the decline of the bearded vulture (gypaetus barbatus) in greece

Ardeola 48(2), 2001, 183-190

THE DECLINE OF THE BEARDED VULTURE GYPAETUS BARBATUS IN GREECE Stavros XIROUCHAKIS*, Anastasios SAKOULIS** & Giorgos ANDREOU* SUMMARY.—The decline of the Bearded Vulture Gypaetus barbatus in Greece. The Bearded Vulture Gypaetus barbatus is considered to be an endangered species in Greece. The latest estimate in the mid 80s gave a population of about 25 pairs distributed over an area of about 8000 km2. In an attempt to update our knowledge on the post-1980 distribution and status of the species, we gathered all bibliographical references for the period 1985-1999 and conducted a field survey (1995-2000) in almost all traditional territories. Results revealed that an 84% loss of the species’ population and a 75% shrinkage of its breeding distribution have taken place during the last decade. The present population consists of four breeding pairs that are distributed over 2000 km2 in Crete or an estimated 25 individuals. Population decline has been most pronounced in the mainland (>90% loss), where only one pair seems to have been left in the borders with the former Yugoslavian Republic of Macedonia. Poisoning and direct persecution seem to have had the most serious impact on the species’ decline. Conservation actions such as safeguarding of nesting areas and reduction of human persecution are urgently needed for the long-term survival of the Greek population of Bearded Vultures. Key words: Distribution, disturbance, Greece, Gypaetus barbatus, illegal shooting, poisoning, population size. RESUMEN.—El declive del Quebrantahuesos Gypaetus barbatus en Grecia. El Quebrantahuesos Gypaetus barbatus es una especie en peligro de extinción en Grecia. La última estima poblacional, realizada a mediados de los años 80, resultó en 25 parejas, distribuidas en un área de unos 8000 km2. En un intento de ampliar nuestro conocimiento sobre la distribución y estatus de la especie en los años posteriores a 1980, recopilamos todas las referencias bibliográficas del periodo 1985-1999 y realizamos un trabajo de campo (1995-2000) en casi todos sus territorios tradicionales. Los resultados revelaron que durante la última década se ha reducido la población de la especie en un 84% y que ha sufrido una pérdida del 75% en su área de distribución como reproductora. La población actual cuenta con cuatro parejas reproductoras distribuidas en un área de 2000 km2 en Creta, o una estima de 25 individuos. La reducción de la población ha sido más pronunciada en la región continental (con una pérdida de más del 90%), donde tan solo una pareja parece permanecer en los límites con la República de Macedonia. El envenenamiento y la persecución directa parecen haber tenido el impacto más grave sobre la supervivencia de la especie. Acciones de conservación, como el salvaguardar las áreas de cría o la reducción de la persecución humana, son necesarias y urgentes para asegurar la supervivencia a largo plazo de la población griega de Quebrantahuesos. Palabras clave: Caza ilegal, envenenamiento, Gypaetus barbatus, distribución, perturbación, Grecia, tamaño poblacional.

INTRODUCTION The Bearded Vulture Gypaetus barbatus is a cliff-nesting raptor that inhabits mountain regions of Eurasia and Africa (Cramp & Simmons, 1980). It has been classified in up to five subspecies (Dementiev & Gladkov, 1966; Brown & Amadon, 1968; Glutz von Blozheim et al., 1971), although Hiraldo et al. (1984) distinguish only two on the basis of plumage patterns: Gypaetus barbatus barbatus, that occurs

in Europe, Northern Africa, Asia Minor, Middle East and reaches up to Mongolia and China, and the somewhat smaller, with no black ear tufts, Gypaetus barbatus meridionalis, that occurs in East and South Africa. The Bearded Vulture feeds primarily on bones of small- and medium-sized carcasses coming from wild animals or domestic ungulates in areas of extensive pastoral activity (Hiraldo et al., 1979; Cramp & Simmons, 1980; Brown & Plug, 1990; Heredia & Heredia, 1991).

* Natural History Museum of Crete. University of Crete, P.O. Box 2208, Heraklion 71409 Crete, Greece. e-mail: [email protected] ** Hellenic Ornithological Society. Em. Benaki 53, 10681 Athens, Greece. E-mail: [email protected]

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XIROUCHAKIS, S., SAKOULIS, A. & ANDREOU, G.

Information on the population size and breeding distribution of the species in Greece in the 1980s and 1990s was obtained from the following sources:

HOS archives in the last 15 years and mapped them on 1:50000 maps acquired at the Military Geographical Service. In an attempt to validate many of these observations, we crossed references to the same birds mainly on the basis of the proximity of their geographical location. Moreover, we searched in detail the Standard Data Forms of the review of the Important Bird Areas (IBA) inventory in Greece. Fieldwork for the IBA network update took place during the years 19951997, and in that period almost all mountain areas of Greece were visited. 3. Personal communications. We collected and checked all sightings of the species reported by people active in mountain areas (e.g. forestry staff, nature lovers, climbers, stockbreeders, birdwatchers and wildlife biologists) for the period 19901995. We assessed the reliability of these records by asking the actual observers for a detailed description of the species (e.g. body shape, silhouette, plumage and flight behavior). 4. Fieldwork. In an attempt to confirm site occupancies in continental Greece, we visited the traditional areas of the species and searched all territories that had been reported to be active at least till early 1990s, namely the mountains of Parnassos, Giona, Vardousia and Olympos. We surveyed typical Bearded Vulture habitats such as upland pastures and the alpine zone above the treeline during the years 1998 and 1999. In addition, an average of 10 days per month was spent in the field during the years 1996-2000 in the island of Crete in all areas located over 400 m a.s.l. Fieldwork took place from early morning to sunset although effective searching effort ranged from 3 to 11 hours per day.

1. Bibliographical references and unpublished reports. Although the literature on the status of the species is limited, we reviewed and assessed the few existing papers and relevant data in official and unpublished reports. 2. Archives of the Hellenic Ornithological Society (HOS). We considered all Bearded Vulture observations listed in the

Observations were made mainly from vantage points with good view over the sampling areas by using 10x50 binoculars and 30-60x spotting telescopes. Bird sightings were also mapped on 1:50000 maps. To estimate population size we paid particular attention to recording individuals of different ages. Classification was based on plumage patterns (Forsman, 1999), and we allocated each vulture sighted

The bulk of its population is concentrated in Central Asia and the Himalayas (del Hoyo et al., 1994) while in Europe the species is regarded as endangered since it has disappeared from most Central European countries during the XIXth and the XXth centuries (Bijveleld, 1974). The present European population consists of no more than 120 breeding pairs which are distributed in the Pyrenees (Spain, France), the islands of Corsica (France) and Crete (Greece), and the Alps (France, Switzerland, Italy, Austria), where the species has been reintroduced (Tucker & Heath, 1994; Frey & Llopis, 1995; Xirouchakis & Giannatos, 1997; Heuret & Rouillon, 1998; Fasce, 1999; Heredia & Razin, 1999; Hofbauer-Hofer, 1999). In Greece, the Bearded Vulture was common in the beginning of the XXth century and was present in almost all continental massifs and mountains of Crete (Glutz et al., 1971; Handrinos, 1985). It was even reported as existing on the island of Rhodes (Salvatori & Festa, 1913; Tortonese & Moltoni, 1947). However, it declined dramatically in the very last decades (Grubac, 1991; Tucker & Heath, 1994; Handrinos & Akriotis, 1997), possibly due to: (a) habitat loss and degradation; (b) disturbance at nesting sites; (c) food shortage; (d) indirect poisoning from illegal use of poisoned baits; and (e) direct persecution by man. In this paper we review data available on its status over the last 20 years, aiming at determining its current distribution and population size. Reasons for the decline and conservation actions in need are also discussed. MATERIAL AND METHODS

Ardeola 48(2), 2001, 183-190

THE DECLINE OF THE BEARDED VULTURE GYPAETUS BARBATUS IN GREECE

to one of four age classes: juvenile (0 until 2124 months), immature (21-43 months), subadult (43-60 months) and adult (> 60 months). We defined as core areas of Bearded Vulture the sites of major activity (Brown, 1984), which incorporated one or more of the following features: (a) nests; (b) summer and winter roosts; (c) bone storage sites (e.g. old nests, potholes, rock crevices) and bone dropping areas, and (d) rocky outcrops producing thermal currents suitable for soaring that were regularly used by the birds. The location of these sites were registered with the use of the Global Positioning System (GPS) and plotted on a LAT/ LONG map by applying the DMAP program (Morton, 1999). Core areas that had been occupied by a breeding pair or a solitary adult, as well as traditional nesting areas where one or

185

both birds were present but no breeding activity occurred, constituted a Bearded Vulture territory (Heredia & Heredia, 1997). For the breeding distribution of the species, we regarded the IBAs that had supported Bearded Vulture territories during the last two decades (Grimmett & Jones, 1989). Relevant sizes of these areas were derived from the reviewed IBA inventory (Heath & Evans, 2000). RESULTS AND DISCUSSION The total range of the species has contracted considerably during the last two decades in all mainland massifs and, to a lesser extent, in the mountains of Crete (Fig. 1). Table 1 lists the

FIG. 1.—Distribution of Bearded Vulture in Greece in the 1980s (hatched area) and the 1990s (solid black area). [Distribución del Quebrantahuesos en Grecia en los años 80 (área rayada) y en los años 90 (área oscura).] Ardeola 48(2), 2001, 183-190

186


TABLE 1 Breeding distribution of the Bearded Vulture in Greece in the 1980s and 1990s. [Distribución del área de cría del Quebrantahuesos en Grecia en los años 80 y 90.] IBA name [Nombre de la IBA]

Size (km2) [Tamaño (km2)]

1980s

1990-1995

1995-1999

Mainland [Continente] 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13.

Vouna Evrou Koilada Filiouri Oros Tzena Koryfes Orous Voras Olympos Mountain Oros Othrys Kerketio Oros (Koziakas) Ori Athamanon (Tzoumerka) Oros Tymfi Ori Vardousia Oros Giona Oros Parnassos Ori Agrafa

740 770 131 520 420 840 230 550 550 210 250 194 212

+ + – + + + + + + + + + +

+ – + – + + – – – + + + +

– – ? – – – – – – – – – –

150 200 540 120 440 290 540 150

+ + + + + + + +

+ + + + + + + +

– + + + + – + +

20

16

6

7916

5427

1990

Crete [Creta] 14. 15. 16. 17. 18. 19. 20. 21.

Krioneritis Mountain Koutroulis - Ag. Dikaios Lefka Ori Oros Kedros Oros Idi (Psiloritis) Asterousia Ori (Kofinas) Oros Dikti Oroi Thrypti kai Ornon

Number of sites [Número de emplazamientos] Total range (km2) [Extensión total]

IBAs where Bearded Vulture territories were found in the 1980s and in the 1990s. Out of the 20 sites where the vulture was proved to breed or regarded as a breeding species until the late 1980s, only six supported active pairs in the late 1990s, all of them located in Crete. Taking into consideration that not all habitats within this area (ca. 8000 km2) were equally suitable for the species, the present breeding distribution covers an area of about 2000 km2 revealing a minimum shrinkage of 75%. Regarding its population size, the Bearded Vulture has suffered a loss of 84% in less than two decades. The decline was most pronounced in the mainland, where the species is about to Ardeola 48(2), 2001, 183-190

become extinct. There were about 25 breeding pairs during the 1970s and possibly early 1980s, with 11-13 pairs in the mainland and 12 in Crete (Handrinos, 1985). The species still held 18 territories up to the mid 1990s. Five were located in continental Greece with 1-2 active pairs in Parnassos and Giona mountains and a handful of birds scattered in the massifs of Tzena, Eastern Rodopi and Olympos. The remainder (13 territories) were located in Crete, where there were 10 pairs and a few single birds (Fig. 2). After 1996, the Bearded Vulture population continued to decline resulting in only one pair in continental Greece, on the borders with the

187


FIG. 2.—Bearded Vulture territories in Crete in 1999. [Territorios del Quebrantahuesos en Creta en 1999).]

former Yugoslavian Republic of Macedonia. Reproduction in the rest of the mainland seems unlikely after 1995, when the last observation concerning a juvenile bird took place between the Vardousia and Giona mountains (Hatzivarsanis, pers. com.). In Crete, the population seemed rather stable, but only if the previous estimates of 10-12 pairs were accurate (Vagliano, 1981; Hallmann, pers. com.). During the period 1996-2000, the Cretan population followed the previous mainland’s trend, i.e. a rapid increase of the number of territories occupied by single birds. At present, the island hosts no more than 25 individuals including four bree-

ding pairs, which are the last in Greece, and probably in the Balkans (Table 2). The number of juvenile and immature birds is chronically small and ranges from 23-38% of the total population, revealing a low reproductive output and/or a low juvenile survival (Table 2). The reasons for the species decline in the mainland remain largely unknown, although the indiscriminate laying out of poisoned baits for mammalian carnivores is suspected to have been the main one (Poirazidis et al., 1995; Antoniou et al., 1996; Papakonstantinou, 1998). Solitary-nesting scavengers such as the Bearded Vulture that feed on small carrion are most

TABLE 2 Age class distribution of the Bearded Vulture population in Crete. [Distribución de las clases de edad de la población de Quebrantahuesos en Creta.] Age–group [Grupo de edad] Juvenile [Juvenil] Immature [Inmaduro] Sub–adult [Sub-adulto] Adult [Adulto] Undetermined [Sin determinar] Total number of individuals [Número total de individuos] Total number of pairs [Número total de parejas] 1

Vagliano, 1981;

2

Hallmann, pers. com.;

3

19811

19922

19963

19984

19995

20005

2 5 – 23 –

1 – 6 45 6

6 4 1 20 –

5 7 2 22 –

3 4 1 22 –

2 4 0 18 –

30

58

31

36

30

24

10-12

14-16

9

10

7

4

Xirouchakis & Giannatos, 1997;

4

Xirouchakis et al., 1999;

5

This study.

Ardeola 48(2), 2001, 183-190

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susceptible to poisoned baits (Brown, 1991). Poisoning can hardly be documented, but it has recently been proved to be the primary source of the species mortality in the Pyrenees (Antor, 1999). Natural causes or potential limiting factors, such as scarcity of nest sites and food availability (Newton, 1979), appear to have had little or no importance. All mainland massifs still offer good nesting opportunities, while reduction in food supply cannot explain the disappearance of the species in just five years. Bearded Vultures, as bone scavengers, can afford food shortage more than any other vulture species (Houston & Copsey, 1994). Moreover, the mountain complex of Vardousia-Giona-Parnassos, which has been the historical stronghold of the species (7-8 breeding pairs in Parnassos Mt. alone; Krueper, 1862), still hosts about 190000 transhumant livestock (National Statistical Service, pers. com.). Food shortage was much more unlikely in Crete, where more than one million sheep and goats (both transhumant and semi-feral) exist (Ministry of Agriculture, pers. com.). On the contrary, there is evidence for the impact of human persecution. At least seven birds have been found shot or verified of being so during the last ten years (Table 3). Shooting could have been favoured by the vast network of track roads, constructed for the promotion and reinforcement of pastoralism or fire protection that has been developed in the island. At present, an average of 1.5 km of track road lies in every square kilometer of Bearded Vulture territories and 63% of the core areas of the spe-

cies are placed at a distance shorther than one kilometer from a road (this study). This high density of roads in the vicinity of nest and roosting sites may induce a high potential of human disturbance, and is inversely related to the species’ breeding success (Donázar et al., 1993). The conservation of the species has been quite problematic. The Bearded Vulture occupies enormous home ranges (i.e., 300-400 km2; this study), where a combination of threats may occur. In the meantime, adult birds show remarkable site fidelity and prefer to occupy traditional core areas in degraded territories than neighbouring ones with less human pressure. So far, most conservation actions have been orientated towards the designation of Bearded Vulture core areas as Special Protection Areas under the Birds Directive 79/409/EEC. Moreover, management plans have already been elaborated for some of those sites, while in Crete a supplement-feeding scheme is under way (Xirouchakis, 1998). Nevertheless, in the mainland, the species recovery seems almost impossible. A reintroduction project would be the ultimate solution, but the release of captivebred individuals might result in a waste of time and funds as long as bait use prevailed. In Crete, the presence of solitary birds with no mate is expected to increase if the shooting of raptors continues. The sub-adult/adult ratio of the island population has been 1:20, meaning that a high adult mortality could hardly be compensated by potential replacements. The enforcement of the law and the rise of public awareness are the most urgent conservation measures

TABLE 3 Incidences of direct persecution of Bearded Vultures in Crete (1990-2000). [Incidencias de la persecución directa del Quebrantahuesos en Creta (1999-2000).] Area [Área]

Year [Año]

Age [Edad]

State [Estado]

Source [Referencia]

Dikti Dikti Dikti

1991 1992 1993 1997 1998 1998 2000

Shot [Disparado] Shot Shot and stuffed [Disparado y disecado] Shot and stuffed Shot and stuffed Shot Shot

Vagliano, pers. com. Frey, 1994 This study

Lefka Ori Lefka Ori Idi Idi

Adult [Adulto] Adult Immature [Inmaduro] Immature Immature Adult Adult

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This study This study This study This study


in order to reduce direct persecution. Until then, the long-term survival of the species in its last stronghold in Greece and in the rest of the Balkans looks rather uncertain. ACKNOWLEDGEMENTS.—We are very grateful to C. Misiakos, V. Hatzivarsanis, B. Grubac, R. Tsiakiris, H. Papaioanou and C. Poirazidis for providing us with their personal observations, G. Arnellos and G. Roussopoulos for their assistance in fieldwork and C. Grivas for collecting some of the data on pastoralism. We also thank the Hellenic Ornithological Society for allowing us access to its archives, the Natural History Museum of Crete for technical support, J. J. Negro and an anonymous referee for comments on the manuscript and S. Roberts for improving the English. This study has been partially funded by a LIFE project of the European Union (B4-3200/98/444).

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