THE AUK

A QUARTERLY JOURNAL OF

ORNITHOLOGY

VoL. 77 JULY,1960 No. 3

COURTSHIP AND TERRITORIAL BEHAVIOR OF HAIRY

LAWRENCE I,[ILHAM

THE presentstudy of a pair of Hairy Woodpeckers( villosus),made in a swampnear Seneca,Maryland, indicatesthat this specieshas a lively courtshipin which the femalemay attract a mate to her fall and winter territory by drumming and then join him in display flights. I observedthis behavior in the pair HF-HM from mid-October1958, until nest excavationin April 1959, in all a total of 130 hours. The phenomenadescribed are not readilyobservable in any one year, and I have encounteredthe prolongedtype of pair formation in only one of the yearsfrom 1951 to 1960 in which I havebeen study- ing Hairy Woodpeckersin the sameswamp. Thesebirds appear to be moreor lesspaired the year aroundunder usual circumstances. Hairy Woodpeckersare not easy to study in woodedcountry, and this may explain why publishedaccounts of their life histories,such as thoseof Bent (1939), are far from complete. Hailman (1959), for example, has pointedout that the drummingof female Hairy Woodpeckersis not mentioned in most accounts. As describedbelow, the female HF did an extraordinaryamount of drumming. Individual recognitionof the woodpeckersstudied became possible with closeand prolongedobservation. Figure 1 givesthe headmark- ings by which I distinguishedHF and HM as well as of two other Hairy Woodpeckerswith whichthey had occasionalcontacts. Certain featuresof habitand territory,given below, further aidedin the recog- nition of individual .

TERRAIN AND TERRITORY Territory and drum trees. Observationswere centralized in the terri- 259 260 K•n_x.•t,Courtship ofHairy - •[%odpeckers [ Vol.Auk 77

M.LE$ FEMALES Figure 1. Variations in the black and white markings on the heads of four Hairy •Voodpeckers,which aided in recognitionof individuals. The male HM and the female HF are represented by the two central figures. tory of the femaleHF, wheremost of the courtshipand the later nest excavationtook place. The terrain consistedof a rim of trees sur- roundingthree to four acresof open swamp. Sincethe openarea was dry duringthe fall and was frozenduring muchof the winter, I was able to walk aboutthe centerof I-IF's territory and adequatelyview her activities. There were severalindications that the territory of I-IF had fairly definiteboundaries. One was that shecontinually made rounds of certaindrumming trees, of which three were visitedon many occa- sionsand five otherswith lessfrequency. She wouldalight at particu- lar spotswhere she could obtainthe greatestreverberation. The farthestdistance between regular drum trees was 450 yards(Figure 2). The width of HF's territory was in the vicinity of 250 yards,as esti- mated by the locationsof conflictsand distancesbetxveen two of the main drummingtrees. The male HM had an adjacentterritory, ap- proximately400 yards long, but I had less completeobservations on its dimensionssince •nost of the activitiesconcerned xvith pair formation took placein the territory of his mate. Territory and conflicts. A secondcircumstance that servedto estab- lish the boundariesof HF's territory consistedof sevenconflicts with intrudingHairy Woodpeckersthat I observedin boundaryzones (Fig- ure 2) in the courseof nine months. Five of theseconflicts were be- tween females,and two were betweenrival males. There was a ten- dencyfor conflictsto be repeatedin the samezones, for two of the female conflictswere in one zone and two took place in another. Con- flicts in a third zone were of a differentpattern. On 14 March HM fought another male, and on 21 March 1959, his mate HF fought a rival femalealong the sameboundary, which was not far removedfrom the tree where HF excavateda nest hole in late April. Nest sites of three different years bunched. The territory of HF July19601] KILI-IAM,Courtship ofHairy I•oodpeckers 261

TERRITORY

OF

b ß "

ß DRUMTREES OF 9

I •O YARO5 I O •T HOLES • CONFL•TSWITH RIVALS Fibre 2. D•am of •e fall and win•r territo• of the female Hai• W•ker HF, show•g the l•tions of her main d• wees, the zones of •da• conflicts,and •e ncst sitesof th• su•essive years.

was not only the site of nest excavationin 1959, but also of nest holes whereI hadobserved parent Hairy Woodpeckersfeeding their young in 1957 and 1958 (Figure 2). The three nestholes were within a distance of 100 feet.

PAIR FORMATIONIN FALL ANDWINTER Drumming.I hearddrumming from HF's maindrum tree during Septemberand October 1958, but it was18 October before the swamp becamedry enoughfor me to start consistentobservations. The female HF drummedhundreds of timeson favorable days. Sucha daywas 8 November.HF begandrumming at 7:45A.•., whenthe swamp was coveredwith frost and skim ice. She drummed 54 times in five minutes on what I called her China Tree becausek had a reverberationand tone,due to its hardness,which I couldrecognize at 800 yards. Her drummingrate of 11 burstsa minuterepresented an intenselevel of behavior.This intensitywas also reflected in anothertype of drum- mhlg. At about8 A.M.,On the samemorning, I foundHF feeding 262 KH•H^•.r,Courtship ofHairy Woodpeckers [ Vol.Auk 77 amonglow willows,but pausinghere and there to drum one or two burstsin placesof no particularresonance. She drummed19 bursts on eight differentspots within 10 minutes. It appearedas if shehad a great urge to drum even when feeding. I watchedher drumming from 2:35 P.vt. until sunsetof the sameday, and by dusk I had heard her drum at least 400-500 times. The drummingof HF was particularlystriking becauseno other speciesof woodpeckerin the swampdid muchdrumming during the fall, and because,with continuedobservation, it becameobvious that HF was trying in a persistentfashion to attractthe male HM. This situationwas clearly seen on 9 November. On this day, HF drummed a total of 98 bursts in 20 minutes as she moved from her main China Tree to a dead willow closeby the territory of her mate HM. She stoppeddrumming as soonas he flewacross to join her. The pair were togetherfor about15 minutes. HF did not alwayscome close to HM's territory when trying to attract him by her drumming,for she often drummedon her Low Tree, which was nearly450 yardsaway, and he wouldfly to her there. On 26 December,for example,HF's drumming rangout clearlyfrom a hollowportion of the Low Tree. I watchedas sheflew to the top of an adjacenttree as if expectant,then flew to join HM in the top of a deadelm right abovewhere I stood. Suchmeetings were alwaysof muchthe sameform. The two birdsabove me rested within aboutfive inchesof eachother withoutdisplay of any kind and exchangeda rapid jeek, jeek vocalization.

Figure 3. Duet flight of the pair of Hairy Woodpeckers HF-HM, whleh took place above the treetops, usually over the territory of HF. July1960 ]1 KXL•XAM,Courtship of Hairy Woodpeckers 263

Displayflights. HF and HM usuallylaunched themselves off on a displayflight after their ]eek,]eek greetings.I termedthese perform- ancesduet flights. When standingin the centerof the swamp,I could watch the two Hairy Woodpeckers,one rising and one falling as they swunggreat bounds and loops above the treetopsof HF's territory,now one and now the otherin the lead as if withoutapparent aim. These flightswere not pursuits; HF and HM wouldalight peacefully,fairly closetogether, in pausesbetween flights. The duet flightscentered, primarily,over the woodswhere the 1957,1958, and 1959nest excava- tions were all located(Figure 2). HF performeda secondtype of display. I termed it the Floating Flight, and I had viewsof HF in theseflights on six occasionsbetween 1 Novemberand 28 December1958. A floatingflight on 8 November was of specialinterest. HF had done much drumming,as described above, and had participatedin many duet flights with her mate. At sunset,which was about4:30 P.M., I was standingin the openswamp when HF, flying toward me in boundingflight, suddenlybroke into a batlikeflutter with alternationsof floatingwith wingsheld motionless, at an angleof 45 degrees. She made tweeck,tweeck notes at the same time. I have not heardthese notes from a Hairy Woodpeckeron any other occasion. HF alit on a dead oak, drummed five or six bursts,

Figure 4. The female Hairy WoodpeckerltF in a floating display flight. then went off on a longflight up swamp,as I presumed,to roostfor the night. Thesefloating flights of HF alwaystook place when she was flyingto or awayfrom a meetingwith her mate. If maleHairy Wood- peckershave a similardisplay flight, I havenot observedit. 264 K•Lu^•,Courtship ofHairy Woodpeckers [ Vol.Auk 77

Tapping. The tappingof the Hairy Woodpeckerscame as a surprise, for it was doneunder different circumstances than thosethat I (1958) had observedfor Red-belliedWoodpeckers (Centuru,r carolinua). The tappingof both speciesis at a countablerate of two to three taps a second. HF had drummedalmost incessantlyduring the morning of 22 Novemberwhen, at 11:30 A.•., she alightedon a small tree 30 feet from me. She now tapped9 or 10 times,loud and clearly,paused, then tappedeight more seriesfor a total of about80 taps. I heard HF tap on four occasions between 9 November and 7 December. None of this tappingwas associatedwith any obviousnest hole, but on 1 February 1959,I sawHM fly to a freshexcavation and tap threebursts just below it. I believedthat HF wasnearby for I heardjeeks. The excavation belongedto a pair of Red-belliedWoodpeckers, which nestedin it the followingMay. Conflicts. HF was facinga rival femaleat one of her territorial boundaries in each of the five conflicts that I observed between Novem- ber 1958and March 1959. A conflicton 17 Januarywas representative. HF alit on a tree trunk abovethe intruder, pointingher bill upward and almost backwardas she did a bill-waving dance,which involved jerking of her head and body as well as half-startingmotions with her wings. Her rival posedas if frozen with her bill pointedstraight for- ward. HF droppedto a lower position,then pursuedher adversaryup the trunk. Suchdance displays are carriedout by both sexes,but all conflictsI haveobserved have been between Hairy Woodpeckersof the samesex. Conflictsare silentaffairs if only two woodpeckersare en- gaged. If a third , a mateof oneof the participants,is nearby,one may hear vocalizationssuch as chewi, chewi or ]eek, ]eek. I heard bothof thesenotes on 17 January. Skutch(1955) has givena good descriptionof two male Hairy Woodpeckersdancing in conflict.

ACTIVITIES oF THE MALE A lane, which servedas a boundarybetween the territoriesof HF and HM (Figure 2), affordedme a wide view of the exchangesof visits betweenthese two woodpeckers.The femaleHF made only occasionalvisits to HM's territory. I wouldhear an exchangeof jeeks, but I neversaw her drumnor did I witnessany duet flightson his side of the lane. HM visitedhis mate'sterritory far more frequently,in responseto her persistentdrumming. He, however, sometimestook the initiative. I heardhim beginto drum on a numberof mornings during the fall and winter at times when HF was silent. He would move to drum trees successivelynearer to her territory, and on 7 July196011 Kt,.tt^•t,Couriship of HairyWoodpeckers 265

I-iF FigUre5. A conflictbetween two female Hairy Woodpeckers along the territorial boundary of HF. The owning female HF threatens by jerking her body about and waving her hill while the intruder (upper figure) has tem- porarily assumed a frozen pose. 266 KILHAM,Courtship otHairy Woodpeckers [ ¾ol.Auk ??

Decemberhe finallyalit on a deadlimb by the lane. His headfeathers were raisedas he calleda sharpspeck, speck. I then heardleek, leek and watchedhim fly over the boundaryto join HF on a baretreetop. Within a minutethey flew off togetherin a duet flight. The pair of woodpeckershad duetsof drummingin whichthey appearedto be answeringeach other, although each remained within its own territory. An examplewas 13 December.I was standingin the laneat dawnwhen I sawHF fly to her ChinaTree at 7:28 ^.•. She drummedat a rate of eight to nine timesa minutefor the next 22 minutes. H1V[began drumming after shehad started,and, as in other duets,his drummingcame at only half of her rate so that I heardtwo burstsfrom HF for every one burst from him. HM spentincreasing periodsof time in HF's territory as the winter progressed. He occa- sionallydrummed there, but in a weakmanner, on indifferentplaces, and he never usedher main drum trees. I locatedhim far up in HF's territoryon 17 and 18 January. On eachmorning he ascendeda num- ber of trees,drumming at the basesof small,dead limbs as he did so at rates of up to nine times per minute.

NEsT-HoLE ]•XCAVATION The pair HF-HM becameless demonstrative in late winterwhen the drumming and breedingactivities of Downy (D. p•bescens)and of Red-belliedwoodpeckers became increasingly evident. HF continued to drum on her main China Tree but at a slower rate and in a more sporadicfashion. The last extensivedrumming that I heard from her was on 7 April 1959, when she drummedfor 40 minutesat a rate that varied from three up to infrequentperiods of nine times per minute. HF and HM becameincreasingly difficult to locate. I was excited, therefore,on 25 April to discoverthat HF was excavatinga nesthole in a living ash tree, 40 feet abovethe swampand 50 feet from the nest hole of the previousyear (Figure 2). HF did all of the excavating during the two morningsthat I observedher. Her activitieson 26 April were of particularinterest. She was working out of sight, but she cameup at intervalsin order to throw sawdustfrom the entrance. She threw out 37 billfulsin one successiveepisode. Within a half-hour period she cameout completelythree times, flew to a main drumming tree nearby,and drummedbriefly. It appearedthat she wantedHM to visit her. When he arrived, whichwas usuallywithin a few minutes, he might visit the excavationfor a brief look, fly to her at the drum tree, and exchangea variety of notesranging from leek to foick and chevY. HM wouldthen fly away,leaving his mateto excavatealone. July1960 j] KILItAM,Courtship of Hairy Woodpeckers 267

Whena pair of Bluebirdscame by to lookinto the excavation,the femaleHairy flew at themwithout excitement. The situa- tion changedwhen a Starlingarrived. HF now displayedby uptilting andwaving her bill whilejerking her bodyand starting her wings; the samethreat display she had usedagainst territorial intruders of her own species.I neverencountered HF after 26 April. There wasnever any sign of actualnesting during the next month,although the excavation was completedso far as I couldtell by havingmy sonexplore it with a probe. I found HM back in his original territory but without evidence that he hada matein May. It is possiblethat HF hadbeen killed.

COMPARISONSWITH OTHER WOODPECKERS The aboveobservations were made on a singlepair of Hairy Wood- peckers. Consideringthe wide territoriescovered by thesebirds, the shynessof the females,the difficultiesof recognizingthe sex unlessthe individualwoodpecker has its backto the observerand is not too active, it would appearthat a satisfactorylife historyof D. villosusmay be workedout only by concentrationon favorablesituations such as I have described.The findingswere not altogetherunique. A secondpair of Hairy Woodpeckers,located 1,000 yards farther downin SenecaSwamp and observedfrom 23 Novemberuntil 6 December1958, paralleledthe pair HF-HM in the followingrespects: (1) The femalewas extremely shy and restless,taking long, boundingflights from one end of her territory to another. (2) She drummedat a fast rate of 8-11 times a minute,and shedrummed more frequently than her matewho drummed at only one-halfher rate. (3) The male was not only easierto ap- proach,but his sharpcall speck,speck made him lessdifficult to locate. His mate resembledHF in never makingthis vocalizationunder ordi- nary circumstances.Inaccessible terrain madea detailedstudy of this secondpair nearly impossible. In his studieson bandedHairy Woodpeckers,Shelley (1933) de- scribed two instances where females took the initiative in the selection of nestingterritories. In one casethe femalealso selectedthe nest site, and her mate rarely came near while she was excavating. He might, however,come to a tree 40 feet away xvhereshe would join him. "I shouldexplain that with this specieseach sex has a separateterritory, that of the male being closeto but separatefrom the female'sterritory. The male occupieshis territory exclusivelyduring the winter.... " Shelley'snote giveslittle descriptionof methodsof communication.It states,however, that when the male and the female of one pair came togetherin the spring"there was no activemating display." The pair 268 KILa^•,Courtship ofHairy Woodpeckers [ Vol.Auk 77

HF-HM likewisecarried on little displayat this season.My hypothe- sis is that Hairy Woodpeckersare more or lessmated the year around and that performancesassociated with initial pair formationare not alwaysobservable in any oneyear in one locality. This mayapply also to PileatedWoodpeclcers (Dryocopus pileatus). In years of observa- tions on this species,I have only once (1959b) encounteredan indi- vidual activelyseeking a mate. This particularwoodpecker, a male, did a great deal of drummingwithin a territory 700 yardslong, the length having been determinedby the greatestdistance between his main drummingtress. The lead of the femalein pair formation,which I havedescribed for D. villosus,is alsocharacteristic of someother speciesof the Dendrocopos.The Great SpottedWoodpecker (D. major) offersa closecomparison to D. villosusif oneconsiders the followinginforma- tion: (1) Pynn6nen(1939) hasdescribed a duet flight (Hintereinan- der-her-Ja#en)and a floatingflight (Schwebeflu#)in the courtshipof this Europeanspecies. Both sexeshave red under tail covertsthat are displayedin the Schwebeflu#.Blume (1958a) hasmade an illustrative sketchof this performance.His term flaternd-schwebendenFlut7weise is especiallydescriptive of the floatingflight that I observedfor D. villosus. (2) In furtherobservations Blume (personal communication) foundthat two ringedfemales of D. •najorremained on theirbreeding territoriesthe year around whereas the males changed. The drumming territoriesof thisspecies are 400-500 meters long. (3) Blume(1958b) has alsodescribed the tappingand drummingof the .The circumstancesattending the tappingparallel those found for D. villosus. The DownyWoodpecker is, in my experience,the mostdifficult of easternwoodpeckers to study. Its activitiestake place with surprising quickness,and sex recognition,if one wantsto make it in a matter of seconds,is not alwayspossible. Shelley, however, as quotedby Bent (1939), statedthat "the femaleselects the nest site on her winter or year-aroundterritory." In conclusion,it wouldappear that at leasttwo patternsof early breedingbehavior are recognizableamong woodpeckers. In one of these,as represented by Centuruscarolinus (Kilham, 1958) and Melan- erpeserythrocephalus (Kilham, 1959), the maletakes the leadin pair formationand tries to attracta mateto a potentialnest site by hisloud and repeatedbreeding calls. The attractionof a mate is different in somespecies of Dendrocopos.As illustratedby D. v•ilIosu,%the female may take the lead in pair formationand attract a male to her winter July09611 '[ KILH^M,Courtship o/Hairy •Voodpeckers 269

territoryby repeateddrumming. Neither the Hairy nor the Downy Woodpeckerhas a breedingcall. A comparativestudy of the breeding behaviorof theselatter two specieswould be of considerableinterest.

SUMMARY

1. The courtshipand pair formationof a pair of Hairy Woodpeckers, in which the female attractedthe male from his territory to hers, were studiedfrom October until the time of nest excavationin the following April. 2. The courtshipactivities of the femalewere most intense in Novem- ber and early Decemberwhen shemight drum 400-500 burstsin a day, at a rate of 10 burstsa minute. Such drummingmight go on for 20 minutesat a time. The male might respondby drummingat a rate of four burstsa minute from his territory. Drumming ceasedwhen he flew acrossto join her. 3. When the pair was in the territory of the female,the two birds usually (a) greetedeach other with the vocalizationjeek, jeek, and (b) restedwithin a few inchesof eachother, without display. (c) The pair might then have a duet flight over the treetopsof the female's territory. The male often returnedto his own territory after about 15 minutes. 4. The female sometimesdisplayed a floating, fluttering type of flight,accompanied by the vocalizationtweeck, tweeck, when approach- ing or leavinga meetingwith the male. 5. The femaletapped intensively during the late fall. Tappingby the male was observedon only one occasion. 6. The fall-winter territory of the feanalewas approximately450 yards long, and its boundarieswere markedby (a) the round of her drummingtrees and (b) the zonesof conflictwith rival Hairy Wood- peckersat the periphery. 7. Of seven conflictsobserved, five were between females and two were betweenmales. All took place at the female'sterritorial boun- daries. Both sexesdid a bill-waving,body-jerking dance when in conflict. 8. The male spentincreasing amounts of time in the female'sterri- tory during the spring. Drummings,vocalizations, and displayswere all diminished at this season. 9. The femaleexcavated a nesthole in late April in closeproximity to nestholes used by Hairy Woodpeckersin two previousyears. She appearedto do all of the excavating. 270 KII,HAM, Courtship ofHairy Woodpeckers [ Vol.Auk 77

L•T•A•u• CxT•

BENT, A. C. 1939. Life histories of North American woodpeckers. Smithson. Inst. Bull., 174: 13-45. BI.umE, D. 1958a. Verhahensstudienan Buntspechten(Dendrocopos major). Vogelwelt, 79: 65-88. BLUME, D. 1958b. fOberdie instrumentalenLautiiusserungen bei Schwarzspecht, Griinspecht,Grauspecht und Buntspecht. Vogelring, 117: 65-74. HAIl,MAN, J.P. 1959. Drummingby femaleHairy Woodpecker.Bird Banding, 80: 47. KILHAM, L. 1958. Mutual tapping,nest hole selectionand pair formation of Red-belliedWoodpeckers. Auk, 75: 318-329. I(ILZtAM, L. 1959a. Mutual tapping of the Red-headedWoodpecker. Auk, 76: 235-236. KILH•M, L. 1959b. Behavior and methodsof communicationof Pileated Wood- peckers. Condor, 61: 377-387. PVNN6NEN,A. 1939. Beltr/ige zur Kenntnisder Biologie FinnischerSpechte. Ann. Soc. Zool.-Bot. Fenn. Vanarno,? (2): 1-166. SHEt,L•¾,L. O. 1933. Some notes on the . Bird-Banding, 4: 204-205. SXUTCH,A. F. 1955. The Hairy Woodpeckerin Central America. Wilson Bull., 6?: 25-32. 7815 AberdeenRoad, Bethesda 14, Maryland.