Breeding success of Lesser Kestrel Falco naumanni breeding in nest boxes and other sites in urban areas in southern Italy Gnezditveni uspeh južne postovke Falco naumanni v gnezdilnicah in drugih gnezdiščih na urbanih območjih južne Italije Michele Bux1, Giuseppe Giglio2 & Marco Gustin3 1 Conservation Department LIPU-BirdLife Italia, Via Trento 49, I-43100 Parma, Italy, e-mail: marco.gustin@lipu.it Renovation of historic buildings has a strong negative impact on Lesser Kestrel, by reducing nest site availability and reproductive success. In order to test the efficacy of nest boxes as conservation tools, we studied the occupancy rate of nest boxes and compared Lesser Kestrel breeding success in nest boxes and urban nests sites in southern Italy. The results showed that nest boxes are a useful management strategy. The reproductive parameters (mean laying date, brood size, number of fledged young) observed in nest boxes do not vary significantly from those in natural urban sites (wall cavities and attics). Key words: Lesser Kestrel, Falco naumanni, breeding success, nest boxes and urban sites, Apulia, Italy Ključne besede: južna postovka, Falco naumanni, gnezditveni uspeh, gnezdilnice in urbana območja, Apulija, Italija 1. Introduction The Lesser Kestrel Falco naumanni is a colonial species that breeds in cavities in rocky cliffs, on man-made structures and, more rarely, on the ground (Palumbo 1997, Vlachos et al. 2004, Mascara & Sarà 2006). In western Europe, this species is closely tied to human activities, feeding in agricultural areas (Palumbo et al. 1997) and nesting primarily within urban areas (Negro 1997, Palumbo 1997, Bux et al. 2005). This is the case for colonies in Apulia and Basilicata (southern Italy), where pairs breeding in rural or natural habitats are extremely rare (Palumbo 1997). One of the major threats to populations breeding in Mediterranean countries is the destruction of cavities in walls and roofs, due to building renovation (Catry et al. 2007). The use of man-made nest boxes has proved to be a useful conservation tool for many bird species (Premuda et al. 2000), which can partly compensate for the loss of urban breeding sites, however, data on the use of nest boxes by Lesser Kestrels and their breeding success is still scarce (Gonzales & Merino 1990, Pomarol 1996, Catry et al. 2004 & 2007, Shulman-Liven et al. 2004). The aims of this study were: (1) to quantify the occupancy rate of nest boxes by Lesser Kestrels; and (2) to compare the reproductive parameters of pairs breeding in nest boxes with other pairs breeding in 'natural urban' sites such as cavities in walls and attics. 2. Methods 2.1. Data collection In January-February 2007 we installed 200 nest boxes in the towns of Gravina in Puglia (40°49'N, 16°25'E; N = 102), Altamura (40°49'N, 6°33'E; N = 50), Acquaviva delle Fonti (40°53'N, 16°50'E; N = 22), Cassano delle Murge (40°53'N, 16°46'E; N = 12) and Laterza (40°37'N, 16°47'E; N = 14). The study area includes SPA "Murgia Alta" (code IT9120007) and "Area delle Gravine" (code IT9130007) located in the southern part of Apulia region, between 300 and 580 m a.s.l. The Lesser Kestrel breeding population Figure 1: Nest box distribution in Gravina di Puglia (Ba) in 2007; empty black circles: nest boxes not used; filled black circles: nest boxes used or visited by Lesser Kestrel Falco naumanni; the size of the circles denotes number of nest boxes for each site: small circle 1-2 nest boxes, intermediate circle: 3-6 nest boxes, big circle: 7-10 nest boxes; N = 102 Slika 1: Razporeditev gnezdilnic v mestu Gravina di Puglia (Ba) leta 2007; prazni črni krogi: gnezdilnice niso bile uporabljene; polni črni krogi: gnezdilnice, ki so jih obiskale ali uporabljale južne postovke Falco naumanni; velikost krogov označuje število gnezdilnic za posamezno območje: mali krogi 1-2 gnezdilnici, srednji krogi 3-6 gnezdilnic, veliki krogi 7-10 gnezdilnic; N = 102 in the 5 colonies is estimated at 2784-3132 pairs (Bux 2008). The area belongs to the Mediterranean phytogeographical region, with wide extensions of pastures alternating with extensive farming and arboreal stands (olive and almond). Nest box distribution in Gravina di Puglia is shown in Figure 1. Nest boxes were placed on the roofs of private and public buildings, both in historic town centres and in modern neighbourhoods; entrance holes were oriented away from the wall of the building. The nest boxes were constructed of fir and pine wood (approx. 10 kg weight). (Figure 2) The base was 45 x 55 cm; 15 cm height at the front, 25 cm height at the back and a waterproof sheath was placed on the roof which made nest boxes better protected and more durable. In many cases, the nest boxes were placed in groups, 4-5 together on a single building. These nest boxes were placed 1-2 m from each other. Additionally, four small disks were placed at the foot of each nest box in order to prevent them from touching the ground, and to keep humidity at bay. Soil was added to about 1 cm depth inside each box, both to provide a soft substrate for the eggs to be laid on and to prevent eggs from unnecessary rolling. The entrance hole — 6 cm in diameter — was sized specifically for Lesser Kestrels, and allowed only this species to occupy the nest boxes, thus excluding eg. Feral Pigeons Columba livia var. domestica. A side entrance of 9 x 9 cm panel located on the side (left or right) of each nest box made it easier to clean and provided easy access for measuring and ringing the chicks. Each nest box was numbered to facilitate its identification during the monitoring carried out in the breeding season. Nest boxes considered visited by Lesser Kestrels were those in which traces of the species' presence were found, such as tracks on the nest substrate inside the nest box, presence of pellets, and prey remains. Nest box breeding attempts (defined as a nests in which eggs were laid; Steenhof 1987) by Lesser Kestrels were those in which egg-laying and the reproductive cycle Figure 2: An example of a nest box for Lesser Kestrel Falco naumanni placed on the roof of a building Slika 2: Primer gnezdilnice za južno postovko Falco naumanni, nameščene na strehi stavbe took place. Breeding success parameters were also monitored in 38 'natural' nests located in the colonies in Gravina in Puglia and Altamura and the results compared with those for nest boxes. We compare the main reproductive parameters between next boxes and nests placed in attics or wall cavities. The attics are trampling space between roof and extrados of attic. Generally, the Lesser Kestrel breeds on the floor and enters through holes of ventilation or crevices in the roof (made of tiles). The cavities in the walls are holes and niches in the perimetric bearing walls of buildings and are inaccesible to man and, largely, to terrestrial predators (i.e. rats). All the nest categories were visited at least twice between 15 May and 20 Jun 2007. This is the period in which egg-laying (between 15 May and 30 May) and initial chick rearing take place (Bux et al. 2005). If egg-laying did not take place in this period the nests were no longer monitored. We determined the reproductive parameters (clutch size - number of eggs laid, egg-laying date, hatching success, brood size and number of fledged young) by visiting each occupied nest 4 or 5 times. Means ± SE (standard errors of the mean) are presented and differences between nest sites were determined using one-way ANOVA, Mann-Whitney U Test and Kruskall-Wallis post hoc test. 3. Results In total we examined 58 nests, of which 27 (46.6%) were in attics (category a) 20 (34.5%) in nest boxes (category b) and 11 (19.0%) in cavities (category c). The occupancy rate of 200 nest boxes installed in 2007 was 8.0% (at least one egg laid) and in addition 39 (19.5%) boxes were visited by Lesser Kestrels (Table 1). Overall, the average clutch size of the 58 occupied nests we checked was 3.9 ± 1.17 (N = 58) eggs. Nests with three, four and five eggs were the most frequent clutch sizes representing 88% of all nests surveyed (Figure 3). The average clutch size was 3.81 ± 1.36 (N = 27) eggs for nests in attics, 4.00 ± 0.77 (N = 11) eggs for nests in cavities and 3.95 ± 1.10 (N = 20) eggs for nest boxes. Overall, the first egg was layed in May in more than 90% of the cases, with a peak in the second decade. The earliest egg was laid on 9 May, and the latest on 3 Jun. The mean laying date was 12 May (N = 9) in attics, 11 May (N = 7) in cavities and 17 May 1 2 3 4 5 6 Clutch size / Velikost legel a> ig 4.5 (D g4.0 13.5 (D 1*3.0 & M ^2.0 u S" >» ■a 1.0 a> u J0.5 "ro.o attic nest box cavity Figure 3: Clutch size for 58 Lesser Kestrel Falco naumanni nests studied in 2007. The variable shows a tendency towards normality (Kolmogorov-Smirnov test d = 0.17331, P < 0.10). Slika 3: Velikost legel 58 južnih postovk Falco naumanni, zajetih v raziskavi leta 2007. Parameter kaže tendenco k normalnosti (test Kolmogorov-Smirnov d = 0.17331, P < 0.10). Figure 5: Numbers of fledged young of Lesser Kestrels Falco naumanni for each of the three nest types: (a) attic, (b) nest box, (c) cavity. Means and standard errors of the means are shown. Slika 5: Število speljanih mladičev južne postovke Falco naumanni za tri tipe gnezd: (a) na podstrešju, (b) v gnezdilnici, (c) v stenskih odprtinah. Prikazana sta povprečje in standardna napaka povprečja. 4.5 ■§4.0 S H 3.5 £