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
SHORT COMMUNICATIONS
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.
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F. ANr•J.FEP,
P,WRO.1981. Cernicalo Primilia (Falco naumanni). Ardeola 28:155.
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population.
Falco naumanni.
RES0MEN.---Estudiamos
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A.M. 1991. Lesser Kestrel hunting bats Br.
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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-
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J.A. DONAZAR-SANCHO,
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Received 3 March 2000; accepted 3 August 2000
los territorios
tradicionales
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