• G

.,·

1 ·I

Ecologv of th G ld - e ,o en Eagle

By Jerry ~1cGahan

-0) .f·

~

~

~s

Yor.. 85

~~ ..

THE AUK A QUARTERLY JOGRXAL OF

ORNl'fHOLOGY~

JAXUAR\." 1 1968 Xo. 1 ------ --------- ----- ·----· ·-- -------

ECOLOGY OF THE GOLDEX EAGLE

THE _-\merican eagles have declined oYer much of their former range. Recently a notable decrease in the number of Bald Eaglt'S (llaliacctus lrucoaplwlus) occurred on the ca:;tern coast of the Cnited States (Carson, 19(12): this decline emphasized the need oi determining population norms ior th~ Golden Eagle (.Iquila c!IrysaNos) :'O that any reduction could be rl'cognizrd early and the po!'sible cau:-;cs bolatccl and eYaluated.

The :-;tability oi Golden Eagle populations is threatened by :-;eyeral fac­t.Jr:->. :\lthough a icdC'ral law was Pnacted in 1962 to prO\·ide protcctim1 inr this ~pecit'S, limited ~ea:::ons h:we been reopened in many oi the west­

t)\,·r.n :-;tate!\ for killing c~~~les that :\re purported to be taking li.\·c~tnck. T~e 'M,·Idt·~pread u~e of pe.stlcldcs ha.s mtrnduced another threat ( ( ramp, 196.1:

l>l'Witt and Buckle\', 1963: Lockit> and Ratclific, 190-l; \Yat.son and ~for-

:!:111, I <>{1-l).

The ron.scrYa t ion and managenwn t of any :-pecies is con tingcn t upon an undt·t':-landing oi it<;; population dynamics. The effect:' of a new endron­nwntal influence imprt•.s.sed upon any population of organisms can only he dt tt·rmincd accurately if a thorm~gh :-tudy has been made earlier. The c•hjtct of this paper is to prodde basic information. Thc den!\ity, produc­tivity. nt•st ing :-;ucce:->s, and mnrta 1i t y of a ~Inn tan a pnpula t ion o i Golclm Ea de.s wt•re dct crm i ned: nc.sti ng 1 H' ha vi or and mm·t•nwn ts were o h:-:t'n·cc I. Tiw"t' cia ta can aid i 11 determining the effects of such change~ as tlw ex­p:nll kd use o i pest icicles, by comparing them l'itlwr with data taken \Yht•re jlt·--tit ide k\'els are much higher or with data ohtai1wd ii pc:-ticides are in­trndured directly into tlw study area. In addition, data Pn the fo<ld habit:-; •d thi..; population are of \'alue for l'!'-timating the ecOJHlmk ~tatu!> oi this Llr::e raptor.

St t~DY \tu:.\

'Jl.l· pdndpal :.tudy an·a (.\n•a .\) j., JH'.tr Lidll!! ... lon. ~fontana, in n:nlral and \.':t:.t~

r•:, l'.ul. Counl\' and \\'l':.ll•rn !:'Wl'l'l:!ra-. ... Count\". Th1• an·a j, 30 t,, 11 mill•.:, and .: · h,,:\., ~~ lnw~l ... hip:->, ;\n•a B ch·-i:!nall'" tlw _,;II rnundim.( rttlltlln ;1i •outh·n·nlt;tl \! •:.I. : •. 1 uol ita huh-d in Lh1• prindp;tl -t 1:d\ an·a.

Th1· \uk. H:l: 1 1.? j11m.try. l'll1:-l

I\.

2

Area :\ i~ hurdt·rt.'d hy thl' Bri1l!.!1'r. Crazy. and .\h:-ar11ka mnunt:dn ratH!\.'5. Elt·,·a­tions ran!!t' tr<lln 4,000 to 10.000 it·l'l alw\'l' :-~·a ll·wl. Tl·mpcrature~ an· mild ami the annu::l pn·dpitatiun i:' twar 12 to U indw.:-. Pt•r;-;i:-tl•nt local and thermal currenb prc\'ail in thl' ar1':t ant! may bt• imp11rtant i:trtor:- in dl'lirllitin!.! ~nital•k tll'.:-tim: lt·rri-

toric:;. 0\·cr hali oi :\rt•a :\ j,. rulti\'ated inr hay. winter wht•at. :md barley. Other wgl'la-

tion on the IO\n·r :-lopl'=' betwct·n 4.000 and u,OOO it•t•l t·on~i:'t:> oi wlwal!.!r:t~st:- (.-lgro­pyro/1 ;;pp.). il';:;rut·s 1 Fr.i! ucu ;;pp.), ncccllt•gra':-cs <St ipa :'Jlp.), j uncgra~~ { K oelrria crhtata), and wild rye I Elymus :-pp.) intcr::pt•r;o;ecl with ::agt•hru:'h ( :!rlt'mi.,in I ridt'/1-tata) and junipl·r Urwiperus scopulorum). Dnu~la~ iir tPscudot.wga mt'n:;it·sii) t:t•ow:­at lower altitude;:; and l(ld!,!cpnlc pine (l'inu.> cmrl Mia) Ol'CUpics fhe hh:lwr ~!opt·~.

Tht• in lcrnwclia tc :'lope' bt•t wet·n 5.500 and i ,;;oo iccl arc char:H:lcri1.~d by w.!.!~·ta t ion oi alpine ie::cucs ( Frsluett o&:ina.}, blm'gl'asst·:; (l'ou :'pp.), and hairgrasst•s ( /Jr;,clram psitt ;;pp.). Sa!.!cbru:;h :1nrl juniper be!.! in i.o dimini~h as ninebark (!' lzy.wcarpus sp.}, ~now­bl·rry (Symplwricarpos ;:;p.) .. and arrow-woud I J'ilmnwm sp.) become more plentiful. D11Uglas iir and lod!,!cpolc pine arc still the mo:-l prL'\'alcnl types oi timber al thi:; alti­tude. En)!clmann spruce ( Picra t'llgdmcu:ni), alder I :llllll'i :;pp.), and willow (Salix

spp.) grow in the wet bottoms. On the hi)!h :-In pes bel ween i .000 and 10.000 icct alpim· ft•.;;;cuc,; and sed!.!c5 (Carrx

spp.) arc prominent. Lod!!cpolt· pine is the· dominant timbt·r type. Suhdnminant tim­ber con,;i:>ll' oi Dou!!la;, iir, alpine iir ~ ..1 bit'.' /11 'io(lfrpa) ami limber pim· ( l'inrts

jll'xilis).

XF.ST Lnc:\TIO:"':S ! i

Locating nesb pru\'ed a time-consuming and challenging physical- task. ~Io~t oi the ne§t:' obsen·ed in this study were located from ~Jay through August! 1962. Food habit data were gathered from ~Iay through July. 1962-i 96-t. })ata on nest sites and proclucti\'ity were takrn in 1963 and 196-t hnn :\lay through July, excrpt for dnta on egg production obtained in mick\larch of 196-t dncl 1965. Sewral nests were vi::;ited only once during the ne~ting season: others were approached up to 10 tinw;o; during one season to gather additional information on t!w food habits. ( 'omplete data were iJ!uixailabit' ibr suint' m·st-.. l~t·nn~ not all the ne:'t~ an• reprt'­

sentecl in e\·ery aspect of the study. Scst sitcs.-Of the total of 02 occupied and unoccupied nests found~ 62

per cent were located on cliffs (Table 1 ). Tht..·~e nests were u::;uall,.- in positions accessible only by ropes. The nt';-..t most common nest sitr ( 26 nests) was the Dowda:- fir. a tree characterized by large limbs that pro\'idc ideal support for the hea\'y, bulky IH.'Sb. l"noccupied nests were classified as Golden h<J.glr nests if they wen' large l'nough to exclude the possibility of being Buteo nests or if they contained eagle feathers.

In \Yyomin~. Colorado, and ~ew ~Ie:dco, \Yellein•ancl Ray ( 196-t) found that of i9 occupied and unoccupied ne:-;ts, S7 per ctnt were on cliff~, 9 nests ( 11 per cent) were in trees. and 1 nl'.:;t wa:; on the ground. In Scot­land, \\"atson ( 195i) found that 70 1wr cent of 64 nr.sts were placed on

rocks: t~f' r<.'St in p~ne trres.

l)))

•

l\IcG.\JI,\X, Ecology a.f Tlir Gold('!! Eagle 3

TABLE 1 :\lJ~lDER (MW Pt:RCENT.\CE) 01:' GOI.DF.X E,\GU: :\ESTS lX \".\RlOUS SITES

JX :\RJ~.\S :\ .\XD B

1963 196-l

.Yr5t sites Unocwpird Oaupicd Cnorcupit·d Ocwpird ..tllnests1

l'liif 32 (59) 22 (71) 35 (67) 21 (70) 57 (62)

Duu!!las fir 15 (2S) s (26) 15 (29) i (2.~) 26 (29)

Cottonwood 1 (2) 1 (3) 1 (2) 2 (7) .) (3)

Pondc-ro!'a pine 2 (3) 0 (0) () (O) 0 (0) 2 (2)

I Jt·:u1 snag 2 (4) 0 (0) 0 (0) 0 (0) 2 (2)

t;ruund 2 (4) 0 (0) 1 (2) 0 (0) 2 (2)

Totals 54 (100) .n (100) ~] ( 100) ,,0 (100) 92 (100) ..,_ ------

• .\11 n•·,ts for whkh this infor111ation was rCtl•nl!•d, r('~anllt·~~ o( the years t•l cun~tructiun, destruc­t•""• t-c.:up;llitm, tlr abandunmcnt.

Other im·estigators have found diiferent ratios for nest site locations. ln :\Iaska, 23 nests were all on cliffs (~furie, 19-1-4). Tn Scotland, Gonion ( 1<~55) claims that most Golden Eagle nests of the central highlands are in ~cots fir (Pinus syZ....•cstris), while in the Hebrides nests are always on diff~. In ('a1ifornia (Dixon, 1937) ea!.dcs nesting in trees use oaks (Qucr­(TIS ~pp.) and eucalyptus (l~ucalyptus ~pp.). The choice oi nest !'ites is, oi cour::e, limited by the rnnge oi endronmental po%ibilitie:=;. The similar iindings of this study and \\.ellein and Ray's probably reilt·ct a similarity r·i enYlwnments: both study areas were m the foothills of the Rocky

~ luuntains. Of all ne:-.ts (occupied and unoccupied) in my study, 81 per cent were

;1t altitudes between 4,000 and r1.000 ieet (Table 2). \Yellein and Ray • 1%4) found 85.5 per cent of all their nests in thr southern i~oc1dcs in thi-. altitude rangt'. again probably reilt•cting similarity of habitat. The hi:.:lw~t altitude of nests locatl'd in t·ithcr my :\rra A orB was 7,000 feet; t!tn·e occupied nests wNe nhscrn~d at this elevation. Packanl t 1945)

~

T.\BLE 1 ~l"~IIILH (.\~o PI.Rn:\T.\Gd Ol' (;uun.;o;- E.\m.l: ::\t:ST::> .u Y.\H.HH·s :\JTnrors

IX .\1a \S .-\ .\XD B

~-::::::... -::-...=:....:.....-=.=::.:=::=---=:=:-.:=.~ ---- ·-. ,.....------.-·-·~- ,......_..., .. ----·- -·----· .. ·~·---· .. ------~ -- -~-~·-~--- ... ~-- .,..--... --~.---- .. -- ....

.!::i:udc 19tJJ. 196-t r1!U .~f' <' --------------- .f!lt.'('.\(SI

iut.l r"llorcupil'd Oaupit·d l'uoccupird o,-cupicd -·· .... _ -· -----· ------ ··- -- ---- -- ~·------- --- .. ·---- --~--- ,._ _______ ..

J 'I \-.4l)00 2 {4) 1 (·0 ·' (6) 0 em -~ (4) •.• ·., 'J)OQ 24 ( 48) 10 (.\7) 26 (5~) 11 ( ·11) .:.( (46) •tJ ·t.OOO lS (.\6) 10 (,\j) 11 ( 2i) 11 { -11) 1S (.)~)

• :f':·i,COO ~ ( 10) Ill) .{ (7) .\ Ill) s (10) .c.(; .-\COO (2) ·' ( 11 1 12) 2 ( i} 4 (5)

ltt·~:.J-, 50 ( 100> ,_

( 11)01 -~~ I !COl 1~ (100) so !1001 • I • I

\'l l'nt' lor \lhkh 1hi, inft•lm;lliN\ "·" !t• .. :•l•tl fi'\!.Hdk" ,,j 1hl' Yt\11' .,j tl'll'!tlllli•·l1, ,Jt,IIIIL· • ' , ,,,qun, ••r al~o~:tolunnu·ul.

T.\BLE .:.

E:-..:1'11:-l'I\J ;-; ur OnTI'II.Il CIJII' :\1!'1:;. i'l(l.\· l'Jb-l •. \1a.\:-> ;\ .\:s'll B

S or lit y I J>fl' (I' Ill I

2 (())

2 (10)

Diral i/111 11.! c.rp<•Slll'l" -- -· -··~· ·-- ........ - _.. -J~a~t

.\" f /'rr 1'1'111 1

( 2.:.) (2·0

Jrf.\1 .Y f l'rr tt'lll J

-l -l

CIS) ( lll)

St~~tllt .Y ( 1'1'1' 1'1'111 J

11 10

(50) (-1~)

-·- -- - .. - ·-··-'---

found an t'111JllY Golden Eagle ne~t at 9,500 feet in Colorado. ancl \Yellein

and Ra\· ( 196-t) one at 10,000 feet. In 1963. 11 of 22 cliff nc~ts wert· nn !'outhern exposun·:-;. 5 faced ea:-:t. -+

faced west. and although as many cliii;-; with northern fxposures were a\·ailable. only 2 nests were found on them (Table .1). Differences ob~en·ed in i 96-l were n(·gligible. Tlwsc data suggpst that nest-site preference is in­fluenced by the direction of the sun's rays. Exposure should be important during the early spring months. particularly f1>r the eg!.!~ and incubating adults in ).larch "·hen the an'rage monthly temperatttrL is oftcl' below freezing. E\·cn in the warmer months of June and July. nests facitig !'nuth and ea:-;t might be preferable: tho~e with ea:-;terly expnsurt:':' \\·ould'=' ren'i\'l' • the warm mornin~ sun and l1e shaded in the hot a ftrrnoons. In Scotland \Yat::on ( 1 ()57) found that most of tiw tH':->ts in his sludv area faced either north or east. which he also noted was bow most of the eli ffs faced.

Proximity oj ncsts.-The maximum and minimum dis~ances between neare_:;t neighbors for 17 occupiNI nests in I 063 were 10.5 mile..; and l.2 miles. J n 196-l the maximum distance wa;-; I 0.2 mill's. and the minimum distance of 1.0 mile separated t\\'o nest::. on thr same long semicircular cliff. one facing ~outlnrrst and tlw other :-o\ttheasl. In 19.W ).Iurie ( 19-l--t)

found two pnir::: of eagles nesting 1.5 mile:-> apart. ~fany pnirs of eagles build more than o11P ne:->t. They generally usc the

:-:ame nest through consecutiw nesting seasons. C\'<.'11 though they repair the supe-rnumerary nests and attend them re~ularly until the rggs are laid. Supernumerary nests "-ere found for 20 nesting pairs. or 56 pPr cent of 36 occupied n<.':::.ts visited from 1961 to 1 9(>5. Pair:-; with more than one nest had an an~rnt:e of l.S ~upernumerary ne:-:b. One pair attended eight nest~. no two of them farther apart than 0.3 mih·: 11 pair~ ha<l one suprrnumer­ary nc;;t each. the remaining S pairs had l\\O or th.•e additional nc~t~. \\'atson ( 1957} reported a total of 6-l t')Ti(•s that belon~ecl to 12 pairs of ea~ks in Scotlnncl. :\single pair in California hacl 12 nests (Dixon, 1937). I found the distance• separating nrsts of a singlr pair highly variable: they ran~ed from a few feet to 3.8 miles. Lockie and Rat eli ife ( 196-1-) found alternate nest::; 111 Scotlnnd ranging from a few yard~ to 3 mileg apart.

1)))_

J .. ~ftG.\HA;.;, F.rology of The Go/elm Eaglt• 5

TARLE 4 Co::\£1',\RISO~ Ul' C1.UTC'JI SrzEs r'RO:\t Dtl'FERF.XT ARE.\S

An·a a1!ll im•t•stiga tor

Caliiornia (Dixon, 1937) (';diiornia (Hanna, 1930) C:alifornia (Slevin; 1929) 'rutland (Gordon, 1927) (' ol<~rado <Jollie, 1943) 1

~lunt:llla (present study)

X 11m ba o j rlufrlrt•s iu samplo

Utiknuwn unknown

21 S2

5 .:!0

·--·--·

Frrquenry of dijjere11l clutrlz si::es (per cent)

1 e,~g 2 eggs 3 eggs

10 80 10 35 60 5 19 67 14 18 72 10 20 80 0

5 so 1$

~ ··Till' (;nldt•n Eagll': Its lift• hi,tury, hl·lla\'iur. and ccolugy, .. :.\I. S, tlb.;t•rtation, t'niwr~ity oi l'uln· ~.J.!,t. l Q4~le

In 1963 the average density for 17 known nesting pairs of Colden Eagles in :\rea A was one pair per 74.2 ~quare miles. ln 1964 the same area sup­p<~rlt·d 19 known pairs for an a\'erage density of one pair per 66.3 square ·!.ill-:;. These figtires e~press the maximum area per pair, for areas in­;l.lhited by humans are included. and unknown nesting pairs nuty also ha\'e hn·n present. Dixon ( 193 7) mapped the actual areas 27 nesting pairs of l;~>ldrn Eag1es used in California; ranging from 19 to 59 !'quare miles, tlu·;-~.- a\·eraged 36 square miles. or the equi\'alent of one township. Arnold 1 I 1'54) located 6 pairs of t•agles on 6 adjacent townships in Colorado. l.ut kit.• ( l%4) determined each of 13 Colden Eagle pairs in Scotland oc-1-.ljlied an aw.'rage of 27.1 squnre mile~. In another Scottish study \Yatson

;·•.:;; l iound the a\'erage area for t•ach oi 5 pain; oi t.1ugh•!'i wa::; 0 fquar~ ':.dt•:--..

T.\BLE 5 Yot'X(: H \1Tlll-:n vw FIJIH:J.u. 11)(.13-lrJIJ-l. :\llt·.\S .\ '='ll B

=:..::- ..:.-4- .... --

'· .. ~ · •t·r oi rw~tin!! diort-: 11163 -., .::::!,tt oi rwqint: cfim·ts 1064 \. -:1,~~t·r hatched 11J6.3 -., .::.l•tr hatdwd 1964 "-~~-~~~·number hatclwd pt•r lll':<t IIJ6.) \· P.l1't' number hatclwd per ne~t 1%-1 ' v,;:..'l' numbl•r hatched pt•t· 1\l':-l 1%3 -lllu4 '. · · !.rr : h:cl!!l'd IIJ63 \v:.l,a ih-d!.!~d 196-l \ -r: .. :.:c· numltt:r ikd!.!ed [ll'l' tW:-t JCH1\ t '<~ • .l\'l· nmnhcr flt•d!!~'d Jll~r l1l':-L 111h4 .~H~.:~\' nurulwr ill•dt:t•d per nt·~t l•liJ.\- I<Hd ; •• 1\ :.t 11i hatchl'd that ih-d!!cd JIJ(J' ' -· "'",! ui l1.1tl'lwcl that ik·d!!l'd 1%t

• 1 o: t ui h:tldll'd that ikdt!l'd 1 cu,; l'lld

. I rm .I

13 19

'' ,-_, 1 {,C}

1.-12 1.:q

lS 1,.{

I '~ 1 21 1.2:-\

:-:u; ~:; 2 :-\ '.i

.11'1'11 B

:-1 11 14 II)

J.i;\ 1.h4 Lu~

11 1~

1 . .\l'\ 1 fd I . .'.\

;s ll wo \ll).h

~-_... ... -----.. --.~ .... --·~ --~

. I rt'cl .I and B

21 .\0 36 -1:'

1.71 1.50 1'\IJ

29 -11 u~ 1..\7 1.3 i

:-10.6 CJl.l XhA

6 [

.\uh ,. . 'ul. ''·'

T:\BLE C•

St' \1:\t.\~Y (II' PHt·S ('u\tl't•:>n to,;1

.... ~----.: .... ·:"':. _____ ..... -.;::-:::

] Wt-/

----- -------- -----·-·-Prey lypr:' S f l't•r n·nt J S f l'rr rrnt 1 S t/'a rt'lll J S ( Pt•r ct'lll)

--..-~--· ----- ... --- __________ ,.._ - --)lammals ~3 (~5.0) ·-- ~~~.5) -!H1 ( :->6.2) ~54 U~i .0)

*'\,:l;l

Bird:' 15 (15.0) 45 (1 Ll) (12 ( 12.i) 121 ( 12.4)

Reptile:; 0 (0.0) 0 !0.0) 4 (0.1'\) 4 (0.4)

Gamr spccirs 9 ( !J.O) 30 ( 7.4) -~~ (!).9) Si Ut~)

:\on-game :;peril'S 89 (91.0) .'6CJ (92.0) 4.'-1 t$!J.S) SIJJ (IJO,IJ)

Domc:;tic species 0 (0.0) 1 (0.2) 0 (0.0) 1 (0.1)

--···~·· -· - ---------·-- ._, -----I Jl.t-•••1 on 'l5 ~mnplin~• t.tkt•n irum .)S tw-t,.

l 1 WHll'CTI\'lTY

Clutch si:;c.-Jn 196-1-, 1.) nests pwclucccl 29 eggs: m 1965) 7 nests con­tained U eggs, an average of 2.1 egg:; per nest for the 2 years. Three nests contained 3 eggs: one nest held only 1 cg!.!, and the remaining nests con­tained 2 eggs each. Table -1- lists clutch sizes recorded in CaliforniJl, Colo­rado. and Scotland. The percentage:' of clutche=- in <.'ach of the tlfrc·e ~ize categorie~ do not differ stati~ticalh· amon!..!; tht>!'L' area:'. z. . - .

JI atrhing and jlcdging succcss.-1 n 1963 and 196-1- a total of 45 succc~~-ful ne::.ting efiort!' hatched S 1 young for an awrage of 1.8 young per nest. Of tho:'e hatched iO ( 86.-1- per cent) flrd!..!;ecl. an average of 1.56 flcclglings per ne:;t. Combining the~e data with tho:-:t' irmn unsuccessful ne,:-;ting at­tempts yields an average of 1.5<) yottn!..! Jll'r ne:'t hatclwd ancl 1 . .1 i per tH'"'t

fledged (Table 5). D~i.Ul ol.Hai11t:tl hy \Yellrin nml Hay ( 1 Oo.!) irnm 2.1 m.•sts r~Yt><tl similar

productivity in the southern Rockie,:-;. whl'l'l' 1. ~9 young hatched per· nest­ing attempt, an average of 1..;2 birds pei· m·:-:t il~ dgt'<l, ~i11d S5.7 per et'nt iii all young fledged. not counting iour youn!_! the : .. ··e..tigators took for study

purposes. In Scotland, \Yatson ( 195i) rt'corded lower pro luctivity values; 5 nests

produced 0.8 young per annum Jlt'r pair over a l?·year period. Th~rc also Brown and \Ya tsnn ( 196-1-) recorded fewer than 1.3 eaglets reared for each of 97 successful ne~ting~. and Sanclrman ( 195 7) record eel 1 A young

fledged for each of 19 sttcce:'siul nest:::. •

FooD H,\BIT::l

Remains of prey were counted, recorded, retno\·Nl from the nest, and when po:-;sible identiiied. Pellets regurgitated by both adults and yuung were counted. collected, ancl stored. To nid in analysis of pellet content~. microscope slides wrre pn•parecl of hair:-; of the difiNent resident mammals, for use with mammalian hair keys P,lathiak. 193S: Spence. 1963). Tn all,

9))

• ;-

;.ln+ ] McG,\1!,\X, Ecology aj Tltt· Golden Eagle 7 !\Jr.:'.

TABLE 7 Fuoo tH:' ~1-:sn~G GoJ.DEX E.wr.F.s, ARI,As :\ .\XD R, 1962-196-l1

----·--· -·· ·-~- ·-·-- --------- .. ____ ., ----- ·--19n2 19(53 196-J. Total

l'n•y .~p~·cirs Sdt'lzlific namr Per Per Per Prr .v ceut .Y Cl.'lll .v cent .v emf

\\'hitt:t:til jackr.t!>hit Lepus t tl'i~'ll.w:ndii .18 39 156 39.0 1il 35.5 365 37.2 t ·~~aontail (desert S yl·i!ilag us aut! u/Hmii, • J 33 126 31.5 161 33.-l .H9 JJ" ·'- _,o

.wd mountain) s. 111/lltlllii

Y dluw-lwllicd .lfarmola jlwc.•iimtf ris 11 11 26 6.5 33 6.8 iO 7.1 rn.1rmot

Ki( harcbun 's ~round Citt•llus ric/lt.lrdwuii 0 0 ,-_;, 6.2 19 3.9 +l 4.5 •quirrd

!l!.td. -hilll:d :\1 :t).!pit• Pica ;pica i f H.\ -L5 19 3.9 44 4.5 lrt.l\ P:1rtridgc Padi.r pr•nlix 2 2 9 ' ' 13 .u ZG ' -~-1

\LJ!,•th r I fawn) Odoroilt·ux ht•mimzus ~ 2.0 15 .u 24 2.-l Hha·l:ruu~c Den dra.~a pus ob,,c ur us 5 5 ~ 2.0 6 1.2 19 1.9 f.,li;:tail \\'l'a::l'! .lfu.,lclrz jrt'1lala 0 0 0 0 w 2.1 10 1.0 ~--~l·l;wu~c Cent rort•rnts uro- 0 0 2 0.5 8 l.i 10 1.0

plwsinnus \ •·I~· 'lon!.!lail. Rich- .l/ icrot us ~pp. 0 0 -l 1.0 5 1.0 9 o.s .nd-,n·~. and others)

l .~~·.tt Horned Owl Bubo ~·ir.~inianu.~ 1 1 2 0.3 3 0.6 6 0.6 l:Ld.t.Iil prairie do,~! Cynomy.1 lu.!o<·idrittu,· 0 0 :> 1.1 0 0 5 0.5 I<··! :-h.titl'Cl Flicker CoiaPlt's ra.fcr 0 0 2 0.$ 2 OA -l 0.4 t\:: . .::·rtt:lkt-11 Phca~ant l'hmiatws rolrhiru.,· 0 0 0 0 4 0.8 -l OA l': .. r..::hcorn antdopc .lntilompra alltcrinmrz 1 1 2 0.5 0 0 3 0 .. \

· 1.1 I\ ll)

'-!' rh·arl'cl Owl .biojflllllllli'IIS 0 0 ' 0.5 0 0 1 0.2 i':.wk r:ttt!l-:-nakc Crotalu\ <·idrfil· 0 0 0 0 2 0.4 2 0.2 t :,: kntiiit-d snakl' 0 0 0 0 2 0.4 2 0.1 "'''lJ-t•d ~kunk .lft•phiti, l111'pltiti,· 0 0 0 0 l 0.2 1 0.1 , •• ·~ 1l(•il1\' Rrl'llti:on r/,•na/lf/11 0 0 0 0 i 0.2 i o.i !:.,. 1 .~ t:til wnndrat .\'t'0/011111 cilll'l'l'tl 0 0 1 0.2 0 0 1 0.1 \L:,tt.ii Oudatrr{ :iilt•titiclr' u 0 I u.2 0 0 1 O.i . •• ::·,··tic Limb O&·i~ "J!Jl • 0 0 1 02 0 0 1 0.1 : ... l . .:·l'.tn·tl Owl . bio 111 us 0 0 1 0.1 0 0 1 0.1 ''·~ ·p·t.tiiL"d ( ;rou~c l'l·diocal cs p!w 'irtn diu~ 0 0 1 0.2 0 0 1 0.1 \l ~. ·h 11,1\\ k Circu., n•aJu·us 0 0 0 0 1 0.2 I 0.1 "':-rruw Hawk Fttlro ·'P~Il'i.'l riu., 0 0 0 0 1 0.2 I 0.1 ! ~ ~- IJow C olu 111 ba /ida 0 0 0 0 1 0.1 I 0.1 H .•• \. 1 nl··tlinl!) 0 0 a 0 1 0.2 I 0.1 !. :·l•ill~·d C'urlew .\'1111/l'lliU.\ 1111/l'riCrllllrS 0 0 0 0 1 0.1 1 0.1

-- --.~----- ------- -. ~ .. ___ ,. ___ .. ~--·---.. ! ... ~.: ••n •1'i '·llllJ'lilll{' 1akt·n inm1 .Is 111 -1~.

- ,,unple:- were tnken from 3~ t•yrie:-;, which included .)21 pellet:>, or 3.4 :""r ~nnph·. From these 9~0 pn.•y :-pecimen~. or 10.; per :;ampling. were • ;,.~<tiiil·d. indicating the minimum number oi indidcluals that the yariou=-1 l,·:Hifh·d items could repre!'ent.

id•ntijinl prcy.-Of the 9XO :-:1wcinwn:-: of prey idl·ntiiicd. ~7 per cent •Hrc· mammals (Tal>ll' 6). Of the mammal:-:. ~0 JH'I' rl'nt \\'l'I'C lagomnrph:-:. \~ : 1 ::,·t~til jackrabbit:-: \\'l'l'e tlw maJor prl'y :-pt•dt·:-:. compn~ing 42.7 pl'r et•nt •! •!.c· mammals and 37.2 pt·t· r('nt ni all pn•y itt•m;-; ( T~thlt• 7). Dl':'l'rt and ~ '-•::::tain cottontail:-: "'l'l'!' JW:trly a:-; ph·ntifuL n·JH't•:-t·ntin!.! 37.4 JWI' l.'ent

s [ .\uk

r .. t. ~·'

of the mammals and .;2.6 per cent oi tlw total. Birds compo.:'ed 12.4 ptr cent of the total numbt•r oi prey :'prcimen::. with Black-billed :\fagpies the most prevalent. representing 36 per cent oi the birds. Gray Partriclgt• ancl Blue Grouse were fairly common. together Cllll1posing 3i per cent of the birds. The only reptiles tallied wen· iour snakes. representing only 0.4 per

cent oi the tota1 number of prey indidduab. Game and domestic sprcics.-Game and domestic spt.•de:; represented

only s.g per cent oi the prey recordt'<L Of all the gamr ~pedes, 30 per cent oi the incli\·iduab were Gray Partridgt.•s. :\Iule deer fawns repre:-ented 28 per cent, Blue Grouse. 22 per cent. and Sage (;rouse, ll per cent. The remaining S per cent included Ring-necked Phc:umnts. pronghorn antt•lupl' iawns. and a ~harp-tailed (;rouse. lt is not known how many of these were

taken as carrion. Predation by eagl(•:; on live game of nunH.·rous species and· on domestic.

species has been repmtecl by many ob:'erwrs in \'arious )laces. -~;olden t

Eagles ha\·e been known to kill m· attack bighorn ~heep (C'<.•is cczua(lt'llsi.n lambs ( Kenm•cly, 194~). pronghorn antelopr (Lchti. 194 i), whitet~i~ deer (Odocvilcus <.'irginiauus) (\\'iliard. 1916). mule deer (Craighead and Craighead. 195 6 l. dotne:-;tic gee:-e (Smith, 1915). chicken~ (:\I ussclman. 19-~2). calyes (\\'nod. 1946). and lamb:-; (Gordon. 1955; Lockie. 1964: Lockie ancl ~teplwn. 1959}. Other inn:--tigators ha,·c obsen·ed that eagl(•:-; either neglect or only ycry slightly affect \'arinus domestic and game ani­mals (.-\rnold. 1954: Brown and \\'at:-;on. 1964: Lockie and Steplwn, 195CJ: Stt:phen. liJSOL In the pre?ent -;turl}'- mu.· pair nf (;olden Eagles nested 200 yards from a ::.mall iarm with se\'eral hundred chicken:-;. In thl' 5 years the eagles hacl nested there they wen· ne\'er k tio\\'11 to pel'y un the pmil try.

Jndeecl. predation on dome~ tic :-pecie:-; in thi:-; :"llldy wn=- negligihlt-. On Area :\ during thl' inyrstigatiun 26.000 to 28.000 :-;lwep were reared, with an annual producti11n oi apprm:imatl·ly 1~.COO lamb:::. yet none wa:-; found in 702 prey item:>. The n•mains of om: lamb. pn:~;;ihly taken a:> carrion.

were found at thr foot of a nc~t in :\n•a B. Otlrrr jood habit ;'i/zulits.--Otlwr Amt:rican :'tlHlie~ han• abo ~hown a

predominance oi lagomorphs. ranging from 2~ to <10 per Cl'nt. in tlw dit.'t:; of Golden Eagle:' L-\rnolcl. 1954: Carnie. 1954: (;Jo.~l. 192.5: ~Ic:\tN'. 1935: \Yooch!l'nl. l952). In :-r\'Nal European ~tudic•:-:: a\'ian form~ made n large proportion ni the prey: bird:-;, u:-;ually ptarmigan or grouse ( Lagopus. Tctnw, L.'•rurus l, wen· taken almo:->t a:' freqm•ntly as rabbits (Hagen. 1952: Lock it' and ~tephen, 195<J: Cttl'nclnrfer. 1939). 1 n a few ~tuclit•:-:: rabbits or hares were not prrdominant. :\[uric ( 1 ~14-l) reports OlH' popula­tion in Ala~ka that li\'ed primarily on gn.uncl ..;quirn•b (Citt'lll s undulatus), Capcrcaillie ( Tctrao urogallun Wl'l'l' the mo:<t pre\·alent prey ::pecit·~ in a

:;tudy in Finland (~ulk<W<I. 1959).

. . . j 1 1 ~

l

lan. 1 !•ill:\ .J

-~--. --·--Age

;\t•.-1 lir:g-lun·nilc ;\dull t'nknown

McG,\n,\~. Erology (lj Tltc Goldi'Jz Eaglr 9

TABLE 8 Am: Co.!ltl'O:ilTIOX 01' :\fokTAJ.JTms, 1962-1964, :\Rr .. \S :\ A:'\P B1

--------···---- ~ .. ----·--1962 11)63 196-1 Tolal

.v Pa rrul s Prr rt'ltl .v Prr ern/ .Y Prr cent ·-·-------

3 60 i 58 4 so H 64 0 0 1 17 0 0 2 9 2 40 0 0 0 0 2 9 0 0 3

,. -.1 1 20 4 IS - --~ _,.. ____ -·· -·--·-·---

t Tllh l:lbh· 1lnt•s nul lndudt• till' four lnl!llktll•at.:lt• murlalitit•s rulkrltd Clllbitlt• my ,ttuly ar<'a •

.:\ f 0\'E~ll~:-\TS

1 n I 96 3 and 1964 5J..., \'Oltt1" were handed with eithel' reuular <H· ··Lok-, ' ' .. ~ ~

tite'' bands and cnlor marked with braided polyethylene rope and poly-\'inyl chloride tape. Bands from four eagles were n.'CO\'ered southeast of tlw hamlin.~ sites. The youngt'St eaglt'. :'('\'en months of ag(', was shot near .Kerr\'ilh•. Texas, 1,290 miles l'rom the handing site. Two other eagle!', ap­proximately one year (l)d, were taken in "'yoming, 210 mile~ and 350 mile~ di:-tant from the point oi rdt>a:-:e. Thf.' iourth eagle, found with an injured win.~ and later banded and relea:1'{1. wa:: found dead 90 miles south{;'a:;t of

Q'i\ tht• n·IP:~>e site. Band roco\-crics fr<>m other (;oldrn Eagle >Indios ha,·e also lj indicated north· south mo\'ement!', e\·idently migratory (Cooke, 1041, 1950:

:'pniinrd, 1964). \\'hile :\furic (1944) reported migration oi the total <'agle population of

.\It. .\I<:Kinh'y .:\ational Park in .-\la~ka. where the eagle!' a1Th·e in :\farch .md lt•;p;p in OctolJC!r, t'ome population:-: in tlw :·outhern pmtt: of tlw mnge :;;:ty :-ho\\' only local or intra-ran!!• mo\'t•nwnts during tht• annual cycle. 1 arnit· (1<15-i) claimed that i n•ro\'.erie:-; ot33 )Oung handt•d in ('alii"ornia indir:ttl'd no PXten~h·e mn\'t•ment of the population .

.\r(lJn'.\I.IT\'

In tlw pn•:-:t•nt :-:tudy 22 (;oJd<·n Ea!.dt•s \rt·n· found d!.'ad from 1962

: !:rnuuh I 96-+. 0 f t he;;c 14 were ne:-:t lin~!'. :\ l':-:tli ng mortality is more ap­i·'-~rt'nt than mortality of the wide-rantdng immature and adult birds. The :ru:idl'lll'l' oi mortality among immatun.• and adult t•agle$ i:-: probably greater :h;!tl ht·n• indicatt•cl. :\11 four bands n•cm·prcd wt'n' takt•n from immature '.t::h·-. ... hot or found dcaci from <)Q to a I mo:-t 1.300 111 ilt'!' from the study

~l:u: <'a\1::-t•d the death of I 0 em.dt•:..: I,; mnn· dit•d from unknown cau!'c'!'. !;,.: .. w orw JH:';o;t containinu tlw rrmain:-: of a porcupine the remain!' of one : .!!;· ic·:llh\'rt•d ymmg bird \\'l't'l' found. :\o quill:: \\'l'l'l' found in the bini. ·' :::t11 had ht•t n dead a lmo:-t a mon 1 h :tnd wa:-; h<Hily dt•cnmpo:-:ed (for a · .\ " ,,j cit-at h irnm pon·upitw quill~ :-t't' Lnno. I ll22).

--

10

Jfumau iulaftrcHCL-Yount! W<'rt' tak('ll from ne,t:-; in !<eHral in~t:incc:-:. yet the adults returned the iollowing year to occ:upy the ~amc nest. and in one case succe5:-;fulh· reared anothrr vount! tht• followin~ vear. 1 n 1962 an - - . ~ -adult male was ~hot at one nest; the single young was al~o iound dt•ad. The nest remainrd empty for 2 year~. hut wa~ again occupied in 1965. Sandeman ( 195i) relates nine instancr:> where one member of a pair of Golden Eagle.:' was killed: in six of the:>e cast•:' a pair was pre~ent the fol­lowing season. In Cai!' ;nia. the iemale of a pair was .shot in December: but two eagles bt>gan nesting there .in February (Dixon. 1 Q,, i). The dr­structh·e effects of human intcrferrncc on nesting eagle populations may be huifered by a surplus of unmated adults.

I am indebted to J. J. Crai!!head ior incentiw, suppurl. and ad\'icc. Sincerl' thank!< )!O to cwry mt•mb(•r oi the ~t;tii oi the l\lnntana Coopl'rativc \\"ildliic Rc~L·arch l'nit. I thank al:;o P. L. \\'ri!.:ht and R. S. Hoifmann, ior both tinw and addrc; and J. S Sumnrr. \\'. L. Stani!!l't. D. I.. Albrecht, ami C. F . .:\lrC:ah;tn, Jr., for iiclcl as,:i~tancc. I am al~o thankful ior hl'lp uh'cn me hy my family, Chark:~. Sr., :\lice. ancrprclocly .:\IcGOlhan, and hy Elizalwth <L Sale. The :\lontana Coop~ratiw \\'ildliic kc~carch l'nit, the t:nh·ersity of .:\fontana. the :\Jontana State l'i;-;h and Gamr Dl•partm~nt. and the \\'ildlifc :\f ana!!cmcnt 1 nstit u tc contributed I o the study. which ''a:' \'a ribtisly ii­nanccd by the Xational .-\uduhnn Society. tlw Frank :\1. Chapman 2\fcmorial Funcl oi the American Mu~eum oi .:'\atural Hbtt~ry. tlw :\ational \\'ildliic Federation. and the

l'. S. Fish ami \\'i)!lliic Scrvicl·.

St;)DJ.\HY

From 1962 to 196$ ecological ~tudit•s \\Nl' mad{• of nestin!.! Golden Ea­gks primarily in a 1.260 :-:quart' mil~· an.·a in ~ottth-central ~Jontana. :\Io:::t ne!'bi were on cliii::; between <•lc\'ations of l.OOO and il.UOO feel. AittttJ='i haif of the cliff ne:;t;:: faced ::,outh, only about om•-tcnth iacecl north.

The average den~ity of nesting pair~ ( 17 · 19) in 1963 and 1964 ranged from 66.3 to 74.2 ~quart· mile~ per pair: the di:-::tancr .sep:uating tH'ighbor:; varied from 1.0 to 10.5 mile:;. :\fore than hali oi the pairs ob~erved at­tended more than nne ne:::t . .such supcrnunwt·ary ne.st:; averaged 1.8 per pair and ranged from several feet to 3.8 milt·:; apart.

From 1964 through 1965.20 ne.sb produced 42 eg~s (2.1 e.!.!~S per m•st): in 1963 and 196-1-. 4.5 ~ucce:-:-ful nr:;ts produced X 1 young ( 1.8 young pet· eyrie). of which iO ( 86.4 per cent) ill•dgt>d ( L$ 6 per lltt'.St).

From 38 eyrie:=: 9XO prey individtml.s wt'l'e identified. ::\fammal;:; ( 8 7.0 per cent) e~pecially lagomorphs predominated. Thl' whitetail jackrabbit was the most numerous prl'y spt'cies (,1 7.2 per cent). Bird:; represented 12.4 per cent. Oi the total prey 8.8 per cent were game species. chiefly Gray Partridge and young mule deer. Xo prNlation on domestic :~pt•cies

was observed in tht• principal .study area.

i . ! i i 1

!

')·. (

J

....

l\IcG.\11,\:\, Ecology of The Goldrn E11glc 11

In all 55 youn~ ~·.-ere banded of which 4 were recovered from 90 to al­most 1,300 miles southeastward.

From 1962 to 1964, 2 2 Golden Eagles, of which 14 were nestlings, were found dead. )Jan caused the death of 10 of these birds; 12 died from un­

known causes.

LinR.nrRE CITED

Ali~OLO, L. \V. 1954. Th~ Golden Ea~ic atHI its economic status. l 1• S. Fish and

\\'ildlifc Scrv., Circular no. 27. I!RoWx. L. H., Axn :\. \\'.\Tsox. IIJ64. The Gnluen Eagle in rela lion to its food

::upply. Ibis, 106: 7:{-100. C\k:m:. S. K. 1954. Food habit:; oi Golden Eagles in the coast r.tnges oi California.

Condor, 56: .1-11. ('.\1\Sil~. R. L. 196.?. Silent. .::pring. Bo:;ton. Houghton 2\lifilin. ('ou~-:1: • .:\1. T. 1941. Return!' irom )Jandccl uirch:; n·con~ric:: of some banded birds

of pn•y. Birci-Banding, 12: 1:\0-HJO. L'•,uJ.:t:. ::\1. T. 1950. Rt•lurns imm banded hirt!s. Bird-Bandinl!, 21: 11-18. C!\ \Hll!E.\D, ] • ] ., .\:\I> F. C. CR.\ItlHJ-:.\n. ] R. 1 Y56. Hawk~. ow b. and wildlife. Harris­

ltur;.:, Pcnnsyl\"ania, Stackpole. t'l~\\11'. S. 1963. To~ic chemicals and bini:: of prey. Brit. Birds, :56: 124-139. llunn. ] , B .•. \XI> J. L. H n· KI.IS. 1963. Pc:;t icid('-l'a!!ll' relatiun:.-hips. Pc::tidde­

wildliie studies. C. S. Fi:-h and \\"ildliie St•r\"., Circular no. 199. lh\ux. J. B. liJJi. The Gulden Ea!!le in San Diego County. California. Condor,

39: 49-56. li: ll\'ll, ll. K. 1925. Fidel :-tudit-s oi tlw diurnal raptort•s oi l'a::.lern and rt·nlral Kan-

~a:-. \\'il~on Bull .. ;{7: 1.\3-149. l;··!.uu:.:, 3. P. 19.?i. Day~ with the (;oldl·n Ea!!lc. London. \\'illiam:- and :\nn.:alt•.

1 i••IH'\•~. S. P. 19~~. The Unldt•n E:t!!lt•: kin!! nf bink :\cw York. Cilatll'i.

II \•,J "· \'. 1952. RndtJglt·tw m! viltpll'it-n. (hln. Gylcndal. ll\\:.0'.\, \\', C. 1930. :\utt•:-. on lht• t;uldl'n Eaglt· in ~outlll'l'll Caliinrnia. Condor,

:~2; 121-123.

l\1 ''\l'ln', C .• \. 19-t~. Unlth·n Ea!!lt• kill,- hi!!lwrn lamb. j. ~lamm:tlnl!y. 29: (18·C>9.

L\:\o, A. 1922. Golth·n Eagle ( !qui/,, tltr,\'~ados) and pun·upitw .. \uk. :~9: 25;-i-239.

l.Pm, R. \\'. 1947. Tlw Goldt•n Ea!!lc attacking antl'loJW. j. \\'ilcll. 2\IJ!tnl, 11: J-lS-.\49.

J.. 4 J.:tL _'. D. 1%4. The hn•l·tling th-n~ity of the Goltll·n Eadc and iox in n·lation In inod !'Upply in \\\•:-tt•r Rn.,:-, Scotland. Scolti~h ~at., i J: bi- ii.

L• • 1>11 , j. D., .\~n D. :\. R\1t'l.ll't'E. l %4. In:-l!cficidl'S and Scuttbh (;nlckn Eagle~. lldt. Bird~, 57: SIJ-102.

!, •• }\lf:, J.D., ,\xn D. SnYllh~. l'J;\lJ, E.ttdc, lamh.., :mel land man:H!t•mt·nts on Lewis . . \nimal Ecol., 28: 43-50.

~~. \lt.t., \\'. L. 19.\5, Food habits ni t;omnwn hawk:.. l". S. lkpt. .-\gric., Circular nu . • JiO.

).1 \t 111\J.:, H. :\, lCJ.\~. :\ J..l')' to h:dr:. oi the mammal-: of ~out hem ~lkhbm. j. \\'ildl. )!gmt., 2: 251-2(JS •

. \!• lll, A. 19-t-t. Tht• woln:~ oi ~luutl! ~ld\.inley. V.turM of llw :\at1. P:ilk~ t>i the t · S . no. 5.

'-:: •. ,ll~L\~. T. E. t•l.t~. E;r:.!ll'" ni \\l'~ktn llli11uh .\ul;, il9: 103-JOi.

_ .. --

12

62: ,\il-.W-1.

[ .\Ilk

\'ul. ,.;;>

liJ-1~. Till' hird' oi Rocky ~lnttntain ~ational Park. Colorado. Auk.

S.\:>;nh~t.\~, P. \\'. Jll5i. TIH• hn·t·din!! :;urn·:-~ oi (inlrkn Ea;!Ic., in the :;outlwrn Grampi;m.:. St:ottbh ~at.. 69: 1-1:-i -152.

St.F.\'1!\. J. It t<J.?lJ. :\ contribution to <tUr kn(lwkd!!t' oi lhc nc:<ting hahit,; of the Gol!hm Eadt•. I'roc. Caliiornia :\cad. Sd., 18: -15-it.

S~tltH. :\. P. JIH;\. Bird:: of the Boston :\fountain.-•• \rkan~a:;. Condor. 17: 41-i\i. Sl•t:~n:. L. E .. jR. lOu.~. Study of iclcntiiying charactt•ri::tics oi mammal hair. \\'ildl.

Di::t·a::c He::l·arch Lab,, Wyomin.!! Fi::h :llHI (Jame Comm. Sl'mTnRr>, \\'. R. 1CJ64. Golrlcn En.gk• i\OCJ-5011-1. Bird-Hanrling, :~:>: I.:!J-12-1. Sn:l'lllS, D 1950. Day:; with till' Gnlrkn Eagk. Gl:t"J.:ll\\', Srlltland, Dnnald~o11. Sn.K.\\',\, S. 19::9. Kutkitn ra\'inno::ta pumnhnito:duccn rtd1ipoulclln. Suonwn rii::ta,

13: 69-·i.?. t'Tn~noRn:R, 0. 19.,9. Die Erniihnm!! clt•t· «h:ut::rht·n Raulwogd and Euk·n. Bt•r!in.

Xcucln.m (XL•umar:.:l). \\'.\TSII~, A. 195i. The breeding :;uc:n•;;:: of (;olclt•n Ea.!!lt•:; in the northeast Highland::.

Scc11tish X.1t.. 60: 153-169. \\',,r;;ox. :\., .\:-;n X. C. ~ImwAx. l!Ju-1. l{L•:>idue ... uf IH'guno-chlorim• iml'\'ticirlc;; in a

Golden Eagle. Brit. Birds, 57: J41-J-l4. \\'HLFIX, E. G .• • \XD T. R.\Y. liJCl-1. Ea!!ll' inwstitmtion-~cw :-.h·xicn anf \W;;krn

Trxn::o. Wildt. RL•::orarch {.ab .. Culor:ulo. i \\'u.r •. \Ril, F. C. l CJ 1 u. X ole:> on llll' (;ntdL·n Ea!!ll' ,., :\ rit.ona. Cnndnr. 18 :F00-.?01. \\'wm. D. T. 1CJ46. Eyt•-witm·~.; :u.'l'tHtnl oi (;o)dt·n Ea:.:Jc killing calf. Concltll', 48:

14.;, \\'ounm:Ro, \\'. tCJ5.?. Food hahit::. oi tht• GoldL•n E:u:lc. J. \\'i1 '' :\l.!mt.. 16: -t;;i-

459.

Dcparlmcnt of Zoology, Unh.:crsily of .Mo11taua, 1lfissoula, .lion/ana (Present address, Dcpartmmt oj Zoology, l'uh•crsity of Wisconsin, Jlarli~

son, lrisconsin).

•

-