CAMIEL HEUNKS, ECKHART HEUNKS, GÜVEN EKEN AND BAHTIYAR KURT

A Great Bustard Otis tarda survey in Turkey during April 2000 located 83 birds in four different areas within the Konya Basin. Birds were found on three different display grounds. Habitat descriptions of display grounds do not suggest any exclusive relationship between Great Bustard distribution and habitat, but human activity is substantial in all areas and there are strong indications that the suitability of display grounds is dependent on the relative intensity of human activity. Numbers may still be significant in this region, but the species is subject to heavy disturbance and the status of these populations is far from secure. Extrapolation of basin-wide numbers is difficult given current data. Additional surveys are recommended to discover new display grounds and to gain an insight into seasonal movements by Great Bustard. Conservation action is recommended to safeguard the Turkish Great Bustard population in the near future.

INTRODUCTION
	GREAT BUSTARD Otis tarda is globally threatened and has considerably declined in numbers during the 20th century. The European population estimate is 24,945-29,983 individuals (Heredia et al. 1995), of which Iberia, where populations have remained largely stable since gaining legal protection in 1980, holds most (c. 50% of the world total). Turkish populations are also apparently large (3000-4000, Goriup & Parr 1985, 800-3000 birds, Heredia et al. 1995), but remain very poorly known, their conservation status being much less secure than that of the Spanish population. Given the dramatic alteration rate of natural rangeland in Turkey, conservation is urgently required to avoid fragmentation of viable populations and secure meta-populations from extinction. The Great Bustard can be used as a flagship species to increase public awareness of the international importance of steppes and dry grasslands in Turkey. One of the priorities of the species' Action Plan was to survey and identify key areas for Great Bustard in Turkey (Heredia et al. 1995). Therefore, we aimed to determine the size and distribution of its population in the Konya Basin. The species is widespread in the Palearctic between 35°N and 55°N (Cramp & Simmons 1980). It has adapted from its original steppe habitat to pseudo-steppes with low-intensity farming and a mosaic of pastures. In contrast to west and most central European populations, some central and eastern European populations are migratory to a variable degree, wintering perhaps several hundred kilometres from their breeding areas. Great Bustard is highly sexually dimorphic, with adult males weighing 10-15 kg, but females only 4-5 kg. They generally occur in separate flocks. Between late winter and early spring males concentrate at traditional arenas, where they compete to retain or gain the highest possible hierarchical status within the flock, before dispersing over a wider area (an exploded or dispersed lek) to display individually and attract females.
STUDY AREA
	The richest and most important area of rangeland and natural grassland extant in Turkey is on the Central Anatolian plateau, associated with the closed basins of Tuz Gölü and Konya. This area—termed the Konya Basin—has been identified as requiring urgent conservation action, and identified as a priority by the Society for the Protection of Nature-Turkey (DHKD) during research in 1998-2001. DHKD is seeking to promote basin-wide management within the region, which covers an area slightly larger than the Netherlands, in addition to its extensive rangelands, the Konya Basin also has a number of very important wetlands for birds. Fourteen of the country's 97 Important Bird Areas (IBAs) are here (Magnin & Yarar 1997). The basin is outstandingly rich in globally threatened and near-threatened birds. Main threats to wildlife in the Konya Basin are: conversion of grasslands and steppe to arable cultivation; overgrazing of grasslands; irrigation of agricultural lands; drainage of, and diversion of water from wetlands; artificial water-level increases in certain lakes; and pollution of water courses and lakes. To ensure focused conservation planning in the future, DHKD executed a biodiversity survey in the Konya Basin in 1998. The principal output of this survey will be a Biodiversity Hotspot Atlas (Eken & Magnin in press). Faunal surveys have been undertaken in the basin to identify internationally important hotspots, principally using selected rangeland/wetland birds as indicator species.
METHODOLOGY
	Within the Konya Basin, four study areas were selected for detailed surveys. Each area included at least one known site for Great Bustard, as well as unsurveyed, potential areas. Great Bustard observations were extracted from the Konya Basin database (basin-wide survey, April-July 1998). Study areas are plotted in Fig. 2. The areas ranged from c. 225 km2 to 898 km2 (Table 1), but all were surveyed with equal intensity. For standardisation purposes it was decided to use census methodology identical to that employed during inventories of the Spanish Great Bustard population (Alonso & Alonso 1992, 1996, Alonso et al. 1995, 1997). Thus, plots were surveyed from a car, driven at low speed and stopping frequently at points with a panoramic overview to search for birds. Areas were subdivided into different units based on accessibility. All driveable paths were used to ensure maximum coverage; these access routes were identified from detailed maps (1:100,000). Ratio of area surveyed (in km2) to length of itinerary (in km) varied from 2.65 to 3.74 (Table 1). Field work was undertaken on 8-29 April 2000. Censuses were undertaken between dawn and dusk with a midday interruption at 13.00-15.00. Each study area was subject to a 3-6 day continuous survey. Where possible roads between study areas were used as transects, being driven slowly to search for Great Bustards. Table 1. Great Bustard Otis tarda survey intensity in different study areas. The itinerary (in km) is the total distance driven in each  area (which are plotted in Fig. 2) Figure 2. Map of the northern part of the Konya Basin with the study areas highlighted. Areas 2-4 are situated at the border of Tuz Gölü Area Surface (km2) Itinerary (km) Surface/Itinerary 1 225 85 2.65 2 383 160 2.39 3 898 240 3.74 4 754 215 3.51 Total 2260 700 3.23 Birds were observed with telescopes. All observations were immediately mapped using a Global Positioning System (GPS) and the total number of birds, sex ratio, behaviour (resting, feeding and interacting) and habitat type were also recorded. Additionally all noticeable forms of disturbance (hunting, presence of domestic livestock and intense drainage or tilling of land) were recorded. Display grounds were subsequently revisited to provide additional counts and further observations. Interviews with local people were used to derive information on current and former Great Bustard numbers, distribution and status.
RESULTS
	Numbers and distribution Great Bustard was found in all study areas (Table 2), with a total of 83 birds, 34 males and 49 females. The latter were more numerous in all areas, with male/female ratios ranging from 0.0 to 0.74. Age of individual birds could not be positively recorded. Birds were very shy and easily disturbed. Except disturbed individuals, all birds were almost sedentary during the day. Great Bustards were not recorded outside the study areas along transects or elsewhere. Table 2. Great Bustard Otis tarda records in the study areas (plotted on Map 2). Area Male Female Male/Female Total 1 7 11 0.64 18 2 13 18 0.72 31 3 0 1 0.00 1 4 14 19 0.74 33 Total 34 49 0.69 83 The majority (95%) were recorded on display grounds. In each area, except 3, we found a single display ground. Several attempts were made to determine the exact layout of each display and the total number of birds using them. Generally, birds were active at display grounds throughout the day. However, the maximum counts were obtained early in the morning (areas 1-2) and just before sunset (area 4). Though displays were counted more than once, Table 3 shows only maximum numbers. Area Display ground(s) Male Female Male/Female Total 1 1 7 10 0.70 17 2 1 11 18 0.61 29 3 0         4 1 14 19 0.74 33 Total 3 32 47 0.68 79 Habitat preferences As most observations concern birds on display grounds, characteristics of these areas offer the best insight into habitat preferences of Great Bustard at this season. However, habitat descriptions of display grounds do not suggest any exclusive relationship between Great Bustard distribution and habitat (Table 4). Neither vegetation, nor geomorphology or dominant land use distinguishes display grounds from other areas. Birds occur in agricultural areas with slight relief, as well as on level areas with semi-natural vegetation. Table 4. Characteristics of display grounds in study areas 1, 2 and 4. Display Description Area 1  Hilly, treeless area completely covered by large monotonous cropfields and surrounded by montane cultivated area. Extensive agriculture. During winter and spring inaccessible due to muddy roads. Area 2 Flat depression with large cropfields and bare ground (old cropfields) surrounded (at distance of >1000 metres) by treeless rangelands with semi-sedentary domestic sheep on higher slopes. Area 4 Flat area with small dunes and natural, herbaceous vegetation (primary steppe) dominated by salt-resistant species (Artemisia sp.). The area is immediately south-east of Tuz Gölü and surrounded by extensive rangelands. During winter and spring inaccessible due to muddy roads. Though difficult to quantify, there is strong evidence that the suitability of display grounds is dependent on the intensity of human activity: all were situated relatively far from settlements, intensively used cropfields or rangelands. Moreover, the accessibility of display grounds is limited by terrain (muddy roads) and lack of infrastructure. Disturbance Disturbance of Great Bustards by human activity is substantial in all areas. Though again difficult to quantify, there is evidence that birds are heavily disturbed by all kinds of human presence. Like most areas of Turkey (which has approximately four million hunters), hunting is very popular in this region. Tracks of hunters were found everywhere and, according to our interviews, Great Bustards were hunted throughout. Additionally domestic livestock (mostly sheep) disturbed birds. Herds of sheep use rangelands under a semi-nomadic regime. Rangelands generally occur close to villages (< 3000 metres), at lakeshores, and on slopes and hills. Natural vegetation in these areas is heavily overgrazed. Finally birds are significantly disturbed by agricultural activities, especially intensive cropping, which accounts for most labour, water and pesticides that threaten birds. Currently huge areas are being irrigated and cultivated with intensive crops. Drainage canals are under construction throughout. Discussion and conclusions Our survey discovered much valuable information concerning the central Turkish Great Bustard population. Though limited by time, we were able to define numbers, distribution and disturbance within a large area. The species' population in this area may still be significant, but is heavily disturbed and its status is far from secure. We believe that the possibility of double counts can be eliminated and that at least 90% of all Great Bustards present in the study areas were located. Nevertheless, extrapolation of numbers in the study areas to achieve a basin-wide population estimate is very difficult based on current data. The study areas we investigated were not chosen randomly, but based on records from earlier surveys. Therefore, numbers in these areas are likely to be well above average and extrapolation would be inappropriate. Habitat data for the entire basin are unavailable, making it impossible to arrive at a total Great Bustard population for the basin by such means. Moreover, we are unable to prove a direct relationship between habitat and Great Bustard distribution, which is obviously driven by the intensity of human disturbance, but is difficult to quantify. Finally, our distributional data are based on that for displaying birds, which may be difficult to correlate with habitat. The period chosen for field work was ideal to collect reliable population data. Firstly, birds were relatively easy to detect because of their behaviour. The clumped distribution and the birds relatively immobile behaviour enabled us to double check our counts, but avoid duplication. Finally, observation conditions were very good due to the short vegetation and good weather. Recommendations Further surveys in early spring are needed to monitor these display grounds and discover new such areas. Additionally, surveys during the breeding season and winter are recommended to discover if these birds perform any seasonal movements. Finally, conservation work is a priority to safeguard Turkish Great Bustard populations in the near future. Display grounds and adjacent land require extra protection, at least in spring and during the breeding season.
ACKNOWLEDGEMENTS
	The project was initiated and undertaken by Working Group International Waterbird & Wetland Research (WIWO) and Dogal Hayati Koruma Dernegi (DHKD). We thank Cem Ozlemir and Fatma Aral (both of the Ankara IBA caretaker group) for their contribution to the field work; OSME and Het Vogeljaar for their financial support of the project; Sjoerd Dirksen (WIWO) for his efforts to arrange finance; Jan van der Winden (WIWO) for his practical and theoretical remarks; and Juan Carlos Alonso (University of Madrid), Paul Goriup (Chairman IUCN Bustard Specialist Group) and Gernant Magnin (WWF) for their useful comments.
REFERENCES
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