THE JOURNAL OF RAPTOR RESEARCH A QUARTERLY PUBLICATION OF THE RAPTOR RESEARCH FOUNDATION, INC.

VOL. 37 MARCH 2003 NO. 1 j RaptorRes. 37(1):1-7 ¸ 9003 The Raptor ResearchFoundation, Inc.

COPULATION BEHAVIOR OF A POTENTIALLY DOUBLE-BROODED OF PREY, THE BLACK-WINGED (ELANUS CAER ULE US)

JUANJ. FERRERO,1JUAN M. GRANDE,AND JUAN J. NEGROs Departmentof AppliedBiology, Estaci6n Biol6gica de Do•ana (CSIC), Pabell6ndel Peni, Avda. M a' Luisa s/n 41013, Sevilla,Spain

ABSTRACT.--Raptorsshow high copulation rates when compared to other . This fact has been generallyattributed to sperm competition.However, copulation rates in raptors tend to be seasonally bimodal, with an early peak outsidethe female'sfertile period that cannot be explained by the sperm competition hypothesis.We studied the copulation behavior of the Black-wingedKite (Elanus caeru- leus),that, unlike raptors previouslystudied, may raise two broods consecutivelyin the same breeding season.The first recorded copulation occurred 44 d prior to the onset of laying and the last one on d 66 after. We observed three seasonalpeaks in copulation fYequency.The first two peaks (40 and 10 d befbre egg laying, on average) correspond to the normal pattern in raptors. To explain the first peak, we propose three hypotheses:(1) pair bonding, (2) mate assessment,and (3) territorial sig- naling. Unfbrtunately, we have been unable to elaborate further predictions that would distinguish among these three hypotheses.The second peak, during the fertile period, may be attributed to sperm competition. The third peak, previouslyunreported in raptors, occurred 50 d after the onset of laying, the mean time lag betweenfirst and secondclutches in the area. These late copulations, which were also perfbrmed by pairs that laid one clutch, may reflect the propensityof the speciesto lay secondclutches (we recorded six replacementclutches and five secondclutches out of 98 breeding attempts). This third peak of copulationsmay also have a fertilization function and may be related to sperm competition. KEYWORDS: Black-wingedKite; Elanus caeruleus;copulation behavior;, sperm competition; territorial signaling.

COMPORTAMIENTO COPULATORIO DE UNA RAPAZ CON DOBLE NIDADA POTENCIAL: EL ELANIOCOMI•N (ELANUSCAERULEUS). RESUMEN.--Lasaves rapaces suelen presentar altas tasascopulatorias cuando se las compara con otras aves.Este hecho ha sido generalmenteatribuido a la competenciaesperm•ttica. Sin embargo,la tasade c6pulasen avesrapaces tiende a presentarun patr6n estacionalbimodal, con un primer pico antesdel periodo en que la hembra es f•rtil, que no puede ser explicado por esta hip6tesis.En este trabajo estudiamosel comportamientocopulatorio del elanio cornfin (Elanuscaeruleus), que a diferencia de las otras rapacespreviamente estudiadaspuede sacar addante dos polladas consecutivasen la misma tem- porada de cria. La primera c6pula se observ644 dias antesdel inicio de la puestay la filtima 66 dias despu•s. Observamostres picos en la fi-ecuenciacopulatoria a lo largo de la temporada de cria. Los primeros dos (alrededor de los dias 40 y 10 antes de la puesta) correspondenal patr6n observadoen otras rapaces.Para explicar el primer pico proponemos que se considerentres hip6tesis:(1) reforza- miento de los lazos de pare•ja,(2) valoraci6n de la calidad del compafiero y (3) sefializaci6ndel terri- torio. Desafbrtunadamente,no hemos podido elaborar prediccionesque permitan distinguir entre estas

Presentaddress: Tirso de Molina, 14, M•rida 06800, Badajoz,Spain. Correspondingauthor's e-mail address:[email protected] 2 FEP,aE•O ET AL. VOL. 37, NO. 1

tres hip6tesis.E1 segundopico, durante el periodo f(•rtil de la hembra podria atribuirsea fen6menos de competenciaespermatica. E1 tercero, observadopot primera vez en rapaces,ocurri6 50 diasdespu6s del inicio de la puesta,lo que coincide con el intervalo medio entre primerasy segundaspucstas en la zona de estudio. Este tercer pico, que tambi6n se detect6 en aquellasparejas que solo hicieron una puesta, podria refiejar una propensi6n en esta especie a realizar segundaspuestas (encontramos seis puestas de reemplazo y cinco segundaspuestas en 98 intentos de crla). Este tercer pico de c6pulas estarfa probablemente relacionado con la competenciaesperm•ttica. [Traducci6n de los autores]

The copulation behavior of birds has been a maintained through the year.The mate-assessment popular research topic among behavioral ecolo- hypothesis(Tortosa and Redondo 1992, Negro et gistsin the last two decades (e.g., Birkhead et al. al. 1996, Villarroel et al. 1998) states that the fe- 1987, Birkhead and M011er 1992). This interest has males may acquire information on male quality been triggered by the observation of widely vari- through copulations.Assuming that copulations able copulation rates between species (i.e., fkom are costly,better males would be able to copulate one to several hundred copulations in a single more often. The territorial signaling hypothesis breeding season),and the realization, through mo- (Negro and Grande 2001) proposesthat raptors lecular paternity assessment,that extra-pair fertil- signalterritory ownershipto conspecifics,and pos- izationsare common in certain species(Petrie and siblyto other avianspecies, by copulatingfrequent- Kempenaers1998). ly and conspicuouslyin the defended nestingarea Male birds seem to have evolved two strategies early in the breeding season. to minimize the risk of paternity loss: (1) close The Black-winged Kite (Elanus caeruleus;also mate guarding (Birkhead 1979) and (2) frequent called the common Black-shouldered Kite in the within-pair copulationsto dilute the sperm of pos- Old World literature) is a small-sized(ca. 300 g) siblecompetitors (Birkhead et al. 1987). Most rap- raptorial bird widely distributedin Africa (Cramp tor speciesprobably employ the secondstrategy as and Simmons 1980). In southern Africa, it breeds malestypically provide food to the female through- continuously,while in other areas of Africa it out the pre-layingperiod and, therefore, are pre- breeds mostly in the spring and fall (Cramp and cluded from guarding their mates effectively Simmons 1980, Brown et al. 1982, Mendelsohn (M011er and Birkhead 1992). Raptors show high 1983). The speciesis slowlycolonizing southern copulation rates, although the seasonalpattern of Europe (Ferrero 1994, Ruffno 1994). In Spain, copulationsin thesebirds is not consistentwith all egg-layingpeaks in March (Cramp and Simmons predictions of the sperm-competitionhypothesis. 1980, unpubl. data), but in someyears some pairs Many raptors show an early peak of copulations may lay eggsas early as November or as late asJuly 20-65 d before laying, before the femalesare fer- (Ferrero and De Lope 2001). tile (M011er1987, Negro et al. 1992, Villarroel et Our aim with this paper is to describethe cop- al. 1998, Mougeot 2000, Negro and Grande 2001), ulation behaviorand pattern of Black-wingedKites. and somespecies copulate after clutchcompletion, Contrary to all raptorial speciespreviously studied, well into the chick-rearingperiod (Ellis and Powers the Black-wingedKite may raise two broods in a 1982, Sodhi 1991, Holthuijzen 1992). In addition, year (Mendelsohn 1983) and could have evolveda extra-pair copulations,and also extra-pairfertiliza- distinct seasonalpattern of copulations(i.e., some tions, are infrequent in raptors,and this again calls copulations are expected to occur a•er the first into question the sperm-competition hypothesis clutch). (Negro et al. 1992, 1996, Villarroel et al. 1998, Ne- gro and Grande 2001). There are at least three METItODS alternative hypothesesfbr high copulation ratesin We studied a breeding population of Black-winged raptors. The pair-bonding hypothesis (Newton Kites in Extremadura, southwestern Spain. The ma•n 1979) statesthat the membersof the pair copulate breeding habitat used by Black-wingedKites in the area frequently to maintain or to reinforce the pair consistsof fragmentedsemi-open Mediterranean oak for- ests (mainly Que•'cusrotundifolia) with an understory of bond. Copulations are expected to occur all cereal crops (cultivated"dchesas"; Ferrero and Onrubm through the breeding period, but are not neces- 1998). The stronghold for the European population (es- sarily restricted to this period if pair bonds are timated at 1000 breeding pairs [Ferrero 1994]) is located MARCll 2003 COPULATION IN BLACK-WINGED KITE 3

Table 1. Number of breeding pairs for which mating sampled once. Theretbre, we believe the incidence of behavior was monitored between 1979 and 2000. pseudoreplication is minimal in our analysis. We analyzed the daily variation in copulation rates dur- ing the fertile period. In previousstudies on copulauon TOTAL behavior of raptors, the fertile period has been assumed No. OF OBSERVATIONS to start around 12 d prior to laying (Bird and Buckland YEAP. PAIP.S (hr) 1976, Negro et al. 1992, Donfizaret al. 1994, Mougeot 2000). With no data availablefor the Black-wingedKtte, 1979 13 123.4 we have conservativelyassumed that the fertile period 1980 12 20.7 started 15 d before the onset of laying and ended around 1987 8 46.9 10 d after when the clutch wascompleted (4-5 eggslayed 1988 26 53.3 with an interval of 2 d between consecutiveeggs in the 1989 12 126.9 clutch [Cramp and Simmons 1980]). For analyticalpur- 1993 2 32.7 posesand given that Black-wingedKites present acUv•ty 1995 14 44.2 peaks at dawn and dusk (Cramp and Simmons 1980), we 1996 2 8.4 divided daytime into three periods: (1) from sunrise to 3 hr later, (2) midday hours (of variable duration owing 1997 6 19.2 to photoperiodicvariation throughout the copulatorype- 2000 3 11.5 riod), and (3) from 3 hr bdbre sunset to sunset. As the copulation rate within the diftbrent observationbouts fol- lowed a Poisson distribution, we fitted a Generalized Lin- ear Model (GLM) with Poisson errors to test for differ- in the dehesasof Extrexnadura and the neighboring ences among the three defined daily periods. Alentejo in Portugal. To analyze seasonalvariation, days of observation were We performed behavioral observationsyear round on grouped into 5-d intervals relative to the estimated onset a total of 98 breeding attemptsin 79 different nesting of laying (considered as day zero), and thus, indepen- territories between 1979 and 2000 (Table 1). We ob- denfly of the period of the year in which each pair started servedsix rcnestingattempts after the first clutch fhiled to breed. to hatch (replacement clutches) and five second clutch- To calculatehatching datesthe 8o' primary feather of es. The observationswere perfbrmed from vantage the oldest chick of three different broods, whose hatch- points at 200-300 m from the nests,using spottingscopes ing date wasprecisely known, wasmeasured twice a week (20-60X) and binoculars (10X). Observers completed through the chicks'growing period until they were about 269 observationbouts lasting 10 rain to 14 hr (mean ob- to fledge. Using these data a linear regression of the servation period: 80 rain). Given that it is unlikely to ob- length of the 8th primary feather on age (in days)was serve copulationsduring very short observationperiods, calculated(age = 0.1837 primary + 10.277, • = 0.9852, only those bouts more than 20 rain long were used to P < 0.0001). This regressionline was subsequentlyused calculate copulation rate and to plot the seasonalpattern to estimate hatching dates •br the remaining chicks m of copulations. We were unable to distinguish between the study.Laying date wasthen estimatedfrom hatching successfuland unsuccessfulcopulations, and therefore date assuminga 31 d incubation period (del Hoyo et al we defined a copulafion as occurring when a male 1994). Data •kom neststhat •hiled early, for which we &d mounted a female. Copulations as well as other distinct not know the laying date, were excluded from analysis behaviors,including prey transfersamong pair members, Copulations during second breeding attempts, for which chasingto intruders, aerial displays,and deliveryof nest observationswere limited, were not considered to profile material, were recorded and timed. the species'seasonal-copulation pattern. Black-wingedKites in this studywere not individually marked. This limitation may have resulted in the detec- RESULTS tion of intruders, and thus, observationof extra-pair cop- ulations. Nonetheless,any intrusions by conspecificsdur- Copulation Behavior. Each pair of Black-winged ing observationswould be easily detectable, as home Kites usually copulated at 3-4 exposed perching rangesof kitesare relativelysmall (2-4 km2, Mendelsohn 1983, Bustamante 1993, J. Ferrero unpubl. data), tree sites in the nesting territory (not further than 150 cover in the dehesasis sparse (3-9 trees/ha), and terri- m from the nest). These perching sites tended to torial birds may be observed continuously.In addition, be high and leaflessbranches at the top of a tree, Black-wingedKites are strongly territorial and intruders which along with the bold coloration of the birds are evicted from the nesting areas (Mendelsohn 1983, (white breastand belly,bluish grey upperparts) and seeResulLs). The absenceof marks may alsohave caused pseudoreplication due to the inclusion of data from the their noisy vocalizations made copulations very same pairs observed tbr more than one year. However, conspicuous.No copulationswere recorded at the given the length of the study period (21 yr), and even nest. Copulation duration averaged 11.01 + 0.45 considering that 13 territories were monitored twice or sec (• _+ SE, N = 75). even three times, the long time lag betweentwo consec- On 16] instances, we recorded the behavior of utive observationsin the same territory (5.8 _+4.8 yr, on average), it is unlikely these territories were occupied by the kites immediately before copulation took the same individuals.The remaining 65 territories were place. For 55 copulations(34.2%) we did not ob- 4 FERREROET AL. VOL. 37, No. I

seasonand 354.9 + 98.2 for the first breeding at- 3 00- tempt (65 d). Combining data from the different pairs under investigation,but excluding those that laid a sec- rv' 2.00- ond clutch (see Methods), a trimodal pattern emerged in daily copulation rates through the

,-! T breeding season (Fig. 1). There was a first peak o iiii ili:ii. :ii"•i• around d -40 and a second peak at d -10. Kites ::?:.::: :•i started to copulate again around 25 d after laying, resulting in a third copulation peak around d 50, almost coinciding with the mean dates of replace- o.oo_0.00 -50 -25 0 25 50 ment clutches (53.83 + 4.04 d after laying date of Day the first clutch, N = 6) and close to the mean date for secondbreeding attempts (secondlaying date, Figure 1. Mean + SE frequencyof copulation/hr of the 62 + 3.76 d after laying date of the first clutch, N Black-wingedKite related to the onset of laying (d 0). The line was adjusted with a normal kernel smoother. = 4). We failed to find diffcrences in copulation rates between the three defined daily periods (i.e., 3 hr post sunrise, midday and 3 hr to sunset), as serve any prior social behavior among mates. In the change in deviance of the GLM was not signif- some cases, two or more characteristic behaviors icant (P = 0.36). No copulations were detected in preceded copulation. The male transferring prey twilight, despite the fact that the kites were ob- to his mate preceded32 copulations(19.8%). On served hunting frequently at these times. those occasions, the male waited until the female DISCUSSION finished her meal, then flew directly onto her back and copulated. Thirty-one copulations (19.2%) Patterns of Copulation. Copulations in the were preceded by the delivery of sticksto the nest Black-wingedKite were conspicuous,and thus, eas- by one member of the pair. On 26 occasions ily detectable. Copulations were distributed (16.1%) copulationsoccurred shortly after aggres- throughout the daytime, and were not necessarily sive encounters had taken place with intruding associated to other social behaviors such as mate birds, mainly Common Buzzards (Buteobuteo) and feeding. The two peaksin copulation frequency be- Common Ravens (Corvus corax), which were fore and during the presumed fertile period of fe- chased away from the breeding area. Intruding male Black-winged Kite have previously been ob- Black-wingedKites were observedin 4.8% of the servedin other raptors (Mailer 1987, Negro et al. observation periods (13 out of 269 observation 1992, Pandolfi et al. 1998, Villarroel et al. 1998, bouts). As with the other bird species,intruding Mougeot 2000). The third peak, at day +50, is re- kites were invariably expelled by one or both mem- ported for the first time in raptors, although it was bers of the pair. Only two of these intrusions by anticipated due to the relative frequency of second conspecificswere immediately followed by copula- clutches among Black-wingedKites. Considering tion of the resident pair. only the copulations performed during a single Frequency and Timing of Copulations.A total of breeding attempt (presumablythe first one in the 216 copulationswere observedin 487.3 hr of ob- majority of pairs that we studied), copulation rates servation. The first recorded copulation occurred were high and in the range found in other diurnal 44 d prior to the onset of laying and the last one raptors (see references above, also Balgooyen on d 66 after the onset of laying. The maximum 1976, Rosenfield et al. 1991, KorpimSki et al. number of copulationsseen during a singleobser- 1996). Our estimate for the Black-winged Kite vation bout was nine in 4 hr, which occurred 12 d (around 5.5 copulations/d) is similar to that re- prior to laying a secondclutch. ported by Van Der Merwe (1980) for a pair in Using six pairs for which we have observational South Africa (7 copulations/d in a 15-d period dur- data on more than 10 different days, and consid- ing nest building). ering daytime periods of 12 hr and a copulation As we already discussed(see Introduction), the period of 110 d (Fig. 1) we estimated 600.6 _+ first peak in copulation frequency around 40 d pri- 166.2 copulations/female for the whole breeding or to laying is unlikely related to fertilization, as it M_ARCH 2003 COPUI,ATION IN BLACK-WINGED KITE 5 probably occurswell before the female's fertile pe- and Lessells 1988, Negro et al. 1992, Mougeot riod. Alternative hypotheses,such as mate-assess- 2000). In other speciesthe occurrence of copula- ment or strengthof the pair bond hypothesespre- tions during incubation or even during the nest- dict higher copulation rates at the time of pair ling period are not uncommon (Ellis and Powers formation or pair reunion, but are difficult to test. 1982, Holthuijzen 1992, Don•tzar et al. 1994, Pan- The territory-signaling hypothesis predicts fre- dolfi et al. 1998). Nonetheless, we know of no oth- quent and conspicuouscopulations when a pair es- er raptor speciesin which late copulationsreached tablishesa breeding territory (Negro and Grande similar rates to those of the pre-laying period, as 2001). In the Black-wingedKite, copulations are we found in this study. Copulations after clutch indeed very frequent and almost alwaysoccur on completion are suggestedto be a preventive be- conspicuousperches. The frequency of copula- havior to speed up a replacement clutch if the first tions immediately preceded by agonisticencoun- one is lost (Birkhead et al. 1987). But renesting ters with other bird speciesor conspecificsis not attempts are scarce among raptors, especially in negligible (16%). Our data seem to supportthe larger ones (Newton 1979, Mundy et al. 1992, Mar- territory-signalinghypothesis as a possibleexpla- tinez et al. 1998). Second breeding attempts are nation for the early peak in copulations as sug- even rarer, but do occur in some species (Newton gested for most diurnal raptors (Negro and 1979, Toland 1985). In the Iberian Peninsulaonly Grande 2001), but we cannot discard either the the Eurasian Kestrel (Falco tinnunculus) has been pair-bond or the mate-assessmenthypotheses. observedraising a secondbrood in the same year The secondpeak in copulation frequency,at the (Sanchez 1990, Fargallo et al. 1996). When condi- beginning of the female's fertile period, may be tions permit, the Black-wingedKite may breed two related to sperm competition pressures.However, or more times in a year (Mendelsohn 1983). Ap- some aspectsof the kite's behavior seem to indi- propriate conditions do not seem to be common cate low levels of sperm competition during this in Spain but they do occur, as we observed five second peak. First, as in other frequently-copulat- second-breedingattempts. In small birds, such as ing birds (Tortosa and Redondo 1992, Birkhead passetines,both replacement clutches and multi- and Moller 1993, Bertran and Margalida 1999), the ple breeding attemps are common (e.g., Moller copulation rate decreasedfrom beginning to end 1985), and therefore, copulations are expected in of the fertile period. In the context of sperm com- these speciesafter the first breeding attempt. How- petition, copulation rates should be highest at the ever, we have found no analysison the seasonal onset of laying (Birkhead 1988, Birkhead and pattern of copulationsin multiple-broodedspecies. Moller 1992, but see Birkhead and Moller 1993). The coincidence of the third peak in copulatlon Two intrusions of Black-wingedKites followed by rates with the dates of replacement or double copulation of the resident pair occurred during clutches may be an adaptation related to the ten- the fertile period. However, intrusions by conspe- dency of the Black-wingedKite to initiate a second cifics do not seem to be frequent, at least in our breeding attempt, which they may abortjust before study area. Bustamante(1993) found only six in- laying if food conditions are not adequate. Al- trusions in 146 hr of observation (0.04 intrusions/ though data on female's fertility in this period are hr), and we found just 13 in 487 hr (0.03 intru- lacking, it may be argued that these copulations sions/hr), which is similar to that found in the occur in a fertilization context and sperm compe- Merlin (Falco columbarius,0.02-0.05 intrusions/hr, tition might play a role. Sodhi 1991). Mougeot (2000) reported higher fre- The unusual early laying dates that we recorded quenciesof intrusionsfor the Red Kite (Milvus mil- in some years (i.e., November or December, Fer- vus, 0.7-4 intrusions/hr). rero and De Lope 2001) seem to indicate that in- CopulationsAfter the First Nesting Attempt: Re- dependently of seasonalphotoperiodic and climat- nesting,Second Clutches or SequentialPolyandry? ic variation of the temperate zones, Black-winged The most remarkable finding of our study is the Kites may try to breed if other factors (most prob- existenceof a third peak in copulation frequency ably food abundance) are favorable. later in the breeding season,close to the fiedging Bustamante (1993), in a study carried out in the time of the young produced in the first breeding same area, found that two radiotagged adult fe- attempt. In some raptors, copulationscease at the males had left the nest well before the nestlings end of laying or closeto it (Newton 1986, Birkhead became independant, whereas the male fed the 6 FERREP,O ET AL. VOL. 37, NO. 1 young until they dispersedfrom the territory. In --AND --. 1993. Why do male birds stop copu- three other pairs (with unmarked birds) this au- lating while their partners are still fertile? Anita. Behar. thor was unable to conclude if both adult birds 45:105-118. --, L. ATK•N,AND A.P. MOLLER.1987. Copulation be- remained in the territory or not. We have also havior of birds. Behavior 101:101-138. found some evidence of only one adult remaining BROWN, L.H., E.K. URBAN, AND K. NE•arFON. 1982. The until the young fledge, but this does not exclude birds of Africa. Vol. 1. Academic Press, London, U.K. the possibilitythat other pairsremain togetherand BUSTAMANTE,J. 1993. The post-fiedging dependence pe- m•tiate a second breeding attempt. In thct, we did riod of the Black-shouldered Kite (Elanus caeruleus). not find any evidenceof mate switching(temporal J. RaptorRes. 24:185-190. disappearanceof one of the pair members) in the CP&MP, S. •kND K.E.L. SIMMONS. 1980. Handbook of the six renesting attempts, and at least in one of the birds of Europe, the Middle East and North Africa. second breeding attempts both members of the Vol. 2. Oxford Univ. Press, Oxford, U.K. pair fed the young of the first brood while copu- DELHOYO, J., A. ELLIOTT,AND|. SARGAI'AL.1994. Hand- lating and constructingthe secondnest in a neigh- book of the birds of the world. Vol. II. Lynx Edicions, Barcelona, Spain. boring tree. Unfortunately, as our birds were not DONAZAR,J.A., O. CEBAIJ,OS,AND .].L. TF•I,L^.1994. Cop- marked, we cannot conclude if renesting or second ulation behavior in the Egyptian Vulture. Bird Study breeding attempts (and therefore the third copu- 41:37-41. lation peak) are performed by the samemates, or ELLIS,D.H. ANDL. POWERS.1982. Mating behavior in the as occurs in South Afkica (and in Australia by the Golden Eagle in non-fbrtilization contexts. RaptorRes. Letter-wingedKite, Elanus scriptus),the female in- 16:134-136. volved in the male's second attempt is a different FARGALLO,J.A., G. BI,ANCO,ANt3 E. SOTO-IARGO.1996. individual (Mendelsohn 1983, Marchant and Hig- Possible second clutches in a Mediterranean montane gins 1993). population of the EurasianKestrel (Falcotinnunculus). J. ProptoERes. 30:70-73. ACKNOWLEDGMENTS FERRERO,JJ. 1994. Situaci6n del Elanio Azul Elanuscaeru- The late F. Carbajo initiated this studyand participated leusen el Mediterr'•meo.Pages 101-115 in|. Muntaner in early observations.We are indebted to P. G6mez, M. and J. Mayol (Er)s.), Biologfa y Conservaci6n de las Cortas, M. Cabrero and J.A. Roman for their assistance rapaces mediterr/tneas. SEO/BirdLife Monografias in different periods of fieldwork. V. Pizarro, L. Lozano, No. 4. Pozuelo de Alarc6n, Madrid, Spain. and M.G. Calzado shared with us their wide knowledge -- AND F. DE LOPE. 2001. Breeding phenology of on kites' behavior.We thank|. Seoanefor the amount of Black-shoulderedKites (Elanyscaeruleus) in Extremad- precious time he wastedwith us during data analysis.F. ura (SW Spain). Page 65 in M. Ferrer, JJ. Negro, and de Lope, J. Avi16s,B. Arroyo, D. Parejo, T. Birkhead, and .|. Bustamante (Eds.). 4th Eurasian Congresson Rap- an anonymous reviewer improved an early version of the manuscript with their comments. Fieldwork was carried tors. Book of Abstracts.Sevilla, Spain. out with no institutional financial support. -- •ND A. ONRUBI•. 1998. Expansi6n del/trea de crfa y distribuci6n actual del Elanio Azul Elanus caeruleus I JTERATURE CITED en Espafia. Pages 159-171 ivB.-U. Meyburg, R.D. BALGOOYEN,T.G. 1976. Behavior and ecology of the Chancellor, and J.J. Ferrero [E•)s.], Holarclic birds of American Kestrel (Falcosparverius L.) in the Sierra Ne- prey. 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