Endangered
Monitoring Tigers in the Twenty-First Century India-Part IV
-Vinod Rishi
Here is the fourth 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: vinodrishi@rediffemail.com
The Question of Monitoring Tigers for Tiger Conservation
The shift from field methods to statistical models has, apparently, made no improvement in the monitoring of tiger populations and habitats. The process for search and documentation of even the basic information needed for the conservation of tiger and other
elements in its habitat has become tardy, time consuming, heavy on manpower, uneconomic, unverifiable, time warped and hence redundant and unsustainable. At the least, the field methods were providing results that could be challenged and subjected to verification;
but the current approach is beyond any cross-checking. The choice is: take it or leave it!
Both academic as well as field approaches have been tried out in India, and have been found to have their respective strengths and weaknesses in their application in the monitoring of the populations of tiger and associated wildlife. A quick appraisal of the
two may help in providing an approach for monitoring their populations by acquiring the strengths of the both for immediate use.
(A). Application of Statistical and System Analysis Models
One has to start with the understanding that Statistics is a tool and not an end in itself; and that the statistical models create virtual reality. Even though, in India, attempts were made to promote the statistical models and systems analysis approach in
the first half of the 1980’s (Saharia, Undated), it did not find ready acceptance in the field of wildlife management, even after the advancements and improved availability of computer software and techniques. The chance factor, or probability, gives a feeling
of unreliability to the users, who find field methods giving a better and more tangible picture of the objectives they are concerned with.
The reliability of the statistical models used in the systems analysis approach depends on what information is being fed to the model designer. A model is nothing more than “…an abstraction of the true experimental situation, representing all relevant features
of reality. When used in population estimation, the model will be constructed in such a way that the unknown quantities are expressed in the terms of known or observed quantities” (Overton, 1971). “The first step to successful Systems Analysis is the careful
identification of questions to which the model is to be addressed.” (Overton, 1977). But its acceptability depends on the confidence it can generate in the mind of the user – in this case the wildlife manager.
Systems, especially natural systems, are large and hierarchical, i.e., composed of complexes of systems within systems. The modeling approach depends upon simplifying the systems by assumptions so that models can be derived and solved. But systems analysis
and modeling approaches greatly depend upon the accurate assessment of complex system questions. There is intractability of very large systems for development of differential equations, the difficulty of defining modeling parameters, and obtaining data appropriate
to models. The behavior of a larger system can be understood only to a limited extent from the next lower hierarchical system; it is not a reliable way to predict the behavior of larger system by studying the next lower hierarchical system. “Moreover, the
system properties emerge not only from their components but also from their linkages. As the systems become larger and more complex, our ability to predict system behaviour becomes less certain.” (Reed, 1995).
It follows that the enormous diversity of the tiger occupied ecosystems in India poses a formidable challenge for application of a hypothetical hierarchical model developed in one or two landscapes to the entire range of diverse ecosystems. Models for Satpura-Maikal
landscape cannot be applied to the mangrove forests of Sunderbans or Terai grasslands, or tropical evergreen and semi-evergreen rain forests, or desert and scrub ecosystems. On the acceptance and applicability aspects, a system’s properties are meaningful
for the user only in terms of the hierarchical level in which he is interested.
The reliability of population estimation at field level is closely linked with the reliability of the process of construction of a model. Modeling is an art. The research work and refinement of Systems Analysis, and statistical sampling approaches is massive
in the U.S.A. The adaptation of models developed in other countries, and honed with experience in Indian ecosystems – as has been done in Nagarhole in south India – is encouraging. But it does not obviate the need to develop further experience by working in
other biogeographically and ecologically different landscapes. At present even the basic research in the Indian tiger habitats is patchy and inadequate for developing models one can confidently apply in India.
The current model adopted by the NTCA for evaluation and monitoring of the status of tiger populations needs significant improvement to provide accuracy, validity, and conceptual rigor of the outputs needed for effective management of tiger conservation in
India.
-To be Continued
For earlier parts of the article click on the links below
Monitoring Tigers in the Twenty-First Century India-Part I
Monitoring Tigers in the Twenty-First Century India-Part II
Monitoring Tigers in the Twenty-First Century India-Part III
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Endangered
Monitoring Tigers in the Twenty-First Century India-Part V
-Vinod Rishi
Here is the fifth 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: vinodrishi@rediffemail.com
(B). Application of Field Methods in Census and Research Work
The two field methods to which the field officers who had worked under Project Tiger were exposed used tiger pug marks: one used it as an index for ascertaining individual tiger’s territorial occupancy; and the other, tiger’s identity for estimating tiger populations
in a given area. Over the years the distinction between the two has been mislaid by the current generation of field officers and research scholars, who treat the two methods to be one and the same. A controversy generated by a review of the field censuses
in 1987 killed both methods. The review of the field censuses declared that the field methods using tiger pug marks as a basic index for estimation of tiger populations are unreliable, and give unrealistic and unreliable results (Karanth, 1987, 2003; Day,
Undated; Banks Undated).
(B.I.) The Controversy: Pug marks are not a reliable census index – field methods using pugmarks are defective (Karanth, 1987).
The review of the data from field censuses (Karanth, 1987)
(a). Growth Rates, Density and Biomass of Tiger Populations
Table– 2
Tiger population over the years
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Sites
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1972
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1979
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1984
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1989
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1993
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1995
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1997
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2001-02
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Tiger Reserves
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268
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711
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1,121
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1,327
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1,366
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1,333
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1,498
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1,576
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Outside Tiger Reserves
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1,559
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2,304
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2,884
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3,007
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2,384
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2,010
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2,066
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Total
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1,827
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3,015
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4.005
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4,334
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3,750
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3,508
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3,642
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Compilation based on the periodic reports of ProjectTiger Directorate, Govt. of India.
After analyzing the data from the tiger census figures for 1972 and 1984, and using the information from the research work of some wildlife research scholars in and outside India, the review concluded:
i. Between 1972 and 1984, the census figures show phenomenal growth in tiger numbers over the years in almost all parts of the country:
The Indian tiger population had more than doubled: from 1,827 in 1972 to 4,005 in 1984. There was an exponential increase in the growth of tiger populations in 11 (sic) original Project Tiger Reserves and 14 States of India. Even relatively poor tiger habitats
like Bandipur showed high growth rate of 14%, per annum for over 12 years in succession. The research studies by Schaller in Kanha National Park, Sunquist and Smith in Chitwan National Park and Chitwan Region in Nepal indicate that the growth rates of tiger
populations in excess of 6% were abnormal.
ii. The 1984 census data indicated excessive densities and biomass reached by tigers in Indian tiger reserves.
a. The density of tigers recorded in the research studies by Schaller, Sunquist and Smith in the tiger habitats in Kanha in India, and Chitwan in Nepal, showed that in well protected habitats tigers may reach densities that range between 17 km2 to 11 km2
per tiger; Overall, the densities in Indian tiger reserves ranged between 54.84 km2 per tiger in the Indravathi tiger reserve, and 5.97 km2 per tiger in the Corbett tiger reserve in 1984; The census figures showed that 6 out of 18 tiger reserves, namely, Corbett,
Bandhavgarh, Dudhwa, Sunderbans, Kanha, and Ranthambhore tiger reserves, had tiger densities that ranged between 10.89 and 5.79 km2 per tiger, which exceeded the stipulated range.
b. The tiger biomass in the above mentioned 6 tiger reserves – the Corbett, Bandhavgarh, Dudhwa, Sunderbans, Kanha, and Ranthambhore tiger reserves – exceeded 10 kg/ km2 whereas a really superior habitat can only support a tiger biomass of 7 to 10kg/km2.
Overall, the tiger biomass in the tiger reserves in India ranged between a low of 2.08 kg/ km2 in the Indravathi tiger reserve and a high of 19.58 kg/ km2 in the Corbett tiger reserve.
-To be Continued
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