Raptor Migration in Northwestern Canada and Eastern Alaska, Spring 1982

RAPTOR MIGRATION IN NORTHWESTERN CANADA AND EASTERN ALASKA, SPRING 1982

DAVID P. MINDELL AND MARGARET H. MINDELL

ABSTRACT- Searchesfor migrantraptors in northernBritish Columbia, southern Yukon Territory and easternAlaska weremade between 29 Marchand 29 April 1982at locationsaccessible by road along3 potential,broadfront, migratory routes.Migration activity occurred within an intermountainroute, passing between the Rockyand PellyMountains on the eastand Coastand St. EliasMountains on the west.We sawno migrantraptors corning from a coastalroute north over Chilkator White passes,or corningfrom a Canadianprairie route, eastof the RockyMountains, over the passalong the AlaskaHighway in the SummitLake vicinity. We foundconcentrations of migrantraptors along the Lina Rangeby Atlin Lake, British Colmnbia, and at Johnson'sCrossing and in the Takhini River valley of southern Yukon Territory. Northern Harriers (Circu•cyaneu.•) were mostfrequently seen, followed in decreasingorder by Red-tailedHawks (Buteo jamaicens•s),Golden Eagles (Aquila chrysaetos), Rough-legged Hawks (Buteo lagopus), Bald Eagles (Hahaeetus leucocephalus), and PeregrineFalcons (Falco peregr•nus). Comparison with other studiessuggest that migrantbuteos and Golden Eagles make greateruse of an intermountainroute through northwesternCanada than of a coastalroute alongthe Gulf of Alaska,while migrant Sharp-shinned Hawks (Accipiter striatus) more frequentlyuse the coastalroute.

Migrating raptors seekingthe mostdirect over- inducing travel in a particular direction. Gauth- land route to breeding areasin extreme northwest- reaux (1979) has pointed out that despite the ern North America are funneled into areas of prominenceof migrationin avianlifestyles, routes, northwestern British Columbia, southwestern rates and calendarsof migration are known for few Yukon Territory, southeast and southcentral speciesaside from waterfowl.The purposeof this Alaska. Movementsof migrant raptors to and from study was to learn about distributionof migrant Alaska and northwestern Canada have been little raptorsmoving through northwesternCanada and studied although tens of thousandsof raptors pass eastern Alaska, to locate specificareas of migrant through this region biannually. concentrationfor future study,and to learn about The north-south oriented ranges of the Rocky, timing of regional migration. Cassiarand Coast Mountains along with the Pacific shoreline delineate 3 broadscale,potential migration routes(Fig. 1) describedas follows: 1) Coastal- along the west coast of British Columbia, and STUDY AREA AND METHODS southeast Alaska, then either inland over mountain Between 29 March and 29 April 1982, 3970 km were driven passesor continuing northwestalong the Alaska between Dease Lake on Rt. 37 in British Columbia, Summit Lake coastsouth of the ChugachMountains into central on Rt. 97 in British Columbia and Anchorage, Alaska. Observa- Alaska via the Copper River drainage, PortagePass tions were made in 3 potential, broadscale,raptor migration or other overland routes; 2) Intermountain - routes to compare their relative use. We attempted to observein through the intermountain trenchesin northern areas physiographicallyconducive to concentratingmigrants, suchas along major rivers,lakes, southeast to northwesttrending British Columbia and southwestern Yukon Territ- ridges,and mountain passes.Observations were made from roads ory into the Yukon and Tanana River drainages; or within 3 km hiking distanceof roads,using binoculars or a 20X and 3) Canadian prairies - through Alberta and spottingscope to searchfor and identify migrants.Some of the northeastern British Columbia east of the Rocky mostpromising areas were rechecked on 2-3 non-consecutivedays to reducebias associated with varying weather conditions. Once an Mountains, then crossingthe Rocky Mountains, area was perceivedto be used,we moved to another location.No and headingnorthwest through British Columbia attemptwas made to count large numbersof birdsor to determine and/or Yukon Territory similar to the intermoun- magnitudeof the migration. tain route. These 3 principal routes, all or in part, Raptor migration in interior western North America occurs havebeen described previously by Westet al. (1968) along a broader front (Hoffman 1981, and in press)with smaller localconcentrations of birds comparedto easternNorth America as apparent routes for migrating Lapland (Heintzelman 1975) and elsewhere(Smith 1980, Christensenet al. Longspurs(Calcarius lapponicus ). 1982). We usethe term "route" to denote a broadscale,dispersed Raptor migration is generallya broadfront pas- movement,and do not suggestthat lack of sightingsin any area sage,occurring to somedegree over nearly all land indicatescomplete lack of useby migrants. We attemptedto spend sufficienttime at different locationsin eachof the 3 possibleroutes regionsof the temperatezone. The distributionof mentioned,to enablecomparison of their relativeuse. visible migrants, however, is not random, partly The possibilityof migrantsdeparting from the generalcoastal due to topographicfeatures either discouragingor route by moving northward through Lynn Canal and then into

11 RAPTORRESEARCH 18(1): 10-15 12 MINDELL AND MINDELL VOL. 18, NO. 1 mainland areas was checkedby observingat Haines (Lentnikof from northwestern and northcentral British Col- Cove,Flat Bay)and Chilkatand White Passes.The intermountain umbia and the intermountain route rather than route wassampled by observingat numerouslocations along the AlaskaHighway between Watson and KluaneLakes (Fig. 1) and from a coastalor a Canadianprairies route through alongRt. 3 to Haines,Rt. 2 to Carcross,and Rt. 7 to Atlin. The northeasternBritish Columbia. Late April weather possibilityof migrantscrossing the RockyMountains along the conditions were still severe in Chilkat and White route of the AlaskaHighway was checked from lookoutsin the Passesand along the route of the Alaska Highway vicinity of Muncho and Summit Lakes, British Columbia.We distinguishedmigrants from possibleresidents by behavior. (Rt. 97) through the RockyMountains with 1 to 3 m Sedentarybirds or birds movingsouth or eastwere not counted of snowcover, whereas the Takhini River valleyand unlessthey were southof their breeding range (e.g., Rough- much of the intermountain route were more temp- legged Hawks (Buteolagopus) ). eratewith somebare ground showingby late April. This is not to imply that no migration occurs through thesepasses or areaswith snowcover. Sev- RESUI•TS ANn DISCUSSION eral groupsof 3-6 Sharp-shinnedHawks (Accipiter ROUTEUSE. -- All migrant activityseen occurred striatus)were seen heading south through Chilkat within the intermountain route, passingbetween Pass on 7 October 1980. Weather in these mountain the Rocky Mountains on the eastand the St. Elias passesmay be generallymilder during the fall mig- and CoastMountains on the west.No migrant rap- ration than during the spring, and useby migrants tors were seencoming from a coastalroute north may be correlatedwith the difference. over Chilkat or White Passes or from east of the On 27 and 28 March 1982 an apparentvanguard Rocky Mountains over the pass travelled by the of the Canada Goose(Branta canadensis) migration Alaska Highway in the Summit Lake vicinity.Mig- (over 440 individuals)was seen resting along the rant Northern Harriers (Circuscyaneus), Red-tailed last unfrozen sections of the Fraser River in central Hawks (Buteojamaicensis), Rough-legged Hawks British Columbia, between Lac La Hache and and Golden Eagles(Aquila chrysaetos) were seen in Quesnel.Six Red-tailedHawks were alsoseen 40 to the intermountain route (Takhini River valleywest 30 km south of Quesnel on 28 March 1982. No of Whitehorse)before, during, and after observa- migrantraptors or geesewere observedduring the tions at Summit Lake and Chilkat and White Passes subsequent7 daysspent driving north to Watson (Table 1), suggestingthat the lower abundanceof Lake and observingin the area between Watson migrants coming over the passesand at Summit and Teslin Lakes. On this basis,it seemsunlikely Lake wasnot due only to timing of observations. that large numbersof raptorspassed through nor- Migrants passingthrough southernYukon Ter- thwestern British Columbia or southwestern ritory in mid-April were apparently approaching Yukon Territory before observationsbegan.

Table 1. Observationsites, date, and total raptor sightingsfor Spring 1982 migration in northwesternCanada and Eastern Alaska. (B.C. = British Columbia; Y.T. = Yukon Territory.)

No. migrant Location Dates raptors seen

SummitLake, B.C. 16-18 Apr 0 Johnson'sCrossing, Y.T. 1,14,15,19-21Apr 73 Atlin Lake, B.C. 21-23 Apr 142 White Pass,B.C. 3, 24, 25 Apr. 0 Chilkat Pass,B.C. 8, 12, 13 Apr. 0 Haines area, Alaska• 9-12 Apr 0 Takhini River valley,Y.T. 5, 6, 13, 14, 26 Apr 53 Other2 5-28 Apr 46

•Lentnikof Cove,Flat Bay. migrantraptors were seen at anyone location,and all locationswere within the intermountainroute. SPRING 1984 SPRING MIGRATION 1982 13

Based on physiographicfeatures, 3 sub-routes observedfrom 300 m above the range to half-way can be distinguished within the broader inter- down the slope. mountainroute: 1) betweenthe Rockyand Cassiar At Johnson'sCrossing, Yukon Territory we Mountains,entering Yukon Territory near Watson counted73 raptorsduring 15.2 total hrs of obser- Lake, 2) between the Pelly and CassiarMountains vationduring portionsof 5 daysbetween 14 and 21 and the St. Elias and Coast Mountains, entering April. Johnson'sCrossing is at the outlet of Teslin Yukon Territory near Teslin, and 3) along the east Lake, a northwesttrending lake approximately 80 slopeof the Coast Mountains and Atlin or Tagish km northeastof Atlin Lake. In descendingorder of Lakes entering the Yukon River drainage near abundancethe migrantswere: Red-tailed Hawks, Whitehorse.Observed migrant activitywas greater Northern Harriers,Buteo sp., Rough-legged Hawks in sub-routes 2) and 3). and Golden and Bald Eagles. Recoveries of Alaskan banded birds show that at On 13 and 14 April 23 migrantswere seenduring least some Peregrine Falcons (Falco peregrinus) 5.5 hrs of slow driving and observation in the (Ambrose et al. 1983) and Rough-legged Hawks Takhini River valley, 10 to 50 km west of (Kesseland Cade 1958) crossthe RockyMountains, Whitehorse.The Takhini River valleyreceives mig- and many Alaskan breeding Red-tailed Hawks do rants that have come northwest along Teslin Lake, so as well. Migrants crossthe Rocky Mountains in Atlin Lake, and Tagish Lake (intermountain many regions, however, Williston Lake west of route). The Takhini River valleyis broad, however, Dawson Creek, British Columbia and the Jasper we saw raptors from observationspots on Rt. 1, 3 and Banff areasmay be worthy of future study. km east of Champagne, 2 km east of the Kusawa A coastalroute through southeasternand south- Lake turnoff and at the Takhini River Crossing.We central Alaska, along the Gulf of Alaska is used by sawa total of 10 migrantsduring fasttravel through many raptors basedon observationsby Islieb and the Takhini River valley on 5 and 26 April. Mig- Kessel (1973) and Swem (1982a, 1982b). Dates of rantsproceeding through the intermountainroute migrant passagerecorded by Swem (1982a) were couldpass along Kluane Lake, however,our obser- such that if large numbers flew from the coastal vations there were after the bulk of the Northern migratory route north up Lynn Canal and over Harrier and Buteomigrations had passed.We saw Chilkat or White Passeswe would likely have seen only a few migrants along the Tagish River at some of them. Tagish, Yukon Territory, and the Tanana River SpecificLocations of Migrant Activity.-- Within near Tetlin Junction, Alaska. the intermountain route relativelyhigh concentra- SpeciesAbundances. -- The Northern Harrier tions of migrants were found at 3 locations.On 22 wasthe mostfrequently seenmigrant (Table 2). At April we counted117 raptorsin 6 hrs,flying north each of the 3 main areasof migrant activity,either along the Lina Range on the eastside of Atlin Lake, the Northern Harrier or the 2 buteos as a group British Columbia. This included 65 Northern Har- were mostabundant. The largestflight of Northern riers, 21 Golden Eagles, 18 Red-tailed Hawks, 8 Harriers and Golden Eagles was seen along Atlin Buteosp., 4 Bald Eagles (Haliaeetusleucocephalus), Lake (Lina Range), while the largest flights of and 1 Peregrine Falcon.The Lina Range rises900 Red-tailed and Rough-legged Hawks were seen at m aboveAtlin Lake, and mostof the migrantswere Johnson'sCrossing.

Table 2. Speciespercentages of migrant raptors(n = 314) seenin northwesternCanada and easternAlaska 5-18 April 1982.

Red-tailed Rough-legged Northern Golden Bald Peregrine Hawk Hawk Harrier Eagle Eagle Falcon

% of total sightings 29.1 9.4 40.2 15.7 5.2 0.4 14 MINDELL AND MINDELL VOL. 18, NO. 1

Comparing our study with another conducted Tagish and Teslin Lakes. On the east side of the during the spring of 1982 along the Gulf of Alaska Rocky Mountainsmigrant Peregrinesare consis- coastat SitkagiBeach, west of Yakutat Bay (STem tently observedin spring passingthrough the Ed- 1982a), the Northern Harrier was the most abun- monton, Alberta region (Dekker 1979). The ob- dant speciesalong both the intermountain route served fall passage there is considerablyless, and the coastalroute passingSitkagi Beach. Sharp- suggestingseasonal difference in distribution of shinned Hawks, however, were the second most migrant Peregrines.Although no migrant Merlins abundant speciesalong the coastalroute (26.5% of (Falcocolumbarius) were seenduring our studythey total) while none were seen in the intermountain have been seenboth along the coastalroute (Swem route. Rough-legged and Red-tailed Hawks com- 1982a) and within the intermountain route (Swarth bined accountedfor only 1.8%of the totalsightings 1924, and 1926). along the Gulf of Alaska at Sitkagi Beach, com- Chronology.-- The first migrant Rough-legged pared to 38.5% in the intermountainroute. Golden Hawks, Red-tailed Hawks and Golden Eagleswere Eagles were also comparatively rare along the all seen on 5 April in 1982. The first Northern coastalroute, comprising0.4% of total sightings, Harriers were not seenuntil 14 April. Similarityin compared to 15.7% in the intermountain route. timing of migration for Rough-leggedand Red- Greater use of the coastal route by migrant tailed Hawks is reflected in similar breeding Sharp-shinned Hawks and greater use of the in- chronologiesin portionsof Alaska(Gabrielson and termountain route by migrant buteosand Golden Lincoln 1959, Mindell 1983). Eaglesis supportedby Swarth (1924, and 1926) who found that Sharp-shinnedHawks were "never Although the present studywas not designedto commonin the Atlin, BritishColumbia region, not determinetiming of peak migration,the main mig- even in the fall after southward migration had ration of buteos in the intermountain route begun", and by Islieb and Kessel(1973) who de- through southwestern Yukon Territory and scribedRough-legged Hawks and GoldenEagles as northwesternBritish Columbiaappeared to be over rare migrants,Red-tailed Hawks ascasual migrants by 25 April, while some Northern Harriers were and Sharp-shinnedHawks as fairly commonmig- still passingthrough. This correspondswith aver- rants along the Gulf of Alaska and in the Prince age laying datesover a 4-yr period of 17 May for William Sound region. Swarth did observemigrat- Rough-leggedHawks and 16 May for Red-tailed ing Sharp-shinned Hawks at Hazelton in the Hawks along the Kuskokwim River in western Skeena River valley of westcentralBritish Colum- Alaska (Mindell 1983). On 23 April 1982 we ob- bia, although hawks in this area may have been served a Red-tailed Hawk nest building at Tarfu headed tbr the coast. A tendency for Sharp- Lake near the northern end of Atlin Lake. Swem shinned Hawks to migrate in greater numbers (1982a) found the peak abundanceof migrating alongthe Pacificcoast or along the southernedge of raptorspassing Sitkagi Beach near Yakutat Bay to the boreal forest might help to explain the relative be on 28 April, with stragglersof 7 speciesgoing by scarcityof migrant Sharp-shinnedHawks in inland as late as 8 May. western North America compared to inland sitesin ACKNOWLEDGEMENTS eastern North America such as Hawk Mountain, Pennsylvania,as suggestedby Hoffman (in press). We thank Mark Fuller fbr providinghelpful commentson an earlier draft of this paper. Islieb and Kessel(1973) alsodescribed Red-tailed Hawks as regular fall migrants in southcentral LITERATURE CITED Alaskaalong the GlennHighway between King and AMBROSE,R., P. SCHEMPF,^ND R. HUNTER. 1983. Ameri- SheepMountains in late Septemberand early Oc- can Peregrine Falcon(Falco peregrinus ariaturn) studies tober. This correspondswith fall migration obser- on the upper Yukon River, Alaska, 1983. Unpubl. report prepared for the U.S. Fishand Wildlife Service, vationswe made along the Glenn Highway in 1980 Office of EndangeredSpecies, Anchorage. 19 pp. and 1981, and with observationsby Bob Dittrick CHRISTENSEN, S., O. Lou, M. MUELLER, AND H. (pers. comm.). WOHLMUTH.1982. The spring migrationof raptors Peregrines represented 0.8% of the sightings in southern Israel and Sinai. Sand,•ouse3:1-42. along the Gulf of Alaska, and 0.4% in the inter- DEKKER,D. 1979. Characteristicsof Peregrine Falcons mountain route. Swarth (1926) also saw migrant migrating through central Alberta, 1969-1978. Can. Peregrines within the intermountain route at Field Nat. 93:296-302. SPRING1984 SPRINGMIGRATION 1982 15

GABRIELSON,I.N. ANDF.C. LINCOLN.1959. The birdsof SMITH,N.G. 1980. Hawk and vulturemigrations in the Alaska.The StackpoleCo. Harrisburg,Pennsylvania. Neotropics.pp. 51-65in Migrantbirds in the Neo- 922 pp. tropics.Keast. A. and F. Morton,eds. Smithsonian GAVTHREAVX,S.A., JR. 1979. Prioritiesin birdmigration InstitutionPress, Washington, D.C. 576 pp. studies. Auk 96:813-815. SWARTH,H.S. 1924. Birds and mammalsof the Skeena HEINTZELMAN,D.S. 1975. Autumn hawk flights: the Riverregion of northernBritish Columbia. Univ. of migrationin easternNorth America.Rutgers Univ. Cal. Publ. in Zool. 24(3):315-394. Press,New Brunswick,N.J. 398 pp. SWARTH,H.S. 1926. Reporton a collectionof birdsand HOF•'MAN,S. 1981. Westernhawkwatching. The News- mammalsfrom the Atlin Region,northern British letterof theHawk Migration Assoc. of North America Columbia. Univ. of Cal. Publ. in Zool. 30(4):51-162. 6(1):1-5. SWE•4,'F. 1982a. Resultsof the Sitkagi Beach raptor HOFFMAN,S. In press.Raptor movements in inlandwest- migrationstudy, spring 1982. Unpubl.report pre- ern NorthAmerica: a synthesis.Proceedings of Hawk paredfor U.S.Fish and Wildlife Service, Office of MigrationConference IV, Rochester,N.Y., March EndangeredSpecies, Anchorage, Alaska. 21 pp. 24-26, 1983. SWE•4,T. 1982b. Resultsof the Sitkagi Beach raptor ISLIEB,M.E. ANDB. KESSEL.1973. Birdsof the north migrationstudy, autumn 1982. Unpubl. report pre- gulfcoast- Prince William Sound region, Alaska. Biol. paredfor U.S.Fish and Wildlife Service, Office of Papersof the Univ.of Alaska,No. 14. EndangeredSpecies, Anchorage, Alaska. 14 pp. KESSEL,B. ANt)T.J. CAr)E.1958. Birdsof the Colville WEST,G.C., L.J. PLYTON, AND L. IRVING.1968. Analysis River northern Alaska.Biol. Papersof the Univ. of of springmigration of LaplandLongspurs to Alaska. Auk 85:639-653. Alaska, No. 2. M•NI•ELL,D.P. 1983. Nesting raptors in southwestern Departmentof Zoology,Brigham Young University, Provo, Alaska;status, distribution, and aspectsof biology. Utah 84602. Addressof secondauthor: 11 South 200 East, Lin- BLM-AlaskaTechnical Report 8. Bureau of Land don, UT 84062. Manage.,Alaska State Office, Anchorage. 59 pp. BLM/AK/TR-83/08. Received2 December1982; Accepted I May 1983

Position Available -- NATURALIST/STAFF BIOLOGIST. Hawk Mountain Sanctuary Associationseeks a naturalist/staffbiologist for a two-yearposition beginning in August 1984. Responsiblefor- all field studies,including fall raptor migratoncount. Will alsoparticipate as resourceperson in educationprogram. Excellentopportunity to initiate new studiesand analyzemigration statistics.Computer systemavailable. Minimum qualificationsare M.S. in biologyor related field, experiencein conductingfield studiesand data analysis/write-up,experience with raptor identification,and ability and interestin working with volunteersand general public. Computer experiencestrongly preferred. Salaryplus housingon grounds.AppLY TO STANLEYE. SENNER,EXECUTIVE DIRECTOR, HAWK MOUNTAIN SANCTUARYASSOCIATION, RT. 2, KEMPTON, PA 19529.

HawkMountain Research Awards. The Hawk Mountain Sanctuary Association isaccepting applications forits eighth annualaward for raptor research. Toapply for the $500 award, students should submit adescription oftheir research program,acurriculum vita,and 2letters ofrecommendation by30 September' 1984,to James J.Brett, Curator, Hawk MountainSanctuary, Rt.2, Kempton,Pennsylvania 19529. The Association's Board of Directors will make a final decisionlate in 1984.Only students enrolled ina degree-grantinginstitution areeligible. Both undergraduate and graduatestudents areinvited toapply. The award will be granted onthe basis ofa prqject'spotential toimprove understandingofraptor biology and its ultimate relevance toconservation ofNorth American raptor populations.