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Ecology and Conservation of European Forest-Dwelling Raptors Iñigo Zuberogoitia & José Enrique Martínez (Eds.) Estudios Medioambientales Icarus S.L.

Marc Galvez.

Published by: Departamento de Agricultura de la Diputación Foral de Bizkaia © Diputación Foral de Bizkaia All rights reserved. No part of this publication may be reproduced in any form or by any means without the prior permission of the copyright owner. Edited by: Iñigo Zuberogoitia & José Enrique Martínez Estudios Medioambientales Icarus S.L. Project Supervision: Antonio Galera Coleto, Director of the Department of Conservation, Natura 2000 Network and Biodiversity. Graphic and maps Design: Antonio Secilla General Design: ITZEL Digital, S.L. Printer: Berekintza, S.L. Cover photo by: Sparrowhawk. Juán Sagardía. Translators: Phillip Thomas José Delgado Maria Francia Iñiguez Puebla Mikel John O´Rourke Rally Haigh

I.S.B.N.: 978-84-7752-489-2 D.L.: 1730-2011

When the aeolian energy invades the foraging areas of an endangered vulture Dimitris Vasilakis1*, Beatriz Cárcamo1, Stefan Schindler2, Javier Elorriaga3 & Theodora Skartsi1 WWF Greece, Evros Project, Dadia 68400 Soufli, Greece University of Vienna, Department of Conservation Biology, Vegetation and Landscape Ecology, Rennweg 14, A-1030 Vienna, Austria 3 Sociedad para el Estudio de las Aves Rapaces (S.E.A.R.) C/Karl Marx, 15, 4ºF, 48950 Erandio, Bizkaia, Spain *Correspondence: Email: ecodadia.otenet.gr 1

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years a decline in the breeding success has been noticed, along with a higher presence of immature individuals involved in the breeding activities. Besides the poisoning events, which cause the death of mainly adult individuals and has proved to negatively affect the population, other possible reasons that would explain what seems like stagnation of the population have been investigated through several research studies carried out since 2003.

The last colony of an endangered vulture The cinereous vulture (Aegypius monachus) colony in the Dadia – Lefkimi – Soufli Forest National Park (DNP) in Thrace, northeastern Greece, has been the only breeding population in the Balkans for the last 20 years. Since 1987, a systematic monitoring of the breeding activity of the species has been carried out, being one of the longest monitoring programs of a bird species ever undertaken in Greece. The size of the population has been estimated in 65 ± 14.6 mean number of individuals, and the maximum number recorded was 89 individuals in January 2001 (Skartsi et al., 2010). The number of breeding pairs increased from only six in 1987 to 16 in 1993 (Skartsi et al., 2008; Skartsi et al., 2010). The population recovery can be attributed to the establishment of conservation measures by WWF Greece in collaboration with the Environmental Office of the Evros Prefecture and the Soufli Forest Service, such as the protection of the nest sites, the establishment of a supplementary feeding station, the public awareness and the actions taken to combat the unintentional poisoning. The numbers have stabilized around 20 breeding pairs since then, with a slight increase after 2005, while during the last

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Poirazidis et al. (2004) found that suitable nesting habitat availability was not a limiting factor for the expansion of the cinereous vulture population. They also found that the species’ nesting habitat consists not only of pure pine forests but also of mixed pine-oak forests and broadleaf forests with isolated mature pines. Fundamental requirements for nest site selection were the occurrence of mature nest-trees, steep slopes and high elevations and not exposure, type of nest-tree or kind of surrounding forest. The conducted genetic studies (Poulakakis et al., 2008) haven’t showed any alarming results, as the sex ratio of the population is balanced, no evidence of genomewide genetic erosion exists and results also indicate that the recorded demographic bottleneck suffered during the twentieth century was neither critical nor lasting long enough to have had an impact on genetic variation at the species level. Poulakakis et al. (2008) also found strong evidence that historical isolation has led to the differential accumulation of mutations in the Iberian and the Balkan populations, and concluded that they represent distinct evolutionary significant units, having in mind that “historical ecological exchangeability (Crandall et al., 2000) can neither be supported nor rejected due to lack of data”. Finally, the presence of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCs) appear to be too low to have any negative effects on the population (Goutner et al., submitted).

Cinereous vulture landing in a perch inside the strict protection area. WWF Greece/G. Mercier.

Range use of the species, a need to conserve the population on a larger scale

these seasonal maps were merged leading to an annual UDM and finally to a multi-annual UDM. In this analysis the individual was used as a sampling unit, a particularly suitable technique when inferences are going to be made about a population (Otis & White, 1999). Therefore, this final map reflects individual, seasonal and annual variation in the range use and could be considered representative of the population.

Vasilakis et al. (2008) provided a first insight into the range use of the species in Thrace. It was documented that foraging cinereous vultures prospect a much wider area (appr. 3000 km2) than DNP (430 km2), which constitutes only one seventh of the total area used. The vultures search for food over vast areas, travelling far away from their familiar vultures’ feeding station in Dadia visiting Bulgaria and the adjacent prefecture (i.e. eastern Rhodopi), encompassing within their home ranges thinly populated areas where traditional stock-raising practices are still common. In this paper we report further on the range use of this population using additional data from several years and individuals, and provide a further insight on its long distance movements analysing satellite telemetry data.

The core areas of the home ranges showed a high variability for different individuals depending on season and age but several high activity centres far from DNP were common (Vasilakis et al., 2008). They could represent potential breeding areas, important foraging and roosting grounds or areas where vultures gain kinetic energy for locomotion where favourable conditions for thermals, orographic lifts, wave lifts or dynamic soaring prevail.

In this further range use analysis, the individual per season home ranges were merged resulting in a seasonal Utilization Distribution Map (UDM). Afterwards,

The home ranges of the different individuals showed a considerable overlap and like the overall occupied area they showed a prevailing northwest orientation

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(Fig. 96). Taking into account the topography and land use in areas in the east, this could be explained as an avoidance of the intensively cultivated lowland areas, where the deficiency of thermal lifts and the intensive human presence negatively affect their selection for foraging. The high energetic cost associated with flapping flight, which would be the only option for the vultures to feed in such areas in case of emergency, makes them actively avoid the areas. In the present study the home range estimates obtained for breeders were larger than those reported for Sierra de San Pedro colony (Extremadura, Spain; Corbacho et al., 2004; Vasilakis et al., 2008; ). This was not the case for the breeders of Sierra Pelada colony (Southwestern Spain) were the breeding individuals were actively selecting suitable habitats (dehesas) far from the colony (Carrete & Donázar, 2005). In the Sierra Pelada study adult vultures used larger areas during the breeding season, in contrast to what was found by Vasilakis et al.

(2008) in our study area (Fig. 96). This is in accordance with what has been found for other raptors, tied to a nesting place during the breeding season and moving around larger areas during the non breeding season (Newton, 1979). When comparisons of the home range values between the different colonies are being made, it has to be taken into account that no supplementary feeding takes place in the two colonies of Spain. It can be argued that although the vultures in our study area use the vultures’ feeding station quite intensively (Skartsi et al., 2009), they may have not become habituated, therefore their foraging behaviour may have not been severely affected. This has been shown also for other vulture species (Snyder & Snyder, 2005; Piper, 2006; Xirouchakis et al., 2006; Xirouchakis & Andreou, 2009). Thus, vultures continue to prospect vast areas, being exposed to poisoned food and to other mortality factors. Nonetheless, there is much debate on the usefulness and appropriate

Figure 96. Cinereous vulture utilization distribution map of Thrace based on radio tracking during the years 2004-2006 from several individuals (n=10, n=8, n=5 respectively). Vulture colonies, supplementary feeding sites and Natura 2000 sites (SPA and SCI)are also indicated.

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design of an artificial feeding program (Bose & Sarrazin, 2007; Deygout et al., 2009) and although many authors consider it as a valuable interim measure (Gilbert et al., 2007; Oro et al., 2008) the quality of the food that is provided has always to be controlled (Lemus et al., 2008; Lemus & Blanco, 2009). The analysis of the satellite telemetry data revealed that vultures spend 6-14% (n=2) of their time in Bulgaria and 9-10% (n=2) at a distance over 40 km from the vultures’ feeding station. The longest Euclidian distance from Dadia feeding station that a vulture was ever recorded at was 135 km with most of the individuals reaching 80 km. Furthermore, various night roosting places were recorded far from the colony in Greece and Bulgaria with one of them at a distance of 90 km in Kompsatos valley (west of the colony) where breeding of other vulture species was confirmed (M. Panagiotopoulou pers. com.). Some of these night roosting places were located on traditional nesting grounds (Marin et al., 1998) used for breeding also by other vulture species (Stoychev et al., 2004). Moreover, in 2009 three observations of marked individuals from Dadia were made in the Nestos Gorge, which hosts a griffon vulture (Gyps fulvus) colony, ca. 130 km west from the cinereous vulture colony (H. Jerrentrup pers. com.). Previously undertaken conservation and management measures were focused on the breeding colony. The results of the above mentioned studies highlight the necessity to implement conservation actions over a wider area covering the whole foraging grounds of the species. It is of special relevance considering the recent and rapid development of wind farms in these areas.

The wind farm development in Thrace The European Union, attempting to reduce the consequences of the global warming, proposed the Renewable Energy Directive, setting a target of 20% of energy consumption across member states to come from renewable sources by 2020 (EU, 2008). In order Greece’s commitments to be achieved, the share of Renewable Energy Sources (RES) in power production must be of at least 35%. Wind energy is expected to make up the greatest part of the increased RES share in electricity production. The Greek state consequently issued the Special Physical Planning and Sustainable Development Framework on Renewable Energy Sources that sets new

Figure 97. Depiction of the way that is usually used by the different vulture species for locomotion. Soaring in thermals vultures gain kinetic energy elevating themselves higher and then glide descending till the base of the next thermal (drawing from Newton 2007).

standards on wind farm development, having defined three Wind Farm Priority Areas (WPAs). The first of these areas is WPA 1 in the Prefectures of Evros and Rhodopi (GMEPW, 2008) (Figure 98). The WPA 1 carrying capacity was set at 480 typical wind turbines (WTs; 960 MW). It is included in a broader area characterised by the highest diversity and density of nesting and migrating birds of prey in Greece and overlaps by ca 50% with a number of SPAs (WWF Greece, 2008). The first wind farms appeared in the area in 2003 and up to date, nine wind farms consisting of 163 WTs of ca 200 MW total power are established within the vultures’ foraging areas (Fig. 96). To date, more than 80 applications for permits to erect wind farms of more than 1800 MW power within the same areas have been submitted to the relevant state authority (WWF Greece, 2008). Moreover, some 400 MW is planned to be installed in Bulgaria (S. Stoychev per. com.), in the prolongation of the foraging areas of the species. Thus if a large portion of these plans is approved, an over-concentration of wind power production related infrastructure will be built. WWF Greece, conscious of the need of following the development and possible consequences of the wind farm operation on raptors and especially on vultures, designed a post-construction monitoring which was implemented during 2004 and 2005 (Ruiz et al., 2006). In this early attempt it was not possible to relate dangerous movements with mortality, due to the low number of carcasses detected, which in the case of birds of prey and vultures no one was found. Other findings were first estimates of space use for vultures and other raptors in the wind park areas, the occurrence of dangerous flights mainly around the outermost turbines and the

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Figure 98. The Wind farm Priority Area 1 (WPA 1, blue line), proposed wind farm Exclusion zones (red polygons) and Increased protection zone (pink). Circles indicate 32 golden eagle nests, 12 Egyptian vulture nests, 8 long-legged buzzard nests, 1 peregrine falcon nest, and 1 black stork nest as well as several cinereous vulture roosting sites, all buffered with one kilometres radius.

higher proportion of risky behaviour in vultures than in other raptors. The study also confirmed that radio tracking could predict with high precision, which wind farms or which parts of the wind farms were used by the vultures. Four years later in 2008-09 a new post construction monitoring was designed and implemented within the same wind farms (Cárcamo et al., 2009), which basically aimed to complement the previous one and update and refine its results. In addition, trials in order to assess the influence of biases, which affect the ability to detect avian mortality (mainly scavengers’ removal activity and searchers’ detection efficiency), were conducted. Evidence of four collided griffon vultures and one booted eagle (Aquila pennata) was found, as well as a ferruginous duck (Aythya nyroca), a chukar (Alectoris chukar) and a few other species of birds and bats. The average length of time a carcass remained

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in the trial area before it was removed was 23 days, however, both season and carcass size had a highly significant effect on the removal day. Searchers detected on average 66% of the carcasses. As radio tracking could predict with high precision which wind farms or which parts of the wind farms were used by the vultures, Vasilakis et al. (2009) assessed the collision mortality on three different datasets (from visual monitoring, radio telemetry and satellite telemetry). Applying the Band model (Band et al., 2007), depending on the used data set and the avoidance rate (Fox et al., 2006) of 99.0% to 99.5% a yearly mortality of 1 to 5 vultures was estimated for the best studied 71 turbines (Fig. 96), while assuming the random installation of 480 turbines inside the WPA1 but outside the National Parks (Fig. 98), the assessed mortality ranged from 10 to 20 vultures per year.

Vultures and wind farms: do they fly at the same height? UDMs showing areas in which species of conservation concern spend different proportions of their time can contribute to their management, allowing decision makers and managers to conserve vital resources for them. Such maps can be valuable for the spatial planning not only of protected areas (Wilson et al., 2009) but also of conflicting activities like wind farm development and conservation of large raptorial birds prone to collision. In the past, for the creation of such UDMs radio-tracking techniques were employed. Radio-tracking data are bidimensional and do not provide information about the altitude of the individuals. The problem of the flying height is intensified when large soaring raptors are being studied. Vultures have evolved to fly passively and soar or/and glide using the atmosphere’s kinetic energy (Pennycuick, 1972; Pennycuick, 1998, Fig. 97). Vasilakis and Akriotis (2009), aiming to apply cinereous vulture’s UDMs for the better spatial planning, of refuted activities in its foraging areas, used data from satellite transmitters to investigate the flying height. It was found that vultures flew at similar heights and mainly rather low. No significant differences were detected among individuals regarding their flight height. The vultures’ flight height was not affected by ground altitude or the increment of distances to a vultures’ feeding station. The median flight height was 68 m, the 75% quartile 183 m, and in 68% of the records vultures were flying at flight heights between 30 and 110 m, which is concordant with those covered by the revolving rotors (rotor risk zone) of the wind turbines used in the area. Apparently, vultures exploit the orographic currents, which are the main source of commercially used wind energy too, more than thermals.

Mitigating the impact of the wind farms The prefectures of Rhodopi and Evros are internationally acknowledged as of exceptional ornithological importance. Therefore, WWF Greece (2008) issued a position paper, which defines locations and sites within and around WPA 1 where special prerequisites should be fulfilled for the wind farms site selection. More specifically, the proposal establishes wind farm Exclusion zones and Increased protection zones (Fig. 98). This proposal sets forth data collected so far on a specific number of species outside DNP (cinereous vulture, griffon vulture, Egyptian vulture Neophron percnopterus, golden eagle Aquila chrysaetos, long-legged

buzzard Buteo ruffinus, and, partially, the black stork Ciconia nigra and the peregrine falcon Falco peregrinus). For the cinereous vulture and the griffon vulture, the data used are derived from long-term monitoring programs using advanced monitoring techniques, such as ringing, tagging, radio-tracking, and satellite tracking. As for the rest of the territorial raptors (see above), the largest possible number of nests was located on the basis of all historical observations (Alivizatos, 1996; Bourdakis, 2003) and of a field survey conducted during the summer of 2008. The Exclusion zones are those areas from which wind farm installation must be excluded, due to their importance for the survival and conservation of raptors and other birds, and broadly for the conservation of biodiversity. As such were named: a) the two National Parks (DNP and Evros Delta NP); b) Loutro Forest, a forested area of high significance, mostly covered by mature Calabrian pine (Pinus halepensis subsp. brutia) at an unusual low altitude. In this forest, breeding activity and high roosting concentrations of white-tailed eagle (Haliaeetus albicilla), imperial eagles (Aquila heliaca) and spotted eagles (Aquila clanga) were observed; c) the griffon vulture colony and a safety zone around the colony, where during the non-breeding period individuals from other colonies gather to perch. This aimed at ensuring the colony’s communication with other colonies as well as with potential food seeking grounds and d) nesting site, and diurnal and nocturnal roosting places, buffered with a radius of 1,000 m. The Increased protection zones are those areas in which wind farm installation may be allowed, provided that certain prerequisites are met (WWF Greece, 2008). These zones represent the largest part of the home ranges of the raptors, as well as the foraging and movement areas of the vultures. Although human activities including permanent constructions may be permitted inside these zones, they must be planned and adjusted in such a way as to minimize disturbance and restrict negative impacts on these areas.

Future perspectives The survival of the endangered cinereous vulture population in DNP depends on the management of the areas outside the National Park and on an international scale. Its viability in the area remains uncertain, as mortality factors such as poison baits continue to negatively affect the population (Skartsi et al., 2008) and new potential threats have appeared in the vicinity of the nesting area

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and inside the foraging area of the population. This, in conjunction with the evidence for its historical and probable current isolation and the importance of the genetic distinctiveness of this population for the species (Poulakakis et al., 2008; Vasilakis et al., 2008; Vasilakis, 2009) makes the idea of creating a captive breeding stock from this population and a new colony in a suitable site more reasonable. The maximum harnessing of wind for energy production is more than crucial to the country and the planet. However, the cumulative effects from erecting multiple wind farms in a region densely used by endangered resident and migratory birds prone to collision, is a serious threat (Barrios & Rodríguez, 2004; de Lucas et al., 2008). Although low collision rates have been recorded at many wind farms (e.g. Erickson et al., 2001; Percival, 2005; Drewitt & Langston, 2006), some poorly-sited wind farms show high collision mortality (Barrios & Rodríguez, 2004; 2007, Smallwood & Thelander, 2008). The cinereous vulture in this area flies rather low and may use more the orographic currents than the thermals. Vultures spend increased amount of their flying time in the rotor risk zone and probably high collision mortality has to be expected if sensitive sitting of the wind farms is not achieved. The cinereous vulture’s UDM can be considered as a valuable tool for the management of the species in Thrace. However, certain aspects of their flying behaviour like species-specific avoidance rate (Band et al., 2007), activity pattern, flying height over ridges and ridge fidelity need to be further investigated. Nevertheless, it can be argued that managers and decision makers have to be conservative and that based on prevention and on the precautionary principle investors should not be encouraged to locate their investments within 15 km from the colony and discouraged to locate their investments within further highly used areas (e.g the 50% range polygon, see Fig. 96). Similar guidelines have been recently proposed by Carrete et al. (2009), who state that any wind farm planned within 15 km radius from a nest (occupied or not) of the globally endangered Egyptian vulture should be a priori avoided. WWF Greece’s (2008) proposal has to be enforced since there is no doubt that it leads in the right direc-

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Capturing a fledgling for ringing. WWF Greece/N. Pantelas.

tion. The involved authorities must consider that this proposal refers to a quite wide spectrum of endangered bird species and that nesting sites are one of the most important elements for their populations to survive and thrive. Nevertheless, given that the behaviour of all bird species entails a degree of uncertainty, it is in no way to be concluded that if this proposal is fully implemented there will no longer be any possibility of potential collision incidents. Neither should it be concluded that the populations of the rare bird species will not suffer from the changes in their habitats and the increase of their movements’ energy cost. Having this in mind the possibility of a future adjustment of this proposal, in the light of new data resulting from ongoing research or data that will arise following the progression of wind farm installation and operation in Thrace, has to be considered.

Acknowledgments We are grateful to all the European Voluntary Service volunteers who participated with enthusiasm in the actions of WWF Greece – Dadia Project. This paper is based upon work conducted under the WWF Greece project for the conservation of the Dadia Forest Reserve, and especially during the implementation of the LIFE Nature project ‘‘Conservation of Birds of Prey in the Dadia Forest Reserve, Greece’’ (LIFE02NAT/GR/8497) funded by 60% by the EU Commission and 40% by WWF Greece. Funding was also provided by A.G. Leventis Foundation.