Ste-Anne de Bellevue, Qu6bec H9X 1CO, DM Bird, RG Clark

Tags: Bill, Tarsuslength Toe length, American Kestrels, PR, birds, Bird, growth, E. Lack, Oakland Municipal Airport, Robert E. Kenward, RAPTOR RESEARCH Vol, Feedingand Developmentof Sparrowhawk, Toe length, Raptor Research
Content: GROWTH
OF BODY COMPONENTS
IN PARENT-AND
HAND-REARED
CAPTIVE
KESTRELS
by David M. Bird Macdonald Raptor Research Centre Macdonald Campus of McGill University 21,111 Lakeshore Road Ste-Anne de Bellevue, Qu6bec H9X 1CO and Robert G. Clark Department of renewable resources Macdonald Campus of McGill University 21,111 Lakeshore Road Ste-Annede Bellevue,Qu6becH9X 1CO Abstract Twelve female and 13 male American Kestrels(Falcosparveriusw) ere hand-reared and fed to satiation4 timesdaily.The growthof the tarsus,third toe, menus,antebrachium,bill, and skull,aswell asbody weight,were measuredevery 6 daysup to fledging and compared to identicalmeasurementsrecorded from 8 female and 11 male kestrelsraised naturally by captiveparentsprovideda similarbut ad libitumdiet. Parent-raisedbirds grew more rapidly and achievedgreater body sizethan hand-reared birds. Males grew fasterthan femalesfor mostparameters,particularly toe and tarsuslength. Introduction With the advent of captivebreeding programsfor falcons,both for laboratoryresearch (Bird and Rehder 1981, Bird 1982) and releaseinto the wild (Newton 1979), the demand for information on the nutritional health of captive-raisedfalconsis increasing. Ricklefs(1968) felt that nutritional deficienciesmay affect growth ratesof wild birds and advisedthat onlygrowthdatacollectedunder favourableconditionsbe usedfor comparative purposes.Furthermore, hesuggestedthat hand-rearingtechniquescouldprovetobevaluable in this regard. Olendorff (1974) pursuedthis suggestionin a laboratoryinvestigationof 3 buteospeciesb,uthasnotprovidedcomparativegrowthdatafor birdsraisednaturallybytheir wild parents. We had the opportunity to compare patternsof growth of body componentsof captive AmericanKestrels(Falcosparveriusr)aisedby parentbirdswith thosehand-rearedbyhumans. The majorsourceof variabilitybetweenthetwogroupswasfoodavailabilityi,.e., hand-reared birdswere fed to satiation4 timesdaily, and parent-raisedbirds had ad libitumfood supply. Thus, our objectiveswere: 1)to describegrowthof selectedbodycomponentsin the kestrel and to contrastthesepatternswith thoseof other raptoriel species;2) to assestshe effect of foodavailabilityasaresultof hand-rearingon growthpatterns;and3) tocomparethe growth rates of male and female kestrels. Materials and Methods All kestrelswereoffspringbredfromstockat theMacdonaldRaptorResearchCentreof McGillUniversityin Ste.Anne de Bellevue,Quebec.Eight femalesand 11 malesraised by parentsfrom naturally-incubatedeggswere randomly
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Raptor Research 17(3):77-84
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selectedtbr measuringfrom nestboxesin 6 and 8 breedingpensrespectivelyc,omprisinga totalof 9 differentbroods. Twenty-five (12 femalesand 13 males)were randomlyselectedfrom offspring being hand-rearedfrom artificiallyincubatedfirstclutchesP. ensand managementpracticeshavebeendescribedelsewhere(Bird etal. 1976). Hand-rearing techniqueswere asfollows.After day 1 in the hatchermaintainedat 36.5шC,chickswere movedto a styrofoamchestwhichwasthermostaticallyheatedby electricalheatingtape or poultry heatingelements.A tray of distilledwatercoveredbywiremeshwaskeptonthebrooderfloor.The chickswerekeptin wirecorralsorin soupbowls, eachbird identifiedbynon-toxicfelt markerpens.The broodertemperaturewasinitiallysetat 35шCandwasdecreased everyfewdaysuntilroomtemperturewasreachedat2 weeksW. henpinfeathershowedt,hechicksweretransferredtoa plasticswimmingpoollinedwithwoodshavingsT.heyeventuallyfledgedintoaroom6.6x 6.6x 2.5m withafloorof sand and woodenperches. Between 18 and 24 hrs after hatching,the chickswere fed smallpiecesof neonatalmice by blunt forceps.This continued4 timesper dayapproximatelyevery4 hoursbeginningat 0830 hrs,eachtimeto thepointof satiationA. fter about10days,theywerefed day-oldcockerelsand,occasionallyla, boratorymice.Duringthisperiod,cockerelswithout down, beaksand legs,or ·nicewithout skin and tailswere mashedin a Waring blender with vitamin and calcium supplementsaddeddaily.Whentheyoungwereableto feedthemselvesa,t approximately14days,thecockerelsor mice wereblendedwholetoprovideroughage.Asthekestrelsapproachedfiedgingageatabout25 days,thefoodwasmashed lessuntil wholeunmashedcockerelswereprovided. The kestrelsraisedbytheir parentsreliedcompletelyon their parentalfoodsupply: day-oldcockerelsandlaboratory micedippedin bonemeaal nd/orvitaminsupplementpsrovidedadlibitumF. oodconsumptionwasnotrecordedfor either hand-rearedor parent-raisedbirds.Rather,the majordifferencein feedingregimeswasfood availability:continuous parentalattentionto beggingyoungversushand-feeding4 timesper daymaximum. Linearmeasurementwseretakenon theleft sideof thebodywitha Verniercaliperaccurateto0.1mm.The following measurementws eretaken(seeOlendorff 1972): 1)tarsallength,2) antebrachiallength,3) billdepth,4) skullwidth,and .5)bill length. The last3 measurementsweretakenasfollows: 6) third toelength-- thedistancefrom thejoint betweenthedistalend of the tarso-metatarsuasndthebasalphalanxof the third toe,to the distaljoint beforethepointwherethetalonemerges fromthetoe.(Wedecidednottoforceopentheentiretoe,includingthecasingaroundthetalon,to preventanydamage to the toot bones.Therefore, the lastsectionof the toeencasingthe talonwasomittedfrom the overalltoelength.)7) manuslength-- thedistancebetweenthewristandthetipof thethird phalanxapproximatedbythebaseof theprimary feathersgrowingfrom the manus.8) bodyweight-- weightrecordedto 0.1 g on a top-loaderbalance. The first measurementswere taken within 94 hr of hatchingand subsequentleyvery6 daysuntil fiedging.Birds undergoingmeasuringgenerallyhad emptycrops.The meansand standarderrorsof the 8 bodycomponentswere calculated1,7,13,19,9.5and 31 dayspost-hatchinfgor parent-(PR)and hand-reared(HR), maleand femalekestrels. Mean bodysizesof PR and HR kestrelswere compared,sexesseparatelyw, ithin 94 hours post-hatchingusingthe Mann-Whitney U test (Siegel 19.56).An analysisof variance(Steel and Torrie 1960) was used to locatesignificant differencesin bodysizesandgrowthratesof PRandHR of bothsexesF. oreachsex-rearingcombinationb, odyweightsat day 25 and 31 werecomparedto locatesignificantdecays(Ricklefs1973)and growthratesusingthe Mann-WhitneyU test (Siegel 19.56). The growthrate (K) and asymptote(A) of eachcomponentwerecomputedfor PR and HR birdsby sexgrouping accordingtothelogisticmodelof Ricklefs(1967).Forbodyweight,timefor growthbetween10and90%of theasymptote (t10_90a)ndtheratio(R)betweetnheasymptoatendadultweighwt erecalculate(dRicklef1s967). Results SignificantdifferencesbetweenPR and HR male kestrelswere evidentwithin 24 hrs of hatchingfor antebrachium(PR > HR) and manuslength (PR < HR), aswell asbodyweight (PR > HR) (Table 1). No significantdifferenceswereobtainedfor femalesat hatching. - There weresignificantdifferencesin meanbodycomponentsizesof PRand HR, maleand femalekestrels(Table 2, Fig. 1). Furthermore,the significantage-rearinginteractionsdemonstratedthat PR kestrelsgrew fasterthan HR kestrelsfor all componentsexceptfemale skullwidth and bill length,aswell asbill depth of both sexes(Table 2, Fig. 1). The asymptote(sA), growthrates(K), and adultbodysizesof the 7 skeletalmeasuresare shownin Table 3. With the exceptionsof femalebill andtoelengths,wheretheasymptoteosf HR birdswere·>PRbirds,theasymptoteasndgrowthratesof PRbirdsexceededthoseof HR birds.With respecto growthrate,thesefindingswereconsistenwt ith the resultsshownin Table 2. The growthratesof malesweregreaterthanfemalesfor 5components(Table3).Thistrend wasmostpronouncedin developmenot f toeandtarsusandleastpronouncedin manusand
Fall 1983
Bird and Clark -- Kestrel Growth
79
Table 1. Mean body size(1 standarderror) of parent-reared (PR) and hand-reared (HR) American Kestrels within 24 hrs post-hatching.
Body size Component Skull width (cm) Bill length (cm) Bill depth (cm) Tarsuslength (cm) toe length(cm) Antebrachiumlength(cm) Manuslength(cm) Weight (g)
Male HR a 1.56 (.03) 0.63 (.Ol) 0.59 (.01) 1.41 (.o2) 0.55 (.o2) 1.20' (.03) 1.36** (.03) 9.65** (.14)
PRa 1.51 (.02) 0.64 (.Ol) 0.59 (.01) 1.40 (.o2) 0.62 (.Ol) 1.12 (.08) 1.49 (.02) 10.96 (.12)
Female
HR a 1.50 (.04) 0.63 (.Ol) 0.59 (.01) 1.36 (.o2) 0.56 (.o2) 1.17 (.03) 1.40 (.04) 9.92 (.17)
PRa 1.49 (.02) 0.64 (.Ol) 0.60 (.01) 1.38 (.o3) 0.58 (.Ol) 1.16 (.04) 1.43 (.02) 9.99 (.31)
a samplesizes:HRd', 13;PRd', 11' HR·, 12;PR·,8. *,** meansof PR and HR kestrelsare significantlydifferent, Mann-Whitney U test, P (0.05(*) and P ( 0.01 (**). Table2. Analysisof varianceof 8 bodycomponentsof captivemaleandfemaleAmerican Kestrel nestlings. The main effects in the analysis are age and rearing; one interaction term (age-rearing) is analyzed. Values are F-test statisticsand are significant(P · 0.01) unlessotherwise specified.
Male
Female
Body parameter
Age Rearing Age- Age Rearing Age-
Rearing
Rearing
Skull width Bill length Bill depth Tarsuslength Toe length Antebrachiumlength Manus length Weight NS Not significant.
165.3
17.0
4.5
386.3 57.3 3.4
190.6 14.9 1.5 NS
868.5 97.8 7.8
487.5 74.5 4.5
761.1 62.6 7.7
702.3 56.4 5.3
499.9 136.1 15.1
134.3
7.6
345.6 23.1
145.0 8.0
576.8 49.0
415.7 26.6
537.0 42.9
628.1 28.3
374.6 61.6
1.9 NS 1.3 NS 0.8 NS 4.4 3.8 3.4 3.5 10.6
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o
·
371S .I.-IVI(]· .:10 (%)
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Bird and Clark -- KestrelGrowth
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Table 3. Asymptotes(A) and growthrates(K) of 7 bodycomponents(cm) of parent-raised (PR) and hand-reared (HR) American Kestrels and associated mean (1 standard error) adultbodysizesa.
Body Component
Male
HR(13b)
A
K
PR(11)
A
K
AdultC(72)
Skull width Bill length Bill depth Tarsulsength Toe length Antebrachium length Manus length
2.24 1.21 0.94 4.12 1.59 5.08 5.49
.079 .091 .116 .165 .188 .143 .150
2.30 1.22 0.97 4.29 1.71 5.27 5.53
.121 .131 .125 .207 .228 .175 .172
2.35(.02) -- 0.89(.01) 4.25(.04d) 2.06(.03) 50.04(.03) --
Female
Body Component
HR(12)
A
K
PR(8)
A
K
AdultC(69)
Skull width Bill length Bill depth Tarsuslength Toe length Antebrachiu m length Manus length
2.25 1.22 0.96 4.19 1.69 5.15 5.43
.087 .096 .103 .146 .150 .137 .147
2.27 1.22 0.98 4.36 1.68 5.35 5.59
.134 .120 .115 .182 .182 .172 .164
2.34(.01) -- 0.93(.01) 4.17(.03d) 2.01(.02) 5.19(.03) --
a A and K basedon pooleddata. b samplseizeindicateindparentheses. c meanadult size(1 standarderror) from Bird, unpubl.data,of PR kestrels. dsamplseizeasre:c·,11'·, i0.
antebrachiumTh. egrowthconstanotfskulwl idthforfemalews asgreatetrhanformalesb, ut no consistenpt atternwasevidentwith bill length. Asymptoteasndgrowthconstantfsor bodyweightof PR birdsweresubstantiallgyreater thanthoseof HR birds(Table4). Rateof weightgainof malesexceededfemalesA. lthough weightwasanextremelyvariablecomponentf,emaleswereapproximatel6y g heavierthan malesat, and subsequentto, fledging(Table 4). Basedon the predictivemodelof Ricklefs(1968: 436),the t10_90valuesof malesand femaleswouldbe 15.3and 15.5daysrespectivelyH.owevero, ur correspondincgalculated valuesfor PRmalesandfemaleswere17.6and 18.4days.Therefore,weightgainof captive kestrelws asrelativelyslowT. heweightlossobservebdetweendays25 and31post-hatching
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Table4. Asymptote(A),growthrate(K),numberofdaysrequiredforgrowthbetween10% and90%of asymptotet10.90)andthe ratio (r) of the asymptoteto adult sizefor weight (g) of parent-reared (PR) and hand-reared (HR) American Kestrels.a.
Growth parameter
Male HR(13b) PR(11)
Female HR(12) PR(8)
A
118.9
132.6
130.1
137.7
K
.209
.250
.203
.239
t10_90
21.0
Adult weight(S.E.)c
R
1.05
17.6 113.4(2.0) 1.17
21.6 1.08
18.4 120.2(5.3) 1.15
a basedon pooleddata. bsampsleizeindicateindparentheses. cweigh(t1standarderror)basedon25 c·and269fromBird,unpubld. ata,on parent-rearedbirdsonly.
(Fig. 1)wasalsoreflectedin the ratiosof theasymptoteto adultweight(R > 1.0),signifying thatthe decayphasecontinuesthroughtheearlypost-fiedgingperiod(Table4). In Figure1,growthof PRandHR, maleandfemalekestrelsisexpressedasthe percentage of adultbodysize.At 31dayspost-hatchings,kullwidthhadnotachievedadultsize(Fig.la), its growthtobecompletedfollowingfledging.The K valuesfor tarsuslengthwerehigherforthe PR birdsand for malesthan for the HR birdsand for females,respectively(Fig. lc). Rapid growthof the antebrachiump, rimarilybetween7 and 19dayspost-hatchingr,esultedin PR nestlingsachievingroughly98.5%of adultsizeatfledging(31days)(Fig.lb). HR birdslagged behindPRbirdsbyapproximately5.5%atthisdate.The maximumweightofPR kestrelsat25 dayspost-hatchinwgasfollowedbyasignificanwt eightlossor decay(P· 0.05;Fig.1).A decay phasefor HR birds wasnot observed. Discussion ThevalueosfA, K,t10_90andR asshownforbodyweighitnTable3 aresomewhaletssthan thosecomputedbyRicklefs(1968)fromdatapublishebdyRoes(t1957)for 13wildkestrels from3 broodsT.hisisespecialtlryueforourHRbirdsB. irdandLagui(·1982)showetdhat theirHRkestrewlserepermanentslmy allearsadulttshanPRonesinskulwl idtht,arsallength, antebrachiumandmanuslength,butnotbodyweight. In thisstudyt,heA andKvaluesa,swellasthemeansofbodycomponentisn,dicatedthatPR birdsgrewmorerapidlyandachievedgreatersizethanHR birds.SincebothPRandHR birds receiveda similardiet,we concludethatdifferentialfeedingrateswerethe mainfactor limitingratesofgrowthW. ecannodtisprovtheepossibiltithyatdifferenitncubatiorengimes, i.e. naturalvs.artificialf,or PR and HR birdsrespectivemlyayhavecontributesdome variationa,lthougBhirdandLagui(·1982)notednoeffecot fincubatiotnechniquoenfresh chickweightin their captivekestrels. Ourresultsuggestht atforraptorsf,oodlimitationcanprolongnestingperiodorresulitn smalleor ffspringa, sshownin swifts(LackandLack1951)procellariiform(Lsack1948),and
Fall 1983
Bird and Clark -- Kestrel Growth
83
Red-wingedBlackbirds(Agelaiusphoenice(uDsy)er 1968).Smallersizesare oftenequatedwith lowered survivalprobabilitiesof offspring (Perrins 1965, Thomsen 1971). Although Balgooyen(1976)foundno differencesin ratesof bodyweightgrowthof wild kestrelsassociated with observeddifferencesin feeding rates,he noted that food waslikely not a limiting factor, especiallywhen youngreceivedfood from both parents. The significantdecayin bodyweightwhichoccurredimmediatelyprior to fledgingconcurs with OlendorfFs(1974)findingsin 3 buteospeciesT. he mosttangiblehypothesisproposedto explain this phenomenonis that substantiawl ater lossoccursasfeathersand muscletissues matureimmediatelyprior to fledging(Ricklefs1968).It isunlikelythat adultsstarvenestlings to causenestabandonment(Sumner1929,Welty 1979),sincehand-rearedbirdsexhibitthis weightloss(Olendorff1974,Schmutzand Schmutz1975,Bird andLagua1982). Growth ratesof males,particularlythe third toe and tarsus,were greater than thoseof females.The Cooper'sHawk (Accipitecrooperia) nd Red-tailed Hawk (Buteojamaicensiasl)so exhibited this phenomenon(Ricklefs 1968). To explain this pattern in the Sparrowhawk (Accipitenrisus)N, ewton(1978)hypothesizedthatin specieswherethe maleissmallerthanthe female,the malegrowsmorerapidlyto avoid,or reduce,competitionin the nest.Werschkul andJackson(1979) arguedthat siblingcompetitionisan importantdeterminantdriving the evolutionof aviangrowthrates.We found growthin leg componentsof malesfasterthan femalesin both rearing groups,whichpresumablymakessmallermalesmore mobileand potentiallyabletoleavethenestsooner.However,relationshipbetweensizeofbird andlength of developmentime derivedfrom numerousfamiliesof avianspecies(Ricklefs1973)maybe sufficientto explainthesetrends.Thus, we believefurther researchexaminingcompetitive interactionsamongsiblingsisrequiredto demonstratethat growthratesarea consequencoef Natural selectionactingto reducecompetition(seeRicklefs1982). In conclusion,food limitation resulted in slowergrowth rates and smaller body sizes through 31 daysof age in captivekestrels.One must be cautiousin using hand-rearing techniquesfor growth studiesand propagationof captiveavian speciesfor releaseinto the wild. Acknowledgments We are gratefulto A..|. Bentley,T. Jones,and M. Vetburg for technicalassistanceIr.e Ministaredel'Educationdu Quabecandle Ministbredu Loisir,dela Chasseetdela P·chedu Quabecare acknowledgedfor financialassistanceR.. Olendorff,J. Koplin and R. O'Connor offered criticisms of earlier drafts. Literature Cited BalgooyenT, .G. 1976. Behaviorandecologyof theAmericanKestrel(FalcosparveriuLs.) in the Sierra Nevada of California. Univ. Calif. Publ. Zool. 103:1-83. Bird, D.M. 1982. AmericanKestrelasa laboratoryresearchanimal.Nature299:300-301. Bird, D.M. andP.C.Lagu& 1982. Influenceof forcedrenestingandhand-rearingon growth of youngcaptivekestrels.Can.J. Zool.60:89-96. Bird, D.M. and N.B. Rehder. 1982. The scienceof captivebreedingof Falcons.Avic.Mag. 87:208-212. Bird, D.M., P.C.Lagua,andR.B.Buckland. 1976. Artificialinseminationvs.naturalmating in captiveAmerican Kestrels.Can.J. Zool.54:1183-1191. Dyer, M.I. 1968. Respiratorymetabolismstudieson Red-wingedBlackbirdnestlingsC. an.J. Zool. 46:223-233. Lack,D. 1948. The significanceof clutchsize.Parts1 and 2. Ibis89:302-352.
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Lack,D. and E. Lack. 1951. The breedingbiologyof the Swift(Apusapus).Ibis93:501-546. Newton, I. 1978. Feedingand Developmentof Sparrowhawk(Accipitenr isus)nestlingsJ. . Zool.(Long.) 184:465-487. 1979. The populationecologyofraptors.ButeoBooks,Vermillion S.D. 399 pp. Olendorff, R.R. 1972. On weighingand measuringraptors.RaptorRes.6:53-56. 1974. Somequantitativeaspectsof growth in three speciesof buteos.Condor 76:466-468. Perrins,C.M. 1965. Populationfluctuationsand clutch-sizein the Great Tit, Parusmajor. Anim. Ecol. 34:601-647. Ricklefs,R.E. 1967. A graphicalmethod of fitting equationsto growth curves.Ecology 48:978-983. 1968. Patternsof growthin birds.Ibis 110:419-451. 1973. Patternsof growthin birds. II. Growthrate and modeof development. Ibis. 115:177-201. 1982. Someconsiderationson siblingcompetitionand avian growth rates.Auk 99:141-147. Roest, A.I. 1957. Notes on the American Sparrow Hawk. Auk 74:1-19. Schmutz,S.M.andJ.K. Schmutz. 1975. Rearingandreleaseof twoyoungAmericanKestrels (FalcosparveriusR). aptorRes.9:58-59. Siegel,S. 1956. Nonparametricstatisticsfor the behavioralsciencesM. cGraw-Hill BookCo., Inc., New York. Steel,R.G.D. and J.H. Torrie. 1960. Principlesand proceduresof statisticsM. cGraw-Hill Book Co., Inc., New York. 481 pp. Sumner,E.L., Jr. 1929. Comparativestudieson the growthof youngraptors.Condor31:85- 111. Thomsen, L. 1971. Behaviorand ecologyof Burrowing Owls on the Oakland Municipal Airport. Condor73:117-192. Welty,J.C. 1979. The life of birds. 2nd edition. SaundersCollegePubl., Philadelphia,Pa. 623 pp. Werschkul,D.F. and J.A. Jackson. 1979. Siblingcompetitionand aviangrowthrates.Ibis 121:98-102.
THE PRICE OF SUCCESS IN GOSHAWK TRAPPING by Robert E. Kenward, Mats Karlbom and Vidar Marcstr6m Institute of Zoophysiology Box 560 S-75122 Uppsala Sweden Abstract Four Swedishtrapsfor goshawksare describedF. alling-endtrapsweremostsuccessfuolf 3 live-baittraptypesb, utweremoreexpensivetobuildandlesseasilymovedthansprung-roof Raptor Research 17(3):84-91

DM Bird, RG Clark

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Title: GROWTH OF BODY COMPONENTS IN PARENT‐AND HAND‐REARED CAPTIVE KESTRELS
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