Vol.1906XXllI] J JENKINS,Variation in theHairy . 161 heard the songof the Hermit Thrush. Although I had spentmy life in the winter home of this and its habits were as familiar to me as those of the Mockingbird,I had neverheard it utter a soundother than a low, guttural, monosyllabicnote expressiveof alarm and kindred emotions. I was thus unpreparedfor the marvelousand elaboratesong I heardon that 19th day of March, 1905. It marks an epochin my ornithologicalcareer. Referring to my jom-nalof that date I find the following: "I was out in Lively's woods early Sunday morning, March 19, 1905. Recent rains had damp- ened the woodsso that a gloomyaspect pervaded the whole scene. I was standingdown the ravine whenoff in the distance,apparently over in the pasture, I heard the faint notes of what I was sure must be the Wood Thrush; its songbeing familiar to me in consequenceof my late temporary residence in the District of Colmnbia. I hastened in the direction of the soundsand as I drew near the edgeof the woodsdescried a bird sitting in a small wild plmn tree. It seemedannoyed at my intrusion. I stopped to look at it and finding only a Hermit Thrush started on in questof the singer,when to my surprisethe bird settled downupon its perchand com- mencedin low notesthe sweetestand purest songI have ever heard. A loveliermelody never fell upon more'grateful ears. Thenotes, liquescent and ventriloquial,beginning afar off, approachingslowly and finally burst- ing upon me, are impossible to be described." Mr. Brewster tells me that he has heard them singing in the swamps of JacksonCounty in early spring.

VARIATION IN THE (DRYO- BATES VILLOSUS AND SUBSPECIES).

BY HUBERT O. JENKINS.

Tins studywas originallyintended to be limited to the western forTnsof the Hairy Woodpeckerbut later it see•neddesirable to includedata that had accmnulatedconcerning all of the forTns. The numberof adult spe&nensof eachform examinedwas as follows:D. •. harrisi,43; D. •. hyloscopus,104; D. •. monticola, 7; D. •. leucomelas,9; D. •. •illosus, 12, and D. •. auduboni,3. This includesa largenumber of intermediatesand doesnot include some 30 immature . I,wish to thank Mr. JosephGrinnell, Mr. W. K. Fisher, Prof. 162 Jr•Nr:xNs,Variation in theHairy Woodpecker. [iAuk April

J. O. Snyder,and Prof. O. P. Jenkinsfor numeroussuggestions and assistance.For the privilegeof examiningspecimens I am greatlyindebted to the United StatesNational Museum,the Cali- fornia Academyof Sciences,Mr. JosephGrinnell, and Mr. W. Otto Emerson. The Hairy Woodpeckeris a form widely distributedover the continentof NorthAmerica, ranging from Alaska and Hudson Bay to Central America and ,from the Atlantic to the Pacific Oceans. The bird varies somewhat in localities distant from each other so that differentgroups have been given different subspecific names, but fromtheir close similarity and habits all are regardedby some authorsas belongingto the samespecies. Its nearestrelative is evidentlythe , which is muchsmaller, although the only differencein plumageof the DownyWoodpecker is the barringof theouter tail feathers,which are pure white in theHairy Woodpecker.In the West, althoughinhabiting the sa•negeneral localities,the two species are not often found immediately together. In the East, however,this separationdoes not hold. The food questionno doubtis asvital a questionwith them as with anyother animalsand on thisaccount the birds have come to occupythe par- ticularregions best supplying their wants. I•n the West the Downy Woodpeckerfrequents the willowsand creek beds,orchards and valleydistricts, where it is constantlyon the lookoutfor grubsand larvae,digging them out of bark or spearingthem with its long pointedtongue, while the Hairy Woodpecker,a stronger,hardier bird, occupiesthe mountainousdistricts and seemsespecially to lovethe pineforests. Many specimensindicate this by the telltale pitchleft ontheir breasts. In the depthof winterit is foundaway up in theBoreal Zone of theSierras, making the chips fly in search of its favoritefood, undisturbed by the rigorouscold. However, it is notan abundantbird and is veryshy of man. Whenyou ap- proach,it sidlesaround on the other sideof the limb and watches youwith one eye and if it suspectsinjury in theleast, is gonein a moment,swinging high over the treetops uttering its shrill,quick peek,peek. As mentionedbefore, the Hairy Woodpeckerdiffers more or less in differentregions, and has consequently been split up intoseveral subspeciesor varietiesby systematists,who recognized the differ- Vol.1906XXIII'] J JENKINS,Variation in theHairy Woodpecker. ]63 164 JENKZNS,Variation in theHairy Woodpecker. 1April[Auk encesas soonas materialbegan to accumulate. Linnaeus• in his 'SystemaNatural' of 1766first formallynamed the species.He gaveit thespecific name of •:illosusand placed it in thegenus Picus. This genuswas later restrictedto certainEuropean and the genusDryobates was proposedto includethe American form,so that ourHairy Woodpeckerhas become Dryobates vill9sus. In 1783 Boddaert 2 discovered that the birds in Canada which re- sembledvillosus in markingswere considerablylarger, and since this differencewas constant he separatedthe Canadianform under the name Picus leucomelas.Some fifty yearslater Swainson,3 in examininga numberof specimensof the Hairy Woodpeckerfrom different parts of North America,came to the conclusionthat thoseinhabiting the southernUnited Statesshould have a sepa- rate name and he called them Pieus auduboni. He had but one specimen,from Georgia,and took the risk that othersfrom that localitywould conform to histype, and he provednot to havebeen mistakenin his conclusions.Audubon 4 discovereda new species on the Columbia River in 1839, Malherbe '• another in southern Mexico in 1845,and Cabanisø in 1863 separatedthe southern California bird from Audubon'sharrisi and calledit Dryobates hyloscopus.Audubon's bird wasa verydark-breasted form, dis- tinct from anythingyet known,while Cabanis'sbird was a light- breastedform, morelike the easternvillosus, but yet with certain characters(to be mentionedlater) separatingit from villosus. In rather recent years, as more specimenswere acquired,the Cabanisform was found to includemore than onerace. Anthony7 describeda larger bird from the Rocky Mountainsand Nelsons found differencesin specimensfrom the arid tablelandsof north- ern Mexico. When we get togethermaterial from all over North Americawe find that all the Hairy Woodpeckersbelong to one species,and

Linn., S. N., ed. 12, I, 1766, p. 175. Boddaert, Tabl. P1. Ertl., 1783, p. 21. Swains. in Sw. & Rich., Fauna Bor. Am.. II, 1831, p. 306. Aud., Orn. Biog., V, 1839, p. 191. Malherbe, Rev. Zool., 1845, p. 374. Cab. & Heine, Mus. Hein., IV, ii, 1863, p. 69. Anthony, Auk, XV, Jan., 1898, p. 54; ibid., XIII, Jan., 1896, p. 32. Nelson, Auk, XVII, 1900, p. 259. Vol. XXIII] 1906 J JENKINS, Variation in the Hairy Woodpecker. 165

.j 166 JEerings,Variation in theHairy Woodpecker. kApril[Auk

Boddaert'sleucomelas and Malherbe's]ardini are subspeciescon- neetedby linksstill existingfor the wholelength of North America. In Dryobates•illosus leucomelas the underparts are entirely pure white. The upperparts are blackexcept for a white stripedown the back. The crown and sides of the head are black. There is a whitestripe over and behindthe eye,and anotherrunning from the nasaltufts aroundunder the eye to spreadon the sideof the neck. In the male there is a scarletnuchal band whichis wanting in the female. The young of both sexeshas the whole crown partly red or yellowish. The outer feathersof the tail are white and the inner black. The wingsare marked profuselywith white spots. Analyzingthe wingwe find that the primarieshave four to seven large round spotson either web which are placedequally distant apart. The proximalfour spots are always present and each of the threedistal ones, although generally present in all primariesexcept the first, is lesspersistent than its respectiveproximal neighbor. Thus the seventhor mostdistal spot is oftenabsent, especially in the shorterprimaries. The secondarieshave five spotson the outer web, which are round and as large as the width of the web permits. The inner webhas six spots, which are quitelarge, and the two proximalones are confluent. The greatercoverts have four spots,as shownin the figure,and the lessercoverts are crossedby two bars. Rarely, spotNo. 1 is omittedfrom the greatercovert and in the lessercovert there is a slightvariation tending to shortenthe longaxis of the proximalbar. The range of this form is northernNorth America from the interior of Alaska (Ft. Reliance)to Labrador and southto about the northern border of the United States. It does not include the PacificCoast region. D•:yobates•illosus •illosus is muchthe sameas D. •. leucomelas in colorationand markingsbut is a decidedlysmaller bird. The pri•nadesand secondarieshave on the averagethe samespotting pattern,but the three-spottedgreater covert predominates over the four-spottedform, and many of the mediancoverts have, instead of two bars, two roundedor irregularlyshaped spots which are rarely coalescedto form a centralstreak. Vol.1906XXIIIq J Jr.NK•NS, Variation in theHairy Woodpecker. 167

Its distributionis the UnitedStates east of the RockyMountains and north of about 35 ø N. Lat. Dryobatesvillosus auduboni of the southcrnUnited Statesis a small dark bird. The wing spottingis very.little differentfrom that of the other two forms just mentioned. The spotson the primaries and secondariesaverage very slightlyless iu number. Of coursethey are smallerin size than in leuco•nelas,but com- pared with the size of the feather they are relativelythe same. The greatercoverts have lost spots 1 and 2 but 3 and 4 are alwayspresent. The mediancoverts have a singlespot which is variablein sizeand shape. Comparedwith leuco,r•elas, auduboni is extremely different. Com- paredwith villosusthe differenceis not so great. Bet•veenthe ex- tremesof thesesubspecies there are intermediatesin size. So that if we proceedfrom north to southwe find a gradualand certain decrease in size. One writer t records a distinct linc between auduboniand villosusin the southernAlleganies. He saysthat he found •illosusoccupying the Balsamregions above 4000 feet, and auduboniin the lowlandsup to 4000feet, and that all birds'are easilydistinguished. Very likely intergradationdoes not take place at that point. However,it cel•ainlydoes at otherlocalities. Proceedingfrom eastto westwe find the birdsgradually losing the white wing spots,and when we reach the Pacific Coast the closedwing showsbut little white. In the southwesternUnited Stateswe have Dryobatesvillosus hyloscopus.It is morenearly the sizeof D. •. villosus. The under partsof someexamples of hyloscopus,on closeexamination, show a slighttinge of brownishred, but the distinguishingcharacter is foundin the spottingof the wing. Thc outerweb of the primary has but three spots. These correspondwith the threeproximal spots of the eastern form, but are much reduced in size. The inner web hasretained the four proximalspots, which are also reducedin size. The secondaryhas lost all but the mostproximal spotfrom the outer web. The inner web has the samenumber of spotsas that of the easternbird, but the spotsare smallerand the two proximal onesare not confluent. The greater covertshave only spot No. 4 left. The median coverts are either entirely black or have a white streak down the center. This form is

• Brewster, Auk, IIl, p. 104. 168 Jg•I•s, Variationin theHairy Woodpecker. [April[Auk found in California, Lower California, Arizona, and New Mexico.. Someof the specimensat hand fromNew Mexicoare intermediate in spottingbetween the westernand easternforms but are nearer the western. Dryobates•illosus harrisi has the wing spottinglike hyloscopus but the light partsare a deepsmoky brown. The extremeof this form is found at VancouverIsland and alongthe coastregion of British Columbiaand Washington. There, all birds are uniform smokyand the wings have a uniformscarcity of spots. In northern Californiaand southern Oregon, harrisi and hyloscopus intergrade. In the SiskiyouMountains are found birds that vary from pure white to very dark. At Sitka, Alaska, harrisi has becomevery muchlighter and somespecimens show a great increasein wing spotting. Three specimensfrom Ducks,B. C. (a regionbetween the Rocky and CascadeMountains), have charactersof both leu- comelasand harrisi. The under parts are pure white while the wings are scarcelyspotted. A fourthspecimen from the same localityis profuselyspotted and hencenearer leucomelas. Dryobatesvillosus monticola, found in the Rocky Mountains from Coloradoto Montana, has a scarcityof wing spotslike the other westernforms but is largerthan hyloscopusand the under parts are said to be pure white withoutany reddishtinge as with somehyloscopus. (In the seriesat hand there are few specimens of this form, but I believe that when more material has accumu- lated, the rangeof D. v. monticolawill be foundto extendno far- ther south than Colorado or farther north than southern Montana and will includeUtah, northernNevada, easternOregon, south- easternWashington and southernIdaho. The evidencefor the southernboundary is the fact that D. •. hyloscopusreaches its maximumsize in the northernSierra Nevadaswhile specimens fromArizona and New Mexicoare comparatively quite small. The northernboundary is indicatedby intermediatesbetween D. •. leu- comelasand D. •. monticolataken in Montana. And if any form is to be found in the arid interior of Washingtonand Oregonit wouldnot likely be D. •. harrisi,since that form is not foundout- sideof the Humid CoastBelt in Alaska.) Dryobates•illosus jardini is smallerthan hyloscopus,the under parts are very dark, and it inhabitsthe mountainousportions of Central America and Southern Mexico. Vol.1906XXIII'I / J•NK•NS,Variation in theHazry Woodpecker. 169

Dryobatesvillosus intermedius, ranging in the territorybetween hyloscopusand jardini, is smallerthan hyloscopus,larger than jardini, and is alsointermediate in smokinessof the underparts. Besidesthe eight subspeciesmentioned, there are two island formsthat arenot known to intergradewith the continental species. Dryobatespicoideus • inhabits the Queen Charlotte islandsoff BritishColumbia. It hasthe whitestripe on the backbarred or spotted,and is entirelydistinct from any otherform. Dryobatesmaynardi includes two subspecies,D. m. maynardi• of the southernand D. m. l•igera of the northernBahama Islands. In 'The Auk,' XXII, April, 1905,pp. 12•J•126, Mr. Allen has shownthat l•iger and maynardiintergrade, but it seemsthat neither one intergradeswith the mainland auduboni. (The name Dryobatesmaynardi 191ger (Allen) is more nearly correct than Dryobatesvillosus piger Allen, if we wouldfulfil the require- mentsof "the test of intergradationfor subspecies."ttowever, havingrecognized the subspecies,it is to be admittedthat'the com- binationis reallyof minorimportance.) Viewingthe Hairy Woodpeckersas a wholewe seethat there are certainvariations in the structureof the birds corresponding to certainregions. Why thesevariations e3:ist we cannotsay with certainty. It is probablythrough natural selectionand the sur- vival of thosebest fitted to escapefrom enemiesor to obtainfood in the particularregion that they inhabit, but why a profusely spotted bird can get along better in certain localitiesthan in others,and a large bird can get along better in the north than in the southis hard to say. Taking up the linesof variationseparately we have first, the Spotting:-- It is plainthat the spotson the innerwebs and proximalends of the feathersare more persistent.So we might reasonthat the westernbird is morehighly developed, as follows: that the spots so commonamong the Woodpeckerswere originallydeveloped for somegood service, as for directivemarkings, etc.; but to make thebird less conspicuous while climbing up darkcolored tree trunks, the white on the outsideof the closedwing was greatlyreduced.

• Osgood, N. Am. Ftmna NO. 21, 1901, p. 44. 2 Ri(lgwt•y, Manual N. Am. Bds., p. 282 (1887; see Cory, Auk, 1886, p. 375). s Allen, Auk, XXII, 1905, p. 124. 170 JENKINS,Variation in theHairy Woodpecker. I.[AukApril

Thus notonly would the bird morenearly resemble the background, but the attractivefeature of largewhite spots on blackfeathem would be doneaway with. To reducethe white on the closedwing it was only necessaryto eliminatethe spotsfrom the exposedportions of thefeathem, namely the outer webs and the endsof theflight feathem and coverts,for the innerweb of eachflight feather is coveredby the outerweb of the precedingfeather and onlythe distalends of the covertsare exposed. This is just what we have in the Western Hairy Woodpeckerwing. The spotson the outerwebs of the see- ondariesare reducddto a singleone at the baseof each feather, whichis alwayshidden by the greatercoverts. The spotson the exposedparts of the greatercoverts are reducedin numberand size,or morecmnmonly are entirelyabsent, and the spotson the median coverts are either absent or reduced to a mere streak. Sev- eral spotson the outerwebs of the primariesstill persistbut they are fewer in number and are much reduced in size and are, con- sequentlyvery inconspicuous. When the bird is in flightit doesnot needthis protective colora- tion but probablydoes need the spotsfor the sa•nepurposes for whichthey wereoriginally developed, and we find that nearlyall of the spotson the pa•s of the wingthat wereune•rposed when it was closed,namely those on the inner websof the flight feathers, are still retained. The inner web of the secondaryhas lost only the outermostspot, and the inner web of the primary the three outer spots,but thesewere the smallestspots in the easternbird and of the least importance.When the bird flies, the wing is thrown up as often as down, and the strikingcontrast of white and black is about,though not entirely,as effectiveas beforeto all observersexcept those that may be directlyoverhead. Thus we have the leastpossible contrasting shades on the bird at rest combinedwith the greatestpossible contrasts on the bird in flight, and given that the contrastin flight is of use to the bird, then this combinationis an advantageand was devel- opedas such. Could this theorybe absolutelyproven we wouldstill have to explainwhy all of the Hairy Woodpeckershave not developedin like manner. If we draw a geographicalline betweenlight and heavilyspotted forms this line wouldin part coincidewith the geo- graphicalline betweenthe Arid West and Humid East. But I Voi.1906xxIII] J JE•K•s, Variationin theHairy Woodpecker. 171 greatlydoubt if aridity and humidityhas anythingto do with the wing spotting. We might say that the more highly developed form has had more enemiesand more competition,but such a statementneeds yet to be proven. As for the darkeningof somecolors of birds, it has been said that it is an advantagein any humidregion xvhere there is a great deal of shade. So we find the rangeof the darkestwoodpecker (D. •. harrisi)exactly coinciding with that regionof North Amer- ica whichhas the greatesttotal shade,namely the PacificHumid CoastBelt. D. q:.jardini is saidto inhabitan extremelyhumid regionin southernMexico, but scarcityof data from that region preventsforming definite conclusions in regardto it. If we draw geographicallines separating forms of equal size, theselines will nearly coincidewith parallelsof latitude. Very likelyeither the morerigorous climate of the northhas eliminated all birds exceptthe larger and hardier, or else there is a direct physicaleffect on the individualcausing it to growlarger. It is a strangefact that the DoxvnyWoodpeckers vary exactly as the Hairy in size,wing spottingand coloration,and for every continentalform of the Hairy Woodpeckernorth of Mexicothere is a correspondingform of the Doxvny. In Mexico the latter is not found.

AYERAGES OF MEASUREMENTS (IN MILLIMETERS) OF THE FORMS OF Dryobales

Form No.of' Toe Claw Tail Wing Bill I SpecimensSc•Tarsns

24 18.5 10.5 82 129 33 D,,.v,;leucomelas I 25 18 10.5 79 128 33 D. v. villosus 22.5 18 10.5 79.5 125 33 21 t7 10 76 121 29 D. v. auduboni 21.5 17.5 10 64.5 113 29.5 20.5 16 10 68 115 29 D. v. harrisi 23.5 18 10.5 79 128 32 23 18 10 80 124 31.5 23 17.5 10 78 126.5 33.5 D,,.v,l bylos,,copusi 22 17 10 77 123.5 30 D. v. hyloscopus• 22 16.5 10 75 124 32 21.5 16 9.5 75 122 28 D. v. monticola 23.5 17.5 10.5 83.5 132.5 34.5 21.5 16 10 85 130

California• north of 35 ø N. L•t. Except C•lifornia• north of 35 ø N. Lat.