Monitoring Tigers in the Twenty-First Century India-Part VI
Here is the sixth part of an article published by Shri Vinod Rishi in
The Indian Forester. Vol.136:10. Wild Life Special.
Shri Vinod Rishi is IFS – retd. and a Former Additional Director General of Forests (Wildlife), Govt. of India; E-mail: email@example.com
(Continued fro last month)
The experimental evaluation of field methods (Karanth, 1987).
Because the field methodology for tiger censuses depended on the identification of individual tigers from their foot-prints, an experiment was also conducted for its validation in a zoo. In it, 33 pugmarks tracings were obtained on two different substrates
from four captive tigers, and presented for census to 6 wildlife managers, who were claimed to have been actively involved in such work and gained experience ranging between 4 to 12 tiger census years.
The participants made 72% statistically significant correct choices in distinguishing the pugmark impressions of left and right, front and hind feet, and of male and female tigers. But the participant with 12 years of tiger census experience declined to identify
the tigers. The rest of the five participants, having 4 to 6 census years of experience, could not identify a single tiger from the pugmarks, and the number of tigers counted by them from the tracings ranged between 6 and 24.
Based on the above discussions, the Review concluded that the field methodology was unreliable. (Karanth, 1987).
Revisiting the Controversy
(1) Evaluation of the Basic Premises for Field Censuses
Certain premises had been made before discussing the research based arguments in the review of the field censuses. There were misconceptions apparent in the premises because the literature did not support them. Some of the basic premises were:
(a) S.R. Choudhury had argued that every tiger could be individually identified from its pugmarks.
Choudhury neither denied, nor argued in favor of pugmarks; he is on record having cautioned the users that “Much rigorous and prolonged practice in the field is necessary to be able to distinguishing from similar looking pugmarks, different tigers in the same
or contiguous localities…A pugmark on sand or deep fluffy soil often looks very different from its true shape and size…if true tracings of pugmarks were taken from comparable soil conditions then it is one of the very confident parameters to be collected.”
(b) The investigator asserted there was no validation carried out of the field method.
The literature shows that the Co-operation Census Technique was validated by S.R. CHOUDHURY by carrying out control and field trials in Delhi Zoological Park on Nov 21 & 22 1970; in Khara and Chilla forests from Dec 2 to 17, 1970; in Nandankanan Biological
Park on Dec 28, 1970; and again in Khara and Chilla forests from Jan 27 to Feb 11, 1971 (Choudhury, 1970b, 1971).
(c) The investigator treated two different methods as one and the same:
-To be Continued