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AND TEMPORAL VARIATIONS IN THE DIET OF THE COMMON KESTREL (FALCOTINNUNCULUS) IN URBAN ROME, ITALY EMANUELE PlATTELLA Dipartimentodi BiologiaAnitaale e dell'Uomo(Zoologia), Univers'ita di Roma "La Sapienza" Viale dell'Universita32, 1-00185 Rome,Italy LuCA SALVATI PiazzaE Morosini12, 1-00136 Rome,Italy ALBERTO MANGANARO Via di Donna Olimpia152, 1-00152Rome, Italy SIMONE FATTORINI Dipartimentodi Biolo•a Anitaalee dell'Uomo(Zoolq•a), Universitadi Roma "La Sapienza" Viale dell'Universita32, 1-00185 Rome,Italy KEY WORDS: CommonKest'rel; Falco tinnunculus; diet;,avi- quently occurring in urban areasin higher densitiesthan an prey;urban area;Rome, Italy. in farmland areas (Village 1990, Shrubb 1993). Never- theless,few studieshave described detailsof the feeding Several studies have described the ecology of raptors ecologyof kestrelsin theseurban areas(Quere 1990, Ro- urban areas (e.g., Galeotti 1994). Common Kestrels manowski1996). Therefore, the aim of our studywas to (Falco tinnunculus)breed in many European towns, fre- describethe composition of the kestrel diet and any sea- JUNE1999 SHORTCOMMUNICATIONS 173 Table 1. Common Kestrel (Palcotinnunculus) diet in urban Rome, Italy SUMMER WINTER PREY NUMBER PREY PREY NUMBER PREY (%) B•OM•SS(%) (%) B•o•,4•ss(%) MEAN SD MEAN SD MEAN SD MEAN SD Stylommatophora 0.6 1.3 0.1 0.3 0.1 0.2 0 0.1 Scorpiones 0.2 0.6 0 0 0 0 0 0 Mantodea 0 0 0 0 0.5 1.1 0.1 0.4 Orthoptera 5.2 4.4 0.4 0.4 22.1 12.8 3.1 3.2 Dermaptera 0.4 1.0 0 0 1.2 2.6 0 0 Coleoptera 29.3 11.9 1.4 0.8 30.9 14.7 1.9 0.8 Hymenoptera 0.1 0.2 0 0 2.7 4.6 0 0 Unidentified insects 0.3 0.5 0 0 0.1 0.2 0 0 Sauria 15.1 6.1 7.2 4.7 9.6 7.9 5.8 4.5 Columbiformes 0.9 1.4 10.8 15.8 0.1 0.2 3.2 5.6 Apodiformes 4.8 5.4 9.4 10.6 0.3 0.9 1.1 2.9 Passeriformes 21.7 9.6 41.6 15.4 4.4 2.8 16.4 10.0 Unidentified birds 2.4 4.1 5.3 10.4 0.1 0.2 0.3 0.8 Insectivora 0 0 0 0 0.5 0.5 0.2 0.3 Chiroptera, 7.0 9.7 4.1 6.5 0.6 0.8 0.4 0.6 Rodentia 12.1 6.6 19.6 12.6 26.8 8.7 67.3 15.5 Total prey 1123 16504 g 1238 11 574 g sonal variation in a Mediterranean urban area like Rome, period, when kestrelsgenerally feed close to nests (Vfi- Italy. lage 1990). Using the mean size of hunting rangesgiven in Village METHODS (1990) and Shrubb (1993), habitat compositionwithin a 1-km radius of nests (3.14 km 9) was characterized as We conducted our study in urban Rome where Com- farmland, wooded, modern urban, and ancient urban. A mon Kestrelsoccur at higher breeding densities (0.1-2.3 sequential Bonferroni test (1989) was used to adjust the pairs/kin•) than anywhereelse in Italy. The kestrelsnest significance level to the number of comparisonsusing in scaffolding holes in Roman ruins and monumental the same data set. A minimum probability level of P < buildings (Salvatiand Manganaro 1997). We assessedthe 0.05 was accepted (all tests were two-tailed). Statistical diet by analyzingpellets and prey remains collectedfrom analyseswere performed using STATISTICA software 16 sitesduring the years1996 and 1997.A total of 13 and (version 4.5, 1993). Resultsare presented as mean + SD. 7 pellet sampleswere analyzedfor the springto summer (breeding period) and winter, respectively.In the city RESULTS center, pellets were collected every month from April 1996-March 1997. We identified 1123 prey items at breeding diets (86.4 Pellets and prey remains were dissectedin water. Prey --- 85.9 prey per nest) and 1238 prey items in the winter remains were identified using diagnostickeys (Mangan- diets (176.9 -+ 120.3 prey per roosting site), for a total aro et al. 1990) and by comparisonwith museum speci- biomassof 28 078 g. The number of prey itemsper pellet mens in the Zoology Museum, "La Sapienza" University, Rome, Italy. Mean weights for each prey taxon were es- varied from 1.6-3.7 in summer (2 = 2.8 -+ 0.5), and from ureated using data from Mediterranean areas (Mangan- 2.7-4.9 in winter (2 = 3.2 + 0.7) (t = -1.45, df = 18, P aro et al. 1990). The number of individuals (scored as = 0.165). minimum value) was calculated taking into account all Kestrelspreyed on speciesranging in size from ants different kinds of prey items found. Paired anatomical (Messorsp., 0.01 g) to adult Feral Pigeons ( Columbaliwa, parts were counted as belonging to the sameindividual. 300 g). Throughout the year, the main prey groups were This method allowed us to estimatethe frequencyof oc- insects,reptiles, birds, and mammals. Beetles (especially currence of prey numbers (PN) and biomass (PB) for families widely distributed in Mediterranean areas like each prey categoryand to relate PN and PB to the habitat scarabs and tenebrionids) and birds were most common- compositionof hunting areas. A Spearman Rank Correlation was used to assessrela- ly consumed in summer and grasshoppersand small nons among prey numbers for the most important prey mammals were most common in winter (Table 1). Birds categoriesand between the habitats of hunting areas and and mammals were the main prey groups by biomass prey categories found in the diet during the breeding Other prey included molluscs,scorpions, and ants. The 174 SHORTCOMMUNIGATIONS VOL.33, NO. 2 00% 9o% 8o% [] Birds 7o% fit Mammals 6o% [] Reptiles 50% ß Insects 40% 30% 20% lO% 0% I I I I Incubation Nestling Post-fledging F•gure 1. Diet of the CommonKestrel (Falco tinnunculus) in an urbanarea of Rome,Italy duringthe breeding season. number of Feral Pigeonstaken waspositively correlated prey in Mediterraneanareas (Village 1990). An increase with the the number of Swifts(Apus apus) taken (r• = in birds in the diet of TawnyOwls (Strixaluco) has also 0.63, P < 0.005, N = 20). The number of passerinestak- been observedin European towns (Galeotti et al. 1991), en was negatively correlated with the number of rodents probablybecause of the greater availabilityof birds and (rs = -0.70, P < 0.001, N = 20) while the number of the decreasedabundance of rodents in these areas (Gal- shrews(Suncus etruscus and Crocidurasp.) takenwas pos- eotti 1994). mvely correlated to numbers of rodents taken (rs = 0.60, In some European cities, kestrelstake prey far from P < 0.01, N = 20). The number of Swiftstaken waspos- their nest sites (Quere 1990, Romanowski 1996). In mvely correlated with ancient urban areas (rs = 0.76, P Rome,however, kestrels hunt near their nestsduring the < 0.005, N = 13) and negativelywith farmland areas(rs nestingperiod most likely because a widevariety of prey = -0.77, P < 0.005, N = 13). By contrast,the number is availableboth in the city center (birds,bats, and rep- of rodentstaken waspositively correlated with farmland tiles) and in the suburbanopen areas (small mammals, areas (rs -- 0.93, P < 0.001, N = 13) and negativelywith reptiles, and insects).