j. RaptorRes.34(4) :327-329 ¸ 2000 The Raptor ResearchFoundation, Inc.

NOCTURAL

ACTIVITY

OF LESSER KESTRELS UNDER

ARTIFICIAI,

LIGHTING

CONDITIONS

IN

SEVIIJ.E, SPAIN JUANJos• NEGROANDJAVIERBUSTAMANTE Department qfAppliedBiology, Estaci6nBiol•fficadeDo•ana, CSIC,Avda. Ma•a Luisas/n, 41013 S•illa,

CIRO MELGUIZOANDJos• Lugs Ru•z Sociedad Protectora deAnimalesy Plantasde Sevilla,C/SantaAna 10, Sevilla,5)9ain .JUANMANUELGRANDE Department ofAppliedBiology, Estaci6nBiol•gicadeDo•ana, CSIC,Avda. Maria Luisas/n, 41013 Sevilla,5pa•,n KEY WORDS:

Lesser Kest•el;Falco naumanni;

tivity;fora,•ng behavior, p• deliveries.

nocturnal ac-

under ornamental lights, (2) determine which fiøactlon of the colonywasactiveat night, (3) determine the function of nocturnal activity,and (4) describe this unusual behavior in a typicallydiurnal species.In addition, prey deliveriesby adults were recorded at selectednests during day- and night-time hours to determine the relative contribution of nocturnal activitiesin raising nestlings.

LesserKestrels (Falconaumanni) are migratory, colonial small falcons.Kestrelsin westernEm'opeanpopulations breed mainly in holes and crevicesin large historic buildings within towns and villages, or often in abandoned t?arm houses scattered across the countryside METHODS (Cramp aud Simmons1980, Gonz•tlezand Merino 1990, We monitored seveu nests in the Gathedral, which Negro 1997). The speciesis consideredEndangered in were clustered in two groups of three and four nests, western Europe (Biber 1994). In the city of Seville in southern Spain, three Lesser respectively.In E1 Salvador,where there is alsoornamenKestrel colonies remain in the downtown area. To our tal illumination at night, we observed a group of five knowledge,uo other city in westernEurope as large as nestsand a group of four nests.Nestswithin each group Seville(population750 000) currentlyhasLesserKestrel were close enough to permit simultaneousobservation fiøomvantage points in the street, at an averagedistance colonies.In Seville,the main colony of about 70 pr is from the nests of about 40 m. Surveyswere conducted located in the Cathedral.This Gothic building is the larg- on days3, 11, 17, 20, and 21 June 1998, coincidentalwith est cathedral in Spain and third largestin the Christian the period when young were in nests.Focal uestswere world. One smaller colouy is located in E1 Salvador (25 monitored with 10X binoculars and 20-60X spotting pr), a BaroquechurchnicknamedSeville'ssecondcathe- scopesduring three ti•ne periods: •nidday (1200-1400 dral located about 500 m awayfrom the Cathedral itself, H), late afternoon (1800-2000 H), and night (2200-2400 and another is at Montesi6n (7-10 pr), a small chapel H). The first two periods occurred during full daylight Sunset took place at about 2130 H during the study peabout 1.5 km from the Cathedral (C. Melguizo and J.L. Ruiz unpubl. data). The size of the city'spopulation of riod, and ornamental illumination was ou between 2200LesserKestrelshas not changed significantlyin the last 2400 H, coincidental with our nighttime observations Total observation time amounted to 30 hr/nest. Obser10 yr (JJ. Negro, C. Melguizo, and J.L. Ruiz unpubl. vations were not extended after 2400 H because,prior to data), although the kestrelswere surely more abundant this study,we had observed that kestrelsroosted as soon in the past,when numerousbreeding coloniesthrived in as the lights were turned off. different city buildings (Gonz•dezand Merino 1990). During observations,we recorded iustancesof young Reports from the early 1970s (Andrada and Franco being fed by adultsand the sexof the tEederby plmnage 1974) indicate that Lesser Kestrelswere active at night characteristics(Cramp and Simmons 1980). We tried to around the Cathedral,where they apparentlytook advan- ideutify prey, but deliverieshappened so quickly that •t tage of the powerful ornamental illumination that high- was impossibleto identify them iu most cases.Bctweeu 2300-2400 H, we also recorded the maximum number lighted this historic building. However, no systematic of kestrels that were flying together over the Cathedral studywas ever conductedto determine whether Lesser and E1 Salvador,respectively. Kestrelswere active at night on a regular basisat the Observationswere carried out with the help of 40 stuCathedral or at other locations in the city. The fraction dents of the Facultyof BiologicalScieuces,Universityof of birds involved in nocturnal behavior was also unSeville.They were trained on speciesrecognition and &fknown,althoughAndradaand Franco (1974) suggested ferent aspectsof breeding biology prior to taking obserthat up to 50% of individualsin the Cathedralcould be vatious. They carried out observationsin groups of two active on any given night. The goalsof our work were to: and were randomly assignedto the four observation (1) determine if LesserKestrelswere active every night spots.Each group observedfbr an average of 6 hr At 327

328

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VOL. 34, NO. 4

Table 1. Maximum number of Lesser Kestrelsseen flying together each night (2300-2400 H) of the study period In 1998 at the Cathedral and E1 Salvador in Seville, Spain. No.

OF

NUMBER IN FLIGHT

BREEDING

PAIRS

03 JUNE

11 JUNE

17 JUNE

20 JUNE

21 JUNE

Cathedral

70

26

23

22

55

33

E1 Salvador

25

5

10

19

15

21

least one of us was present with each student group to supervisefieldwork. Differences in feeding rates were not significant between the two churches (one-way analysisof variance [ANOVA], P > 0.05), so data fbr the 12 focal nests were pooled for analysis.Differences in feeding rates (feed•ngs/hr) during the time periods were also testedusing a one-wayANOVA. For this analysis,we usedall observed feedings, including those instancesin which the sex of the feeder

was unknown.

To test for differences

in feed-

ing rates between males and females along the different time periods,a two-wayANOVA wasused.Period and sex were used as factors, and the analysiswas restricted to those observationswhere the sex of the feeding parent was known. RESULTS

LesserKestrelswere active every night we made observations. The number

of kestrels that we observed simul-

taneouslywhile flying at night ranged between22-55 in

downtown area with a height of about 98 m. Some kestrels descended to the nestsfrom time to time, although prey deliverieswere rarely observed. A total of 411 prey deliverieswere observedat the focal nests,44 of them during night observationperiods.Feeding of nestlingsvaried significantlybetween the three daily periods (F = 25.56, df = 2, P < 0.001). On average, we observed 1.3 prey deliveries/hr/nest during midday, 2.1 prey deliveries/hr/nest in the afternoon, and 0.4 prey deliveries/hr/nest during the nocturnal period. A two-wayANOVA showedsignificant differences between sexes (F = 7.451, df = 1.66, P = 0.008), periods (F = 31.52, df = 2.66, P < 0.0001), and the interaction effect between these two factors (F = 3.30, df = 2.66, P = 0.042). Males provided more food items to the young than females during the day (Fig. 1), as previouslyre-

ported (Donftzar et al. 1992). Nocturnal feedings to young by both males and females were very tincommon

the Cathedral, and 5-21 in E1 Salvador (Table 1). There-

DISCUSSION

fore, a large fraction of birds from each colonywasactive every night. Kestrelstypicallysoared together in circles over the illuminated buildings. The flock of soaringbirds would suddenlydisperseand individualswould chaseand eat flying insects.Nocturnal flightstook placeat different heights over both the Cathedral and E1 Salvador.Often

We present the first description of nocturnal activityin LesserKestrelsand examine its possiblecontribution to the successfulraising of young. At the Cathedral and E1 Salvador,lights used to illuminate the buildings at night attracted large quantities of insects making them both

the birds circled and hunted above the Giralda, the Cathedral's bell tower, which is the tallest structure in the

1.4

1.1] 0.8

0,6

visible

and accessible

to kestrels.

The

insects

also attract-

ed significant numbers of pipistrelle bats (Pipistrelluspipistrellus),which were sometimesfound among prey remains of kestrels nesting at the Cathedral (Negro unpubl. data). Bat hunting by LesserKestrelsis uncommon, and the fkw published records involvedindividuals that were hunting at dusk or in daylight (Carbajo and Ferrero 1981, Paterson 1991).

The unusual nighuime activity of Lesser Kestrels included a fairly large fi'actionof the adults in each colony In fact, we believe that, at some time, all adult birds in

the two colonies were active at night. Kestrelsremained activeuntil midnight, when the lightswere turned down, approximately 2.5 hr after sunset. Unfortunately, lights 02 did not stayon for the whole night, and we do not know whether the kestrelswould be able to extend their activity MIDDAY AFTERNOON NIGHT period even further. Compared to daytime hours, nest provisioning was Figure 1. Prey delivery rates (• _ 2 SE) by male and female LesserKestrelsduring three periods of observa- minimal at night, so we inferred that the main purpose of the adult kestrels' activity at night was to feed themtion at the Cathedral and E1 Salvadorin Seville,Spain. 0.,4

DECEMBER2000

SHORT COMMUNICATIONS

selves.Daytime feeding rates at nestswere similar to those found in other areas of southern Spain (2.0 prey

deliveries/hr) and Portugal (2.2 prey deliveries/hr), but lower than in rural areas of northern Spain (3.9 feedings/hr) where distancesto foraging areaswere shorter (Negro 1997). Lesser Kestrels in Seville breed in colonies in the old

downtownarea, far from foraging placesin the city outskirts.While their nocturnal activitymay not result in a significantincreasein the prey deliveryto the nestlings, it could facilitate feeding of adults during the breeding seasonperhapsmaking their urban existenceeasier(Tella et al. 1995). Urban sprawlaround the city is already affectingthe hunting areasof the kestreland it could jeopardize the future of this population.Therefore, nocturnal feedingby the breeding populationcould make the difference that permits the large kestrel coloniesto continueto thrive despitebeing encroachedby manykilometers of apartment blocks in every direction. Although LesserKestrelsare typicallymigratory,some birdsremain all year round in southernSpain (Andrada and Franco 1975, Gonz/tlez and Merino 1990) and, specificallyin Seville(Negro et al. 1991). Andradaand Franco (1974) suggestedthat nocturnal activitycould go on through the year at the Cathedralbut it remains to be seen whether wintering kestrelsare activeat night in Seville.

Further

studies are needed

to assess the actual

effect

329

calos en el entorno de la ciudad. Es posible que la extensi6n de la caza a horas nocturnas permita que los Cernicalosperduren afin en el centro de Sevilla. [Traducci6n de los autores] ACKNOWLEDGMENTS

We are very thankful to the volunteerswho helped us with the fieldwork: A. Ruiz, A. Crespo, M. Diaz, C. Chamorro, M.E. Fernfindez, P. Ibarra, M.C. Aroca, D. Ciudad,

Le6nidas,A. Iglesias,P. Aranda,J. Chaves,M.C. Torres, C. Garcia, J. Renfel, Zurina, Sonia, R. Balbontin, L. Fernfindez, P. Alvarez, M. Narvaez,J. de la Rosa,G. Ortega, Susana,A. Alonso,J.R.Garceta,L. Morales,J.HernSndez, Antonio, Reyes,Aura, E. G6mez, A. G6mez, M. Martin, I. Moreno, D. Doblas, M6nica, Rocio, and J. Esqmvias. The manuscriptbenefitted from the commentsof T.W. Carpenter and O. Hatzoffe. LITERATURE

CITED

ANDRAD^, J. ANDA. FRANCO. 1974. Actividadnocturna en P•lco naumanni. --

^Nr• --..

Ardeola 19:471. 1975. Sobre el grea de invernada

de

Falconaumannien Espafia.Ardeola21:321-324. BIBEP,, J.P. 1994. LesserKestrel in G.M. Tucker and M.F. Heath [EDS.], Birds in Europe: their conservationstatus. BirdLife

Conservation

Series No.

3. BirdLife

In-

ternational, Cambridge, U.K. CARBAJO, F. ANr•J.FEP, P,WRO.1981. Cernicalo Primilia (Falco naumanni). Ardeola 28:155.

of nocturnal activity on adult kestrel foraging strategy, CRAMP, S. AND K.E.L. SIMMONS. 1980. Handbook of the birds of Europe, the Middle East and North Attica. not onlyduring the breedingseason,but alsoduring the Vol. 2. Oxford Univ. Press, Oxford, U.K. remainder of the year. It is also important to clarify the role of nocturnal foraging in long-term survivalin this DON•ZAR,J.A., JJ. NEGRO,ANDE HIRALDO.1992. Functional analysisof mate-feedingin the LesserKestrel population. Falco naumanni.

RES0MEN.---Estudiamos

la actividad

nocturna

del Cerni-

calo Primilia (Falco naumanni) en dos colonias de cria situadas en edificios hist6ricos del centro de Sevilla (Sur

de Espafia).Nuestro objetivofue describirestecomportamiento inusual asi como su importancia relativa para la alimentaci6nde lospollos.Seobservaron12 nidosdurante tres periodosdiarios (1200-1400 H, 1800-2000 H y 2200-2400 H) en Junio de 1998. La mayoriade los cernicalos adultos de ambas colonias estuvieron activos cada

noche a lo largo del periodo de estudio mientras funcionaba la iluminaci6n

ornamental.

La actividad

cesaba

Ornis Scand. 23:190-194.

GONZALEZ, J.L. ANDM. MERINO.1990. E1Cern/calo Primilia (Falco naumanni) en la Peninsula Ib•rica. Ser•e T6cnica, ICONA, Madrid, Spain. NEGRO,JJ. 1997. The LesserKestrel. Birdsof Western PalearcticUpdate,1:49-56. , M. DE LARIVA,ANDJ.BUSTAMANTE. 1991. Patterns of winter

distribution

and abundance

of Lesser Kes-

trels (Falconaumanni) in Spain. J. RaptorRes.25.3035.

PATERSON, A.M. 1991. Lesser Kestrel hunting bats Br. Birds 84:151.

cuando era apagadala iluminaci6n a medianoche.Los cernicaloscapturabany comian insectosen vuelo lievando pocaspresasa losnidos.LosCernicalosPrimillas,por tanto, permanecen activospor la noche para incrementar su ingestadiaria de alimento y no para alimentar a suspollos.E1desarrollourbanisticode Sevillaest• redu-

TELLA,J.L., E HIRALDO, J.A. DONAZAR-SANCHO, ANDJ:J.NEGRO.1995. Costsand benefits of urban nesting in the LesserKestrel.Pages53-60 in D.M. Bird, D.E. Varland, and JJ. Negro lEDs.I, Raptorsin human landscapes.

ciendo

Received 3 March 2000; accepted 3 August 2000

los territorios

tradicionales

de caza de los Cerni-

Academic Press, London, U.K.