FALCO NAUMANNI

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Kestrels could go under the roof ... females could not see directly out and entry was 8 cm in diameter. ... case the str
j RaptorRes.30(3):169-172 ¸ 1996 The Raptor ResearchFoundation, Inc.

ARTIFICIAL

NEST

STRUCTURE

DESIGN

AND

MANAGEMENT

IMPLICATIONS

FOR

THE LESSER KESTREL (FALCO NAUMANN1) MANEL

POMAROL

Direcci5GeneraldelMedi Natural, Gran Via 612, 08007 Barcelona,Spain KEYWORDS: Falco naumanni; lesserkestrel;management;, structuresin Spain, efforts to reestablishlesser kestrels have had only limited success. nestbox;,Spain. This study tested designsfor artificial nest structures A•sTP•CT.--The European population of the lesserkes~ that would be easyto install. Two kinds of nest structures trel (Falconaumanni) has experienced a sharp decrease and a specialentrance tile were designedand tested in m recent decades.Becausethey nest mainly in man-made severalnesting coloniesof lesserkestrels. The studytook place in Monegros (Aragon) and Catstructures,building deterioration has been an important

causeof local declineswhen roofs collapseand nest sites become limiting. I tested two designsfor artificial nest structuresto be used in old buildingsand a specialroof tile that should increase the availabilityof nest sitesin Spain. The first structure was made of wood and fitted under the roofs of buildings. Of 229 structuresinstalled, 41.4% were occupiedby 95 pairs of kestrelsnestingin buildings.The specialroof tile was testedas a nest en-

alonia, Spain.In Monegros,about 98% of the kestrels

nested under roof files in abandoned buildings. In this area, an increasing population of >200 pairs of lesser kestrelsis dispersedover more than 30 colonies(Tella et al. 1993). In Catalonia,a reintroduction program wasbeing developed (Pomarol 1993) and a few small colonies had recently been established. One artificial

nest structure

was made out of wood and

trance in deteriorated roofs. Of 94 tile entries installed,

wasfitted under the roofs of buildings (Fig. 1; Gonzfilez

23 were usedby 51.1% of all pairs.The secondneststruc-

and Merino 1990). A total of 229 of these structures was

tested from 1990-95. Kestrelscould go under the roof were used by breeding pairs. Although ceramic nesting files through cracksand holes in deteriorated files. From structuresare easyto install nearly anywhere,care must there, they entered the nest box through a hole that was be taken to avoid locationsexposedto the sun because bored through the reedsand mud usedin the construcceramic structures can develop high internal tempera- tion on roofs. The entry wasapproximately40-60 cm in tures when exposedto direct solar radiation. Both nest length and the tunnel wasnot straightto ensure that the structuresand the tile entry can be fitted to old and new bird could not see directly outside from inside the nest buildingsto prevent roof deteriorationand to allow for structure. Both characteristicsare commonly found in natural, lesser kestrel roof nests.To avoid causing roof the establishment of new colonies. leaks,94 specialroof tiles commonlyused in new buildThe lesserkestrel (Falconaumanni) is a specieswhose ings for roof ventilation, were testedin 1993-95 as entrydistribution has decreaseddramaticallyin recent decades waysto nest structures(Fig. 2). The second nest structure was ceramic and made for (Biber 1990). In Spain, the population decreasedfrom about 100000 pairs in 1960 to lessthan 50000 in 1970 easyinstallation in a variety of conditions.A total of 29 and only 5000 in 1988 (Gonzfilez and Merino 1990). of these structures was tested in 1993-95, in two roofless, Land-usechangesin breeding areas are consideredthe ruined buildings (Fig. 3). It had a lateral entrance so main cause of the decline (Don/tzar et al. 1993) but lack femalescould not see directly out and entry was8 cm in of nesting placeshas alsobecome a seriouslocal prob- diameter. Several small holes (0.3 cm diam.) were made lem. In Spain, 95% of thesesmall and colonialfalcons in the rear to increase ventilation. Both nest-boxdesignsand entry tiles were installed in nest in buildings (Gonz/tlez and Merino 1990), so restoration (closing the small holes in the walls or roofs), de- buildings used by nesting kestrelsso there was a choice terioration and the collapseof old buildingshavecaused between natural and artificial nest sites. several colonies to disappear (Gonz•lez and Merino Becausehigh temperaturescan be reached inside ce1990, Negro 1991,Tella et al. 1993). Use of artificialnest ramic pots exposedto the sun (Tella et al. 1994), three structureshas been recommended to ease the problem changeswere made to ceramic nest structuresto detercausedby the lossof nest sites(Biber 1990, Blanco and mine how the thickness and color of construction mateGonz•tlez 1992). Use of these structures has been an efrials can affect internal temperaturesthat developwithin fective management tool for European and American these pots. In one case, the ceramic nest structure was kestrels(Falcotinnunculusand E sparve•ius) in areaswith made with thin walls (0.5 cm in thickness). In a second poor nest-siteavailability(Hamerstromet al. 1973,Village case the structure was made with thick walls (1.0 cm in 1983). Despite several efforts to install artificial nest thickness) and in the third case, the ceramic structure ture was ceramic. Of 29 ceramic structures installed, 10

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25crn

1ocm

zscrn



Gocm

,

Figure1. Wooden neststructure installed undertileroofsfor nesting lesser kestrels. waswhitewashed. All threetypesof ceramickestrelboxes The spotlessstarling (Sturnusunicolor)alsoused these were installed on the same roof and a maximum/mini-

mumthermometer wasplacedin each.Overa 26-dpe-

structures asdid a similarspecies, theEuropean starling (S.vulgaris), whichhasbeenfoundtobea regularbreed-

riod in July 1994,maximumdailytemperatures werere- er in manydifferentdesignsfor neststructures (Gauthier cordedinsidetheseceramicpotsandwoodennestboxes, 1988). Litde owls(Athene noctua), jackdaws(Corvus monatural cavitiesunder roof files, as well as outside in the

nedula),stockdoves( Columba oenas), dormice(Elyom•s

shade.Datawereanalyzed usingANOVAanddifferences quercinus) and rats (Rattusrattus)alsousedthe structures

between means was determined with a LSD test.

Forty-onepercent of the 229 wooden structureswere

occupiedby 95 knownbreedingkestrelpairs(Table1).

sporadically.

A totalof 94 fileswerefittedin the roofsof buildings usedby four colonies of breedinglesserkestrels. Fiftyfour were installed in combination with wooden nest

structuresand 40 wereplacedovernaturalcavities. Twen-

W-threepairs(51.1%)of the 45 knownpairsnestingin thesebuildingschosethese files as the entrance to their

nestsandstarlings andlitdeowlsalsousedthemsporadically. Twenty-nine ceramic nest structures were located in

twocolonies. Ten (28.5%)of the 35 knownbreeding pairs in these colonies nested in the ceramic structures.

The onlyotherspecies to usethistypeof structure were the spotless starling,housesparrow(Passer domesticus) and scopsowl (Otusscops). Thin-walled ceramicneststructures developed significandyhigher mean temperatures(41.3 ___3.2øC,P < 0.05) than thick-walledceramic structures (39.1 _+ 3.5øC),whitewashed ceramicstructures(34.9 ___ 2.3øC), natural cavities (37.0 +__2.5øC) and wooden nest boxes

under roofs (33.3 +__ 1.6øC).Temperatures in wooden nest boxes installed under roofs also varied less than did

temperaturesin ceramic structures (P < 0.05).

Figure 2. Specialtile used as an artificial entrancefor the lesser kestrel.

Woodenneststructures wereeasyto checkfrominside buildingsminimizingdisturbanceto colonies.Unfortu-

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20cm

$cm dia. F•gure 3.

Ceramic nest structure used for nesting lesserkestrels.

nately, they could not be used in all buildings,particularly in ruins with no roofs or in buildings where it was not possibleto reach spacesunder roofs. Different materialshave been used in constructingartificial nest structures (Soulliere et al. 1992), but few

To prevent further declines of the lesser kestrel in Spain, reconstructionof buildings supporting breeding colonies

of lesser kestrels

should

be done

outside

the

breeding seasonand the holesor cavitiesin wallsof these buildingsthat are suitablefor nestingkestrelsshouldnot be closed,ashas alreadybeen proposedby Gonzfilezand

designs have incorporated ceramic materials (Bernal 1991). Ceramic nest structureshave the advantageof be- Merino (1990) and Biber (1990). If holes must be reing easy to install in any building (they are simply at- paired, nest structuressimilar to those I tested should be tached with concrete) and they do not deteriorate easily. used, even in new buildings, to provide lesserkestrels However, they have a drawbackin their potential to de- with the opportunity to nest and recolonize previously velop high internal temperatures.Temperaturesas high occupied areas.Use of specialroof tiles as accessopenas49øCwasreachedinside ceramicstructuresduring this ings to nestsalso makes it possibleto equip roofs with study and temperaturesas high as 55øC have been re- artificial cavities for lesser kestrel colonies without causported by Tella et al. (1994). Temperature extremes are ing harm to buildings. A simple solution would be to not only lethal to chicksbut alsoeggs(Webb 1987). Var- subsidize the use of these tiles in new constructions in rushing ceramic structurescauseseven higher temperaappropiate areas. tures to be reached (Bernal 1991). My results showed that only ceramic nest structureswith thick and whiteRESUMEN.--Las poblacionesde cernicaloprimilla han pawashedwallsshould be used in placesexposedto sun. decido una fuerte regresi0n en las ultimas d6cadas.Debido a que esta rapaz nidifica principalmonteen edifiTable 1. Use artificial nest structuresby lesserkestrels cios, la escasezde lugaresde nidificaci6n motivadopor las reconstrucciones o el deterioro de estos, son una cau•n Spain. sa local importante de desaparici6n.Dos tipos de cajasnido y una teja especialhan sido recientementeprobados # OF con 6xito. E1 primero rue hecho de madera, y rue coloNEST cado bajo el tejado. De 229 cajasinstaladas,el 41.4% fu# OF NEST STRUC- % OF PAIRS eron usadaspor el 30.5% de las parejasnidificantesen # OF STRUCTURES NESTING IN YEAR COLONIES TURES OCCUPIED BOXES esascolonias.Para evitar el deterioramiento del tejado, seprob6 una teja especialque sirvierade entrada al nido. 1990 I 10 8 30.7% De 94 tejas, 23 fueron utilizadaspor el 51.1% de las pa1991 4 48 19 21.8% rejas. La segundacaja nido fue hecha de cerfimica.De 1992 4 48 26 31.7% 29, 10 fueron utilizadaspor el 28.5% de las parejas. 1993 8 65 33 35.8% Aunque esta puede ser utilizada en cualquier sitio, se 1994 2 29 5 38.4% debe tenor cuidado por las altas temperatufas que se 1995 2 29 4 36.3% pueden alcanzar en su interior. Todos estosnidos artifiTOTAL 21 229 95 30.5% ciales pueden set colocados tanto en edificios nuevos

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J.L. ANDM. MERINO[EDS.]. 1990. El Cernicomoviejos,evitandoel deteriorode estosy favoreciendo GONZALEZ, el establecimiento

de nuevas colonias.

calo Primilia

en la Peninsula

Iberica.

ICONA

Serie

[Traducci6n del Autor]

Tecnica. Madrid, Spain. HAMERSTROM, F., F.N. HAMERSTROM ANDJ. HART. 1973. ACKNOWLEDGMENTS Nest boxes:an effectivemanagementtool for kestrels. I would like to give specialthanksto the Diputaci0n J. Widl.Manage.37:400-403. General de Aragbn and their rangers for making and NEGRO, JJ. 1991. Iniciativaspara la conservaciondel cerinstallingmanyof the the woodennestboxes.To E. Municalo primilia en Andalucia. Quercus 59:18-21. fioz, E Broto,J.Bonfi!andJ.L. Tella for field observations POMAROL,M. 1993. Lesser kestrel recovery project in and to S. Hardie for making my Englishmore readable. Catalonia. Pages24-28 in M. Nicholls and R. Clarke Finally,I thank S. Mafiosa,J.L. Tella and G. Bortolottifor [EDs.], Biologyand conservationof smallfalcons.The helpful commentson the earlier draft of thismanuscript. Hawk and Owl Trust, U.K.

LITERATURE CITED

BERNAL, AJ. 1991. Cernicalosen el alero. Quercus 59:2223.

BIBER,J.p. 1990. Action plan for the conservationof westernlesserkestrelpopulations.ICBP StudyReport 41. Cambridge, U.•

SOULLIERE, GJ., C.A. ALBRIGHT ANDA.E. GEIGER.1992. Comparativeuse of wood duck nest-housedesignsin Wisconsin.

Wildl. Soc. Bull. 20:156-163.

TELLA,J.L., M. POMAROL, E. MuSoz ANDR. LOPEZ.1993. Importancia de la conservacionde los masespara las avesen los Monegros.Alytes4:335-349. •, I. SANCHEZ, F. HIRALDOANDJ.A. DON/{aZAR. 1994. Evaluaci6n de nidales artificiales para el cernicalo

BLANCO, J.C. ANDJ.L.GONZALEZ [EDS.]. 1992. Libro rojo de los vertebradosde Espafia.ICONA Col. Tecnica. primilia. Quercus 97:4-6. Madrid, Spain. DONAZAR, J.A., JJ. NEGROANDF. HImDO. 1993. Forag- VILLAGE,A. 1983. The role of nest-site availability and territorial behaviorin limiting the breeding densityof ing habitat selection,land-usechangesand populakestrels.J. Anita. Ecol.52:635-645. tion decline in the lesserkestrel.J. Appl.Ecol.30:515WEBB,D.R. 1987. Thermal tolerance of avian embryos: 522. a review. Condor 89:874-898. GAUTHIER, g. 1988. Factorsaffectingnest-boxuseby buffieheads and other cavity-nestingbirds. Wildl. Soc. Bull. 16:132-141. Received23 February1995;acceptedI March 1996