,'liiest;. sitè selection by the Red-shouldered HawK (Buteo,lineatus) in sou~hwestern, Qvebec. llichaej, M.,J. Morris

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2 ' '' -' - ' ' - - -_I-v:_:_ -' _ ' ' ' - 'Iest; stè seecton by the Red-shoudered HawK Buteoneatus) n souhwestern Qvebec by chaej M J Morrs ) ' ' M Sc Canddate Department of Boogy McG Unversty Abstract ' - The patterns of nest'ste seecton by the Red-shoudered J àwk j Buteo neatus) wre studed ' 978 ahd'979at t'wo areas n soutw- --- < - western Québec n order'to nvestgate the potenta effects of ths behavor on reprodùctve sôcéess Hawks arrved n the- man study area Vaudreu County) by ate March and began nestng actvtes amost ' : mmedatey A comprson F of thrty nest stes and twenty-fve randomy ocate'd contro stes n that area ndrcated that there were sgnfcant Cp 005) dfferences n severa habtat features between the two groups The nests of' thë Red-shodered awk were typcay ocateé n the most mature sugar mape Acer saccharhm) or'beech Fagus grandfoa) tands _' -r;- ava ab e The nests were usuay ocated n mut-branch forks n the mdde of the forest canopy at a'bout haf of -the tota heght ex -= 49%) of the arge nest trees probaby provdng 'protecton for ncuba;tng aduts and nestngs from predaton and adverse env ronmenta condtons - j f j ) - 'here s evdence that same nestng pars y be -be ta toerate ca- - sderabe human actvty n the mmedate vcnty of ther nests a

3 r f c u' A arety of dscrmnant anayses werè used t? dentfy the habtat féatures whch contrbuted most to the sgnfca'nt p < 0;05) sep-;tj3to of tqe' nsstes from 'the contro ste's Prncpa components anayses dej;onstrated -that sutabe Red-shoudered Hawk nestng habtat as defned by the est stes comprses a recognzabe subsecton of the ayaabe forest habtat n the man study area The possbe mpcatons of these ndngs on the behavora mechansms of nestng habtat' seector by the Red-shoudered Hawk are dscused -

4 t f - - ' J - J ' La sfecton des s tes de ndfcaton par a Bus à Epauet'tes Rouses 'Buteo neatus) dans a sud-ouest du Québèc - > '' par r Mchae M J IDrrs Canddat pour M Sc_ Département de Boog' - Unversté McG - 'I '- q Résumé Les patrons de séecton de de ndfcaton par a use à Epauettes Rousses Buteo --'--'--'-' 979 dans deux régons du sud-ouet du Qubecafn d détetnner 'mpact de ce comportement sur e sucès de arrvées dans a régon d'étude prncpae Compte de Vaudreu) à fn de' mars et ont commencé es actvtés' de ndfcton presqu' mmedaement - - Une-comparson entre trente stes de ndfcaton et vngt-cnq stes ' contrôes choss au hasrd dàns cette régoi' a ndqu q' exste des dfferences sgnfcatves Cp < O:OD entre es deux groupes au nveau de puseurs des caractérstques strùcturaes forestères nds de a Buse à Epauettes Rousses sont typquement s tués dans des Les érabères Acer saccharu) ou des hêtaes Fagus grandfoa) matures ' En gené'ra' es nds sont 'supportés par puseurs branches et sont: stués au meu --ae a voûte à env*ron' à a m-hauteur x = 49%) des - 'rbre choss pour a ndfcaton Ces èaractérstques fournssent probabement aux adutes couvants et àux osons une protecton )

5 ) ' ç - C 'J :- ' f ' r suppémentare contre 'a préd4tdn et es ntempéres I es t evdert t ' que queques' pares nchantes peuvent toérer consderabement 'actvté humane à a proxm té de eus nds L'anayse en coiposan t:es prcpaes' demontrée que 'habtude convenabe' de a ndjfcaton pour a Buse à ; E:auet'tes Rousse te que déte par es 'stes de ndfa'ton une porton défne de 'habtue v comprénd forestère cspons'be dans_a régon 'J ' d'étude prncpae Puseurs es anayses dscrmnançes ont été utsés afr_d'antjfer 'quees caractérstques de 'habtude contrbuent à H a séparaj:qn IDfcat:VL cp < ) des _stes de-i}4fcton et Qes '# contrôes Les mpcaons pôss'des résutats sur es mécansmes comportejœnt;aux de a seecton- de 'habtude de n:dfcaton par a c Buse Epauettes Rousses 'sot dscutée; 0 p '[ ' - j ' ) J- I p t ' '- J r '

6 -- _ <-- _-- _r _ ' ' v : Prefaèe ' a' ' n accordance wth the régatons of the Facuty of Graduate Studes and eseafch and -the DepartIDent of ëogy ths thes's s prese'nted n the format of a pper co-authored w th 'my supervsor ' p Dr R Leman and desgned for submsson ta an approprate journa Add tona--matera jug' paper s' presémtea here' as appendces ta be unessenta for ncuson n ths ' Ths matera 5 referred' ta ' ;Ln the text' 'of hs thess as 'Appendces - 9 but' these w; be chat;tged to references to ths' thess e Marrs 980) when the _ paper à submtted' on the ptterns Ths - thess reports extensve orgna nformaton of nest ste seecton by the Red-sho'udered Hawk There had prvousy be;n very' tte nformaton avaabe on ths aspct o'f thespec::es' 'fe hstory n eastern Canqda C fed work data anays:s and the rtn A of the of the thess were done by Mchae Marrs R E Leman provded advce throughout the course - of the work and co'aboratd pper on the fna fqrmat and con tent of the t ' J 'f f r t ; r _-- :-:_--_''':''_'':'''''''-_''':'''J jm_'-':_

7 v - tudyof ths Acknowedgements type obvousy requ:' the assstance of a ner '; of peope anq wou<f- ke to thank ai those who heped me n the vadous stages of ths work Dr Davd M Brd qtgnay suggested the projeet to me' andoffered many hepfu suggestons on an earer verson of ths thessr _ Dr R E Lemon my supervsor provded expert advce and encouragement; ' Drs M -L Leehowcz and G Be the othef members of my commttee offered addtona suggestons durng the formatve stages of the study; Dr Lechowcz aso offered advce on the statstca anayses and read an earerverson of' Bruce Lyon Aber Kuhnk and Mrs Jo Wrght dv?ged nest ocatons the thess ) and other nformaton on oca - Red-shoudered Hawks to- me;' John Struger ;' Brenda Penak andbruce Lyon asssted n the 'sea:r;ch for addtona nests; Jeff ryant proyded vauabe assstance pud comradere du rng a dffcut 'phase of the feè work; Sara Gresbach fsssted wth the fed work the data compaton and the proofreadn& of the thess J E Hanna of Ontaro and Brenda Penak of the Macdonad Raptor Research Centre permtted use of ther unpubshd ata; me' to receve a copy of a pertnent- manuscpt; of Boogy Photographe Centre reproduced the fgures; Dr James Mbsher arraned for - - ' th staffoffhe Department ' Cena Neubrandt typed the tess; Yves Mauffette;and Lous Forter transated the abstracto Fnay woud ke to thank a my famy and frendforther support throughout the course of thsproject Ths esearch was supported Py grants from the Canadan Natona Sportsmen' s Fund R - 57) and the Natona -Scences and Engneerng Research Coune to R E Leman ) : J f j ' ' f - - -: L

8 L _ Tabe of Contents Abstract Reumé Preface Acknow e dgemen't Tabe of Contents : JI Lst of Tabes ' LsOt of Fgures Lst of Appendces In t ra duc taon Page H IV v v v x x ' - r ; J t-t; ' Study Area e Methods 'f Nest ocaton Characterzaton of nest stes ; Anayss of data Resu ts -- a-a Characterstés of nest s tes î 0 j 0 Dscrmnant functon anayss Prncpa omponents anayss - Dscusson ' L terature C ted ''<' ' Appences 49

9 v Tabe Lst of Tabes Page Me'an vaues of hab ta t features' Cs tandard devaton) at Red-shoudered Hawk nests and random s tes n Vaudreu County -sputhwestern Québec Sgnfcant and'near-sgnfcant dfferences n tree>speces rnean mportance vaues between Red- 3 shoude:ted Hawk nests and random s tes n Vaudreu County Québc --;-; - -;:-:-:- Dstrbuton of the two hghest mportance 5 vaues at Red-sh'oÙdered Hawk nest stes and contro stes n Vaudreu County : J 4 Characte-rstcs of nest trees seected by o Red-shoudered Hawks n sputhwèstern Québec o 0 000' o 8 5 Resuts of stepwse dscrmnant functon 6 anayss between Vaudreu County Redshoudered Hawk nests and random stes Correaton matrx for forest structura - ) varabes random s tes Vaudreu County ' 20 Québec _ 0 0 ' 24 7 Summary of the resuts of prncdpa components anayss of forest structura characterstcs random s tes Vaudreu County Québec 25 '

10 x Lt o Fgures Fgure - Q Thè ocaton of the two study areas VC and MSB) n southwestern Québe showng the approxmate northern' m t f the breedng dstrbuon Of ne Red-shoudered Hawk after Godfrèy 'f 966) 2 DstrbutunYr-Red-shoudeed fiawk nests a_d random stes wth respect te a stepwse dscrmnant functon 3 Ordnatf<on of random stes and Red-- P'age 3 2 ) -+_ shoudered Hawk nests on the frst rof'o components of a prncpa component anayss of forest structura features 27 '& } :; f t ' f' : ; - J '; '-_

11 - _ '''' -'-;-e-t '-k ' -«'' ' '-- T' _ ' ' ' _ : _w_n ----:- - L :_ ' :; ' Ust Of' Apnd:CeS ; - n - Appendx Page Scerttfc names commo names ad code numbers of 'ai trej taxa recorded dung sfûdy of nesf -- s te seecton by Red-shoudered Hawks p -< 2 t ---- southwestern Québec ' 49 ) sgnfcananà near sgnfcant dfferences n ) forstc and strctrà charcterstcs o fores t stands and physographc reatures at Red-shoudered Hawk nests at Vaudrèu County and Mont St Bruno Québec 5Q Resuts of stepwse dscrmnant functon anayss'offorstc composton varabes bèteen Redsnoudered Hwk nests nd'random stes n :-Vaudreu County Québec 5J --' ; -- '- x 4 - Smunary or the resu ts of a prncpa _ L components anayss ontree taxa mportance --vaues randon stes Vaudreu County t 5 - Qubec v I' - Ordna ton of random s tes and Red- shqudered Hawk nests n Vaudreu County Québecon the frst two components 'of a prncpa'components anayss of tree taxa < mportarce vaues '_-- _It_ 'f H - '

12 0 Lst of Appendces Coned) Appendx f 6 Sunnnary of )De resuts of prncpa: components Page' -' ana:yss of forest tructura forstc and ' 7 physographc characterstcs n Vaudreu t' County Québec ' 54 0' Ordnaton of random stes and Red-shoudered Hawk nes ts h Vaudreu County Québec on the hrs t ma componêmts of a prncpa ) component? aiayss of forest structura ' fostc h'))m ànd physographc characterstcs - 8 Matrx of Spearrnan rank correa-ton coeffcents 55 for mportance vaues of tree taxa at rando stes n=25)' n)vàuodru County Québec : : 9 Surnnary of esut- of Scrmnant_ functon anayses -on Red-f:houdered Hawk nests and randott s tes n sou thwes tern Québec : J ' - ' ' '

13 INTRODUCTION The restrcton of breedng actvtes to specfe types of hab:- tats has been noted for many speces of brds Howver the adaptve sgnfcance of such habtat seecton s often not mmedatey evpent and bas yet to be sasfactory<xpaned for many speces Thehypo- thess that ndvduas who seect approprate habtats w enhance ther ndvdua ftnthrough reproductve effcenc'y Kopfer and ' Haman' 965 Orans 97) has recenty recàved mted fed support Gbo et -a 976 Caccamse 9:}7 Keppe and Herzog 978 Brown and' I Goertz 978 wra and Whtmore 979) The mechansms 'of habtt see'c- ' ton contnue ta be nvestgated but muéh of the recent work on woodand c ' brds He;penhde 97 James 97 Anderson ad ' Shugart 974 Whtm'ore ) s based up9n the premse that the prmary proxmate factors Hden 965) used n the choce of nest stes are sorne forstc andor - structra aseccs of the vegetaton confguraton > Ths study nvestgates nest ste seecton by the Red-;shoudered Hawk non-jadom ) neatus n û southwestern Québec as refectec' n the varaton of habtat features qj nest stes and 'suggest& J SODe of the poetla effects of' ths beavor on reproduct;e Success The Red-shoudered Hawk nests n extensve stands tf )ature decdous - forests and sma farm wodots thr0ghout ts breedng range rn cént3fa ' { - - ' and northeastert' o'erca There has been consderabe concern 0 -r- ' expresse recentpeteron 69: Waac;e 99 Bro 97 Rackman and Henny 97 Henny e a 97: Bfdnarz '979) ver aparent decnes n numbers of mgratng and nes'ùng IRed-shoudered awks b n se-rerà parts 'F

14 o 2 of' the spces' range whch may have been caused n' part by the 055 of stabe nestng habat Snyder and Snyder 975) noted that n genera there has been a progressve 0ss of sutabe habtat for most raptor speces n the Unted States and suggested that - safeguardng habtat s the prmary'necessty n mantanng the nunftters of raptors at desrabe' eves Fyfe 976) reported that the Red-shoudere'd Hawk has a ow reatve abundance n sourhern Québec and that ts popuaton n ths area was denng Oueet ) 'camed that there has been a consderabe reducton of Red-shoudered Hawks n the Montréa regon of southwestèrn Qubec and fet chat forest L destructon wps probaby the most mportant factor affectng avan popuatons ths area --- UDY AREA Nest ses of the Rêd-shoudered were studed at 'wo' oca- tes n soùthwestern Québec: Fgure ) near the' northern tmt of the speces breedng range Godfrey 966) The man study area was about ti 200 km 2 n the northwest corner of Vaudreu County VC) ' N ' W) about 45 km suthwest of Montréa It ocated n the Upper St Lawrence secton of the' Great' Lakes - St Lawrence Forest Regon Rowe 72) of' frests Newstrom 978) noted that the mxed forstc composton ' n ths area refects the geographes 0cat9n qf Mont Rg'aud -n the tmston zone of the northern confer-:hardwood foest 0 wth a representaton of many' southern and 'borea speces Rowe 972) ' '- charcterzd the forest cover as broadeafed n' deep cacareou sos whe on s'aow acdc or erodng materàs a represerttaton of

15 ; ; I''''' - - '-<_'''''''''I''''''' J-t f' f't V' P:JI' ----r : r' ) FIGURE The ocaton of the 'tvudy areas VC a'n MSB) n outhwestern Québec showng the a'pproxmate rto';thern '> mt of the' breedng dstrfjuton * * *) of Red-shourered Hawk afte'r Godfrey 966) ) '' j

16 ---' _ * J o

17 '-'-'------_:-_ -_'- 4 confers s usua t The èotunt forest; type n the Uppe swrence ;: see'ton Rose 969 Rowe 972) s coposed of sugar mapie' Acer saceharum) and beech Fagu$ :gra'dfoa) wth red mape rubrum) -;-- _ yew brch CBetua aeghan:yss) bassooq Ta rcana) ohte '- ash C'raxnus amercana) argetooth aspen Pàpuus grantdntata) oaks Quereus spp) and a number of ocay occurrng speces Thft 'terran of ths stud$' are{ s generay fat' ta genty unduatng except for Mont Rgaud a reaty ow maxmum eevaton 20 m) prva-tey owned 40 km 2 mountan whch despte recent resdenta &Jowth remans amost competey coverd 'th a varety f forest assocatons <: Newstrom 978) Oueet 974) 'notd a 368% decrease nthe area of Vaudreu unty farm woôdots fron 95 o 96 'Currenty about 60% of ths study rea s forested much of t on Mont Rgaud Agrcùtura resdenta and ndustra actvtes oèupy the remaea A second study area of about 5 km 2 was ocated at Mont St Bruno - ;: MSB) maxmum eevato 27 -m) Verchères County ' N73 9' u W) about 6' km east of Montréa Ths area s nque geoogea hstory ' f Wather 963 Append-x 2) has resuted -tu pedographc c6arcterstcs ) and' forest assoéatons somewhat' dfferent from those n the man study o area About 75'% of ths area s curenty fotesd and human actvty n the area s rèat vey ght p The c mate n southwestern Québec 5 characterzed by warm and <Y humd'temperate summers a' ong cod wnter5 m'th a 'd;ep snow cover The mean ann)k& -temperature s 6C wth a mean ànnua precptaton of 9ft cm 7? èm of ran and 2 m of snw) The ast 'spr f'g frost ysuay ace urs n May and the frst fat f f frost n the frst k 'of- Octobe; ' 't ' f 0 r

18 - -- j _- ' - -t' > -'--' > ''----- > 5 gvng an average of 55 frost-free days per year The average monthy CI ' tem'perature and precpaton e +4 C and t2 cm n March977 and +7 C and 78 cm n Apr 977 gson 97 Newstrom 978) ' Nest ocaton METIIons Red-shoudered Hawk terrtores that ha'd been' used pror 'to 978 were searched fj[' actve nests from eary March' to the' end of Apr 978 Add:ona- nests n the mn study 'area were oeated by observng soarng terrtora hawks from eaï:'y Mrèh' to 'm-d-maft 978 and 979 A nests n tht St Bruno: :rea'[e ocate n te se manner by : 0 ' f nterested oca resdnts Actve' nests were rguary observed but - eare was taken not to dsturb the nes'ts n order to permt reproductve' :: actvtes to proceed unnterrupted Forty-fve nests used cby Red-;-shouLdered Hawks between '977 and 979 were found ncudng 27 n the V udrêùu County study area and 5 n ) the Mont St Bruno area For the purposes of anayss three addtona nests ocated n other parts of VadreuL County outsde the study ' area are ncuaed wth the nests' front that area These 45 nests were used by approxmate-y 23 nestng pars n the VC the MSB ares area and pars n Due to the arge sze 'of the man study area there' was no ssurance that a nestng pars wer ocated n ether '978 or 979 bot a representatve sampe of nests was found : Characterzaton of Nest Stes C After fedgng was competed:the vegetaton structure around each nest was examned ung a modfcaton of the method of James and J 0 f J r - { - J' J } ' ' J J

19 ' 0 'j Shugart 970) For pürposes of ths stud'y a nest ste 8 defned as the nest tree and a 77 ha cycua ara 75 n radu) centre on the nest tree Fve 004 ha car pots 28 m radus) were ocated at 'each nest one cêmtred on the ne st' tree and one randomy obated' n each o the four prncpa eompass t D ) up to 75 m from the nest In each quadrat' the speces an dameter at breast ght dbh 35 m above ground eye)' of a stems at éast 5 m ta wete recorded green vegetaton ess than 5 m n heght wa The percentage of ground covered by estmated n each quadrat by 20 sgqtngs through- an ocuar tube -James an Shugart 97) 'he - heght 9f the otsde eanopy' was measured wth a Haga atmeter a; the centre of each quadrat CTtus and Mosh:;t MS) The see es heght' an dameter at breast heght of a nest trees and eharaeterstcs of the nest r S octon n the Itree ncudng ts heght number of support eements and fork typ'e were recorded Topographe features measured at eaeh nest ste ncuded dstances from the nest ta 'tje nearest permanent and seasona water sources forest edge path road and hldnan habtaton The trat thee of these nd cate nearby potenta huntng' areas and the' ast three ;are r;oug measurés of nest ste seeuson from dfferent ntenstes of human actvty In arder to characterze the range and dstrbuton of potenta Red-shoudered awk nestng habtat and for purposes of eomparson wth habtat mea'surements taken at nests m ar data were aoected at 25 > contro stes wt'h randomy generatëd co-ordnates Whte and James 978 Montevecch '978 Burger and Shsà 978) n the VC study area' 'f ' Presumaby there w' be sgn fïcat dfferences n the means of any b - '

20 L' 7 factors mportant n the cho e of nest ng hab tat beten the Mat stes and the random stes A more extensve sampi ng of the avaabe hatat woud have heen desfrabe but was not possbe emnate ob:ousy unsutabè- hbtat - ony aras wth a canopy heght of at east 0 m were nc uded 0 the random sampi ng Ttus and Mosher MS); _ Ths type of- study 'assumes that the foe tors meas'ured are of seme ' mportance n the spetîes' proeess of nest ste seecton and' that the y o j 'are measured n sorne meanngfu manner It s often dffcut to den- tft these factors a pror and t s perhaps best done by exapnng the r 'vrabe nformaton on the fe hstory of t2e speces Bednarz 979) empoyed and use data ta examne Red-shoudered Hawk nestng habtat qn a arger - seae Unfornaey ts )pproach coud not be f usèohere bec ause no' aecurate data are avaabe for the study areas due to recent rapd changes n and use patterns _ Anayss of data Data on e forest spec :Les composton were converted to mportance vaues Iv' 5) whch combne each speces f reatve densty reatve frequency and reatve domnance 'basa area) at each ste :=he maxmum possbe vaue or wth 300 as a moqotypc stand Curts and MacIntosh r 95) Trée spec}s that were present at es than three of he 25 ran- dom stes were combned no One group Sze cornposton of each ste_ J r wa converted nt denst es' stemsha) for fve casses foowng the scheme of Curts '959): seedngs 0-25 cm dbh) sapngs J cm dbh) and three casses of mature' trees cm dbh cm dbh and 509 a cm dbh) wth the eve ua combnat on of

21 8 the ast two cas'ses Data from bned because of tqe dfferenees terst es between the two areas the two groups of nest stes VC an MSB) were not com- n the structura and forstc charac- <Wather 963 Newstram 978 Appendx 2) used unvarïate and mutvarate nethods ta compare the VC 'nest stes wth the random stes Mann-Whtney U tests Sege 956) and Student' st-tests at the 005 eve of sgnfcance <twq-taed) were used for the tree speces mportance vaues Bertn 977) and' for apparenty norm dstrbuted data respectvey The computer programs of the Statfstca Ana:yss System Barr to a 976f and the Sta'tstca Package for the Soca Scences tne et a 975) wëre 'used _ n the anayss of data > Dscrmnant functon anayss DFA) was us-ed ta deteijne wheh varabes were the most mportant n dstngushng between VC nests and ' 'random stes Dscrmnant functon anayss near combnatons of varabes nto a functon that mxmozes sepraton between two or more groups whch serves as a better dscrmnant than do any of the varabes taken sngy James 97) Ta judge the ' - ) mportance of a dscrmnant func t on used the crona correaton coeffcent a hgh vaue of whch ndates a strong aby 'of the functon to dscrmrate among the roups Aternatvey the canonca correaton squared can be nterpreted as the proporton of he varance n the dscrmnant functon expa'ned by the groups The J absoute sze of standardzed dscrmnant futt:ton coeffcents aso gves a measure of the mporance of each varabe n dscrmnat ng r ' between groups?f Stes Two methods of seectng the ndependent varabes for 'ncuson n - the DFA are avà'abe Keéka 975) The frst g a stepwse method n

22 - whch -the varabes- are seected For anayss on the bass of ther dscrmnatng power unt the ncuson of any addùona varabes does not provde a mnmum eve of mprovement Varabes are seected on the bass of the r ab ty to mm ze the overa mu t varate F rato for the test of dfferencés among the group centrods whch aso mnmzes Wks' ambda a measure of group dscrmnaton w ks' ambda can be converted to a ch-square vaue for a statstca test of the dscrmnatng power _of any functon Ths method takes nto r consderaton the dfferences between the centrods and the homogene'ty wthn the groups The second method of varabe seecton createa dscrmnant functons dreçty from the entre set of ndepend'ënt varabes rgardess o the dscrmnatng power of each of the < - ndvdua varabes Kecka 975) By defnton Kecka 975) ony ' u one dscrmnant funeton exs'ts between two groups 'AEter a set oe varabes s found whch provdes 'Sat'faetory ds- crmnaton for cases wth 'known group membershps : LS thèn possbe to derve aft new cassfcaton funtïon from the po'oed wthn-grop cavarlance matrx and the centrods of the dscrmnatng varabes y whch w permt the cassfcaton of new cases wth 'uoknown membershps As a check of the adequacy of a dscrmnant fncon one can aso cass fy the orgna set of cases to see how many are correcty cassfed by the varabes used The cassfcaton proèedure produces a probabty of n;embershp n the res'pectve grojp and the case s assgned to t?e group wth the hghest probabty 'cautoned that the separatve powers of a dscrmnant Ryder 978) fun-cton are o ften based upward and advocated the use of other observatons not '- ncuded n the anayss ç as a more aècurate test of :the functon's

23 0 - cassfcaton capabt-yo For the purposes of ths s'tudy the on: St Bruno nest stes were used as '''unnowns'' ta test the predctve ab:ty of J stepwse and drect dscrmnant functons Prncpa components anayss PCA) Barr et a 976) was used to dspay the dstrbuton of nest stes wthn the' potenta nestng habtat Prncpa components anayss reduces' a arge mutdmensona data set to a few new varabes wth a mnmum 088 of nfor maton <' These new varabes are orthogona natons of theorgnt varabes whch expan progressve -' orgna tota sampe varance James 97) smaer portons of the It s-' then possbe to ordnate each observaton on the two new axes varabes) wh:ch account for the most varance: used PCA to anayze the reatonshps etween structura' forstc and physographc varabes for the 25 random stes The resutant factor scorng coeffcents were apped ta the raw data for bath the rand?m stes and the Vaudreu Caunty nest stes n order to dspay whch art of the potenta nestng habtat the random stes) s utzed by the Re'd-shoudered Hawk The smartes and' dfferences between PCA and DFA and ther appcabty to s tudes of avan breedng habtat'are dscussed by James- 97) ) 'RESULTS Character{tcs of Nest Stes ' J n 978 and 979 Red-shoudered Hawks were ffrst observed n the Vaudreu County study area on 24 and 23 March )esp:ctvey Redshoudered Hawks have be reported arrvng n southwestern Quebec' up : ; ': r I ' j I '

24 - ) ' - - to two weeœ befor the se dates Gssen 976) Wthn two weeks of 0 ' ar'rva hawks 'were Qbserved n terrtora fghts; -soarng and cang - above wooded areas and nspec tng od and potenta nets beow 'the ; cano'py Egg ayng as evdenced by Incubatng duts; began no a thn md-apr Hachng took pace n md to ate' M:y Fedgng was :J 'usuay compete by the end of the frst week n Juy 'B Penak pers comm) Great orned Ows }Bubo vr-ganus) anrréd Ow? Strx <4t ' vara) wee aso found nestng n the' VC study area AI nests were ' IJ I C> -qu te arge and co'nstruc}:ed many from stcks wth a Hnng of hemock c Tsuga-canad'enss) wth the excepton of '0ne nest that :appeared tô be o ocaed on an od sq:urre Scurus spp ) or J -crow Çors :brchyrhynch9s) nest Red;;-shoudered fu;wk nests were found n sma- woodot's of ess than 05 ha nd n the mdde ot arge tr-scts of vrtùay unbroken forest There were a number of sgnfcant p < 005) dffereces ' between forest _ -;'t structura features at the nests and rando; stes The nest stes qad t ; 'hgher mean d'ens tes of md'de 9 and od age tr:ees ower speces' rc'h-» ness and Iawer trees Thbe ) te -'nest ts me an renstes of seedungs sapngs' and :rua8 adut -} - Tota' stem basa area and cauopy hegnt were hgher at f There er no''sgnfcant p < '005) dfferençes n mean dstances to nearest easona and perma'nent wate' sourès human hab'taton r'od path or edg'è of fors'n' howver there was a great > -' 0' dea of varaton; n these data coeffcents 'of varaton for nest ' Extreme cases for these meashrem'ents Incuded a nest ' stes - 8-Ô%) 40 m from a road another 50 m from a house atd another ocated 5 m from - ' v the edge ot a gof course faray Nests at MSB' wet;e sgnfcanty p< o D) coser than vc nests to a seasona water source possjby refect- -4 j- r ' ' ;

25 ' -- Q' - f ' -- f t t t - ' r No : ' o ---- '- --::::r- - Mean vaues Red-shouderd : r-- TABLE of habtat features standard âev on) st Hawk nests nd ranom $tes n Vaudre County soptwestrn Québec VARIABLE NEST SITES RANDOM SITES -----< n - 3P) n 25) Name' - ' ) 'fota stem basa area m 2 ha at 35 m) ) J Seedng densty Hha) ) } - Sapng densty Hha) ) ) Densty of stems O2254 cm dbh Hha) ) _7n 262 ) Densty of stems cm'dbh Hha) ) t 94 77) Densty of stems 50-9 cm dbh IIha) 22 26) - 3 ) - Speces he;; 0 'rchness' -IIste) ) 40 4) Canop <m ) ) Thc kness 'f ground eve veget8:on % 5 ' 289 5) Incudes dead stems as one speees -- _ >'_ -' Contnued next page #0 C 333- '94) : 273** t 369** 605*** 4<66*** 65*** 436*** 243* 657*** 030 _v _th '$ t IUIîÔ 'SW't-- ; N o î f t [ [ f t f t 'I JI

26 r-- -vi ' - c TABLE Contnued) Mean vaues of habtat features standard devaton) at Red-shoudered Hawk nests and random-stes nvaudreu County southwestern Québec ) No Name V:ARIABLE NES SITES n - 30) RANDOM SITES n =: 25) t Dstance m) to nearest: ' 0 ' Permanent water ) ) 092 I' Seasona wa ter p '23 20) ) 46 2 Human habtaton ) ) Road ) ) 03 4 Path or tra 83 9) 8 0) 3 IS Edge ot- ferest- 49 <'3'9? ) 74 * Sgnf cant p < 005 ** Hghy sgrfcant p < 00- ; ** Very hghy sgnfcant p < 000 e:j J ' D - =:::::::::: ') 7 f ' ' ' r < - - -'*'f: I;j%Kn t ' w '{

27 >- :''''''''J ;;;;;:' :-::-' -- - _ '---='---' '''' _ ' - -) - _ r'<'j'''''j---'''''''''''-;_:_'-'''-'-' - ng a greater ntnttber of water sources n 'that area and they hm a 8gnfcanty p < 000 ower Mean tota stem basa àrea Appendx 2) Arnercàn beech sugar mape red mape yeiow brch and ronw<tod Ostrya vrgnana) ai occurred at more thn 75% of the VC nest stes The domnant tree spces at the nes: tes n decreasns; rder - of mean mport anc e va ue 'were sug ar mape beéch dead stems red mape basswoodand hemock '--the ran:dom stes taxa wth a constancy of at east 72% ncudèd beech sugar mape rd mape yeow brch e spp) basswood ash Fraxnus spp) and'chery Prunus spp) Dead stems were present at ai nest stes and random stes samped Mean mportance vaues of beech and yeow rch were sgnfcanty p Z - 005) hgher at the nest stes wce the mean 'mportance vaues of grey The brch Betua popufoa) whte pne Pnus strobus) em and cherry wer sgn fcaity ower at the nest stes Tabe 2) At the MSB study area Appendx 2) sugar mape had a sgnfcanty p '< 005) ncreased me'an mportance vaue 948 at MSB 75 at VC) whe a numb-er of other tree speces ncu8ng red mape and basam frabes oasamea) payed sgnfcanty reduced roès or were absent ' Ether sgar mape or beech had the hghest mportance vaue at 23 of the 30 78%) nest ss at the VC study area Tabè 3) Other nests were ocated n red mapie four nests) basswood two nests) and hem- r ock' one nest) stands Àt t;he random stes sugar mape ha a comparabe eve of occurrence but beeéh was much ess st'i'ongy represent:ed *ne of th:j two eadng domnants 2% of the tm compareà tu 6% st the nes'ts) Whte pne and grey brch were each the eadng domnant' at two of the r'andooj stes er were hghy sgn fcant dfferencs bet- t

28 ' - v - r TABLE 2 Sgnfcant and neasgnfcant dfferences n tree speces mean mporfance vaues between Red-shoudered Hawk nests and random stes _ n Vaudeu County Québec Speces Nest-Stes n 30) Random Stes n - 25) ZI ' ' J r ---<-----'- r Fagus grandfoa ' Betua aegharenss Betua papryrfera Retua popufoa Umus spp Prunus spp ead stems % PRES 2 - X r ; ITwo-taed test - Z cacuated *p < % PRES % of stes at whch a z sn 44-G Î % PRES 2 x 96 25' sn 288: Ü ) «from' Mann-Whtney U corrected for Ues ** p < 00 * 000 speces was' found v 227* 223* *** 226* 372*** 327** tsrt' t r MUt wtttttttrfbn C' -- ' VI -t ' f f } j' : I ' : j: II : r ' III r '-

29 -- '- tf' ' - Speces f TABLE 3 'Dstrbuton of the two hghest mportartce vaues IV) at Red-shoudered Hawk nest stes and contro n Vaudreu èounty Number of stes percent of 'tota-) t Nest Stes n 30) stes -Random Stes n 25) ')I : - ' - j t' ; j j f ' ' r f ' saccharum agus Acer rubrum - grandfoa Ta amercana Betua E2Eufoa Pnus st Other speces If '- TOTA - 240) 38) 43) 27) H3) 30{OO) V 2nd Hghest IV 033) 723) 30) 2 7) 827) 3000) Hghest IV 44) 28) 5 20) 4) 28) 28) 28) 2500) 2nd Hghest IV 3 2) 4) 28) 28) 28) 560) 2500) -' 0 ' -- ' I r ' [ : ' 'I ; j - ' '5: ' H :=: '''-''I-''' _ -- _-_ ';;:: t

30 _'-'V'''''''''''_''' u ' 7 ï ween the percentage c strbut ons of the two domnant tree tax' n ô two groups of stes hghest mportance vauf - X 2 = 377 6df p< the 000-2nd hghest mportance vaue - X 2 = df'- p < 0000 At Mont St Bruno there 'Was a reduct n the number of speces amon th J two domnant tree taxa compared fo the VC nests One ste was )ocated n à red oak Qfercus rubra) stand ai of the others were n sugar mae nne nests) or beech fve' nests) ) _ -- Nests were found 'n nne speces of tr Tabe 4) n the two ' study are-as Beech sugar' mape yeow brch and red oak were t most frequenty used speces The nest tres were consstenty among the argest at each ste'wth a mean heght of 285 m and a mean dbh of 456 cm Nest qe ght 'f'a:red from O to 270 m and was postvey correa-td 'Wth canopy heght r = +084 p < 000) Red-shoudered Hawk nests : 'Were typcay oated st 49% of the tota <{teghtof the nest tree reatve nest he&ht) wth nests n beech trees hàvng a sgfcanty ower reatve nest heght Mann-Whtney U test corrected for des p < 000) than those n sugar mapes Thrty-sx nests 80%) were ocated n the' owest sutabe subjectvey j uçged) fork of the nest tree Fort y-one 9%) of the nests were n forks 'of the man trunk the other four n forks of a braych Up to sx tree eements ttunk ana braches) -- J f sup'ported the buk of the nest x = 4 SI = ') wth 4 and 5-way branchng confguratons the most common t-test p <:: There was - no sgnfcant 005) dfferercefbetween :'the 4umber of tree eements supportng nests ocated n sugr mape and beech trees [ ) J Dscrmnant functon anayss Beth varabe ncuson methods were used wth 5 var)abes whè::h :

31 : '_<:J<' I' r '<'':: ' '---'''-< c ' r- Tree SJ)eces Fagus grandfoa saccharum Querèus rubra Betua aeghanenss Other speces ALL SPECIES COMBNED IJ'' t _ r; ' - TABLE 4 Characterstcs of nest trees seected by Red-shoudered Hawks n southwestern Québec Nest Tree Nest Tree N % of tota) Heght m) DBH cm) X sn X sn Nest Heght ') X 'SD '7 9422) ) 297 3' r- ' 489) ' ) ' h) ) Reatve nést heght Nest heghtnest tree heght) x r- ' - r- Reatve Nest Heght -%) X so r ' 'r --J 00 ; I ' :r -'-- ï ' ' Î' [: ) j : II f' [ Id I ; ' ) : II I ' ; II II I ; j ' ' I I - ' j L - r ' f ') ' WJ:de:cf ' L- 'IT'fttst4t MM't'rtt' -- -L _

32 -- -_ :- _I-_ _-_ 'î _ _ 0-''' r - r' '>' -tp' '- _;x 9 showed sgnlfcant» qr neary sgnfcant» dfferences between the random' s tes and the rtests f the Vaudreu County study area' Eght of the S varabes' four structura features and the mportance vaues of our tree taxa were seected n the tepwse DFA pabe 5) to form functon tt accon-td for 00% of the varance n the dscrmnatng varabes andwhch had a canonca 'correaton of 0'828 <X df P < 0000) Ths functon roughy re'presents a contnuum trom mature 'forest stands wth 'a tau canopy hgh densty of mature trees r' and ow' seedng dens ty ta more eary successona stands w th _hgh seedng desü:'y and hgh mportance vaes of grey brch cherry and dead stems The dcrmnant functon was suft?tenty robust to eorrecty cassfy 29 of 30 97%) VC nests 22 of 25 88%) random stes and 4 of 5 93%) Mnt St Bruno neststhere was a hghy sgnfcan't t-test f < 000) dfferene fuctqn between the mean stepwse dscrmnant scores of the VC nests and the random stes Fgure 2) Dsrmnant scores of three of 25 2%) random stes were wthn the range r-- - H_ of the nê';;:a tes' seores The drect dscrmnant anayss yeded comparabe resuts = df p < 0000) Cdrrecty c'assfy ng 29 of 30 Vaudreu County nests 23 of 25 92%) :r;andom stes and '4 of 5 93%) funt St Bru» nests There was agan a hghy sgnfcant o t-test p < 0_0) dfferen'êe between the mean dscrmnant scores of the VC nests and random stes Scores of fve '25%) random sts ' w thn the range of the nes t s tes' scores: were <> Ths functon had an OveraI canonca cn'reaton of 0838 and reed most heavy on the varabes dead stems IV seeding densty and canopy heght for most of 'he dscrtmnatng power of the functon ' ' ;' - ï r

33 '' J - ' - ;r f - t o -- : IJ : j' } '- r TABŒ 5 Resuts of stepwse dcrmnant functon anayss between Vaudreu G0?nty Red-shoudered Hawk ' nests artd randam stes '- -- ' _ ' C '- > ': ; ;- Step Dscrmnant functan coeffcents Entd Wks' ambda Standardzed Unstandard'zed ) ;76 _ Tree densty dbh >255 cm Umus spp IV Prunus spp IV' Betua popufoa IV Tota stem basa area Sedng densty Dead stems IV { Constant 'O33687a ' ' Varabes avaabe to anayss but not entered Wcs' ambda <: ): sapng densty tree densty dbh dstance tonearest road dstance ta nearest seasona water Betua papyrfera IV Betua aeghanenss IV Fagus grandfoa IV' Each varabe entered prqvded n combnaton wth the varabes entered before t thbe8t possbe separaton of the two groups ' ÏIIIIII3t?rttt-'-'-' -- _ t A ':<b-

34 '----_'-- :- ' _ ) '''' ): FIGURE 2 Dstrbut-on of Red-shoudered Hawk nest: and rando stes wth respect to a stepwse dscrmnant fqncton Vertca Unes gve ranges 'horzonta nes gve means and the boxes ncude standard devaton on ec'h sde of the mean See Tabe 5 for a - st of the varabes n standarcfzed coeffcents ths functon and ther ) - ' - r If ' ' II < ' J ' ') f '

35 'IÎ _ ' ' r: -- - ' I NEST SITE: S - '- r- J f ' w 0::: o 0 ) en - - RAN-OOM SITES ' - Z «- Z - -'0-0:=' ) -20 en -C ' - J - ' f j II ' 'r

36 ' Stepwse and drect dscrmnant mportance vaes of 22 tree taxa '- anayses fer' aso done on the The resutng stpwse 22 ftuncton :Încuded eght of these varabes and correcty cassfed 87%' of the nests 88%?f té random stes and 80% of the unknown MSB) stes The' functon Appendx 3)' nad a canonca correaton of 0784 <t< df p < 000) a:d roughy represented a contnuum frpm $ beech-yeow brch assocatons ta stes domnated by dead stems cherry andor strped' mape Acer pennsyvancum) The dscrmnant o scores of three 2%) of the random stes were wthn the range or the nest stes' scores The drect dscrmnnt functon usng these 22 varabes and a 2 canonca correaton of 0809 X z df p = 0003) correcty cassfyg 93% of the VC nests 92% of the random s but ooy 60% of the unknown stes Thè scores of 2% of the random stes were wthn the range of the nest stes' scores The varabes contrbutng 'most to 'the dscrmnatng' power of ths functon were the mportance vaues of sugar mape whte pne grey brch dead stems and beech Addtona stepwse and drec t dscrmnant func tan anayses were dçme on a group of 8 structux:a and topographe varabes nne of t whch were mutpes of other varabes These mutpe varabes were used n' the DFA to determne wbether varabes were nteractng n such a way that ther combnatons were more hghy correated 'wth the specfcty of Red-shovdered Hawk nestng habtat than were the orgn ay measured varabes James 97) The resu s of these anayses were smar ta thase of the athers In the stepwse anayss the two most mportant g varabes n separang the nest stes contnued to be the densty of adut trees and canopy heght Three of the mutpe varabes were seected ater n the stepwse process but added somewhat J f à

37 J ess addtona dscr'nàtng power The overa canonca 'prreaton Q of' the fùcton was' O836 X 2 = 58 9 df p < 0000) and ft t;as n '' f abe to correctycassfy 9% of the known VC nests and random stes) ' cases and 73% of the ùnknown MSB) ones The dscrmnant- scores 'of 6% of the random stes were wthn the range of the nests f scores The 0 : -- drect dscrmnant anayss ré-d heavy on a mu tpe varabe the densty of adut trees squared) ând the densty of young adut trees to separate the two groups The overa canonca corrs)aton of ths functon was '0840 X 2 := df p < 0000) and the J funct-ôn was suffcent; robust to correcssfy 9% of' the known stes and 80% of the unknowns Dscmnant scores of 24% of the f ) random s tes werj wthn the range ôf the scores of the nest 5 tes Prncpa components anayss ;t 'The prncea component's anayss of' ony the structura features of the random St Tabe 6) showed tqat there were sgnfcant p< 05) postve corrèatons between the dens te's of seedhngs sap- Ings and young adut trees There were ao sgnfcant p <' 005) postve correatons between severa Ifeatures characterstc of a mature forest ncudng the canopy heght tota stem basa area and -J the densty of Çdut trees rdde + od 'age stes 255 cm dbh) and sgnfcant p < 005) negatve correatons between sapng densty and two reatures of mature forest mature tree densty and tota stem basa area 'he PCAof the random sté data' Tabe '7) yeded two factors whch acc 55% of the varance n the orgna dtb: set On the frst varance) hgh vaues of tota stem basa area and adut tree densty produced the owest component scores whe ; r f ' )- -f J } '

38 ' <tt a -- ' -' ' '-- TABLE 6 Correaton matrx for fore st tructura varabes random stes Vaudreu County Quebec n 25) Varabe a- o ) j b Varabe Sapng densty Young Adut treedensty Seedng densty Specs rchness Gound Vega Canopy heght Mature tree densty j - Young adut tre7ensty Seedng densty * 04078f ' Speces rchness Ground vega Canopy heght rt Nature tree densty ** * - j '- -' Tota stem basa atea J * * p < 005 r;ç p < 00 O ' r ** '> 06927'* c N j ' j ' ; ? 'IUt:-'-ItrII5fWUUJW n - v '_ - --

39 <'>': h ''* ' :'' _' - ) 0 r- I r r r TARLE 7 Summary of the resuts of prncpa compofterè anayss of forest structura characterstcs random stes Vaudreu County Quebec Factor -oadng pattern r- Fna Scor coeffcent ' after Varmax rotaton) -- Factor Factor 2 Uommunaty Factor actor 2 - p Ground vegetaton Sapng densy densty Sedng ' -) o ' Young adut tree densty -) tj - Mature tree densty Speces rchness ' ' Canopy heght Tota stem basa area Varance %) Cum Varance %) r ? Fna-communaffty after the- 2 prncpa components-factors '' &0 ' _ _-- ' - - _ r:a' ---_ J U'''' '''_<'Y'_-''''-''''''''--- -

40 hgh sapn ànd young adut tree denstes produced'- hgh componeft J scores On omponent 2 an addtona 8% of varance) stes wth hgh 26 ) canopy hegh sand hgh eves of ground eve vegetaton produced hgh fac tor 2 sè res whe h'tg sapng densty produced ow component 2 scores When dstrbuton o'fîvc nests thn the potenta habtat defned by the prndpa component of tjte random ste;s)s examned Fg 3) the nests typcay have hgh vaues for varabes characterstc of mature fotest and reduced vaues for varabes' ndcatve of mmature forest Ths produces the observed èusterng of the nest stes n the upper eft secton of the potenta habtat poygon that area correspondng ta ow component scores and hgh component 2 scores 'ff The area of the nest s te poygon comprses about t 0 45% of the area of the potenta habtat poygon and ncudes fve of the 2520%) random stes Thee were sgnfcant t-test p < 00) dfferences n bath component scores between the VC nests and random stes Addtona PCA' s usng ) ony the tree s'peces mportance vaues and 2)6 gographc forstc and structura varabes of the random r 'stes produced smar resuts w'th a custerng of the nests n sorne reatvey dscrete secton of the potenta habtat when t Is or- nated on the frst two 'prncpa components Whe the mportance vaues of the 22 tree taxa we used JO Appendces 4 and 5) t thet'e was a custerng' of some nest ste aong the JPper 'area of a component where a hgn vaue ndcated reatvey hgh mportarce vaues of bpech t yeow brh strped mape and hem- ock andor redued mpartânce vaues of ':ed oak wh te pne-' and grey J <j'? 'br::ch' There wa$- a sgnhcant t-test ; < 005) dfference n the

41 II> ' Ordnaton of random FIGURE 3 stes and Red:'shoudered Hawk nests on the frst tw'o components of a prncpa component anayss of forest structura features Scores of random stes' are standardzed ta a Mean of 0 and SD of for b?th components See Tabe 7 for dets of varabe oadngs ) } } h t {I r' :) '

42 - ----_--- ' CI) UJ -en C)W t: OC) Orzoo «UJ Z ü ü» ) o - > - J oc Q ; >) Cr') + N + f- Z r- UJ + Z 0 a 0'0 ) J «r- a ) - Z Q: C CJ - '4' cry Q: LL t j '- V f ' r - t- )

43 _ ' 0 J _ J_ ' 28 scores for ths component between the VC nest: stes and the -random t st was no sgnfcant dfference n 'the other component fare: -The nest ste poygo encpased abo; 4' of the area of potenta habtat and ncuded 2 of 25 48%) ranaom stes Whend6 varabe'a are ncfded n the PCA Appendces 6 aud 7) - most of separaton of the nets from the random stes occurred aong f the seco prnpa compongnt where hgh vaues for varabes charac- - terstc of mature forest tota stem basa area adut tree denty) yeded hgh ccmponent two scores Nest ste scores forths component were sgnfcanty t-test p < 000) dfferent from the random ste seoret The nest ste po'y8on for ths PCA comprsed about _24% of the the area of potent a habtat and encompassed seven of 25 28%) random stes DISCUSSION : So ' The Red- shou derd Hawk typcuy starts ts terrtora and nest- 0 ng actvtes qute soon after t arrves n southwestern Québec n md-march the nestng chronoogy that observed was smar to other data from northern areas Beardsee and Mtche 965 Jank 980) 8 part cuary nterest ng because of te consderabe snow cover It freezng temper'atures and generacmatc unpedctabty usuay ejc- ) perenced n ths area from ate' Match to md-apr Wson 9-7) Immemann 97) revewed much of the te:rature on the tmng of avan beedng cyces and concuded; as Làck 950) had done that the tmng of each speces' reproductve cyce has evoved 50 thbt t concdes wth the maxmtan avaabty of ts specfe' food requ'rements Bent 938) recognzd the prob ems c'ausd by the eary nestng habts _-

44 - ' the Great - Horned - Ow and )r suggested that the tmng of the cyce somehow enabed the parents to more easy suppy thar yo'fm wth food u before 'tre suîmer foage 'became too dense 29 Waker 974) conceded J that Great Horned Ows may ncùr a dsadva'ntageous ack pf prvacy by nestng n unfoaged trees but suggested that the ery nestng woud brng young ows ta huntng age when ther norma pt'ey 'due to the < nf-ux of young of the year) are st ther maxmum abundance Portnoy JJr- 9-74)' fet that the tmng of reproducton by Red-shoudered -Hawks--n Massachusetts was aso reated ta the ava ab t y of ther 'prncpa prey snee the tme of hatchng concded wth the emergence from burrows of Juvene Chfunks Tamas stratus) The md- ta ate May -hatchng perod of Red-shodered Hawks n southwestern Québec aso roughy conath the a-e Ma;' an} eary'; Jme : emergence of juvene - J chpmunks n - ths area Smth and Smth 972 Pdd_uck and Fas 973) Basquere 979) sugg';ted that the eary oj;set d-'):ceedng by the Fçx Sprrow Passerea Üï'aca) n Newfounpand may functon to--xeduce the competon for nestng food and that r'epr;ductve success may be -enhanced by a separaton of speces' nestng perods whe Ttus and Mosher MS) have suggested that a smar tempoa separaton of breedng èyces n a gud of raptors may have mp eatons n competton for nest stes The tming of' the Red-shoudered Hawk r breedng cyce s somewhat ntermedate to those of ts potenta - compettors Great Horned Ows and Barred Ows whch usuay overwnter n southwestern Québec Godfrey 972 Quam 973) and Red-taed Hawks Buteo jamacenss) beg n ther nestng cyces ear er than the Red-shoudere for the' Great 938) nstances Where Great Horned Ows or t- J '

45 _ _ -- _'_---'::'---'-'-:--'----: Barred Ows occuped nests used th prevous year I>-y Red-shoudered Hawks The breed ng cyc of the congener e Broad-wnged Hak B'uteo - ' patypterus) wheh apparêmty nests n somewhat dfferent habtat Bent 937) appears to ag behnd that of four weeks n ths area Quam the Red-shoudered Hawk by three or 973 Matray 94'çxJn 976 Jank 980) In southwestern' Québec mature decduous stands domnated by ether sugar mape or bech appear ta meel th --nestng requrements of the Red-shoudered Hawk These two speces are the man 'components of most mature fores stands n the study area Rowe 972 NewstroID 978) Ths apparent p'rference s generay consstent th nformaton from' other J northeastern parts of the speces' range <Wrght 96 Beardsee and Mtche 965 Henny et al 973 Hanna unpubshed data Campbe 975 Root ad DeSmeone unpubshed data Ttus and Mosher MS) Many featur'és of the forest structure<densty of adut trees caropy heght tota 'stem basa area shrub cîensty) at the nest stes were smar ta the observatons of other's Campb'e 975 Portnoy'and Dodge 979 Bednar:z 979 Ttus and Mosher MS) and confrm the pre ference of the Red-shoudered Hawk for th most mature stands of ava abe forest Other characterstc& of the nest stes ncde the vrtua absence of eary successons or xerc tree speces such as grey brch c6err; or whte pne Wather 963 Op de Beeck 972) and reduced understory ; ayers and spec es rchness However ar'as of suh eary sccesona ' forest or a cargs may be very mportant cornponents e huntpg areas) of the overa habtat mosac of the Red-shoudered Hawk ''h forstc cooposton Qf the Vudru êdunty random stes Appendx 8) - - ' - r s smar ta the range of forests descrbed by Newstrom 978) and Op de Beeck 972) but the nest stes refect a tronger representaton of - I

46 -- - '-'_ ---- _ --'- _ - --:_ _ _ 3 k the beech-hem'qek-yeow brch assoc at on 0 ften characterst e of wet-mes'e or wet eondtoos Wather 963 Hose 969) The promnence of ths assocaton at the net stes ay be nterpreted as an ndrect' ndcatonof the' proxma a9uat 7 habt-at that many workers Bent'937 Hausmann 948 Stewart 949 Snyder and Soyder 975) have càmed s an mportant eomponent of dea Redshoudered Hawk habtat Brtn 097]) aso suggested th'at pant abundance ndces mportance vaues)may be eonvenent ndeators of physca faetots such as mosture régme and mcrocmate Wrght 96) fet tht the beech was the favorte Red-shoudered Hawk est tree n 'Iân woods whe he brd nvaraby nests n mapes n the most 0wands a pattern roughy smar to that : observed 'n ths study The reduced subcanbpy and speces rchness at nest 'Stes are pro baby party a product of forest management practces n southwestern Québec SeveraI Red-shoudered Hawk nésts were Iocated n sugar mapie stands managed for producto of mape 6yrup ands speces Management of sugar mape emphaszes the seectve removai of subcanopy ayers and other n ordet to encourage maxmum gtowth of arge producng Crees 'and to permt movement of equpment through the woodot Coons 975) - j Ther:e wa; no evdence of any adverse effects of sugar bush operatons on nestng hawks There has' been consderab dsagreement ove' the sze of wooded areas that can be ut zed by Red- shoudered Hawks Taverner - 938) can)ed that the speces dd no; nsst upon deep woods for ts nestjng habtat and w nest n any tte patch of wood and _Hausmann 948) fet thatr they were sedom found nestng n heavy wooded

47 ----T :--- '' ' 32 '- regot's and Campbe H7?) dscovered Red-shoudered Hawks nestng Œ - woodots as ama as 4 ha n?outhern Ontaro Howev er Bednar z 979) emphaszed the use of arge tracts of' foodpan forest n Iowa and Hamerstrom d97]) 'suggested that the Red-shoudered Hawk prefers to nest deep n the woods to avod' predators such as the Great Horned Ow My observatons suggest that the Red-shoudered Hawk May be qute fexbe n ths regard abe to succ'essfuîy nest n ethe SDa farm woodots or extensve woodands probaby dependg upon the sutabty' of other features of the nest stes Athough the speces' may aso be ab;e t-a y nest n sprsngy cose proxmty to areas of human actvt Y; habtaton Taverner 938 Hausmann 948 ths study) t proab ad -' t' refers secuson but May' be abe to toerate mted human ntruso s nto tradtona nestng areas Aternatvey Svardson O49) and Anderson and Shugart 974) have suggested that te utzaton crf such suboptma breedng habta may be a resut of ntense n raspecf:-c competton The dmensons 'of Red-shoudered Hawk ne st trees n southwest'ern Québec and the ocaton of the nest s at about 50-60% f the net tree heght àre compaabe to observatons from other parts of the speces' range Campbe 975' Por;oy Mosher MS) a?-d Dodge 979 Bednarz 979 Ttus and It has been suggested Portnoy and Dodge 979 Bednarz 979) that the apparent 'preference of Red-shoudered Hawks for rge nest treè- n ure' forest may be due at east n part to' the spec es' requ safe oc-aton for ts fry arge ; nest tp surface a - r 2900 cm 2 voume - IV 45: 000 cm 3 B pénk unpubshed data ) These nests must support the adu t-s and one to four young whch Yh g 00) at fedg ng B 4 ' -