An improved technique for indexing abundance of Himalayan thar
- Department of Entomology and Animal Ecology, P.O. Box 84, Lincoln University, Canterbury, New Zealand
Current monitoring of Himalayan thar (Hemitragus jemlahicus) populations in New Zealand involves a technique based on repeated observations by different, experienced observers. The method gives no measure of error and hence does nor allow for statistical comparison of repeated surveys. We outline a faster and cheaper technique that enables statistical comparison between surveys based on mark-recapture theory. Two counts can be made by the same observer on subsequent evenings, or can be conducted simultaneously by two observers of differing experience provided they do not cue each other to the location of animals. As an example of the use of the technique, we monitored a control operation aimed at reducing thar impact on alpine flora. We recorded a non-significant (P = 0.27) decline in thar abundance from 38 (± 27; 95% C.L.) to 28 (± 19) females (including kids) in the survey area.