse-flies(Maa 1969, Mueller et al. (Pinicolaenucleator). The 10 avianspecies which 1969, Main and Anderson 1970, Wilson and Haas hosted louse-fliesare discussedindividually be- 1980, Wood 1983, McClure 1984). However, in low. less severe climates,the periodof active parasit- ism is extended both earlier in the summerand later FamilyTyrannidae: Alder Flycatcher(Ernpidonax into autumn. alnorurn).One of sevenwas hostto a singlelouse- fly (14%). This is the first known record of O. Seventy-sixlouse-flies were documentedon 57 bequaertion this speciesor family. individualhosts (X=1.3 louse-fliesper host).Sea- sonally, there appeared to be no differencein FamilyCo rvidae: G ray Jay (Perisoreus canadensis). numberof parasitesper host,but this could have Oneof two Gray Jays captured during the louse-fly been a reflectionof low samplesize. Singleadult seasonwas hostto a singlelouse-fly (50%). Maa flieswere foundon 43 hosts(75%), twoflies on 10 (1969) recordedthe speciesfrom other Corvidae, hosts(18%), three flies on three hosts(5%), and but suggestedthat the occurrenceis probably fourflies on one host (2%). accidental or occasional. This is the first record of O. bequaertion thisspecies. Sex was determined on 35 of the collected louse- flies. Ten were identified as males while 25 were FamilyMuscicapidae: Swai nson's Th rush (Catharus females.According to McClure(1984), this skewed ustulatus).Five of six examinedhad one or more ratio is commonin most louse-flycollections. He louse-flies.Four were hostto a singlefly, whilethe indicatedthat upon emergencethe sex ratio is remainingthrush had four louse-flies.Wilson and probablynearer 1:1, but because males are short- Haas (1980) previouslydocumented O. bequaerti lived, need fewer blood meals, and are more active on thisspecies in Alaska.American Robin (Turdus in flyingfrom bird to birdin searchof females,they rnigratorius).One of four(25%) robinswas hostto are less likelyto be encountered. two O. bequaerti.

Overall, frequency of occurrenceof louse-flies Family Emberizidae: Yellow-rumped Warbler appearsto be higherin youngbirds (HY=hatching (Dendroicacoronata). One of five (20%) was host year) than in adults (AHY=afterhatching year). totwolouse-flies. American Tree Sparrow (Spizella Althoughsample sizes were too lowto be meaning-ß arborea).The singletree sparrowexamined was fulfor individualcases, when all hostspecies were hostto a singlelouse-fly. Dark-eyed Junco (Junco lumped,130 HY and 171 AHY birds were exam- hyernalis).Seventeen of 107 (16%) were foundto ined for louse-flies.Significantly more flies were be hosts.Both Wilson and Haas (1980) in Alaska recordedon HY birds (N=2, 25%) than on AHY and Main and Anderson(1970) in Massachusetts birds(N--25, 15%) (p<0.05). No difference (p>0.05) previouslydocumentedDark-eyed Juncos as hosts was noted between male and female hosts in to O. bequaerti. White-crowned Sparrow incidence of louse-flies. (Zonotrichialeucophrys). Ten of 43 (23%) exam- inedwere hoststo 13 louse-flies.Lincoln's Sparrow Duringthe periodof documented louse-fly infesta- (Melospizalincolni/). Both Lincoln's Sparrows cap- tion,13 avianspecies of sixfamilies were captured turedduring the louse-flyseason were hosts.One that did not host louse-flies:Common Snipe had a singlefly, while the other had three louse- (Gallinagogallinago), Tree Swallow(Tachycineta flies. Except for the Dark-eyedJunco, all avian bicolor), Violet-green Swallow (Tachycineta hosts from the family Emberizidaeare new host thalassina).Cliff Swallow(Hirundo pyrrhonota), records.As a family group,30 of 184 individuals Page 66 NorthAmerican Bird Bander Vol.17,No.2 examined(16%) were hostinglouse-flies. McClure,H.E. 1984.The occurrenceof Hippoboscid flieson somespecies of birdsin southern Family Fringillidae:Common Redpoll (Garduelis California. J. Field OrnithoL 55:230-240. flammea).Nineteen of 70 (27%) hadan averageof 1.4 louse-fliesper bird.Maa (1969) notedthat O. Mueller, N.S., H.C. Mueller and D.D. Berger. bequaertioccurred on small passerinesparticu- 1969. Host records and louse-flies on larly Fringillidae. Indeed, as family groups Wisconsin birds. Wisc. Acad. Sci., Arts Fringillidaeand Muscicapidaehad the highest and Letters 57:189-207. incidenceof louse-flyoccurrence. Common Red- pollshave notpreviously been recordedas a host Wilson,N. and G.E. Haas. 1980. Ectoparasites species. (Mallophaga,Diptera, Acari) from Alas- kan birds. Proc. Entomol. Soc. Wash. SUMMARY 82:541-552.

Asinglespecies of louse-fly (Ornithomya bequaerti, Wood, M. 1983. A studyof hippoboscidflies on Maa) was collectedfrom 10 avian host species House Finches. N. Am. Bird Bander representingfive familiesin west-centralAlaska 8:102-103. during 1987. Eight of the hostspecies were new records.Nineteen percent of the individualsof all avian speciesexamined were hostto one or more louse-flies.Although birds were capturedand ex- aminedboth earlierin springand later in autumn, infestationswere recordedonly during the 70-day period from late June throughAugust. Rates of infestationwere higherin youngbirds (25%) than in adults (15%), but no differenceswere noted between sexes of hosts. Fringillidae and Muscicapidaehad the highestincidence of louse- flyoccurrence. The healthof infestedbirds was not thoughtto be compromiseddue to the presenceof the parasites.

ACKNOWLEDGMENTS

We wishto thankH. E. McClure,W. E. Melquist,R. R. Whitmanand J. Wrightfor theircareful reviews of the manuscript.

LITERATURE CITED

Maa,T.C. 1969.Studies in Hippoboscidae (Diptera). Part2. PacificInsects Monogr. 20. Bernice C. BishopMuseum, HonoluluHI.

Main, A.J. and K.S. Anderson.1970. The genera Ornithoica,Ornithomya and Ornithoctona inMassachusetts (Diptera: Hippoboscidae). Bird-Banding41:300-306.

Vol.17,No.2 NorthAmerican Bird Bander Page67 7

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6/'15 I]J25 7/'05 7/'15 7/'25 •]./C,5 •]./15 •]./25 9/05 Medinn Dnte of $nrnplingPeriod

Figure 1. Ratesof infestationof birdsby the hippoboscidlouse-fly Ornithomya bequaerti Maa in west- centralAlaska by 10-dayperiods during summer 1987. Numbers above bars represent sample sizes.

Table 1. Occurrenceof the hippoboscidfly Ornithomyabequaerti on birdscaptured in westcentral Alaska duringsummer 1987.

Name No. with Flies No. Checked % Infested

CommonSnipe - 1 0 Alder Flycatcher 1 7 14 Tree Swallow 10 0 Violet-greenSwallow 5 0 Cliff Swallow 1 0 Gray Jay 1 2 5O Black-cappedChickadee 6 0 Boreal Chickadee 2 0 Arctic Warbler 1 0 Swainson's Thrush 5 6 83 American Robin 1 4 25 Yellow Warbler 10 0 Yellow-rumpedWarbler 1 5 2O Northern Waterthrush 9 0 Wilson's Warbler 2 0 AmericanTree Sparrow 1 2 5O SavannahSparrow 4 0 Fox Sparrow 1 0 Lincoln'sSparrow 2 2 100 White-crownedSparrow 9 43 21 Dark-eyedJunco 17 99 17 Pine Grosbeak - 1 0 CommonRedpoll 19 78 24

Totals 57 301 19%

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