Every big cat leaves its unmistakable mark
A DEBATE on how best to count the tiger population sparked talk of hidden cameras and 3-D photographs at a symposium earlier this year. But most delegates agreed in the end that none of the methods suggested is any more reliable and economical than the pugmark census.
The delegates were told that detailed studies made in the Simlipal Tiger Reserve in Orissa by my colleague S R Sagar and myself indicated that measuring pugmarks and noting their frequency disclosed low representation of pugmarks of tigers in some size-groups, indicating that animals from those particular pug-groups were staying outside established and known tiger territories or were fewer in number.
Identifying categories The first of these categories was of young tigers and leopards separated from the mother and in a transient phase because they had yet to establish their own territories. The second category consists of older animals who have been pushed out by younger and more energetic individuals. The number in this category would be low in any case, because of the higher mortality rate among ageing tigers.
While the pugmark census technique can be improved by including leopard cubs and identifying more than one or two cubs in a litter, the Simlipal studies, covering four consecutive seasons, still showed 68 per cent of the total adult tiger population was female, 36 per cent of the females had all the cubs and 72 per cent of the cubs were born to females having pugmarks in the 12-13.9 cm category. This has prompted the premise that prime breeding females have pugmarks in this particular range.
However, the premise also needs to be linked with a corresponding age-class. In normal circumstances, a tiger cub separates from its mother at age 3, which means that cubs with their mothers may be at any age between newly born to 3 years. The mothers, therefore, can be grouped in three categories, depending on the age of the cubs they are rearing. Of the 36 per cent females that are mothers, there were approximately 12 per cent in each year-class.
While we value the importance of the new radio-tracking technique, if costs, time involved and the volume of data generated were taken into account, the old method of tracking pugmarks is head-and-shoulders above radio-tracking. Human error can be eliminated with practice and exactness in designing pug-impressions can be achieved if the same person traces pugmarks in a particular study area. What computer technology can do is help "tracking scientists" analyse the data they amass so they can draw conclusions.
---L A K Singh is deputy vice chairperson of Project Tiger at Simlipal Tiger Reserve in Orissa.