Abstract
The range of the wild Bactrian camel (Camelus ferus) has been reduced to only three locations worldwide: two in China (Lop Nuur and Taklamakan desert) and one in Mongolia (Great Gobi Strictly Protected Area [SPA] “A”). The population is listed by IUCN as critically endangered. To better understand the movement patterns and habitat needs of wild camels in southern Mongolia several expeditions were undertaken to the Great Gobi SPA “A” between 2005 and 2007. Using a chase method, where camels are darted from a moving jeep, 8 camels were chemically captured using a combination of etorphine-butorphanol-detomidine and tiletamine-zolazepam. In 7 of the camels darted, anesthesia and subsequent recovery was smooth and without complication and these animals were outfitted with satellite radio-collars. However, one camel died during anesthesia of undetermined cause. Extremely low ambient temperatures in the winter season and dry, hot and windy summer conditions greatly hampered fieldwork.
Introduction
Conservation efforts often require capture and handling of animals. Wildlife capture and anesthesia is a complex operation that can cause significant injury or death. Although skill, experience and appropriate veterinary training can minimize the risk, it is necessary to evaluate whether the procedure is necessary and that the potential gains in knowledge for conservation of the species outweigh the risks.7,12
The Great Gobi Strictly Protected Area (SPA) “A” located in the southwestern part of Mongolia bordering the People’s Republic of China is one of the world’s great desert ecosystems. The extremely harsh environment has given rise to unique, particularly well-adapted species, many of which are found nowhere else in the world.24 The large mammal fauna consists of several rare or globally threatened species, namely the wild Bactrian camel (Camelus ferus), the Gobi bear (Ursus arctos gobiensis), the snow leopard (Uncia uncia), the argali wild sheep (Ovis ammon) and the Asiatic wild ass (Equus hemionus).9,14,24 Human pressures for pastures and water on the edges of the Great Gobi SPA and in its buffer zones have substantially increased since the early 1990s and are believed to have led to significant habitat degradation in some areas.18 Thus, in June 2003, a UNDP/GEF founded project "Conservation of the Great Gobi Ecosystem and its Endangered Species" was initiated. The project aims to ensure the long-term conservation of the Great Gobi ecosystem and its umbrella species by building the capacity of the park management authority, improving participation of local communities in the management of the protected area (SPA) and supporting research and environmental monitoring activities through the development of a model conservation program using the wild Bactrian camel as an "umbrella species."18
The range of the wild Bactrian camel has been reduced to only three locations worldwide: two in China (Lop Nuur and Taklamakan desert) and one in Mongolia (Great Gobi A SPA). The population is listed by IUCN as critically endangered and there remain an estimated ∼600 animals in China and between 350 to 1,950 in the Great Gobi A SPA.3,4,11,14,23 The large range in the population estimate is due to the large size, remoteness and harsh climate of the Great Gobi A SPA. Past population estimates often lack a detailed description of the survey methods and more recent surveys use different methods or lack documentation of search effort.2,11,13,14,17 Thus, there is still significant debate concerning population numbers and trends.11 The general belief is that the population is stagnating or declining due to (1) low recruitment of calves caused by wolf predation, (2) habitat deterioration, and (3) illegal hunting.10,17 There are also great knowledge gaps concerning the ecology of the wild camels and data on population dynamics,8,9 behaviour,9 habitat use,16 movement patterns,13 and veterinary aspects1. Even the genetic status and the purity of the three wild Bactrian camel populations has not yet been fully resolved and preliminary results need to be treated with caution.5
Material, Methods and Results
In order to capture camels for radio collaring we employed a chase method where the camel is darted from a moving jeep. This method has been successfully used to dart grey wolf (Canis lupus), Asiatic wild ass (Equus hemionus), Przewalski’s horse (Equus f. prezwalskii),20-22 and a single wild camel and it is traditionally employed by poachers with 12-ga shotguns.1 For remote dart application we used a modified high pressure CO2 dart gun (Daninject JM,™ Dan-Inject ApS, 7080 Børkop, Denmark) with a short 4-cm barrel, as this greatly facilitates movement in the jeep.
During the winter 2005 expedition,19 we used a combination of 4.4 mg etorphine (M99, C-Vet Veterinary Products, Leyland, UK), 10 mg butorphanol (Torbugesic, Fort Dodge Animal Health, IA, USA), 13 mg detomidine (Domosedan, Orion Corp., FI-02200 Espoo, Finland) and 160 mg tiletamine-zolazepam (Tilest 500, Virbac, Carros, France) to anesthetize one male and two female camels. Because the ambient temperatures varied between -15 and -30°C during the day, all drug combinations were supplemented with propylene glycol (Sigma-Aldrich GmbH, 1120, Vienna, Austria) as an anti-freeze. Once an animal was identified, it was chased (35–40 km/h) until the jeep was able to approach within approximately 10–15 meters on a parallel track. It was then easily darted in the rump using standard pressure settings. It is essential to define a chase cut-off time before the procedure is started. Our experience has shown that a chase time of 15 min is easily tolerated without a significant increase in body temperature. To ensure accuracy and reliability, only new, 3-ml darts (Dan-Inject ApS, 7080 Børkop, Denmark) were used during the captures. Once an animal was darted, we attempted to maintain visual contact, but did not disturb the animal before it was fully immobilized. Once the animal was recumbent, we approached on foot from behind and secured the head. Anesthesia was reversed in all cases with 200 mg naltrexone, IV (Trexonil, ZooPharm, Inc., Fort Collins, CO, USA) and 25 mg atipamezole, IV (Antisedan, Orion Corp., FI-02200 Espoo, Finland).
During the summer 2007 expedition, six camels were captured using the method described above.6 In five of six camels darted, anesthesia and subsequent recovery were uneventful. However, the first animal, an old bull (>15 yr) died during the capture event. This bull was easily darted as he ran much slower than the other animals in his group. It took 40 min after darting to locate the bull. The animal was in acute respiratory distress when approached. Naltrexone 250 mg, IV, was immediately administered and the animal’s respiratory rate and effort improved. However cardiac arrest occurred after 10 min and the animal could not be resuscitated. The cause of death remains unknown. Due to the lack of water and approaching sunset we could not perform a complete necropsy. The animal appeared extremely bloated and was noted to have regurgitated. We cannot exclude that it aspirated gastro-intestinal contents leading to its death. Furthermore, we speculate that this animal possibly had a pre-existing medical condition that was also responsible for the very slow pacing.
Discussion
Based on previously published reports1 and subsequent to our experience, we recommend a combination of 4.4 mg etorphine, IM, 10 mg butorphanol, IM and 13 mg detomidine-HCl, IM for the immobilization of adult wild camels. Butorphanol is a mu-opioid receptor antagonist and through its action potentially alleviates the marked respiratory depression induced by the etorphine at the mu-receptor and potentiates the sedative effect at the kappa and sigma receptors. By the addition of 160 mg, IM of tiletamine-zolazepam induction to sternal recumbency is more rapid.
Etorphine was reversed with 200 mg naltrexone, IV and 25 mg atipamezole, IV. Naltrexone has a longer half-life than the standard antagonist-agonist diprenorphine (Revivon, C-Vet Veterinary Products, Leyland, UK), thus eliminating renarcotization, which could leave recovering camels vulnerable to predation or injury.
Losing an animal during field anesthesia is a painful experience. With the male camel in our study, we felt that the long recovery time (and a possible pre-existing medical condition) contributed to the animal’s death. Immobilizing an animal that exhibits abnormal behavior should be avoided. Decreasing the etorphine by 1 mg and omitting the Telazol, results in standing-sternal sedation which makes it easier to locate the animal in the steppe. However, this reduced dosage leads to a prolonged pacing phase in which the animal can cover a greater distance and potentially injure itself.
It is the view of these authors that the risk and cost involved in immobilizing these animals is outweighed by the need to base the wild camel management plan on sound scientific data. Some management issues are urgent and require immediate action. It is our hope that the rest of the plan will remain fluid and integrate the scientific field based knowledge as it becomes available.
Acknowledgments
We are especially grateful for the highly motivated and competent field crew—it was their local knowledge, good organization and humour that made these trips a success. I. Khatanbaatar, Y. Nyambayar and B. Tseveenpurev for their never ending support at camp and looking out for khulans and camels. Thanks for the all careful drivers Davaa-Ochir Avirmed, G. Enkhbold and R. Tumen-Ulzii. Without A. Gerelmaa and her wonderful cooking, we would all have starved. We would like to thank UNDP staff, namely Ms. Vatucawaqa and Ms. Batkhishig for project facilitation, Mrs Narentuya and Mr Enkhbat for organization and support, and the Great Gobi A SPA staff in Bayantooroi for their hospitality and motivation.
This contribution is dedicated to the memory of Gobi A ranger Mr. Choijim—a true Gobi man.
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