In the present work, we review all the relevant information
since the first Regional Atlas of breeding birds (Massa
1985), and we add field data on the species occurrence and site occupancy relative to the period January 2014-December
2016, in order to update the species’ status in Sicily

BONDI', Salvatore

Giardina G

Saitta G

Sara' M

Surdo S

Zanca L.

Archivio istituzionale della ricerca - Università di Palermo

851 Sezione di Biologia Animale, Dipartimento STEBICEF - Via Archirafi 18, 90123 Palermo, Italy 2 Centro Recupero Fauna Selvatica - Bosco di Ficuzza, Palermo, Italy3 Vico 3° San Giorgio 5, 98020 Mandanici (ME), Italy 4 Dipartimento SAAF - Viale delle Scienze ed. 4, 90128 Palermo, Italy* Corresponding author: maurizio.sara@unipa.itMaurizio Sarà1*, Salvatore Bondì1, Giovanni Giardina2, GiuSeppe Saitta3,Salvatore Surdo4, laura zanca1Status of the Golden Eagle Aquila chrysaetos in SicilyApart from its wide continental distribution in the Palae-arctic, Nearctic and, partially, in the African and Indo-ma-layan regions, the Golden Eagle Aquila chrysaetos occurs also in the largest Mediterranean islands (Ferguson-Lees & Christie 2001). The largest population lives in Sardinia (57-70 pairs, Ruiu this volume), 32-37 pairs have been re-corded in Corsica (Seguin et al. 1998) and 16-22 pairs of the A. c. homeyeri subspecies in Crete (Xirouchakis 2001). It has been also listed as vagrant in Cyprus and Malta (BirdLife International 2016), while it became extinct in the Balearics (Viada 2006) and in the Aegean and Ioni-an islands (Xirouchakis 2001). Presence and breeding in Sicily has been recorded since the early XIX century (e.g. Palazzotto 1801 in Massa 1985). More recently, research on the Golden Eagle in Sicily has been usually focused on breeding phenology and distribution during fieldwork for Regional Atlases of breeding birds (Massa 1985, Lo Valvo et al. 1993, AA.VV. 2008), as well as a subject of a PhD thesis and post-doc grant (Di Vittorio 2007, 2011). Such data originating from a specific conservation project in the Madonie Regional Park (Sarà et al. 2011) and allowed for some investigation on the species’ habitat preferences in the island (Di Vittorio & Sarà 2009, Di Vittorio & López-López 2014). Habitat preference modelling showed how mean altitude and slope in the eagles territory are the most important topographic variables, together with the exten-sion of open habitats (arable land and grasslands), to pre-dict the occurrence of the Golden Eagle in Sicily. Actual-ly, the species occupies most of the northern ridge of the island from west (Trapani mountains) to east (Peloritani Mts). Pairs living in the south-western Sicani Mts are con-nected to the main range in correspondence to the Palermo mountains, while pairs living on Etna are embedded be-tween the Nebrodi and Peloritani. The Golden Eagle has never been recorded breeding in the south-east corner of the island (Erei and Iblei Mts). In the present work, we review all the relevant informa-tion since the first Regional Atlas of breeding birds (Massa 1985), and we add field data on the species occurrence and site occupancy relative to the period January 2014-Decem-ber 2016, in order to update the species’ status in Sicily. Observations were usually collected during the courtship displays (Dec-Feb), the late brood presence (Jun-Jul), and extended until the post fledging period (Aug-Oct). Eagle sightings were made either on foot or from a vehicle with a mean travel speed of 30 km/h, stopping at vantage points with good view over valleys and cliffs known as breeding sites or potential territories (Andersen 2007). A 10x42 bin-oculars and a 30-60x spotting scope were used during ob-servations. Whenever possible, and according to Forsman (1999), each sighted eagle was allocated to one of the fol-lowing age groups: a) juvenile of the year, b) young im-matures (2nd-4th plumage), c) old immatures and adults (≥ 5th and older plumages). Old immatures and adults were pooled together as they could not be easily distinguished from distance. Both productivity (number of produced ju-veniles per territorial pair checked) and nesting success (number of produced juveniles per successful pair) have been calculated by observing chicks in the nest that were about two months old, and/or juvenile birds during their post fledging flights accompanied by their parents (Steen-hof & Newton 2007). One of us (GG) scrutinized the data-base of the Regional Rescue Centre based in Ficuzza (Ital-ian League for Bird Protection, Lipu) for the 2001-2016 period to obtain information about species mortality. The cross-checking of databases gave 24 breeding ter-Avocetta 41: 85-87 (2017)© 2017 CISO - Centro Italiano Studi OrnitologiciSarà et al.86ritories known since 1979, 13 in western and 11 in eastern Sicily, respectively (Tab. 1). In the 2014-2016 period, sixteen of them were stable and occupied by territorial and/or breeding pairs, one for-mer stable territory was occupied by a single old adult, two were confirmed as abandoned, and five had not been checked carefully (one of which is a possible double count due to overlap between two close territories). Excluding the deserted and possible double count, and assuming some occupancy in the unchecked sites, the current Gold-en Eagle population in Sicily should cover 17-21 active territories. This means a slight increase of occupancy with respect to previous estimates, as reported in Tab. 2. A to-tal of 215 breeding attempts were recorded, 161 of which were successful and produced 170 fledglings, thus averag-ing 1.09 juveniles produced per successful pair and 0.78 juveniles per checked pair in the 1979-2016 period (Tab. 2). Thanks to some successful pairs that were able to pro-duce two juveniles even in years when most other pairs failed (e.g. in 2007-2011), nesting success is > 1 on aver-age. Estimates of productivity based on the number of ju-veniles produced per checked pair is much more informa-tive about the breeding performances of the species. The 0.65 productivity value in the 2014-16 period was the low-est recorded so far, and could be lined up with the decreas-ing 1990-2012 trend (Di Vittorio & López-López 2014). Nonetheless, productivity values recorded in Sicily are equivalent to those recorded in the central-eastern Alps (1982-92: 0.61 ± 0.01 in Pedrini & Sergio 2001), in all the alpine chain (1978-94: 0.29 - 0.95 in Pedrini & Ser-gio 2001), Spain (2008: 0.80 ± 0.14 in Del Moral 2009); and even higher than values recorded in the western Alps (1972-2008: 0.55 ± 0.30 in Fasce et al. 2011) or in con-cerned populations like the Cretan (1996-1999: 0.52 ± 0.05 in Xirouchakis 2001), or the Central West Carpathian (1984-1991: 0.50 ± 0.28 in Kropil & Majda 1996). Seven eagles (4 adults, 3 juveniles) were admitted in the Ficuz-za Rescue Centre from 2001 to 2016, yielding an average of 0.44 eagles/year. Assuming that such an indirect rate is representative of real mortality occurring in the field, the estimate should have halved with respect to the value of 0.96 eagles/year reported in the 50 years before 1985 (Massa 1985). Nevertheless, for such a small population, the loss of 4 adults in a relatively short period, and of 5 birds from the same area (Palermo mountains) is absolute-ly alarming. In a period of nearly 40 years, only one colonization has occurred (Campo et al. 2003), and currently the bulk of the population is 12-14 pairs that reproduce more or less regularly and this would allow for an adequate recruitment. Actually, it is not possible to decide whether the dropping in the population productivity across time is due to intrin-sic or extrinsic factors (Newton 1998). In the former case, low productivity would be the regulatory consequence of a density-dependence effect, driven by a territorial be-haviour mechanism (Rodenhouse et al. 1997); whereas in the latter case, prey abundance, possibly interacting with weather, would be negatively influencing the reproductive rates of the Golden Eagle (Steenhof et al. 1997). In large territorial raptors, negative density dependence in breeding performances often occurs; for instance it has been record-ed in the increasing population of Golden Eagles in west-ern Alps (Fasce et al. 2011). Together with the Cretan homeyeri, the Sicilian Gold-en Eagle currently presents the less abundant island popu-lation of the Mediterranean, and its peculiar state of small and isolated population makes it vulnerable despite every verification about the causes of low productivity. Madonie SicaniPalermoTrapaniWESTERN SICILYPeloritaniEtnaNebrodiEASTERN SICILY32411031261102§2001(+1)*214-54441134-53310-11Mountain Range Pair Single Deserted NC Range Sub-totalTable 1. Geographic distribution of the Golden Eagle in the Sicilian mountain ranges. NC = not checked during the study period, * pos-sible double count due to territorial overlap with another site; § the known dates of desertion are 1996 in one site and 2005 in another one.Status of the Golden Eagle in Sicily87 The combination of human persecution and reduction in prey availability, as a result of habitat degradation and forest expansion, as a consequence of the abandonment of traditional agro-pastoral practices, have been identified as potential long-term threats in several parts of the distribu-tion area (e.g. Pedrini & Sergio 2001, Xirouchakis 2001). In addition, shooting, poisoning, electrocution and trap-ping are considered the main causes of non-natural mortal-ity (BirdLife International 2016), and most of them have been detected as causes for the birds admitted in the Ficuz-za Regional Rescue Centre. Therefore, even in the case of a potential population in equilibrium with the current carrying capacity of the island ecosystems, further investigation on post-natal dispersal and mortality and continuous monitoring are necessary to prevent any population collapse.REFERENCESAA.VV., 2008. Atlante della Biodiversità della Sicilia: Vertebrati Terrestri. Studi & Ricerche Arpa Sicilia, Palermo 6.Andersen D.E., 2007. Survey Techniques. Pp. 89-100 in: Bird D.M. & Bildstein K.L. (eds), Raptor Research and Manage-ment Techniques. Hancock House Publ., Washington.BirdLife International, 2016. Aquila chrysaetos. The IUCN Red List of Threatened Species. doi.org/10.2305/IUCN.UK.2016-3.RLTS.T22696060A93541662.enCampo G., Provenza A. & Lo Valvo M., 2003. Nuovo insedia-mento di Aquila reale (Aquila chrysaetos) in Sicilia (Aves Accipitriformes). Naturalista sicil. 27: 169-70.Del Moral J.C., 2009. El águila real en España. Población repro-ductora en 2008 y método de censo. SEO/BirdLife. Madrid.Di Vittorio M., 2007. Biologia e Conservazione di cinque specie di rapaci in Sicilia. Tesi di Dottorato. Dipartimento di Biolo-gia Ambientale e Biodiversità, Università degli Studi di Pa-lermo (tutor: M. Sarà).Di Vittorio M., 2011. Rapaci e biodiversità in habitat pseudostep-pici del Mediterraneo. Relazione finale assegno di ricerca post-doc. Dipartimento di Biologia Ambientale e Biodiversi-tà. Università degli Studi di Palermo (tutor: M. Sarà).Di Vittorio M. & Sarà M., 2009. La preferenza dell’habitat dell’a-quila reale Aquila chrysaetos in Sicilia. Alula 16: 219-221.Di Vittorio M. & López-López P., 2014. Spatial distribution and breeding performance of Golden Eagles Aquila chrysaetos in Sicily: implications for conservation. Acta Orn. 49: 33-45.Fasce P., Fasce L., Villers A., Bergese F. & Bretagnolle V., 2011. Long-term breeding demography and density dependence in an increasing population of Golden Eagles Aquila chrysaetos. Ibis 153: 581–591.Ferguson-Lees J. & Christie D.A., 2001. Raptors: Birds of prey of the world. A. & C. Black Publ., London.Forsman D., 1999. The Raptors of Europe and The Middle East: A Handbook of Field Identification. T & AD Poyser, London.Kropil R. & Majda M., 1996. Causes of low productivity in the golden Eagle Aquila chrysaetos in the Central West Carpathi-ans. Pp. 489-494 in: Meyburg B.U. & Chancellor R.D. (eds), Eagle Studies. World Working Group on Birds of Prey, Ber-lin, London & Paris.Lo Valvo M., Massa B. & Sarà M., 1993. Uccelli e Paesaggio in Sicilia alle soglie del terzo millennio. Naturalista sicil. 17: 3-374. Massa B., 1985. Atlas Faunae Siciliae - Aves. Naturalista sicil. 9: 3-242.Newton I., 1998. Population limitation in Birds. Academic Press, Amsterdam.Pedrini P. & Sergio F., 2001. Golden eagle Aquila chrysaetos den-sity and productivity in relation to land abandonment and fo-rest expansion in the Alps. Bird Study 48: 194-199.Rodenhouse N.L., Sherry T.W. & Holmes R.T., 1997. Site-depen-dent regulation of population size: a new synthesis. Ecology 78: 2025-2042.Ruiu D., 2017. Status of Golden Eagle’s nesting pairs in Sardinia: Avocetta (this volume).Sarà M., Di Vittorio M. & Campobello D., 2011. L’Aquila reale (Aquila chrysaetos) nel Parco delle Madonie. Relazione fina-le Convenzione di ricerca Ente Parco Madonie. Dipartimento di Biologia Ambientale e Biodiversità, Università degli Stu-di di Palermo.Seguin J.F., Bayle P., Thibault J.C., Torre J. & Vigne J.D., 1998. A comparison of methods to evaluate the diet of Golden Ea-gles in Corsica. J. Rapt. Res. 32: 314-318.Steenhof K., Kochert M.N. & McDonald T.L., 1997. Interactive effects of prey reproduction and weather on golden eagle. J. Animal Ecol. 66: 350-362. Steenhof K. & Newton I., 2007. Assessing raptor reproductive success and productivity. Pp. 181-192 in: Bird D.M. & Bild-stein K.L. (eds), Raptor Research and Management Tech-niques. Hancock House Publ., Washington.Xirouchakis S., 2001. The Golden Eagle Aquila chrysaetos in Crete. Distribution, population status and conservation pro-blems. Avocetta 25: 275-281.Viada C., 2006. Libro Rojo de los Vertebrados de las Baleares (3ª ed.) 2005. Govern de les Illes Balears, Conselleria de Medi Ambient, Mallorca, 281 pp.Table 2. Number of stable territories occupied by Golden Eagle pairs or singles (plus number of possible other territories) in Sicily; to-gether with breeding performances (± standard error) during the 1979-2016 period. 1979-19831984-19921993-20062007-20112014-20161979-201610 (+3)13 (+2)16 (+1)16 (+1)17 (+4)17 (+7)283191911170373011813172151.001.151.031.291.001.09 ± 0.05Massa 1985Lo Valvo et al. 1993AA.VV. 2008Sarà et al. 2011this study0.761.030.770.690.650.78 ± 0.07Period No. of stableterritoriesNo. of produced juvenilesNo. of checked pairsNestingsuccessSourceProductivity

Status of the Golden Eagle Aquila chrysaetos in Sicily

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Status of the Golden Eagle Aquila chrysaetos in Sicily

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