Counting the tiger

Counting the tiger

News:

1. India’ fourth national tiger census undertaken to ascertain India’s current tiger population.

Important facts:

2. The forest officials involved in the census in Dornala, Prakasam district of Andhra Pradesh, in March, this year.

a. Designed by scientists, at the Wildlife Institute of India (WII) it involves four phases:

b. Using Global positioning systems (GPS), forest watchers, installed 170 pairs of camera trap.

3. Phase-II, involves WII’s scientists accessing remotely sensed landscape and habitat information for later use in the analysis.

4. The tiger census exercise used camera traps in huge numbers, which has turned the entire exercise into a complex process.

5. This year, around 15,000 pairs of camera traps are being placed across protected areas and reserve forests in 18 States.

6. This method, which also factors in the locations of the camera traps to estimate the population size, is known as ‘spatially explicit capture recapture’ (SECR).

7. In the early 1990s, in Karnataka’s Nagarhole National Park, tiger biologist Ullas Karanth used automated camera traps for the first time to individually identify tigers and estimate their numbers.

8. Scientists began using this method to estimate the numbers of tigers in Sumatra, jaguars in Bolivia, and leopards in Africa.

9. The first camera traps found their way into India’s tiger estimation exercise in 2006.

10. Index calibration:

• Once camera-trapping wraps up across the country, all the terms will compile their data and send it to the WII and the NTCA for scientific data analysis.
• Then in a process known as index calibration, the tiger numbers obtained from the more accurate camera-trapping exercises in different reserve forests will be integrated with coarser information from sign surveys.
• This will provide an estimate for the entire country.

11. There are slight changes in survey as compared to last time in the following manner:

• A majority of the States and reserves will use M-STrIPES, a mobile-based application, to collect data on the field. (The ATR, however, is not using it this time).
• To obtain more precise estimates of the tiger numbers, the area in which a single pair of camera traps is deployed (called a ‘grid’, usually measuring four sq km) has been decreased to two sq km.
• More cameras are being used this time, making the current survey more intensive.
• With using more cameras, it would possible to obtain information about smaller fauna through the same camera traps.
• For first time ever, India will be conducting the census along with the three other tiger-range countries — Nepal, Bhutan and Bangladesh. Representatives from these countries have completed their training in India.

12. The pugmark census

• The first method used to count India’s tigers, the pugmark census, was already in use during the launch of Project Tiger in 1974.
• Once every four years, forest guards and watchers would walk across tiger habitats over two weeks, identify tiger pugmarks, and take their plaster casts.
• Based on the shape and other measurements, these pugmarks would be assigned to individual tigers to arrive at an absolute count.

13. Critical aspect:

• The present method of analysis does not address the inherently huge variations in the relationship between the chances of capturing tigers on camera and seeing its signs on the field.

14. Tiger population:

• According to the WII and NTCA, India’s tiger population has been observed to increase at a rate of around 5.8% per year since 2006.
• The estimation in 2014 pegged tiger numbers at 2,226.
• The same year, the news that global tiger numbers grew from 3,200 in 2010 to 3,890 in 2014 caused much cheer.

15. Suggestions:

• Just as the pugmark census was replaced with a more robust camera trap system, there is an urgent need to update existing data analysis methods with new techniques to make the exercise more precise and reliable.
• Another study published last year at the ISI developed a new model using a refined statistical technique that helps to better integrate the data obtained from the two different methods — camera-trapping and sign surveys — to count tigers on a large scale. If implemented, this could reduce the inaccuracies in India’s tiger estimates.
• Other countries are already adopting some of these new approaches and moving away from index-based approaches.
• For instance, the central African nation of Gabon is adopting some of the new capture-recapture methods to count its forest elephant.
• Uganda is also encouraging new approaches for its lion census.
• Existing methods would also need to be implemented more strictly, feel others.
• The methods described in detail in the tiger estimation’s Phase IV protocol (which entails annual camera-trapping to ensure that important tiger populations, such as those in tiger reserves, are monitored continuously) are crucial to capture the huge natural variations in tiger population densities.
• If implemented properly, the intensive Phase IV surveys can give a lot more information.