Vol. 1929 XLVII J SUMNER, Notes On Younit Golden Eagles.

Vol. XLVII1929 JNOTESSUMNER,NotesonYounitGoldenEagles.ON THEGROWTHGOLDENANDBEHAVIOR161OF YOUNGEAGLES.BY E. L. SUMNER JR.(PlatesVII-X).ON April 26, 1925,a nestof the GoldenEagle(Aquilachrysa tos),containingtwo young, was discoveredin a ninety foot sycamore(Platanusracemosa)growingin hilly pastureland of the easternpart of Los Angeles County, California. Frowning cliffs andlofty mountain heights have no part in the landscapeof thisregion, where the gently undulatinghills are treelesssave forscatteringpatchesof oaks (Quercusagrifolia)and the stragglinglines of sycamoreswhichrisefrom the canyonbottomsand markthe water courses. Rather is it a land of Buzzardsand groundsquirrels;and the great pile of stickswhichstoodup againstthehorizonsomesixty feet from the groundseemedstrangelyout ofplace amid these unromanticsurroundings.Numbers237542 and 237543 were placed on the young birds,and constitutethe first banding record for this speciesin thefiles of the BiologicalSurvey. The youngEagleswere coveredwith a downwhichvariedfrom a quarterto a half inch in length,and through which the dark wing-featherswere pushing theirway, giving the birds a somewhatspotted appearance. Bothadults were perchedin the vicinity upon our arrival, but showedthe characteristicunconcernof these birds by silently slippingaway, not to reappearduring our stay.On February 18 of the followingyear the femaleflushedfroma set of two practicallyfresh eggs,now in the collectionof thewriter, but the next year the unusualhappened,and on February27, 1927the nestwasfoundto containthreeeggs,whoseincubationwas judgedto be one week. Thesewere undisturbed,and fromthis time on a visit was made each Sunday, at which time theweightsof our subjectswere recorded,and photographstaken, inadditionto as many notesof interestregardingtheir developmentas the scanttime availablepermitted. The followingreport hasbeencondensedfrommy weeklynotes,the individualidentity of the

TUE A ,VOL. XLVI.PLATE VII.YOUNG GOLDEN EAGLES IN NEST ArRm 26, 1925.

162NotesonYoungGoldenEagles.Auk[Aprilyoung birds being maintained by bands which were changedeachweek to accommodategrowth.February œ7, 19œ7. The female flushed from three eggs at adistanceof 100feet, showingin her reluctanceto leave,lessthan herusual wariness. She disappearedimmediately, not to be seenagainthat day. Weightsof eggs(in grams):No.465252143.0No. 465251143.4No. 3133.7March œ0, 19œ7. Female flushed at 225 feet; male observedcirclingabout, a quarter of a mile to the south. Both departed,not to return while we werethere. A very audiblechirpingsoundcamefrom the nest at regularintervals.No. 465252 just hatched; weight of chick 105.0. Iris cloudybrown; eyes not fully open. Bill black, with hook not veryprominent; "egg tooth" very noticeable. Skin around base ofbill yellow. Feet and legs yellowishflesh-color;claws slightlypaler. Down of two lengths:a thick dirty white coveringaboutone-half inch in length overlaid by a scantier and somewhatlonger growth. Bird unable to distinguishobjects,and chirpsincessantly.No. 465251on the point of hatching;a holein the sideof the eggthroughwhichthe head of the chickcanbe seen. This bird alsochirps,but lessfrequently. Weight 128.6.No. 3 silent. Weight 126.2.A headlessgroundsquirrel(Citellusbeecheyifisheri)in the nest.Shell of first chick had beenremovedand fragmentswere pickedup beneaththe tree.March 27, 1927. Age one week. Female flushedat 450 feet,and flew over the nest twice, at a considerableheight, beforeleaving. All three young hatched and able to take notice ofmovingobjects. Even when I am elevenfeet above the nestthey stretch their necksforward, chirp for food, and follow mymovementswith open bills. When a finger is offered to themtheir criesbecomemorevigorousand feebleattemptsare madetobite it, while small bits of ground-squirrelmeat are eagerlyswallowed. The posteriorhalf of a freshlykilled Crow in the nest, aswell as the older remainsof three ground-squirrels,someof them

TaR AuK, Von. XLVI.PLATEVIII.YOUN(IGOLDEN EAGLES.Urr m MARCH 20, 1927; JUST HATCHING.LOWER: MARCH 27; ONE WE :K OLD.

Vøli9X2 VI]SI7 NrR,NotesonYoun41GoldenEagles.163decayedand full of maggots. The two halves of the third eggshell,wh{chwere p{ckedup on the groundbelow,showthat theline of cleavageoccursat the greatestdiameterof the egg.Althoughmadeas large as possiblethe previousweek, the bandon the largestbird, number465252,is now so tight as to causeanoticeableswellingof the foot. A larger s{zesubstituted,and theinflammation much reducedin half an hour. Iris, skin at baseof bill, and feet, as before,but clawsare grayish,becom{ngdarkerat the tips. Chirps only when disturbed. When lookingabout,this bird can stand upon its tarso-metatarsus and stretch itsneck to the fullest extent.No. 465252Weight .Length.No. 465251357.38 in.232.36 / in.No. 398.24 in.April 3, 1927. Age two weeks. Behaviorof female as before.Only the first two chicksnow present, the fate of the smallestbeingleft to conjecture. The day is dampand cloudy,andwhenlowered to the ground for more careful study both evidently feelthe cold. They chirp continually,and while No. 465252remainswhereverput, the smallerchickrefusesto keep still for any lengthof time, andpersistsin crawlingaway. Egg toothlessconspicuous,owing to increasedsize of bill. Color of soft parts as before,exceptthat clawsare darker.No. 465252Weight .Length .1022.712 in.No. 465251584.78.5 in.No. 465252--A few primary pin feathers fainfly showingthroughthe skin. Chirpsin a muchdeepertone than other bird.Band found to have chafedenoughto draw blood,but foot apparently uninjured.A freshsupplyof greenmaterial, chieflyweeds,alwayspresentin the nest. When venting their excreta, the young turn theirbacksto the edgeof the nest and dischargeto a distanceof sevenfeet clearof the edge,the groundand foliagebeneath.beingspattered on all sides. The feathers of a Meadowlark (Sturnellaneglecta)observed,aswell as the usualremainsof ground-squirrels.April 10, 1927. Age three weeks. Female flushed from a

164AukS , disappearingas usual. The morningbeganinfitful sunlight,but when I was half way up the tree rain commencedto fall, and continuedsteadily for most of the day andall that evening. Both youngstersrear up with open beaksinfeeblemenacewhen I climb over the edge of the nest, but soonsettle down, remainingsilent and motionlesswhen undisturbed.The thick coveringof down seemsfairly adequateto shed theFEB,t MAR. ; t 2027,5IO17 2z r 81522Increasein weight in two nestingGoldenEagles.rain, which is coming down quite hard, but it seemsprobablethat the parent would furnish additionalproteetlonif we werenot present. As soonas they are set down,both birdschirpandrun to the oppositeedgeof the nestfrom me, seto remainfacingmy direction,and the rain preventsanythingbut hurriedwork. Clawsblack;buddingwing-feathersabout a quarter inch long.

PL. TET E ArK, VoI . XLVI.YOUNG GOLDEN EAGLES.UPPER:APriL 3; Two WEEKS 0L ).LOWER:AP uL 24; FIYE WEEKSOLD.IX.

Vol. XL¾I11929ISUMNER,No esonYoungGoldenEagles.No. 465252Weight .Length .1662.413 in.165No. 4652511272.710.2 in.A pieceof ground-squirrel,and part of a cottontail (Sylvilagusauduboniisanctidiegi)in the nest,but decayingremainsof previouskills no longerpresent.zipril 17, 1927. Age four weeks. As we were arriving theadult appearedfrom the north and flew to within 300 feet of usbeforeleaving. Five minuteslater shecameback,flyingstraightfor the nest and carrying a branch of greenoak leaves,someofwhichare foundin the nest at every visit. When about200 feetaway, however,sheagain caughtsight of us, droppedthe branch,and flew away, not to be seenagain.The secondand smalleryoungsteris much the morelively andaggressive.When I climb over the nest it rearsup and waddlestoward me hissing,with open beak and wings upraised. Thelarger bird, on the contrary, lles quietly in the nest, offeringresistanceonly when handled. Both struggleand chirp vigorouslywhenpickedup, but althoughtheir daws and feet are, forthe size of the birds, enormous,they are harmlessand incapableof doing injury. As the bill continuesto grow, the egg-toothbecomeslessand lessnoticeable,and is now but an insignificantexcrescence.The wing quills are now two incheslong, of whicha half inch has burst from 'the sheath.No. 465252Weight .Total length .2668.817 in.No. 4652511880.914.5 in.Totalwingspread.34 in.26 in.lengthof hind claw.1 { in.1 in.Remains of several ground-squirrels-in'the nest, the top ofwhich is graduallybecomingflattenedand packeddown.April 24, 19œ7. Age five'weeks. Female seen only for. aninstant--sailingaway. The smallerbird is as usualthe aggkessiveone, advancingwith open'beak, and feebly striking my.feet 'withup-raisedwings, while uttering its hissinggasp.lrls broWn;skin at baseof bill, and feet, as before,but daws darker. Eggtooth barely visible. Wing feathersfive incheslong, two inchesof which have burst fr6m the sheath.

166SUMNER,NotesonYoungGoldenEagles.No. 465252Weight .Totallength .Total wingspread.Length of tail quills.Auk[AprilNo. 4652512270.016.5 in.38in.2.5 in.2870.019 in.43 in.2.7 in.of which there has burst out 1 in.Bird very quiet, its few protestsoften being uttered in a tone muchdeeper than the original falsettochirpBird obstreperous,but silent except for hissing.The nest, owing to its positionon the crotch, is smaller thanthe averagefor this species,being only four feet in diameter; andsinceour weekly visits were beginningto producea very evidenteffect upon the foundations,it was wired securelyin place at thistime. The usual green naterial present,as well as the customaryground-squirrelremains.May 1, 1927. Age six weeks. Adult observedseveral timesflying about. The smallerbird is more hostile than ever, strikingfeebly with outstretchedclawsin addition to the hissingand thebufferingof wings. Although usually silent when handled, thisbird, when it does protest, showsno changein voice from thefirst high pitched tone. The larger youngsteris as quiet anddocile as usual, taking no notice of me except when handled.When arousedit occasionallysquealsin its earlier high pitchedvoice, but usually with the deeper note. Egg-tooth hardlydiscernible. Iris and soft parts as before. Wing feathersseveninchesin length, of which four incheshave burst from the sheath.No. 465252No. 465251 Weight .3581.7Total wingspread.Length of tail quills.48 in.4.5 in.2606.746 in.4 in.of which there have burst out 2.5 in.1.5 henest itself is quite clean, with but a slight odor and few flies; thecircleof excrementbelowis now forty feet in diameterand all theimmediateleaves and branches are encrusted with white.May 8, 1927. Age seven weeks. Adults not seen. Thesmallereagletusesits talonsoccasionally,but may still be handledwith perfectsafety;the largeryoungsteris as docileas ever. On

THE AUK, Vor. XLVI./.PLATE X.I.YounoGoI vEn//.ßEAOI ES.UPPER.*MAY 1; WEEKS OLD.LOWER: MAY 15; EIGHT W E8 OLD.