Tigers: Taking a census.

How accurate is a census count?:

The enumeration system attempts to count all subjects of the population found in a given area. Accuracy of a census depends upon many factors, but with the tiger being such a secretive and night-active animal none can ever be considered more than a rough estimate. The important thing is that they should, as much as is possible, be based on facts and not guesswork. Some of the factors which lead to incorrect results are:

Pug mark imprints alter depending upon ground conditions, slope, speed, and if the tiger is carrying a weight such as large prey. This results in distortion and duplication as one tiger can appear to be several. On leafy or stony ground marks don't register at all meaning tigers can be missed. In the 1995 census not one pug mark was located on the Kendua or Kende islands of the Sundarbans. In 1997 only nine pug marks were sighted, yet the natives state many more tigers live in this area. Much of the Sundarbans is difficult to count due to the tidal flows which eliminate or change the appearance of pug marks.
Survey teams usually include one or two volunteers inexperienced in the counting process, along with one member of staff. In total, 10,000 people are involved and the census cover an area of 2.5 million square kilometres. This raises the chance of errors being made.
The tiger travels a lot and it has been known for one cat to cross the area of three counting groups, so being registered multiple times and making three tigers out of one.

Results may be deliberately falsified if staff feel their jobs are more secure when there are plenty of tigers to protect. This happened in the early golden years of Project Tiger. It wasn't until after Indira Ghandi's death that suspicion was raised as to the accuracy of the claimed increase in tiger numbers. On top of this, those people involved with tiger shikar (hunting) always had a vested interest in inflating tiger numbers.

People sometimes query if confusion arises between the prints of leopards and tiger cubs. This does not usually occur; the impressions of a 6-month-old tiger cub are already much larger than those of an adult leopard.

In support of the system, counting tigers using pug marks is an age old technique. Expert trackers could identify sex, age, size and weight just from a few pug marks. The more talented individuals received valuable court honours and gifts like tracts of land. The ability to track tigers was a family secret and passed down through the generations from father to son. As with many traditions, tiger tracking was a technique which very much died out over the years.

If it is proven pug marks are too wildly inaccurate to be useful then doubts will be cast over every tiger count conducted the world over. But until an alternative low-cost reliable option is thought of it will continue to be the method of choice. Summed up, all census counts are, by and large, estimates. In this, the tiger census is no different.

Taking A Census: - Page 1: Census Frequency & Methods | 2: Accuracy | 3: What Does A Census Show?

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