@. . '. . ' •.: JJ&

"0' . .•.

., .",," ... ,. ,"

The Journal of the Ontario Field Ornithologists

Volume 12 Number 2 August 1994

Recognizable Forms

Merlinby

Ron Pittaway

IntroductionThree distinct forms of the Merlin(Falco columbarius) breed in NorthAmerica: (1) Taiga Merlin (F. c.columbarius), a medium dark bird ofthe boreal forest (taiga is a Russianword for boreal or northern forest);(2) Richardson's Merlin (F. c.richardsoniis, a very pale bird of thenorthern prairies and aspen

. parldands; and (3) Black Merlin (F. c.suckleyi), a very dark bird of the WestCoast. See Figure 1 and Map 1. Theseforms are also illustrated in Clark andWheeler (1987), Scott (1987) andPeterson (1990). Note that theillustrations in the latter aremislabelled; from left to right theyshould read suckleyi, columbarius, andrichardsonii. Also see the excellentpaintings by Paul Donahue, includingadult males and females of all threeforms, in the Fall 1987 issue ofAmerican Birds 41: 369. In this note I

ONTARIO BIRDS AUGUST 1994

discuss the taxonomy, occurrence,and identification of the recognizableforms of the Merlin in Ontario.

TaxonomyThe American Ornithologists' Union(1957) and Godfrey (1986) list foursubspecies of the Merlin as breedingin North America: (1) F. c.columbarius; (2) F. c. bendirei; (3) F. c.richardsonii; (4) F. c. suchleyi. SeeGodfrey (1986) for ranges of thesubspecies (races) and areas ofintergradation.

Many authorities do not recognizebendirei (western taiga population) asa valid subspecies because it issimilar to columbarius (eastern taigapopulation) in phenotype(appearance) and ecology (Swarth1935, Taverner 1937, Rand 1946,Temple 1972a, Beebe 1974, Palmer1988, Sodhi et al. 1993). Here I follow

75

.'- '.

Figure 1: Adult male Merlins: F.c. suckleyi (top); F.c. richardsonii (middle); andF. c. columbarius (bottom). Drawing by Peter Burke.

VOLUME 12 NUMBER 2

76

Temple (1972al who concluded thatbendirei should be merged withcolumbarius as one subspecies F. c.columbarius because "Phenotypicallyno basis exists for separating the taigapopulation geographically in themanner the present subspeciesdesignations indicate. The clinalnature of the geographic variation inthese populations makes it clear thatany attempts at dividing the taigapopulations will be arbitrary and notreflect accurately either phenotypicor phylogenetic differences ... ' ,.

Swarth (19351 questioned thevalidity of the subspecies suckleyi,suggesting that it may be a darkmorph [phase] of columbarius(bendireil. However, Temple (1972alconcluded that "Merlins breeding inthe coastal forest biome are markedlydifferent from those of the adjoiningtaiga, and an exclusive range for thisphenotype is indicated" .

Plumages, Molts and AgeingThe sexes of adult [definitive basic IMerlins differ in coloration and size.Males vary from pale blue-gray tobluish black on the upperparts.Females are brown-backed (light todark] with a hint of gray on the rumpand uppertail coverts, although this isnext to impossible to see in the field.Males are on average noticeablysmaller than females.

Immature (juvenile Imale andfemale Merlins are brown-backed andare normally inseparable from adultfemales in the field. The full juvenileplumage is worn from the time thebirds leave the nest until the nextspring when the gradual molt to adultplumage begins.

Merlins (adults and year-oldjuveniles Iundergo one complete molt

ONTARIO BIRDS AUGUST 1994

annually, extending from mid-April tolate September (Temple 1972bl. Aftera juvenile has completed its firstannual molt it is in adult plumage.Fall migrants consist of adults andjuveniles in fresh plumage. By thefollowing summer, some birds(especially juveniles I can becomequite faded.

Taiga Merlin (F. c. columbariuslThe Taiga or Boreal Merlin breedsacross the northern forests of Canadaand Alaska (Sodhi et al. 19931. SeeMap 1. Taiga populations fromManitoba westward are classified asthe subspecies F. c. bendirei by someauthorities. In Ontario, Taiga Merlinsbreed from the tree line southregularly to Manitoulin Island andAlgonquin Park (lames 19911. LikeRichardson's Merlin on the prairies,Taiga Merlins have adapted tobreeding in groves of spruce (Piceaspp.] in cities and towns such asThunder Bay (Escott 19861 andArnprior (Mike Runtz, pers. cornm.].Following the discontinuedwidespread use of DDT, TaigaMerlins have increased and migrantsare now seen more regularly insouthern Ontario [Duncan 19931 andreports of wintering birds have alsoincreased in recent years.

In the Checklist of RecognizableOntario Bird Forms (Pittaway 19911, Ilisted the Eastern race (columbariusland the Bendire's race (bendireil asseparate forms. I now believe thatmany bendirei are inseparable fromcolumbarius (Temple 1972a, Palmer19881. In a revision of the checklist Iwill combine the two, and renamethe form as the Taiga Merlin (F. c.columbariusi after Clark and Wheeler(19871·

77

"

co/umbariusrichardsoniisuck/eyi

Map 1: Breeding ranges of Merlin subspecies.

Richardson's Merlin(F. c. richardsonii)The Richardson's or Prairie Merlin isa very pale subspecies breeding onthe northern prairies and aspenparldands (Godfrey 1986). See Map 1.The population includes both residentand migrant birds. This form wasnamed after Sir John Richardson,Arctic explorer and naturalist, whocollected the first specimen nearCarlton, Saskatchewan, on 14 May

1827 (Bent 1938).Richardson's Merlins have been

reported east to southern Ontario(Wormington 1986, Palmer 1988),and there is a report by GeorgeMeyers of a male from Grimsby on 6January 1989 that was accepted bythe Hamilton Bird RecordsCommittee (Dobos 1990). James(1991) questioned Wormington's(1986) sight record at Point Peleebecause "There are a number of pale-

VOLUME 12 NUMBER 2

78

coloured migrants in ROM collectionsconforming to F. c. bendirei".Wormington did not comparerichardsonii with bendirei in his note;however, his description agreesclosely with classic Richardson's inmy opinion. Interestingly, experthawkwatcher Frank Nicoletti [pers.comm.) reports Richardson's Merlinsclose to Ontario in each of the lastthree autumns at Hawk Ridge locatedon the west end of Lake Superiornear Duluth, Minnesota. In addition,Rob Dobos [pers. comm.) observed ajuvenile or female Richardson'sMerlin near Rainy River on 28August 1988.

Earl Godfrey [pers. comm.)considers the Richardson's Merlin tobe a "very well-marked subspecies" .In October 1992, I observed severalRichardson's Merlins in Saskatoon,Saskatchewan. Perched adult maleswere very distinctive with pale blue-gray upperparts, and much palercrowns than columbarius. See Figure1. Adult females and juveniles[immatures] were much paler thancolumbarius and in flight theunderwiogs were not dark like thelatter. In flight at a distance, thesandy-brown females and juvenilescan be very reminiscent of femaleAmerican Kestrels IF- sparverius), orthey can appear like miniature PrairieFalcons IF- mexicanus)!

Some Merlins are intermediatebetween columbarius and richardsonii[Brian Wheeler, pers. comm.). Theymay be treated either as intergradesor as F. c. bendirei of some authorities(AOU 1957, Godfrey 1986, James1991).

ONTARIO BIRDS AUGUST 1994

Black Merlin (F. c. suckleyi)This very dark subspecies breedsmainly in western British Columbia[Sodhi et al. 1993). See Map 1. Seealso the full page painting of an adultmale in Beebe (1974). Black Merlinsare not highly migratory but somemove as far as southern Californiaand New Mexico [Sodhi et al. 1993),and Palmer (1988) cites a record eastto Wisconsin. Interestingly, there is aspecimen of a very dark femaleMerlin in the Canadian Museum ofNature (CMN #8588) that wascollected in Ottawa on 23 March1923 [Michel Gosselin, pers. comm.).I have examined this specimen andfound it to be very similar to severalspecimens of suchleyi from BritishColumbia in the collection. P.A.Taverner wrote on the specimen labelin 1939 "This bird so stronglyresembles suchleyi that the temptationto call it so is very strong". Accordingto Earl Godfrey [pers. comm.)"Whether it is genetically a BlackMerlin is unknown". There are twopossibilities: it is either a far-wandering individual of thesubspecies suckleyi, or an extremevariant of columbarius. Rand (1948)stated that doubtful cases such as thisare best treated as local variants, andsuggested that on annotated checklists"it is not desirable to suppress thefacts of their occurrence; undersubspecies "A" a line might followstating that occasional individualsapproaching (or similar to, oridentical with) subspecies "B" occur,as the data may require" .

Clark and Wheeler (1987) statethat "Characteristics of someindividual Merlins are intermediatebetween those of Black and Taiga".In addition, Brian Wheeler [pers.

cornm.] and Frank Nicoletti (pers.comm.] also report that very darkindividuals suggestive of BlackMerlins occur occasionally in theEast. They believe these intermediateand dark birds are most likelyvariants of the Taiga form. Morerecently, Alan Wormington (in litt.lreported a dark Merlin wintering atPelee in 1993-94. When observedclosely on 13 and 14 April, it was "anexceptionally dark bird suggestingsuckleyi". He believes it was probablya very dark columbarius.

SummaryThree recognizable forms of theMerlin breed in North America:Taiga, Richardson's, and Black. TheTaiga Merlin is the usual form foundin Ontario. Richardson's Merlinshave been reported in southernOntario, and they may be regularmigrants in northwestern Ontario. Aswell, intermediates between Taigaand Richardson's Merlins are seenfrom time to time. Occasionally, verydark Merlins suggestive of the Blackform occur in the East.

AcknowledgementsI thank Peter Burke, Bill Crins, BruceDiLabio, Rob Dobos, Earl Godfrey,Michel Gosselin, Jean Iron, Ross[ames, Chris Lemieux, FrankNicoletti, Richard Poulin, MikeRuntz, Ron Tozer, Mike Turner,Brian Wheeler and Alan Wormingtonfor much vaulable help in thepreparation of this note. Peter Burkekindly provided the illustrationswhich greatly enhance the text. I amgrateful to Phill Holder for producingthe map.

79

Literature citedAmerican Ornithologists' Union. 1957.

Check-list of North American Birds, 5thedition. American Ornithologists' Union,Washington, D.C.

Beebe, F.L. 1974. Field Studies of theFalconiformes of British Columbia.Occasional Papers No. 17. British ColumbiaProvincial Museum, Victoria.

Bent, A.C. 1938. Life Histories of NorthAmerican Birds of Prey. Part 2. UnitedStates National Museum Bulletin 170.Washington, D.C.

Clark, W.S. and B.K. Wheeler. 1987. A FieldGuide to Hawks. Houghton Mifflin Company,Boston.

Dobos, R. 1990. Hamilton Bird RecordsCommittee, 1989 Annual Summary. WoodDuck 44111:3·6.

Donahue, P. 1987. The art of Paul Donahue.American Birds 41: 368·369.

Duncan, B. 1993. Merlins in Ontario: populationchanges. Birders Journal 1: 48-60.

Escott, N.G. 1986. Thunder Bay's nestingMerlins. Ontario Birds 4: 97·10 1.

Godfrey, W.E. 1986. The Birds of Canada.Second Edition. National Museum of Canada,Ottawa.

[ames, R.D. 1991. Annotated Checklist of theBirds of Ontario. Second Edition. LifeSciences Miscellaneous Publications, RoyalOntario Museum, Toronto.

Palmer, R.S. 1988. Handbook of North AmericanBirds, Volume 5, Diurnal Raptors [Part 2).Yale University Press, New Haven andLondon.

Peterson, R. T. 1990. A Field Guide to WesternBirds. Houghton Mifflin Company, Boston.

Pittaway, R. 1991. Checklist of recognizableOntario bird forms. Ontario Birds 9: 49-55.

Rand, A.L. 1946. List of Yukon Birds and thoseof the Canol Road. Bulletin 105, BiologicalSeries 33, National Museum of Canada.

Rand, A.L. 1948. Probability in subspeciesidentification of single specimens. Auk 65:416·432.

Scott, S.L. {ed.}. 1987. Field Guide to the Birdsof North America. National GeographicSociety, Washington, D.C.

VOLUME 12 NUMBER 2

80

Sodhi, N. S., L. W. Dliphant, P. C. lames, andI.G. Warkentin. 1993. Merlin (Falcocolumbarius). In A. Poole and F. Gill (Eds.).The Birds of North America. Number 44. TheAcademy of Natural Sciences, Philadelphia,and The American Ornithologists' Union,Washington, D.e.

Swarth, H.S. 1935. Systematic status of somenorthwestern birds. Condor 37: 199·204.

Taverner, P.A. 1937. Birds of Canada. TheNational Museum of Canada. Ottawa.

Temple, S.A. 1972a. Systematics and evolutionof the North American Merlins. Auk 89:325·338.

Temple, S.A. 1972b. Sex and age characteristicsof North American Merlins. Bird-Banding 43:191·196.

Wormington, A. 1986. An observation of a"Richardson's Merlin" in Ontario. OntarioBirds 4: 62·64.

Ron Pittaway, Box 619, Minden, Ontario KOM2KO