FIVE – PREY SPECIES SURVEY METHODS Chapter Five – Prey Species Survey Methods Purpose and Background A knowledge of prey density and predator–prey ratios would help set limits for validating snow leopard numbers in a particular area. Clearly, there must be sufficient prey to support the predicted predator population. Field studies are needed to better establish how many blue sheep or similar large prey animals are needed to sustain predation by snow leopard at varying densities, with or without the presence of a buffering species like marmot. A snow leopard population is dependent on the number of prey animals present in the same general area. A snow leopard requires approximately 1.5 to 2.5 kg of meat per day, or 40 to 45 g of food per kilogram of its body weight daily (Fox 1989). Because about 30% of ungulate prey consists of unusable items such as bone, skin, or stomach contents, an adult snow leopard would be expected to consume between 700 and 1,200 kg of prey annually. Jackson and Ahlborn (1988) estimated that a population of 150 to 230 blue sheep are required to sustain a single snow leopard without depleting the prey base, but this number could be lower in areas where livestock, marmot, and other small prey are also taken (Oli 1993, 1994a; Chundawat 1994). The snow leopard is an opportunistic predator capable of killing prey more than three times its own weight. Therefore, it may potentially prey on most herbivores found in the same range except for fully grown yak or wild ass (Equus hemionus) (Schaller 1977). In general, food habit studies indicate that the primary prey of the snow leopard consists of the dominant wild ungulates of the region, along with a variety of smaller birds and mammals. Blue sheep and Asiatic ibex are the most common prey items, along with domestic stock, musk deer (Moschus spp.), pikas, hares and gamebirds (snowcocks, Tetraogallus, and chukar partridge). In parts of the Himalayan region, tahr (Hemitragus jemlahicus), markhor (Capra falconeri), urial (Ovis orientalis), and goral (Nemorhaedus goral) are killed in addition to blue sheep and ibex. In the Tien Shan, Dzhungarsky Alatau, and other ranges of the former USSR, red deer and roe deer constitute important prey along with wild boar. Snow leopards may occasionally take Tibetan antelope (Pantholops hodgsoni), Tibetan gazelle (Procapra picticaudata), and white–lipped deer (Cervus albirostris) along the Kunlun and on the Tibetan Plateau. Argali sheep (Ovis ammon) are now too rare to be preyed on much by snow leopards. Wild ass foals (Equus hemionus kiang), young camels, and subadult wild yak (Bos grunniens), may constitute another rare item in the cat’s diet (Fox 1989). Livestock are commonly killed by snow leopards, wolves, and other predators, but loss rates vary seasonally and among different areas. Typically, most losses occur during winter and early spring. Some places suffer almost no loss despite the presence of many snow leopards, while in other places one or two cats have been known to cause considerable damage. Because 66 FIVE – PREY SPECIES SURVEY METHODS marmots hibernate for five or more months of the year, they are only available during late spring, summer, and early fall. Marmots probably play a very important role in helping reduce predation on domestic stock (Schaller et al. 1988; Oli 1993), but the highest livestock loss tends to occur in areas where the natural prey base has been depleted through poaching, habitat destruction, or other factors, or where calves of bactrian camels (Camelus bactrianus) are being poorly guarded. Government authorities consider argali, blue sheep, ibex, markhor, deer, Tibetan gazelle, and most other large prey species as important sport hunting or trophy animals that could attract much needed revenue, provided hunting programs are well–managed and harvests set to sustainable limits. However, species such as argali and Marco Polo sheep are becoming too rare in some places to support even small hunting harvests. Consequently, updated and reliable status and distribution surveys are needed to establish current population levels of all wild ungulates. Data are needed on distribution patterns (past and present), population size, sex and age structure, and general demographic patterns (especially recruitment and mortality rates). Agencies responsible for managing wildlife should also accrue baseline information on each key species’ spatial and habitat requirements, forage requirements, preferred food–items (diet), escape cover and birthing area requirements, and migratory or movement patterns (many species make use of seasonally separated habitats). Such data are particularly important in light of the rapid changes to Central Asia’s rich and unique ungulate fauna due to the expanding human population, road construction, mineral exploration and extraction, livestock development, and many other economic activities. While presence or absence of a particular prey species can be relatively easy to establish, it is considerably more difficult to estimate population size with any degree of accuracy and reliability. Some species (for example, musk deer), are secretive, small, or inhabit cover–rich sites. Others are restricted to rugged mountain terrain (e.g., blue sheep, markhor, ibex), or have been largely extirpated and are now seen only in remote places (e.g., wild yak, Marco Polo sheep, urial, argali sheep, and Tibetan antelope). Population counts are time–consuming and subject to numerous sources of error, and resulting data are often difficult to interpret. Rarely can more than a small portion of an animal’s range be checked, so regional estimates must be based on extrapolated estimates, adding to the inaccuracies. Density estimates can vary widely depending on habitat quality, the methodology employed, skills of the observer, and the amount of effort expended in locating all individuals or groups inhabiting a particular area. Given these factors, the need for standard field methods is critical. This handbook provides basic recommendations for counting large herbivores. The techniques selected are especially designed for mountainous terrain, although some modification may be needed for special conditions occurring within some areas. However, it is imperative that modifications to the procedures listed here are scientifically valid and that the reasons for modifying the procedure are explained in the final report. The report should provide a full account of the methodology employed. Search efforts – number of replications, size of area(s) censused and so forth – must be described to help explain census results. 67 FIVE – PREY SPECIES SURVEY METHODS One could conduct roadside strip counts for hares, counts of burrows for marmot, or call counts during the summer, and territorial call counts for breeding pairs of snowcock, but this handbook does not describe these methods for several reasons. First, counts do not always reliably reflect actual numbers due to differences in activity or burrowing behavior. For example, marmot group sizes vary from one colony to the next and some marmots are more active than others. Colonies tend to be clumped and can be easily overlooked, especially when animals are not active above ground. Because snow leopard surveys are usually conducted in late winter or early spring, marmots may still be hibernating and thus no fresh sign would be present at burrow entrances. Second, counts may be greatly complicated by the large fluctuation in numbers that animals such as hares and small rodents experience from one year to the next. Direct counts depend on a species activity cycle and its ease of visibility. For example, seasonal differences in social behavior may affect group size and detectability, as in the case for snowcock and many gamebirds. Finally, many small prey species are extremely patchy in their distribution patterns, making extrapolation of counts inaccurate. Therefore, as part of the report on large mammal species, this handbook requests the following information on small– and medium–sized prey animals: 1. Provide a list of species known or suspected to occur in the project area, with comments on their status and distribution where information is available. Indicate relative abundance using broad terms such as scarce, common, or very common. 2. Identify major threats and protection measures required. 3. When possible, collect and analyze scats to determine presence–absence and relative abundance in the diet of snow leopards in the area (see Oli [1993b] for the procedures involved). Abundance Survey Objectives 1. Conduct herd counts (census) and estimate population sizes for key ungulate prey species. 2. Characterize important ungulate habitats and list factors likely to limit prey abundance. 3. Make recommendations for the management and protection of all key prey species. 68 FIVE – PREY SPECIES SURVEY METHODS Outputs 1. Completed prey species survey forms (Form No. 3). 2. Report describing status, abundance, and distribution of key prey species. 3. Map showing location of search sites and locations where prey species were observed. 4. Descriptions of habitat types found within the survey area. 5. Black–and–white photographs of the survey area. 6. Suggestions for improving protection and management of prey species and their habitat. Note: Prey species surveys are conducted concurrent with habitat assessment and use the same data forms (Form No. 3). Methods Two basic types of census methods include: Total counts, involving counts of all parts of the survey area for a particular species (i.e., all sites that could offer potential habitat for the species in question). This method may only be practical for diurnal ungulates inhabiting open country, but even then not over vast areas. Sample counts, involving censuses in selected sub–areas and extrapolation of data to the total habitat (or area) available to the species in question. Sample counts are clearly more practical. In addition, counts can be direct, involving actual sightings of the animals themselves, or indirect and based on sign, such as the number of pellet groups which serves as an index of relative abundance (e.g., Barnes and Jensen 1987).