Mass capture devices for large ungulates have been used by humans for millennia. In the open and arid landscapes of the Near East, ancient funnel-shaped constructions of low stone walls leading into a stone walled enclosure or pit (called ‘desert kites’), were used by post-Neolithic societies as a mass-kill hunting strategy particularly targeting goitered gazelles Gazella subguttorosa but also Asiatic wild asses Equus hemionus (Bar-Oz et al. 2011). Rock engravings and historic accounts further support the use and efficiency of desert kite-like structures for the mass capture of different gazelles as well as wild asses in the Middle and Far East (Holzer et al. 2010) but also for other ungulates, e.g. wild reindeer Rangifer tarandus in northern Europe (Helskog 2011) and pronghorn Antilocapra americana in North America (Hockett & Murphy 2009).

In modern times, adapted corral systems for large herbivores have mainly been used for management purposes, e.g. for marking and sorting of semi-domestic reindeer in northern Europe (Helskog 2011), for removal of feral horses Equus caballus from public land in North America and Australia (Boyles 2007, Dobbie et al. 1993), and for shearing of wild vicuñas Vicugna vicugna in South America (Bonacic et al. 2006). However, the use of corral systems for research and conservation purposes has been rare or poorly described (Holzer et al. 2010).

The live capture of Asiatic wild asses is a challenge. Most populations are subject to poaching and are thus very shy (Kaczensky et al. 2006). Recently, Walzer et al. (2006, 2007) refined free-range darting methods for wild asses in Mongolia. Their method involved ambushing and darting wild asses at water points or darting from a pursuing jeep. Although the method proved safe for the animals (no animals were injured or lost in > 50 capture events), it can only be done on reasonably flat terrain, only a single animal can be darted in every capture event and the recommended anaesthetic protocol requires the use of the potent opiate ethorphine (Walzer et al. 2006, 2007, Walzer 2007; Appendix I), which is highly toxic for humans and subject to special purchase and import regulations (Haymerle et al. 2010).

Interest in wild ass research and conservation is high in Asia, but experienced wildlife veterinarians are rare and access to recommended drugs for free-range darting is not readily available in several of the wild ass range countries (e.g. Iran, Kazakhstan and Mongolia). Furthermore, capture methods which allow for the simultaneous marking of entire groups could benefit studies on the social organisation of wild asses. In the following, we describe a corral mass capture device developed in Kazakhstan for live capture of Asiatic wild asses for translocation. By describing the experience from Kazakhstan, we aim to supplement the toolbox of methods available for the capture of free-ranging wild equids.

Material and methods

Results

During 2006-2011, four out of seven different capture attempts were successful and resulted in the capture of 105 wild asses (see Table 1). No fatalities or injuries occurred.

The first capture attempt was done during the daytime using 14 cars (spaced 70-80 m apart) and five horsemen (spaced 30-50 m apart and located in barely passable areas with gullies and scrub) placed in an arc as an extension of one of the funnel wings. A large herd of wild asses located 7-8 km from the trap was slowly pushed towards the corral. However, a subgroup became nervous and subsequently the entire herd panicked and escaped through the line of horsemen and cars.

The second capture attempt was done at night using five closely coordinated cars with spotlights. A small herd of 40-45 animals was found at a distance of 5-6 km and chased by one car in the middle and two cars on each side. When the wild asses reached the entrance of the symmetric funnel design they stalled, but five additional cars joined in to chase them the final 250 m into the corral.

For the third capture, a new asymmetric bow-shaped funnel design was used (see Fig. 2). A herd of 60 wild asses was discovered one kilometre from the enclosure, but only one car was used for the chase. However, the animals were located on the side opposite of the funnel and the single car was only able to turn eight asses towards the funnel entrance. In an attempt to help the single car, two people at the gate turned on a powerful flashlight and ran towards the wild asses, which made them turn and escape past the chase car.

In the fourth capture attempt, 12 cars were used but the capture failed due to the difficulties of coordinating so many cars.

For the fifth capture, three cars chased a herd of 70 wild asses from a distance of 9-10 km towards the trap. Thirty-five wild asses arrived at the wings of the trap, where two other cars joined the chase resulting in the capture of all remaining animals in the corral.

For the sixth capture, three cars chased a group of 45-50 wild asses from a distance of 15 km towards the trap. However, due to the long chase distance and the difficult terrain most animals escaped and only eight asses reached the corral.

For the seventh capture, three cars chased 27 wild asses out of a group of 40-45 wild asses from a distance of 20-25 km into the corral.

Discussion

The adapted corral capture method provided a relatively safe method for the live capture of groups of wild asses as neither animals nor people were injured. Round-ups at night with strong lights reduced the speed of fleeing asses by impeding their ability to see the terrain. The high speed chase only happened over the last ∼ 3 km and over terrain with which the team was already familiar. Free-range darting from a pursuing jeep, on the other hand, often necessitates speeds of > 70 km/hour to catch up with a group and 60-70 km/hour to align with the targeted wild ass for free-range darting. The longer the high-speed chase, the more suitable chase habitat (flat and without high bushes) is needed and the higher the risk of hitting unexpected obstacles becomes, often resulting in car breakdowns (P. Kaczensky, pers. obs.).

The location of the capture corral in Altyn Emel NP seems ideal because it is within the early winter range of the wild asses in the park, and because it is located at a natural landscape funnel created by the Kapchagai reservoir and the Dzungar Alatau mountain range. The disadvantage is that the team had to wait for wild asses to come to the location and had little flexibility to react to changes in wild ass distribution. Ambushing and darting wild asses at water points or feeding sites is also a waiting game but due to the limited man power and equipment needed, there is more flexibility to react to changing opportunities (Table 2).

A quantitative comparison of the effectiveness, risks and costs of the corral capture with the two other methods documented for Asiatic wild asses (Walzer et al. 2006, 2007, Walzer 2007) is not possible as factors are highly dependent on the local situation and the skills of the individual people involved. Consequently, the corral capture method should be seen as an additional method in the toolbox of potential capture approaches which all have their challenges (see Table 2).

The main advantage of the corral capture method over the ambush and free-range chase method is that it allows the simultaneous capture of a group of wild asses and does not require the animals to be anaesthetised (see Table 2). Whereas wild ass groups disturbed or chased during daytime tend to split up quickly, the night time chase seems to allow holding groups together for longer. But even at night time, there are limits and round-ups of large groups over longer distances resulted in adult asses escaping more frequently than young ones (e.g. during the sixth capture, we primarily captured foals). The predominance of young animals likely reduced the potential for interspecific aggression and thus the risk of injury, but also separated several foals from their mothers. If wild asses are captured with the goal of establishing a captive group, it may be an advantage to capture young animals as they are more likely to adapt to captive conditions and less likely to fight. However, for reintroduction or restocking initiatives, yearlings and foals without mares may face high mortalities as they are the least experienced section of the population and generally the most vulnerable to extreme conditions (Kaczensky et al. 2011).

In order to capture complete groups, the corral capture could be potentially further adapted by: 1) primarily rounding up small groups which should be easier to hold together, 2) only attempting round-ups when animals are within 3-5 km of the corral, or 3) coming up with a light-weight version of the present corral and fence system (e.g. use plastic pools and netting) that allows the trap to be quickly erected close to the targeted group. Light-weight adaptation will likely increase the costs, but in the long run would pay off as it would reduce the waiting time.

With the above-mentioned adaptations, the capture corral could allow for the capturing of seemingly stable groups of wild asses. This would for the first time allow the marking of all or most individuals of a social group and enable monitoring of group stability. The results could finally allow the development of a better understanding of wild ass social organisation, which remains largely unknown (Kaczensky et al. 2008, Moehlman et al. 2008, Sundaresan et al. 2007). However, radio-collaring animals should only be done using anaesthesia to reduce stress and risk of injury (Walzer 2007). Handling capture drugs in situations with corralled or boxed asses will be far safer than during high speed chases and would also allow for alternative anaesthetic protocols, not necessitating the use of etorphine (Walzer 2007).