27

Notes

Sharp-shinned Hawk Preys on Batby

Libor Michalak

At 2035h on 30 May 1996, AntonioSalvadori and I, enroute north,stopped along the Trans-CanadaHighway below Lake SuperiorProvincial Park for the night. Takingtime to do some birding before retir­ing as the sun set, one of our observa­tions was of a small b.at (probablyMyotis sp.) fluttering above the treecanopy, moving to about 15-20 mabove the road. While focussing ourbinoculars on it for a closer look toidentify it, out of nowhere a Sharp­shinned Hawk (Accipiter striatus)bolted out of the tree canopy only toappear in our binocular view, impal­ing the mammal with its talons. Incontinuous motion after the catch,readjusting its flight pattern, it flew tothe opposite side of the road where itlanded in some aspen trees, seeminglyto adjust its prey. Only seconds later, itcontinued its flight to the side fromwhich it came. Amazed at what wehad just witnessed, we tried to followthe hawk but lost it due to the densetree cover.

Among the three accipiters, thisspecies shows a strong preference forareas of regenerating young forestwhich have a variety and abundanceof small birds. It takes mostly birds asprey; only rarely does it make otherfood a choice (Evans 1982, Ehrlich etal. 1988). It is agreed that birds com­prise over 90% of the Sharp-shinnedHawk's diet, but other prey to a much

lesser extent consists of herptiles suchas frogs, snakes and lizards (Palmer1988). Bent (1937) and Palmer (1988)note that mammals such as meadowvoles (Microtus spp.) and bats are alsotaken, and Snyder and Wiley (1976)state that food species proportions of93.1 % birds, 2% mammals, 0.6%lower vertebrates and 4.3% insectshave been observed. Insects takenconsist mainly of grasshoppers, crick­ets' beetles, large lepidopterans andcaterpillars (Palmer 1988). MatureSharp-shinned Hawks have beenknown to spend an entire day captur­ing grasshoppers from an open, highperch in exactly the same way as anAmerican Kestrel (Falco sparverius),as noted by Beebe (1973). Lastly, withbats not being common, an interestingobservation was reported by Sprunt(in Palmer 1988), involving Sharp­shinned Hawks arriving at a Texascave to await the evening emergenceof free-tailed ·bats (Tadarida spp.).

AcknowledgementsFor advice and assistance in the searchfor more material on the subject, Iwish to thank Bruce Duncan and ToniSalvadori.

Literature CitedBeebe, RL. 1973. Field Studies of the

Falconiforms of British Columbia. BritishColumbia Department of Recreation andConservation, Provincial Museum BulletinNo. 17.

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Bent, A.C. 1937. Life Histories of North AmericanBirds of Prey, Part 1. United States NationalMuseum Bulletin 167, Washington, D.C.

Ehrlich, P.R., D.S. Dobkin and D. Wheye. 1988.The Birder's Handbook. Simon & SchusterInc., New York.

Evans, D.L. 1982. Status reports on twelve rap­tors. United States Department of the Interior,Fish and Wildlife Service, Special ScientificReport - Wildlife No. 238, Washington, D.C.

Palmer, R.S. (editor). 1988. Handbook of NorthAmerican Birds, Volume 4, Diurnal Raptors,Part 1. Yale University Press, New Haven,Connecticut.

Snyder, N.F.R. and J. W. Wiley. 1976. Sexual SizeDimorphism in Hawks and Owls of NorthAmerica. Ornithological Monographs No. 20.

Libor Michalak, 240 Melrose Street, Cambridge, Ontario N6H 4A6

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29

A Collision of Oldsquaws

byKenneth F. Abraham and Nancy Wilson

IntroductionOldsquaw ducks (Clangula hyemalis)are regular but relatively inconspicu­ous migrants in southern and westernJames Bay (Figure 1). They are mostnoticeable in spring and autumn whenthey traverse northeastern Ontario andwestern Quebec between James Bayand the Great Lakes and the St.Lawrence River, using major rivers asinland flight corridors. In May, flocksare seen flying low over the river ice,often at day break, or swimming inopen water reaches of rivers at thetime of ice break-up. In autumn,

migrants concentrate in James Bayand can be observed passing head­lands on the coast (Sinclair 1986; D.McRae, pers. comm.) en route torivers such as the Harricanaw andMoose which enter extreme southernJames Bay. Oldsquaw migration overland in spring is made at high altitudeand may commence in the afternoon,thus spanning the night (Palmer1976). Both altitude and night flightshelp explain their relative inconspicu­ousness during migration.

Little is known about the charac­teristics of migration in James Bay

Figure 1: Male Oldsquaw. Photo by Don Gunn.

VOLUME 15 NUMBER 1

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other than a few dates of occurrence(Lewis and Peters 1941, Smith 1957,Todd 1963). Here, we add a summaryof observations over the past 20 yearsfrom the Moosonee and southernJames Bay region (Table 1). The earli­est observation was a flock of 24 inHannah Bay on 16 April 1987. Themajority of observations occurred inthe latter two weeks of May (13th-

26th). Such timing coincides withboth observations of peak numbersand departures from Lake Ontario andLake Erie (late April and first week ofMay) and major movements inGeorgian Bay near Manitoulin Islandand Killarney (17-24 May) (Goodwin1975). It suggests a rapid movementfrom wintering areas to spring stagingareas in James Bay.

Table 1. Oldsquaw migration dates in the Moosonee area, including southernJames Bay shoreline at Shipsands Island, Netitishi Point, 'Hannah Bayand East Point.

Day migration was reported in:

April May Sept. Oct. Nov. Dec.

1977 131978 141980 15 21981 16, 23 28 1 201982 16 16,251983 3,4,101984 19 20,211985 25,27 5.,8,91986 261987 16 161988 21,221990 1,18,20,221992 6 251993 21, 301994 7,21 41995 191996 22 3

Total 22 8 8 2Obs.

Ave. 17-18 20-21 7-8 3-4Date

1 Underlined dates had more than 1000 birds reported; maximum was 14, 800 on28 October 1981.

ONTARIO BIRDS APRIL 1997

Fall migration observations wereconcentrated from about 20 Octoberto 10 November, with two notablelater dates. The earliest observationwas on 25 September 1992, and thelatest date of occurrence was 4December 1994. Exceptional migra­tions were recorded at Netitishi Pointby Doug McRae and AlanWormington when 33,000 wererecorded between 13 October and 24November 1981 (Goodwin 1982).Peaks of 14,800 and 3000 wererecorded on 28 October and 20November. Similarly impressive num­bers were recorded by Doug McRaeand Pam Sinclair in 1985 (total of15,640 recorded from 25 October to 9November). A major night movementon 3-4 November 1983 (Abraham)coincided with peak numbers threedays later at Long Point, Lake Erieand Prince Edward Point, LakeOntario (Weir 1984), again suggestingrapid and perhaps non-stop move­ments between James Bay and thelower Great Lakes.

A regular feature of fall birdmigration at Moosonee, Ontario (51 °17'N, 80° 38'W), is the movement ofOldsquaws along the Moose River inlate October and early November.They are often heard rather than seenbecause the passage frequently occursat night. Further, the movements oftenoccur in association with periods ofinclement weather, when low overcastand fog creates poor visibility. Wehave witnessed these night passagesin most years since 1982, when one orthe other of us resided in Moosonee.

Similar movements associatedwith inclement weather have beennoted during spring migration, andnight migration in spring was noted onat least three occasions. On 21 May

31

1993, Wilson witnessed a night migra­tion of Oldsquaws at the Moosoneetownsite. Low cloud cover conditionsexisted, and Oldsquaws could beheard calling for several hours thatevening. It seemed that the birds wereflying in circular or erratic patternsabove the community. Although notvisible, the numbers were estimated tobe at least 100, but could have beensubstantially more.

An Unusual EventOn 5 November 1985, Oldsquawspassed conspicuously along the riverand over the Moosonee townsite. Inthe darkness of early evening,Abraham listened to the calling birdsand observed them from several van­tage points along Revillion Road,which runs adjacent to the river.Oldsquaws were visible in the reflect­ed light at the' lower edge of the lowclouds. Other birds, includingKilldeers (Charadrius vociferus) andyellowlegs (Tringa spp.) were alsoheard. One notable aspect of themovement was that there was no aver­age direction of flight. Indeed, birdscrisscrossed in flight over the townsitein all directions. We could not tell howmany birds were involved, althoughseveral flocks of 20-40 birds were vis­ible simultaneously. At the time, wethought that the birds were probablydisoriented by the town's lights.

Moosonee residents, TommyMoore and Grant Churcher, alsoobserved the flight that night, andAbraham watched and discussed thephenomenon with them at about 2000h, then returned home. At 2030 h,Grant Churcher arrived at Abraham'shouse with a dead Oldsquaw. Heexplained that he and Tommy Moorehad been watching the crisscrossing

VOLUME 15 NUMBER 1

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birds when they heard a dull clap fromabove and were startled a few secondslater as two birds (one adult female,one adult male) fell from the sky andlanded nearly at their feet. Abrahamdissected the female and found that itwas in good condition with abundantbody fat, including heavy abdominalcavity fat. Haematomas were visiblein the neck region, but these were theonly signs of trauma. As there were notall structures present, we concludedthat the birds collided with each otherin the air, and either the collision orthe subsequent impact with theground caused their deaths.

DiscussionFatal collisions between birds inmigrating flocks must be rare.However, disorientation and bird col­lisions with human built structures,particularly by night migrants ininclement weather, are not unusual(Weir 1976, Ogden 1996). Nightmigrants are thought to navigate usingmultiple cues, including visual cuessuch as star patterns, the moon andtopographical features (e.g., coastlinesand rivers) and as such are subject todisorientation. The incidence ofwaterfowl in such kills is relativelylow and usually associated with struc­tures on or near waterbodies, such asdams, power lines and lighthouses. Anexample involving Oldsquawsoccurred at Smoky Falls, Ontario, onthe Mattagami River, on 26 October1986, when at least 27 Oldsquawswere killed when they struck trans­mission wires associated with thehydroelectric dam (Leafloor et al.1996). Abraham received a report ofducks falling /from the sky at DetourLake, Ontario, in December 1987.This was reported by an employee at

ONTARIO BIRDS APRIL 1997

the Detour Lake gold mine, and includ­ed Common Goldeneye (Bucephalaclangula), Bufflehead (B. albeola),and Common Loons (Gavia immer).The weather on all three occasionswas inclement, with either fog or lowcloud. Moosonee, Smoky Falls andDetour Lake are all in remote northernareas, where artificial light sources areuncommon and isolated. TheMoosonee and Smoky Falls eventsindicate either that the Oldsquawswere travelling at relatively low alti­tudes or that they were attracted to thelight source from higher altitudes, andthus to their deaths. Those that did notdie in collisions may have beenharmed by the aimless flying throughthe waste of energy reserves orexhaustion. In addition to the docu­mentation of an unusual event, theseobservations serve as a warning thatthe hazards associated with artificiallight sources are not limited to urbanareas.

AcknowledgementsWe thank the following contributorsto the Moosonee area bird observationdatabase: S. Badzinski, D. Byers, G.Faries, P. Ford, P. Gilboe, M. Hill, E.Hunter, F. Johnson, D. McRae, S.Muldal, P. Pratt, J.P. Prevett, S.Scholten, P. Sinclair, Y.R. Tymstra,and A. Wormington.

Literature CitedGoodwin, C.E. 1975. The spring migration,

March 1 - May 31,1975: Ontario Region.American Birds 29: 844-845.

Goodwin, C.E. 1982. The autumn migration,August 1 - November 30, 1981: OntarioRegion. American Birds 36: 171-174.

Leafloor, J.D., J.E. Thompson and C.D. Ankney.1996. Body mass and carcass composition offall migrant Oldsquaws. Wilson Bulletin 108:567-572.

Lewis, H.P. and H.S. Peters. 1941. Note onbird of the James Bay region in the autumnof 1940. Canadian Field-Naturalist 55: 111­117.

Ogden, L}.E. 1996. Collision course: the hazardsof lighted structures and windows to migrat­ing birds. World Wildlife Fund and FatalLights Awareness Program, Toronto.

Palmer, R.S. (editor). 1976. Handbook of NorthAmerican Birds. Volume 3. Waterfowl (Part2). Yale Univer ity Pre s, New Haven.

Sinclair, P. 1986. The effect of weather on latefall coastal bird migration in Jame Bay. B.Sc.The is, Department of Biology, Queen'sUniversity, King ton.

33

Smith, W.}. 1957. Bird of the Clay Belt of north­ern Ontario and Quebec. Canadian Field­Naturalist 71: 163-181.

Todd, W.E.C. 1963. Birds of the LabradorPenin ula. Univer ity of Toronto Press,Toronto.

Weir, R.D. 1976. Annotated bibliography of birdkills at man-made obstacles: a review of thestate of the art and solutions. CanadianWildlife Service, Ottawa.

Weir, R.D. 1984. The autumn migration, August 1- November 30, 1983: Ontario Region.American Birds 38: 195-199.

Kenneth F. Abraham, Ontario Ministry of Natural Resources, 300 Water Street,Peterborough, Ontario K9J 8M5

Nancy Wilson, Ontario Ministry of Natural Resources, Box 190, Moosonee,Ontario POL 1YO

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VOLUME 15 NUMBER 1

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Nesting of the Yellow-throated Vireoin the Sudbury District

byCharles J. Whitelaw

The Yellow-throated Vireo (Vireoflav­ifrons) , a hardwood-loving species,has been found breeding on Mani­toulin Island (for several years at thesame location), and was listed as aprobable breeder in the Sault Ste.Marie region and as a possiblebreeder a short distance south of theFrench River during the BreedingBird Atlas Project (James 1987). Inthe Sudbury District, the species hasbeen recorded on only one previousoccasion, on 13 May 1984 at a loca­tion east of Espanola near HannaLake. This locality is less than 32 kmdistant from the site discussed in thisnote.

During July of 1995, when sever­al of us were searching for speciessuch as Wood Thrush (Hylocichlamustelina) to bolster our year lists,information was passed on to me byChris Bell that a fairly extensive hard­wood existed along the Bay of IslandsRoad, west of Whitefish Falls,Ontario. A brief examination of thishardwood in Mongowin Townshipduring early October of 1995 revealedthat this area was indeed an attractiveand mature hardwood forest contain­ing species such as Sugar Maple (Acersaccharum), Yellow Birch (Betulaalleghaniensis), American Beech(Fagus grandifolia) , White Ash(Fraxinus americana), Striped Maple(A. pensylvanicum), Mountain Maple(A. spicatum), and a good sprinkling

ONTARIO BIRDS APRIL 1997

of mature Eastern Hemlock (Tsugacanadensis). At this time it was con­sidered worthy of further examinationin the spring of 1996, in the hope thatsome southern hardwood-type speciesof birds could be found during thebreeding season. In early May of1996, before any leaves were on thetrees, a hike was undertaken to furtherdetermine the extent of the hardwoodsand accessibility to the area.

On the evening of 29 May 1996, Ireceived a phone call from FloydCosby saying that he had found whathe believed to be a Yellow-throatedVireo along the main trail, a consider­able distance into this hardwood. Thebird was not in song and was feeding atmedium height on the outer branchesof some of the larger maples, rightbeside the trail. Floyd's descriptionsounded very good and I suggested thathe submit a rare bird report based onhis sighting to the Sudbury Committee,which he did at a later date.

I had been planning to follow thatparticular trail soon at any rate, so on31 May about mid-morning, I mademy way along the trail. After descend­ing the hill to a point near to whereFloyd ·had made his sighting, speciessuch as Least Flycatcher (Empidonaxminimus), Scarlet Tanager (Pirangaolivacea), American Redstart(Setophaga ruticilla) , Black-throatedBlue Warbler (Dendroica caerule­scens), Eastern Wood-Pewee

(Contopus virens) , and Rose-breastedGrosbeak (Pheucticus ludovicianus)were in full song. I had just found thefreshly constructed nest of a LeastFlycatcher, and one of· the ScarletTanager a little farther on, when I heardit: a vireo song with a distinct hoarse­ness and the phrases separated by verylong pauses. I recognized the songright away as that of the Yellow-throat­ed Vireo, having learned it at an earliertime many years ago in an oak-hickorywoodland near Komoka, west ofLondon, Ontario, where the Yellow­throated Vireo bred each year alongwith the Cerulean Warbler (D.cerulea).

The singer was located high in aLarge-toothed Aspen (Populus gran­didentata) which was not leafed out asyet. The plumage was distinctive:plain olive-brown above; white wingbars; and prominent yellow spectaclesaround the eye, with yellow extendingthrough the lores to the base of thebill. The throat and the breast were abright yellow, and the belly was white.As I watched this bird at an estimatedheight of about 20 m, a typical vireo­type nest appeared in the field of view,a little to the right of the singer. Right

35

away, a second vireo appeared withplumage similar to the first bird.This second bird immediately beganfidgeting about the nest, and then thetwo birds flew off together.

I returned on 10 June, at whichtime one bird was sitting on the nest,apparently incubating. The secondbird was silent and not to be seen. Atthis time, two photographs were takenof the nest with the incubating bird.On 14 June, Igor Konikow visited thesite, saw both birds at the nest andheard one bird in song. HeatherBaines, Chris Bell, and RodneyCampbell, accompanied by FloydCosby, saw the nest and birds, butheard no song, on 16 June.

AcknowledgementsI wish to acknowledge informationfrom Chris Bell, Donald Ferguson andJohn Nicholson, which was helpful inthe preparation of this note.

Literature CitedJames, R.D. 1987. Yellow-throated Vireo (Vireo

flavifrons). Pp. 348-349 in Atlas of theBreeding Birds of Ontario (M.D. Cadman,P.FJ. Eagles, and EM. Helleiner, compilers).University of Waterloo Press, Waterloo,Ontario.

Charles J. Whitelaw, 4195 Frost Avenue, Hanmer, Ontario P3P lE3

Recognizable FormsThis regular feature will appear again in the August issue of Ontario Birds.

VOLUME 15 NUMBER 1

36

Nest Re-used by Wood Thrush

byValerie E. Wyatt

The Wood Thrush (Hylocichlamustelina) is typically double-brood­ed, building two nests and laying twoclutches of 3-4 eggs each summer(Bent 1949, Terres 1980, Peck andJames 1987). In many multi-broodedspecies, the second nest may be builtby the female while the fledglingsfrom the first are still being fed by themale (Martin and GeupeI1993). In thecourse of searching for Wood Thrushnests for a study of nesting productiv­ity in the summer of 1996, we discov­ered seven probable occurrences ofdouble-brooding, where second nestswere built within 6-50 m of the firstsuccessful nest. We also observed asingle Wood Thrush nest in which twobroods were raised. Although nest re­use has been documented for otherpasserine species (Nickell 1957,Briskie and Sealy 1988, Curson et al.1996), it is apparently very rare in theWood Thrush (Bent 1949, Harrison1975). In a 19 year study of a colour­banded Wood Thrush population inDelaware, Roth reported just threecases of nest re-use out of 389 nest­ings (Roth et al. 1996).

The nest was found on 31 May, ina stand of maple saplings in a woodlotnear Elmira, Ontario. The contents,three Wood Thrush eggs, were easilyviewed with.a mirror attached to theend of a telescoping painter's pole.Three young hatched on approximate­ly 10 June, and fledged from the nest

ONTARIO BIRDS APRIL 1997

as it was approached by us on 20 June.Young Wood Thrushes were observedin the area for the next two weeks, andan adult was observed feeding afledged youngster in the area on 2July.

A new Wood Thrush nest w.aslocated on 10 July, 56 m north of theoriginal nest. This area had been care­fully searched one week earlier,specifically to find a second brood ofthe same pair, as the male had beensinging above the sapling stand nearlycontinuously. There was no othersinging male in the area, suggestingthe nest was built by the same pair.The new nest contained one Brown­headed Cowbird (Molothrus ater)egg, but although a singing male andfledged young were in the area, noadults were observed on or near thenest. The cowbird egg remained,apparently abandoned, until 26 Julywhen it disappeared.

We also checked the first nestwith the mirror on 10 July, but it wasempty. To our surprise, a visit to thenest on 12 July revealed three WoodThrush eggs, with the male WoodThrush singing nearby. On 18 July, weflushed a large unidentified bird, per­haps a Common Grackle (Quiscalusquiscula) or a Blue Jay (Cyanocittacristata), from near the nest, and dis­covered that only two eggs remained.Another egg disappeared before 22July, leaving only one tiny featherless

young in the nest. The agitated parentwas seen frequently. The singleyoungster fledged on 1 or 2 August.

The nest was located at a heightof 2.75 m, in the fork of a 4 m SugarMaple (Acer saccharum) sapling (dbh= 3.0 cm). The nest tree was sur­rounded by nearly uniform densemaple saplings of similar size. Therewas a sparse ground cover of mapleseedlings and a canopy of maple andHop Hornbeam (Ostrya virginiana)trees, approximately 15 m in height.Nest position, nest tree size, and sur­rounding vegetation were typical ofmost of the 61 Wood Thrush nestsfound in Waterloo Region woodlotsthis summer.

There are several possible rea­sons why passerines avoid re-usingold nests, including predator knowl­edge of the site and parasitic insectinfestations. However, in this case itmay be that the second nest construct­ed was abandoned due to Brown­headed Cowbird parasitism (Harrison1975). The subsequent re-use of theoriginal nest represented a saving oftime and energy for the Wood Thrush(Briskie and Sealy 1988, Curson et al.1996), or reflected a shortage of highquality nest sites, although to us, thesapling stand appeared uniform(Briskie and Sealy 1988, Curson et al.1996).

AcknowledgementsThanks to Andrea Spender, who firstdiscovered the new eggs. This fieldwork was carried out as part of a studycoordinated by Mike Cadman and

37

Lyle Friesen of the Canadian WildlifeService and Jock MacKay of theUniversity of Waterloo, and was fund­ed through the Ontario Ministry ofNatural Resources (EnvironmentalYouth Corps), the Canadian WildlifeService, Environment Canada'sBiodiversity Convention Office, andthe University of Waterloo. Helpfulcomments on an earlier draft of thisnote were provided by Mike Cadmanand Lyle Friesen.

Literature CitedBent, A.C. 1949. Life Histories of North

American Thrushes, Kinglets and TheirAllies. United States National MuseumBulletin 196, Washington, D.C.

Briskie, J. V. and S.G. Sealy. 1988. Nest re-useand egg burial in the Least Flycatcher,Empidonax minimus. Canadian Field­Naturalist 102: 729-730.

Curson, D.R., C.B. Goguen and N.E. Mathews.1996. Nest-site re-use in the Western Wood­Pewee. Wilson Bulletin 108: 378-380.

Harrison, H.H. 1975. A Field Guide to Birds'Nests. Houghton Mifflin Company, Boston.

Martin, T.E. and G.R. Geupel. 1993. Nest-moni­toring plots: methods for locating nests andmonitoring success. Journal of FieldOrnithology 64: 507-519.

Peck, G.K. and R.D. James. 1987. BreedingBirds of Ontario: Nidiology and Distribution.Volume 2: Passerines. Life SciencesMiscellaneous Publications, Royal OntarioMuseum, Toronto.

Nickell, w.P. 1957. Robins use same nest forthree sets of eggs in one season. Auk 74: 95.

Roth, R.R., M.S. Johnson and T.J. Underwood.1996. Wood Thrush (Hylocichla mustelina).In The Birds of North America, No. 246 (A.Poole and F. Gill, editors). Academy ofNatural Sciences, Philadelphia, and AmericanOrnithologists' Union, Washington, D.C.

Terres, J.K. 1980. The Audubon SocietyEncyclopedia of North American Birds.Alfred A. Knopf, New York.

Valerie E. Wyatt, 1331/2 Weber Street W., Kitchener, Ontario N2H 4Al

VOLUME 15 NUMBER 1