Habitat Use and Spatial Dynamics of Takhi Introduced to Hustai National Park, Mongolia

BIOLOGICAL CONSERVATION

Biological Conservation 124 (2005) 277–290 www.elsevier.com/locate/biocon

Habitat use and spatial dynamics of takhi introduced to Hustai National Park, Mongolia

Sarah R.B. King 1, John Gurnell *

School of Biological Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, UK

Received 27 August 2004

Abstract

The successful introduction of captive bred takhi or PrzewalskiÕs horse, Equus ferus przewalskii, into Mongolia in the 1990s is a good example of the benefits of ex situ conservation and one of the few examples of the recovery of an animal after it became extinct in the wild. This is also particularly interesting because virtually nothing was known about how takhi lived before they died out, and the introductions have enabled us to study how they have settled, and their ecology and behaviour within their former natural range. In this paper, we describe the movement, home range size and shape, and habitat use of takhi at one of the release areas, the 570 km2 Hustai National Park in Mongolia. Harem home ranges varied between 129 and 2399 ha, with 80% core areas of between 61 and 1196 ha. There was no relationship between range size and harem size, or length of time since release. Initially, harems stayed near their release enclosures, but over time they established home ranges further away. There was little overlap between home ranges of different harems, but neither was there evidence of exclusive range use. The more nutritious vegetation at lower elevations was pref- erentially selected. Thus the present situation looks good, but, as the population continues to grow, we anticipate that there will be potential problems related to intraspecific competition for water and vegetation resources, and the potential for hybridisation with domestic horses belonging to the local people. We consider the time it may take for takhi to reach carrying capacity within Hustai National Park and emphasise that continual monitoring of the population is essential because interventional management is likely to be required in the future. Ó 2005 Elsevier Ltd. All rights reserved.

Keywords: Home range; Habitat use; Equus przewalskii; Takhi; Reintroduction

1. Introduction 27% of the 116 reintroductions considered by Fischer and Lindenmayer (2000) were classiﬁed as failures, with Collections of animals and plants are increasingly the success of a further 47% not known. Moreover, the being seen as opportunities for ex situ conservation, respective roles of ex situ and in situ conservation strat- notably with respect to captive breeding programmes egies are open to debate (e.g. Balmford, 2000; Entwistle and subsequent release of captive-bred animals back in and Dunstone, 2000). Captive breeding and reintroduc- to the wild. However, to date there have been few suc- tions are lengthy, complex and expensive processes cessful examples of such a strategy; approximately (IUCN, 1995; Balmford, 2000) but may be vital for the survival of a species in the wild (e.g. Spalton et al., 1999; Kleiman and Rylands, 2002). * Corresponding author. Tel.: +44 20 7882 3041. Before reintroduction of captive bred takhi or Prze- E-mail addresses: [email protected] (S.R.B. King), j.gurnell@ qmul.ac.uk (J. Gurnell). walski horses, Equus ferus przewalskii, into Mongolia 1 Present address: School of Renewable Natural Resources, Univer- in the 1990s, the last authenticated sighting of a takhi sity of Arizona, Biosciences East, Rm. 325 Tucson, AZ 85721, USA in the wild was in 1969, near the Tachyn-shar mountains

0006-3207/$ - see front matter. Ó 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.biocon.2005.01.034 278 S.R.B. King, J. Gurnell / Biological Conservation 124 (2005) 277–290 in the western Gobi desert (Bouman and Bouman, served in temperatures of between 14 and +34 °C. 1994). The captive population of takhi in European Hustai National Park has a mountain forest steppe hab- and North American animal collections is descended itat that consists of steppe, meadow, grassland, shrub from animals captured at the beginning of the 20th Cen- and woodland communities (Wallis de Vries et al., tury. In 1945, only 31 horses remained in captivity, and 1996). Water flows down most of the major valleys as only nine of these bred. A species survival plan was set streams, which are permafrost fed and covered by gravel up in the USA in 1979, followed in 1986 by a European at places along their length. breeding programme (Europaisches Erhaltungzucht- Programm or EEP; Bouman and Bouman, 1994). By 1.2. Study animals the start of the 1990s, there were more than 1500 horses in captivity. In 1992, reintroductions began to Tachyn Between 1992 and 2000, 84 horses were brought to Tal, by the German Christian Oswald Foundation and Hustai National Park from reserves in Europe, where the Mongolian government, and to Hustai National they had been kept in large (over 40 ha) grassy enclo- Park, by the Dutch Foundation Reserves Przewalski sures. The horses were released as a harem into acclima- Horse in association with the Mongolian Association tisation enclosures of 40–45 ha; these enclosures were a for the Conservation of Nature and the Environment minimum of 4 km apart and visually separated from (Bouman, 1998). each other. Although most of the horses had been kept For animals kept in captivity for many generations, together in Europe and were released together, others there is a potential for loss of genetic variability (Foose, were introduced on arrival in Mongolia. Harems are re- 1986; Ryder, 1986; May, 1991) or attenuation in sur- ferred to by the name of the dominant stallion (see Table vival skills (Box, 1991; Brock et al., 1994; Shepherdson, 1). One harem was given a hard release (TurgenÕs har- 1994; McPhee, 2003; Mathews et al., 2005). Thus there em), but other releases followed a 6–24 month acclima- was concern that released takhi would not be able to tisation period. Up to four harems other than the ones survive after being bred in captivity for 13 generations studied were also present towards the end of the study (Klimov and Orlov, 1982). Moreover, there was no period (see Table 1). knowledge about the ecology of takhi in the wild before they became extinct, and so it was not clear how the released animals would cope in their new surroundings. 2. Methods Between 1995 and 2000, we carried out a series of studies on the behaviour and ecology of released takhi Mongolian rangers and biologists gathered positional in Hustai National Park. In this paper, we report on data of the harems at Hustai National Park for the full the spatial dynamics and habitat use of the horses. year from 1995 to 1997, and for the winter months Against the background of changes in population size (December to March) from 1998 to 2000. Detailed during the study period, we consider the establishment observations were carried out by the first author be- of home ranges by the harems in relation to their release tween June 1998 and July 2000, totalling 860 h. The point, size, interrelationship between the ranges of dif- standard procedure was to find a harem at dawn and ferent harems, and utilisation of the habitat within these follow it until 1400 h. The same harem was located at ranges. Finally, we consider what might happen in the 1400 h the next day and followed until dusk. Every future as the population continues to increase. By exam- 10 min during an observation session the position of ining these factors we hope to be able to provide infor- the harem was recorded with a Global Positioning Sys- mation on a reintroduction that currently appears tem and marked on a large-scale map, together with successful, with an aim to helping future reintroduction weather details. Once accustomed to the presence of projects. the observer, the horses were watched on foot from a distance of about 15 m and their behaviour recorded; 1.1. Study site these results will be considered elsewhere (see King, 2002). Hustai National Park is 150 km south west of Ulaan The per capita growth rate per year for harems with Baatar, the capital city of Mongolia. It covers 570 km2 more than three years of census data have been esti- along a southwestern spur of the Khentei range of mated using the formula r = [ln(Nt/N0)]/t, where Nt is mountains (47° 410 N, 105° 540 E). It was made a reserve the number of animals alive t years after reintroduction, in 1993 and designated a National Park in 1999. Hustai and N0 is the number of animals released (Komers and National Park borders the Tuul River, with an altitude Curman, 2000). Where mares changed harems, for the of between 1100 and 1842 m and a continental climate purposes of this calculation they were included in the (mean annual temperature = 0.2 °C and yearly rain- harem with which they were released. However, because fall = 270 mm, most of which falls in the summer; Wallis mares move between harems, and the number of horses de Vries et al., 1996). During the study, horses were ob- per harem is likely to decrease over time as the number S.R.B. King, J. Gurnell / Biological Conservation 124 (2005) 277–290 279

Table 1 Harem composition and harem range and core areas (ha) in Hustai National Park between 1994 and 1998 Harem Year Release No. adults No. foals Total No. ﬁxes Period Home range Core area enclosure and juveniles harem size Paritet 1995 1 7 1 8 142 July–December 191 96 1996 7 2 9 194 January–December 751 275 1997 6 3 9 131 January–August 881 257 1998* 7 4 11 423 June–October 1233 499 1999* 11 5 16 1166 April–November 1223 408 2000* 14 2 16 586 May–June 709 126 Mean (SD) 832 (387) 277 (156)

Bayan 1998* 1 6 2 8 395 June–October 210 61 1999* 8 2 10 628 April–October 1114 496 2000* 9 3 12 315 May–June 748 320 Mean (SD) 690 (455) 292 (219)

Margad 1999* a 14 2 16 762 May–October 684 345 2000* 12 3 15 270 May–June 277 126 Mean (SD) 480 (288) 235 (155)

Khaan 1994 1 6 4 10 1995 9 3 12 194 April–December 1089 469 1996 9 4 13 228 January–December 999 367 1997 13 5 18 1998* 15 7 22 389 June–October 609 249 1999* 7 4 11 199 April–June 1100 523 Mean (SD) 949 (231) 402 (121)

Ares 1998* 2 6 3 9 144 July–October 744 240 1999 9 0 9 2000 9 3 12

Patron 1994 2 6 5 11 1995 9 3 12 159 April–December 2399 1196 1996 14 4 18 156 January–December 1904 894 1997 13 2 15 141 January–July 1653 718 1998 12 7 19 1999 15 5 20 2000 16 5 21 Mean (SD) 1985 (380) 936 (242)

Turgen 1996 b 4 1 5 96 June–December 751 260 1997 3 0 3 6 January/April 129 68 Mean (SD) 440 (440) 164 (135)

Bohemian 1998 4 6 0 6 1999 3 0 3

Mark 1998 5 7 0 7

Manlai 1999 a 4 0 4

Mangir 1999 a 4 2 6 2000 6 1 7 Harem range area = 95% kernel estimates, core area = 80% kernel estimates. a = wild born bachelor stallion acquired mares. b = harem hard released from travelling crates near release enclosure 1. There was no diﬀerence in mean home range size or mean core area among years, irrespective of harem

(home range: F5, 15 = 0.56, P = 726; core area: F5, 15 = 0.78, P = 0.578; these include the data for Ares). Mongolian rangers collected data prior to 1998. * = data collected by SRBK; = no data. 280 S.R.B. King, J. Gurnell / Biological Conservation 124 (2005) 277–290 of stallions competing for mares increases (Linklater ulation, and 12% of the population died. The increase in and Cameron, 2000; Linklater et al., 2000), changes in births in 1998 was mostly produced by three free-rang- numbers of individuals within harems do not reflect ing harems (19 of the 25 births). Predation by wolves, overall population growth. Thus, we also consider pop- Canis lupus, was low with a mean of 2.8 horses taken ulation growth based on changes in population numbers each year, all one year old or less (16% of all foals born between 2002 and 2004 (see Anonymous, 2004); no fur- between 1994 and 1999). It appears unlikely that preda- ther introductions took place after 2001. tion affected population growth at the time of the study. Home range and habitat use data were analysed using In July 2000 there were 91 free ranging horses, a Arcview 3.2. One hundred per cent and 95% kernel har- density of 0.2 horses km2 over the entire Park. The em range areas were calculated (see Worton, 1989; Sea- yearly mean density of horses within a harem between man and Powell, 1996; Hooge and Eichenlaub, 1997), 1995 and 2000 was 1.8 horses km2 (N = 24 harems, the latter excluded occasional forays outside the areas. SD = 1.3 horses km2, range from 0.5 horses km2 Utilisation curves were used to estimate core areas; in for Patron in 1995 to 5.4 horses km2 for Margad all cases these were 80% of the total range area (King, in 2000). In 1995, 1996 and 1998 the home range 2002). and size of every harem was known. The density of ANOVA was used to test whether the yearly range horses over the area covered by these harems was areas since release changed in a systematic way. Param- 0.8 horses km2 in 1995, 1.2 horses km2 in 1996 atric or non-paramatric correlation techniques were and 1.8 horses km2 in 1998. In 1999, density of har- used as appropriate to compare the area overlap of each ems within Hustai National Park was 0.01 har- yearly harem range with the range in its previous year, ems km2 (N = 7). and the movement of range centres from one year to The per capita growth rates (r) of three reintroduced the next. Harem range use was examined according to harems with census data spanning more than three years season and temperature using Kruskal–Wallis tests, be- were: Paritet 0.69 – 1995 to 2000, Patron 0.65 – 1994 to cause the data were not normal. For analyses of sea- 2000, and Khaan 0.79 – 1994 to 1998. Thus, these har- sonal and altitudinal effects on activity, movement, ems were very successful and doubled in size over these and range size, the yearly range or core areas for partic- time periods. However, Khaan lost half his harem in ular harems have been treated as independent. 1999 to Margad when numbers dropped from 22 to 11 Eleven vegetation categories or habitat types were (Table 1), and he subsequently lost the rest of his harem distinguished within Hustai National Park (Wallis de the year after. A more realistic indication of population Vries et al., 1996). The areas covered by the different growth rate can be obtained by considering population habitat types within each home range, and those that numbers after 2001, when no further introductions took were grazed or used for shelter or water, were measured, place. In 2002 there were 142 horses in Hustai National and habitat selection indices (Manly et al., 1993) calcu- Park, and this increased to 162 horses by June 2004, of lated. Preferences were formulated using v2 tests. The which 84 were reintroduced (Anonymous, 2004). This seasonal (spring – March to May, summer – June to Au- gives an overall per capita growth rate (r) of 0.066 per gust, autumn – September to November, and winter – year. This growth rate must be treated with caution December to February) use of vegetation was based since it is based on only three years of data. on data from all years and this was compared with the vegetation available to them within their total range 3.2. Harem range and core areas area over all years. Between 1995 and 2000, 95% kernel harem range areas ranged from 1.3 to 24.0 km2 and 80% core use 3. Results areas from 61 to 499 ha (Table 1, Fig. 1). There was no difference in range area among years (F5,15 = 0.56, 3.1. Numbers and density of horses P = 0.726; note, horses were observed for different periods of time within each year). Both mean range and core Of 115 foals born between 1994 and 2001 (Table 1), areas were significantly different among harems (range 57% were still alive at the end of the study reported here area: F5,14 = 6.61, P = 0.002; core area: F5,14 = 7.65, (see Anonymous, 2004, for an update of population P = 0.001, these exclude the single home range estimate numbers). Twenty-six per cent of deaths were caused for Ares, Table 1); mainly because PatronÕs mean range by babesiosis (piroplasmosis), which particularly af- and core areas were significantly larger than those of the fected newly released horses (three died from this in other harems (Table 1). 1998 and nine in 1999; previous deaths from this disease There was no correlation between number of fixes are also possible, but were not diagnosed). Most other and size of harem range or core areas (Table 1; range deaths were foals (63% of all deaths). In each year area: rs = 0.035, N = 21, P = 0.881; core area: (1995–2000), on average, foals made up 25% of the pop- rs = 0.092, N = 21, P = 0.691). In addition, there was S.R.B. King, J. Gurnell / Biological Conservation 124 (2005) 277–290 281

SD = 27%; Table 2). There was no signiﬁcant correlation between the number of years since release and the degree of overlap (range area rs = 0.34, N = 11, P = 0.313; core area rs = 0.40, N = 11, P = 0.255;). In general the trend was for a decrease in range overlap over the years (Table 2). The harem range centres did not move very far from one year to the next, with a minimum movement of 0.4 km and a maximum of 1.8 km (Table 3). However, distance from initial range centre after release to range centres the following years appear to show a movement away from the release enclosure. The harems tended to stay close to their acclimatisation enclosures in the year after release, then move further away to settle in a nearby valley.

3.4. Overlap between the ranges of diﬀerent harems

Paritet, Bayan and Khaan were released from enclosure 1, Turgen from outside enclosure 1, and Ares and Patron were released from enclosure 2. MargadÕs was a naturally formed harem (Table 1). Overlap between yearly harem ranges was analysed to see whether harems moved to the same areas of Hustai National Park after release. The degree of range overlap between harems varied from 0% to 89% (mean = 39%, N = 21, SD = 30%); core areas overlapped 0% to 66% (mean = 18%, N = 21, SD = 21%) (Table 4). There was no correlation between number of years since release and amount of overlap between harem ranges (r = 0.26, N = 21, P = 0.253) or core areas (r = 0.17, N = 21, P = 0.459). In 1995, when ParitetÕs harem was first released and Fig. 1. Eighty percent core areas of the study harems in (a) 1998 and KhaanÕs and PatronÕs had been free ranging for one (b) 1999. Ranges show the core area of the entire harem, but the names of the dominant stallions are used. Paritet, Khaan and BayanÕs harems year, there was no overlap between any of the core were all released from enclosure 1 (in 1994, 1995 and 1998, areas. Core areas overlapped in 1996 after TurgenÕs respectively). AresÕ harem was released from enclosure 2, and Margad harem was released. TurgenÕs core area in 1996 and acquired KhaanÕs mares in 1999. 1997 was overlapped more than any other harem except AresÕ in 1998 (Table 4b). PatronÕs core area did not overlap with any other harem between 1995 and 1997, no correlation between number of months since release and did not do so during the rest of this study (SRBK, and harem range (r = 0.22, N = 31, P = 0.235) and core pers. obs.). The bachelor group moved among the home area (r = 0.01, N = 31, P = 0.976), or between the ranges of all (SRBK, pers. obs.). number of adults and juveniles in each harem and range Changes in overlap among core areas indicate range (rs = 0.220, N = 21, P = 0.337) or core area (rs = 0.346, shifts and/or a change in area used. For example, Ba- n = 21, P = 0.124). Despite the small sample sizes, we yan overlapped with Ares in 1998, but in 1999 he used tested for a year effect, but there was no significant dif- a larger area and his harem overlapped with all the ference in range or core area among years (range area: other harems. The bachelor stallion Margad took most H5 = 3.56, P = 0.615; core area: H5 = 5.09, P = 0.404). of KhaanÕs mares in 1999, and although they were using the same valley, their core areas only overlapped 3.3. Harem range shifts between years by 23%. By mid-summer, KhaanÕs remaining mares were taken over by another stallion and they moved Overlap of individual harem ranges between years to a different valley. Thereafter MargadÕs harem varied between 31% and 100% (mean = 59%, N = 11, increasingly used KhaanÕs previous range; in 2000, SD = 26%) (Table 2). Overlap of yearly core areas var- 50% of MargadÕs core area overlapped with KhaanÕs ied between 11% and 100% (mean = 45%, N = 11, 1998 core area and 57% with KhaanÕs 1999 core area. 282 S.R.B. King, J. Gurnell / Biological Conservation 124 (2005) 277–290

Table 2 Harem home range and core area shifts expressed as a percentage of overlap from one year (column) to the previous years (row) Year 1996 1997 1998 1999 2000 (a) Overlap of home range Paritet 1995 100 93 75 89 87 1996 75 47 60 41 1997 62 64 45 1998 62 44 1999 37 Bayan 1998 98 18 1999 33 Margad 1999 31 Khaan 1995 78 * 23 36 1996 * 31 34 1997 ** 1998 41

(b) Overlap of core area Paritet 1995 100 82 24 86 89 1996 79 39 78 45 1997 48 76 44 1998 47 9 1999 25 Bayan 1998 51 0 1999 11 Margad 1999 20 Khaan 1995 61 * 23 4 1996 * 34 7 1997 ** 1998 19 * = no data for Khaan harem in 1997.

In 1999 and 2000 there were four other harems in day and the presence of flies. Although ranges were Hustai National Park (Table 1). Although there were slightly larger in winter, there was no significant differ- no data for these harems, it is possible that total overlap ence in the size of the ranges or core areas in different was larger than shown in Table 4. The harems appeared seasons (range areas: F3,39 = 0.49, P = 0.693; core areas: to distance themselves from each other but there was no F3,39 = 0.62, P = 0.605). evidence of exclusive use of an area by any harem. The In core areas, horses were found more often at a harems appeared to select a home range in a valley higher altitude during the summer than in spring or au- where there were no previous horses, and where the har- tumn (there were too few data for winter; median in ems were separated by ridges. However, Bayan broke summer = 1500 m, spring = 1425 m and autumn = this trend by tending to use the same valley as Margad 1400 m; Kruskall–Wallis H2 = 613.31, P < 0.0001). in 2000. Moreover, observations by the Mongolian There was also a diurnal trend in the horses movements rangers indicate that all harems sometimes use the same (Fig. 2). In the morning, when it was cool, the horses valley during the winter. spent most of their time grazing in the valleys. As the temperature increased, the horses moved to higher ele- 3.5. Habitat use within the home range vations where they could avoid flies and direct solar radiation by standing near rocky outcrops or in forest Habitat use within the home range was influenced by until the weather cooled enough for them to come down several factors including temperature, season, time of to graze again. This pattern was less marked in spring S.R.B. King, J. Gurnell / Biological Conservation 124 (2005) 277–290 283

Table 3 Distance from the centre of the home range in one year to the centre in all other years since release Year 1996 1997 1998 1999 2000 Paritet 1995 0.5 1 2.7 1.6 1.6 1996 0.5 2.3 1.2 1.2 1997 1.8 0.8 0.8 1998 1.2 1.2 1999 0.1 Bayan 1998 0.5 3.2 1999 2.7 Margad 1999 1.4 Khaan 1995 0.4 * 1.6 2 2.8 1996 * 1.3 1.7 2.5 1997 *** 1998 0.9 >1.2 The arithmetic mean of all points was used to find the centre. Figures given are the distance from the centre of the row to the centre of the column. * = no data for Khaan harem in 1997. and autumn when the weather was cooler and the horses sibirica in Mountain steppe II. Although these species spent more time at lower elevations. did not have the high crude protein content of needlegrass they had a higher crude fibre content (van Diere- 3.6. Vegetation use within the home range ndonck and Wallis de Vries, 1993). Grazing was observed in Woodland by most harems Habitat composition of the different haremsÕ ranges in most years (Fig. 3) and understorey vegetation such varied slightly, but all 11 vegetation classes described as Spiraea media and Cotoneaster melanocarpa was ea- by Wallis de Vries et al. (1996) were grazed at some time ten rather than trees. The area covered by other vegeta- (Table 5). However, all harems in all years did not ran- tion classes (Upland steppe, Shrubland I, Shrubland II, domly select vegetation classes (all v2 statistics, P < 0.05; Meadow II and Scrub) was small. Fig. 3). They most frequently selected vegetation classes from lower elevations (i.e., Meadow I, Tussock grass- 3.7. Seasonal use of the vegetation land and Lowland steppe; Fig. 3). Meadow I (dominated by bentgrass, sedge and Iris lactea) was The harems selected more vegetation classes in spring preferred by Bayan in 1999 and 2000, and by Khaan and autumn than in summer, and few classes were se- in 1998. Although most preferred, Meadow I was not lected in winter (Fig. 4). From spring to autumn vegeta- used by Khaan in 1999, and little by Margad. tion classes at mid to low elevations were used, with the ParitetÕs range did not include Meadow I vegetation exception of using woodland in the spring. In winter, and they preferred Tussock grassland (Fig. 3). Tussock vegetation at mid elevations was used. Lowland steppe grassland contains the needlegrass species Achnatherum was selected in every season of the year, and Shrubland splendens and Stipa krylovii which have high levels of I and Mountain steppes I and II were selected in every crude protein and crude fibre (van Dierendonck and season except winter. Harems observed in winter pre- Wallis de Vries, 1993). Tussock grassland was not found ferred Lowland steppe. Woodland was not used at all in Khaan/MargadÕs home range. in the autumn and winter, and Tussock grassland and Lowland steppe was selected significantly more than Upland steppe were selected by at least two of the three most other vegetation classes, and had a high selection harems in spring and autumn, but not in summer. index for all harems except Bayan in 1999 and Khaan in 1998 (Fig. 3). This vegetation class includes the wheatgrass Agropyron cristatum, which featured largely 4. Discussion in the diets of feral horses, and is dominated by the needlegrass Stipa krylovii. 4.1. Numbers Both Mountain steppe vegetation classes were found in every home range, and one or both were significantly The reintroduced population of takhi increased in selected by the harems (Fig. 3). These were dominated size during the study period, and continues to grow by Festuca lenensis in Mountain steppe I and Festuca (Anonymous, 2004). This was despite loss of half the 284 S.R.B. King, J. Gurnell / Biological Conservation 124 (2005) 277–290

Table 4 Overlap of home ranges and core areas between harems expressed as a percentage of the area covered in each year Year Harem Home range area (ha) Harem Total % of core area overlapped Paritet Khaan Patron (a) Home range 1995 Paritet 191 – 86 0 86 Khaan 1089 15 – 4 19 Patron 2399 0 39 – 39 1996 Khaan Paritet Turgen Patron Khaan 999 – 42 25 0 51 Paritet 751 56 – 53 0 87 Turgen 751 34 53 – 0 85 Patron 1904 0 0 0 – 0 1997 Paritet Turgen Patron Paritet 881 – 13 0 13 Turgen 129 89 – 0 89 Patron 1653 0 0 – 0 1998 Khaan Paritet Bayan Ares Khaan 609 – 14 0 29 35 Paritet 1233 7 – 0 12 14 Bayan 210 0 0 – 41 41 Ares 744 24 19 12 – 18 1999 Paritet Bayan Margad Khaan Paritet 1223 – 8 6 37 40 Bayan 1114 9 – 11 9 23 Margad 684 10 19 – 49 66 Khaan 1100 41 9 30 – 68 2000 Paritet Bayan Margad Paritet 709 – 8 0 8 Bayan 748 8 – 5 13 Margad 277 0 14 – 14

(b) Core area Paritet Khaan Patron 1995 Paritet 96 – 0 0 0 Khaan 469 0 – 0 0 Patron 1196 0 0 – 0 1996 Khaan Paritet Turgen Patron Khaan 367 – 5 20 0 21 Paritet 275 7 – 34 0 35 Turgen 260 29 36 – 0 66 Patron 894 0 0 0 – 0 1997 Paritet Turgen Patron Paritet 257 – 16 0 16 Turgen 68 59 – 0 59 Patron 718 0 0 – 0 1998 Khaan Paritet Bayan Ares Khaan 249 – 4 0 0 5 Paritet 499 2 – 0 3 5 Bayan 61 0 0 – 33 33 Ares 240 0 5 8 – 14 1999 Paritet Bayan Margad Khaan Paritet 408 – 5 0 31 35 Bayan 496 4 – 5 1 9 Margad 345 0 7 – 23 32 Khaan 523 0 1 15 – 39 2000 Paritet Bayan Margad Paritet 126 – 0 0 0 Bayan 320 0 – 1 1 Margad 126 0 1 – 1

Columns overlap rows. There was no diﬀerence among the harems in the overlap of home ranges (F6,14 = 1.66, P = 0.204), but there was a diﬀerence among the overlap of core areas (F6,14 = 3.53, P = 0.024). S.R.B. King, J. Gurnell / Biological Conservation 124 (2005) 277–290 285

25 1550

1500 20

1450 15 1400 10 1350 Elevation (m) Temperature (C)

5 1300

0 1250 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 Hour of day Grazing Resting Moving Mean elevation Mean temperature

Fig. 2. Diurnal activity of the horses (% of total) according to mean elevation and temperature (SDs not included). The horses were observed in different activities at different times of day (H = 17.38, d.f. = 4, P < 0.002), and at different temperatures (H = 577.12, d.f. = 4, P < 0.0001) and different elevations (H = 630.21, d.f. = 4, P < 0.0001). The horses were found at higher elevations in the middle of the day (H = 120.35, d.f. = 15, P < 0.0001) and at higher temperatures (H = 1279.18, d.f. = 15, P < 0.0001).

Table 5 Habitat classes at Hustai National Park according to landscape features and dominant plant species (based on Wallis de Vries et al., 1996) Habitat class Dominant species Landscape Altitude Slope Scientiﬁc name Common name Meadow I Iris lactea Dwarf iris Streamside 1100–1400 Tussock grassland Achnatherum splendens Needlegrass Valley terrace 1100–1400 Lowland steppe Artemisia adamsii Wormwood Footslope 1100–1400 South Stipa krylovii Needlegrass Upland steppe Thermopsis lanceolatus False lupin Footslope 1300–1500 South Stipa krylovii Needlegrass Shrubland I Caryopteris mongholica Bluebeard Rocky slope 1300–1600 South Amygdalus pedunculata Sweet almond Mountain steppe I Festuca lenensis Tundra fescue Ridge & topslope >1300 Mountain steppe Festuca siberica Siberian fescue Mountain slope >1400 North Shrubland II Spiraea aquilegifolia Spiraea Gully 1100–1600 Meadow II Geranium pratense Meadow cranesbill Combe >1300 Woodland Betula platyphylla Asian white birch Mountain slope >1400 North Scrub Betula fusca Birch Topslope >1400 North horses released in 1998 to babesiosis. Babesia equi and but gain protection from maternal antibodies (Donnelly B. caballi are endemic to Mongolia and transmitted by et al., 1982). Thus local domestic horses and takhi born the tick Dermacentor nutalli. Unless treated, between in Mongolia do not appear aﬀected by the disease. In 25% and 100% of cases are fatal (West, 1992). However, contrast, newly introduced animals with no immunity animals can acquire immunity during the course of an and that may become stressed for reasons such as trans- infection, and mortality depends on the general immune port, release, or poor body condition in early spring, are status of the animal, and the virulence of the piroplasm likely to be susceptible. In particular there is a high mor- (Schein, 1988). Foals can be infected during pregnancy, tality rate during the initial infection of older animals 286 S.R.B. King, J. Gurnell / Biological Conservation 124 (2005) 277–290

Paritet harem (1998, 1999, 2000) Bayan harem (1998, 1999, 2000)

1 1 M1 TG TG M1 0.5 0.5 R TG LS S1 W LS LS S2 0 MS2 US MS1 LS S1 W MS2 0 M2 0 250 500 W S1 US MS1 S1S1 LS MS1 0 150 300 S MS1 MS2 log wi MS1 TG W S2 log wi TG -0.5 S2 LS US A -0.5 MS2 S2 S1 MS2 S MS2 MS1 -1 -1 R S2 W W M2 TG S -1.5 -1.5 (a) Area of vegetation i (b) Area of vegetation i

Khaan harem (1998, 1999) Margad (prefix 1; 1999, 2000) and Ares (prefix 2, 1998 ) harems

1.5 0.6

0.4 2M1 1LS M1 2MS1 1 1LS 0.2 2M2 1MS1 2US 1M1 1US 1US 1S1 1S1 0 0.5 0 150 300 2MS2 LS -0.2 1MS2 1MS2 1W M2 MS2 S1 LS -0.4 1M2 1W 0 2LS log wi 1M1 2S1

log wi US S1 0W 150 300 -0.6 MS2 -0.5 -0.8

-1 -1 -1.2 2M1 2W STGUS S2 -1.4 1M2 MS1 -1.5 W MS1 (c) Area of vegetation i (d) Area of vegetation i

Fig. 3. Habitat selection indices (wi, logged for presentational purposes) plotted against area of each vegetation type (i). M1 = Meadow I, M2 = Meadow II, TG = Tussock Grassland, LS = Lower Steppe, US = Upper Steppe, S1 = Shrubland 1, S2 = Shrubland 2, MS1 = Mountain Steppe I, MS2 = Mountain Steppe II, W = Woodland, S = Scrub, A = Agricultural Area, R = Rock and Stones. Habitat classiﬁcation based on

Wallis de Vries et al. (1996). A value of log wi > 0 represents positive selection, = 0 represents no selection, <0 represents avoidance. Squares indicate habitats were not selected at all, but were arbitrarily assigned a value of 0.05 so that they appear on the figure, circles indicate wi values significantly 2 different to zero (v P < 0.05), triangles indicate insignificant wi values or where expected values <5.

when brought from a country, such as Holland, where Rubenstein, 1981) were generally smaller than at Hustai B. equi is not endemic (Schein, 1988). National Park. In general, differences in home range size Most losses to the population resulted from the death are related to vegetation quality and distribution of re- of foals. Diseases such as strangles (infection by Strepto- sources such as water and shelter (Leuthold, 1977). No coccus equi) accounted for some of these deaths, as well trends in harem range size with time after release were as predation and the harshness of the Mongolian winter. found, or with harem size (cf. Zervanos and Keiper, 1979; Berger, 1986; Linklater et al., 2000), and there 4.2. Home range use was no suggestion that forage was limiting. However, Mongolia suffers from periodic droughts and severe win- Harem range sizes varied between 1 and 24 km2 ters and these will affect the vegetation growth. It is pos- (mean 9.2 km2, N = 21, SD = 5.64 km2) and are similar sible that harem ranges will be smaller when forage in range to feral horse populations in Alberta, Canada quality is good; this was found in reintroduced Arabian (2.6–14 km2; Salter and Hudson, 1982) and in New Zea- oryx, Oryx leucoryx, whose ranges became smaller in land (1–18 km2; Linklater et al., 2000), but smaller than areas where rain had fallen (Corp et al., 1998). those in North America (8–48 km2; Pellegrini, 1971; Fe- Similarity in size of reintroduced takhi home ranges ist and McCullough, 1976; Berger, 1977, 1986; Miller, and feral horses under similar circumstances implies 1983a). Home ranges of horses in England (2.5– not only that feral horse management techniques could 3.2 km2; Tyler, 1972; Gates, 1979), and barrier islands potentially be applied to this population, but that they (3–6 km2; Keiper, 1976; Zervanos and Keiper, 1979; are using similar survival strategies. Thus takhi did not S.R.B. King, J. Gurnell / Biological Conservation 124 (2005) 277–290 287

Spring Summer

1 1.5

2S2 1TG 3M1 0.5 3US 1 2LS 3LS 2M1 2US 3S1 2M1 2TG 2S1 1LS 0.5 1TG 0 2MS1 3M1 1W 1MS2 2US 0 400 800 1W 3MS2 3S1 2M2 3US 1LS 2MS1 0 log wi 3M2 3W 2MS2 2S1 -0.5 3W 1S1 3MS2 log wi 2W 02S 1S2 1MS1 800 1MS2 3LS -0.5 2W 1S2 1S1 -1 3M2 3MS1 1MS1 3S2 2M2 -1 3S2 2LS 3MS1 2S2 1US 3TG 2MS2 1M1 1M1 1US 3TG -1.5 3S -1.5 2R 2TG 3S (a) Area of vegetation i (ha) (b) Area of vegetation i (ha)

Autumn Winter

1 1 2M1 3M1 2R 3US 1TG 0.5 3M1 0.5 3LS 3M2 3LS 1LS 2LS 2S1 3US 2S2 1LS 2TG 1MS1 1S1 0 0 3MS1 3S1 3MS2 0 2MS1 400 800 0 400 800 3MS1 log wi 1S1 3MS2 log wi -0.5 -0.5 1US 1MS1 2US 2MS2 -1 -1 3S1 3S 1M12M2 2S 3TG 1M1 1US 3TG 3W 3W 1MS2 1TG 1MS2 3S 1W 3S2 2W 1S2 3M2 3S2 1W 1S2 -1.5 -1.5 (c) Area of vegetation i (ha) (d) Area of vegetation i (ha)

Fig. 4. Habitat selection indices (wi,, logged for presentational purposes) plotted against area of each vegetation type (i). (a) = spring, (b) = summer, (c) = autumn and (d) = winter. First number 1 = Paritet, 2 = Bayan, 3 = Khaan/Margad. M1 = Meadow I, M2 = Meadow II, TG = Tussock Grassland, LS = Lower Steppe, US = Upper Steppe, S1 = Shrubland 1, S2 = Shrubland 2, MS1 = Mountain Steppe I, MS2 = Mountain Steppe II, W = Woodland, S = Scrub, A = Agricultural Area, R = Rock and Stones. Habitat classification based on Wallis de Vries et al. (1996). A value of log wi > 0 represents positive selection, = 0 represents no selection, <0 represents avoidance. Squares indicate habitats were not selected at all, but were 2 arbitrarily assigned a value of 0.05 so that they appear on the figure, circles indicate wi values significantly different to zero (v P < 0.05), triangles indicate insignificant wi values or where expected values <5. lose an ability to adapt to the wild despite 13 generations of better vegetation (Miller and Deniston, 1979; Berger, in captivity, just as this trait has not been bred out of 1977, 1986). Most studies on feral horses show extensive horses despite 5000 years of domestication. spatial overlap between ranges (Keiper, 1976; Miller, Characteristics of the ranges of all harems were that 1983a; Linklater et al., 2000), although horses appear they included a permanent water source, an area of to avoid each other temporally, as they did at Hustai rocky outcrops near a ridge, and patches of forest that National Park (King, 2002). After release, harems were used in the summer. The harems of Ares, Bayan, stayed near the release enclosure in the first year, then Khaan and Margad all overlapped at one particular moved a little further away to settle in a valley. The har- place along the stream where pools were formed and ems selected valleys that were visually separated from the banks had been eroded to form a salt lick. How- each other, but as the population increases and more ever, in the main, the home ranges occupied separate overlap occurs, more valleys will be colonised and smal- valleys, defined by ridges which peaked at about ler ridges within a valley may separate the harems. In 1600 m, but which also joined at passes and along winter harems seemed more tolerant of close proximity watercourses. to each other (Mongolian rangers, pers. comm.), imply- As the size and number of harems change through ing that at this time being near other harems is more time at Hustai National Park, competition for resources important than having exclusive access to a food source. may increase. For example, larger harems have been More work needs to be done in this season to examine if shown to have priority of access to water holes (Miller lack of spatial segregation between harems is for ther- and Deniston, 1979), and also tend to be found in areas mal reasons, or for greater protection against predation. 288 S.R.B. King, J. Gurnell / Biological Conservation 124 (2005) 277–290

4.3. Vegetation use case predation was not a major cause of mortality. How- ever this is not true for all introductions (e.g., Matson Plants change in nutrition and palatability through et al., 2004). the year (Novellie and Winkler, 1993), and in Hustai The horses in this study tended to remain near their National Park the takhi preferred some species in their acclimatisation enclosure upon release, although they early development stages, and avoided others after they did move further away over time. Thus repeated use of had flowered (Salter and Hudson, 1979; Duncan, 1983; a release enclosure could lead to intraspecific conflict Miller, 1983b; Putman et al., 1987; Enkhee, 1998). The and overexploitation of the nearby habitat. However, takhi selected vegetation classes dominated by grasses this does not seem to have occurred at Hustai National and fescues which have a high fibre and crude protein Park (enclosure 1 was used in 1994, 1995 and 1998, and content (van Dierendonck and Wallis de Vries, 1993). enclosure 2 in 1994 and 1998; enclosures 4 and 5 were Although grazing was observed on all vegetation classes only used once); there was little overlap between ranges overall, takhi did not select all vegetation classes in every of different harems, although exclusive range use did not year, nor graze on all vegetation classes present. occur. All harem ranges at Hustai National Park con- Vegetation available to takhi affected their altitudinal tained access to a water source, and this has also been movements through the year. They spent more time at seen in feral horse studies. Releases should therefore low to mid elevations to shelter from inclement weather, be near a permanent water source, and this could be and to feed on the most nutritious vegetation that was used to encourage animals to move further from a re- found in the Lowland steppe (Salter and Hudson, lease enclosure. In addition shade areas and access to 1978). All the takhi had good condition throughout minerals seemed necessary for each harem. In compari- the year, and in the spring tended to have retained more son with feral horse studies, it appears that range size body fat than local domestic horses (SRBK, unpubl.). depends on habitat quality, and this should be taken As the takhi population grows there is potential for into account in assessing target release sites. Impor- overgrazing to occur, especially on vegetation classes tantly, takhi appear to use their habitat in a similar in the valleys that are preferred. Thus management will way to feral horses, so management techniques of feral be needed in the future to ensure that this is kept under populations could be applied. control. It has been suggested that Hustai National Park (area 570 km2) should be able to support a population of 400–500 horses (Bouman, 1998), equivalent to a 5. Conclusions and the future of takhi at Hustai National density of 0.9 horses km2 or 42 harems with the cur- Park rently observed 12 horses harem1. However, because of the topography and availability of water, Hustai So far, the introduction of takhi to Hustai National National Park may not support 500 horses. For exam- Park seems to have been successful, although this assess- ple, in the western section of Hustai National Park ment is based on a time period that only approximates there are streams in most valleys, but in the east (c. one generation (see Gross, 2000). Despite this, there is 144 km2) there are only three ephemeral streams. little evidence that takhi have lost any ability to survive Horses require a reliable water source, along with in the wild through many generations in captivity. All the presence of good quality vegetation and places harems bar one were given a soft release, and main- for resting both by rocks near ridges and among trees. tained in acclimatisation enclosures for at least six At present, the takhi population appears well below months, thus allowing animals to get used to both the carrying capacity. Taking the rather tentative 2002– climate and disease vectors. The importance of a suffi- 2004 estimate of per capita growth rate per year of cient acclimatisation period is shown by the greater suc- 0.066, it will take 15.5 years for the population to cess of harems, such as PatronÕs, ParitetÕs and KhaanÕs, reach a carrying capacity of 450 horses. which were acclimatised for two years, compared to the A future problem is the likelihood of hybridisation those that had a hard release (TurgenÕs harem) or were with domestic horses as the takhi expand beyond the acclimatised for only six months (Mark and BohemianÕs Park boundary. Local people value hybrid offspring. harems). These harems suffered greater mortality, with Hybrids will need to be identified and either controlled, only two horses from Turgen and BohemianÕs harem neutered or prevented from re-joining the population. surviving a year after release, and only one from MarkÕs. Contraception may be a better way of limiting the pop- Local diseases were the main cause of mortality, sug- ulation than removing animals (e.g., Gross, 2000). Fu- gesting knowledge of potential diseases should be ob- ture studies at Hustai National Park will provide tained before animals are brought to the release site, insights into dispersal, harem formation, and the effects and continuous monitoring post-release with immediate of intraspecific competition as the population increases. veterinary attention is desirable. Although target release In addition studies of the horses over the winter may sites should be surveyed for potential predators, in this provide more insights into the habitat use and any S.R.B. King, J. Gurnell / Biological Conservation 124 (2005) 277–290 289 changes in social structure during this critical season. Duncan, P., 1983. Determinants of the use of habitat by horses in Takhi born in Hustai National Park could be used for a Mediterranean wetland. 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