Abstract

Wild Bactrian camels (Camelus bactrianus ferus), the sole extant form of the Old World Camelidae, have a range which is now limited to the Gobi ecosystem of southern Mongolia and north central China. Population estimates for wild Bactrian camels have variously been estimated at 500–900 individuals, with substantial evidence of further decline. In recent years, several investigators have suggested that this decline is due primarily to poor recruitment of young into the population. To identify the causes for this continued population decline, a consortium representing three U.S. zoological institutions (Denver Zoo, the Wilds, Zoo Montana) an NGO (Nature Conservation International, Germany) and two Mongolian governmental agencies (Mongolian Academy of Sciences and Ministry for Nature and the Environment) has developed a multi-faceted initiative to conserve wild Bactrian camels.

In March of 1997, a large-scale aerial census was conducted to determine as accurately as possible current population parameters. This survey covered all of Region A of Great Gobi Strictly Protected Area (39,865 km²) in southern Mongolia, which is believed the home to all wild Bactrian camels in Mongolia. North-south, parallel transects, approximately 15 km apart, were flown, covering a distance of more than 1,700 km. All sightings of wild Bactrian camels, as well as all other mega-vertebrates, were recorded by a team of 10 observers. Results of these observations were analyzed using the computer program DISTANCE. The team observed 277 camels in 27 groups (mean group size = 10.26±12.38 S.D.). Population estimates for wild Bactrian camels were 1,985±803 S.E., with a density of 5.0±2.0 camels/100 km².

In a second phase of the project, veterinarians and biologists traveled to the Great Gobi Strictly Protected Area in November of 1998 to develop field anesthesia protocols and to collect initial biologic samples for detailed analysis. Working with a small “semi-tame” population that has resulted from an earlier attempt to establish a captive-breeding program, several anesthetic combinations were evaluated. Over the course of 7 days, 15 anesthetic procedures were conducted on 14 individuals (2 domestic Bactrian camels and 12 wild Bactrian camels). Anesthetic regimens used consisted of variations of:

Etorphine + Ketamine + Xylazine (EKX) with antagonism by Naltrexone + Yohimbine Telazol (Tiletamine + Zolazepam) + Ketamine + Detomidine (TDK) with partial antagonism by Yohimbine
Ketamine + Xylazine (KX) with partial antagonism by Yohimbine

Drugs were delivered to the animals either by CO₂ powered Pneu-Darts or by hand injection (Original plans to simulate field capture procedures by darting with a Pneu-Dart Rifle were complicated by the confiscation of the rifle by Chinese authorities in Beijing on 10/30/1998). As a result of the approachability of these "hand raised" animals, darting distance was generally >15 m; however, manual restraint of non-sedated animals was not possible.

• Eight procedures (three males and five females) used etorphine (2.5–4.0 mg; total dose; x=3.2 mg) + ketamine (0.3–0.6 mg/kg; x=0.5 mg/kg) + xylazine (0.1–0.4 mg/kg; x=0.2 mg/kg)
• Five procedures (five females) used telazol (1.1–1.6 mg/kg; x=1.3 mg/kg) + ketamine (1.0–1.3 mg/kg; x = 1.1 mg/kg) + detomidine (0.03–0.04 mg/kg; x=0.04 mg/kg)
• Two procedures (one male and one female) used ketamine (1.0–2.4 mg/kg; x=1.7 mg/kg) + xylazine (0.4–0.5 mg/kg; x=0.45 mg/kg)

All animals were extensively monitored during anesthesia. In addition to basic monitoring of heart rate, respiratory rate and body temperature, attempts were made to monitor multiple physiologic processes during anesthesia through the use of portable, electronic monitoring devices provided by the Heska Corporation. Attempts to monitor SpO₂, heart rate (electronically), end-tidal CO₂, respiratory rate (electronically), ECG, serum chemistry and blood gasses met with variable success as a result of the unique physiology of the camels, and the harsh field conditions present in the Gobi Desert. There were no mortalities resulting from the anesthetic procedures and a preliminary assessment suggests that wild Bactrian camels do respond differently to various anesthetic agents than do domestic camels.

Significant differences were noted in the effectiveness of the anesthetic protocols (Table 1). Time to effects varied significantly. Time to first effect (TFE) and time to recumbency were shortest for EKX followed by TKD and KX respectively. However, despite complete antagonism of the anesthetic drugs in the EKX protocol, recovery was slower. Subjectively, this appears due to the fact that EKX produced a deeper plane of anesthesia than either TKD or KX.

Table 1. Effectiveness of the anesthetic protocols (x time).

Physiologically, the protocols produced differing effects. While there were fluctuations in the level of oxygen saturation of the peripheral blood, as measured by pulse-oximeter, with all of the protocols, TKD (x=86.1%) and KX (x=84.6%) resulted in better oxygenation than EKX (x=80.4%). This trend may however reflect the lighter plane of anesthesia resulting from these protocols. Cardiovascular parameters showed more remarkable differences. Mean heart rates were highest for EKX (52.8 bpm) with TKD (40.4 bpm) and KX (33.1 bpm) following respectively. Additionally, subjective evaluation of mucous membrane perfusion appeared better in EKX.

Evaluations of venous blood gases (chosen over arterial samples due to practicalities of collection from camels in the field and with heavy hair coats) and peripheral blood pH, suggest that animals anesthetized with the EKX protocol experienced substantial acidosis when compared to either a “standard” mammalian model or the camels anesthetized with the other protocols. Based on samples collected at the end of each anesthetic episode, the EKX group showed a mean peripheral blood pH of 7.15, compared to 7.34 for both the TKD and KX groups. Analysis of mean PCO₂ for the three groups showed a notable elevation only for the EKX group (EKX = 58 mm Hg; TKD = 39 mm Hg; KX = 47 mm Hg). These results can be best interpreted as resulting from a deeper plane of anesthesia in the EKX group resulting in both central nervous system depression and less effective ventilation. The reported acidosis is most likely respiratory in nature, which is further supported by a lack of disturbance in the anion gap for any of the groups (EKX = 15 mEq/L; TKD = 12 mEq/L; KX = 11 mEq/L).

In addition to samples collected for physiologic monitoring, a large number of biologic samples were collected for hematologic, parasitologic, genetic, and endocrine evaluations. Samples collected included:

1.  Blood for complete blood count, serum chemistry, exposure to infectious diseases, genetic studies, reproductive and stress hormones, hemoparasites and serum banking

2.  Feces for gastrointestinal parasites, fecal hormone metabolites, fecal DNA and diet evaluations

3.  Hair for genetic studies

4.  Ectoparasites and skin scrapings

5.  Body measurements for weight estimations, development of body condition scoring system and identification of transmitter placement for future telemetry and satellite tracking studies

6.  Biopsies and cultures of atypical lesions

Analyses of these samples are currently underway.

Based on the findings of these studies, several individuals from wild herds will be captured in 1999 and 2000 for the application of either radio-telemetry or satellite collars. These animals will serve both as focal individuals and sentinels for studies of the ecology and behavior of the wild population. Efforts are currently underway to identify several Mongolian biologists who will be trained in modern ecologic techniques to serve as the primary field researchers for this phase of the project.

Another component of the program is the development of non-invasive endocrine monitoring techniques to assess reproductive patterns in the population. Working initially with captive, domestic Bactrian camels in U.S. zoos, efforts are underway to develop techniques for the assessment of estrogen, progesterone, and testosterone metabolites in Bactrian camel fecal samples. Once adequately validated in the laboratory using the domestic animal model, wild Bactrian camels will be monitored to determine if any reproductive abnormalities exist.

The ultimate goals of this project are to determine the causal factors for population decline in wild Bactrian camels, and to develop strategies to prevent a continuation of this pattern. While this species clearly has great cultural, biologic and economic value, it may be most important as a “flagship species” for the Gobi ecosystem. In addition to the inherent benefits of conserving one of its most important wildlife taxa, Mongolian conservation efforts should benefit from the extensive training of numerous Mongolian biologists and veterinarians as well as the transfer of technology to in situ conservation initiatives.

Acknowledgments

Dr. T. Galbatar, Mongolian Academy of Science; James Wingard, GTZ - Mongolia; Gamchimeg Wingard, Denver Zoological Foundation; Mr. Avirmed, Great Gobi Strictly Protected Area; Mr. Myagmarsuren, Mongolian Ministry of Nature and the Environment; Mike Foley, Tiger Express; Dr. Tim Johnson, Heska Corp.; Dr. Mark Atkinson and Stacy Clausen, The Wilds.

Literature Cited

1.  Alsobayil, F.A. and K.R. Mama. 1999. Anesthetic Management of Dromedary Camels, Food Animal Medicine and Management, a Supplement to the Compendium of Continuing Education, 102–111.

2.  Kaneko, J.J. 1980. Clinical Biochemistry of Domestic Animals, Academic Press

3.  Reading, R.P., H. Mix, B. Lhavasuren, and E.S. Blumer. Status of Wild Bactrian Camels and Other Large Ungulates in Southwestern Mongolia, Oryx (in press).