The national animal of India, India is home to 80% of tigers in the world. As of the Tiger Census (2018), India has a population of 2967 tigers. The tiger population in India has been increasing each year since 2006 due to the reserves set up by the Project Tiger initiative of the National Tiger Conservation Authority.
Every four years, the National Tiger Conservation Authority conducts a census of the tiger population in India. The data from the last four censuses is shown below. The overall tiger population is steadily increasing in India. The total count of tigers went from 2226 (2014) to 2967 (2018) - an increase of ~33% over 4 years, and a net increase of ~110% over 12 years.
The census data also measures the population of tigers in each of the states in India. The data is shown below. Clearly, trends at the state level do not necessarily replicate overall national trends. Madhya Pradesh saw the biggest increase of ~71% (308 to 526), followed by Maharashtra (~64%) and Karnataka (~29%). However, in Chhattisgarh, tiger populations decreased significantly (~58%), while in some states like Mizoram and Nagaland, the count dropped to 0 (in the North-East region).
Region-wise population data is another useful way of looking at the tiger population trends in India. The data is shown below. Central India and the Eastern and Western Ghats show the greatest increase in the last 4 years (~50% and ~26% respectively). This aligns with our state-wise results, since Karnataka lies in the Western Ghats, while Maharashtra and Madhya Pradesh are in the Central India and Eastern Ghats region. Similar to our state-wise results, the North-East hills region and the Sundarbans region show very little increase in tiger populations.
What could be the reasons for such variations in trends in different parts of the country? We boiled the various reasons to three possible factors.
There are 53 reserves under the Project Tiger initiative in India. However, some of the reserves have proven to be effective in their purpose, while other reserves, not so much. We took a subset of factors we believed are important when it comes to the effectiveness of reserves and their function. Of course, these factors are not all that determine how effective a reserve is. The following factors were only analyzed on 5 reserves: Palamau, Bandipur, Ranthambore, Sariska and Jim Corbett due to a lack of data for the other reserves.
Clearly, from the available data, there seems to be a rough correlation (although not completely accurate without the presence of additional data) between the factors and the growth rate of tiger populations in the reserves, indicating that they do influence the effectiveness of reserves. Greater yearly funding translates to more resources to manage the reserves better, more area covered by the rangers implies more prevention against poachers and lesser the age of the ranger, the more physically fit they are to perform their duties. However, the correlation is not perfect, and there are other factors that influence the effectiveness of reserves.
To demonstrate the impact of climate change on tiger populations, we chose to analyze the Sundarbans region. The Sundarbans is a region located in the delta of the Ganges and Brahmaputra rivers in West Bengal, India. From the above data, we can see that the tiger population in the Sundarbans has not witnessed any significant growth in the past 12 years. This is because the Sundarbans is a low-lying area, and the rising sea levels have caused the water levels to rise in the Sundarbans, which has led to the destruction of the mangrove forests, the tiger's natural habitat. This has led to the decline in the tiger population in the Sundarbans.
The below data is for the years 2000-2007. Clearly, there is a correlation between the sea level rise and the tiger population in those years. However, the data for the years 2008-2019 is not available, and hence, we cannot make any conclusions about the current situation.
Human interference is also a major factor affecting the tiger population. Below are the tiger mortality statistics for the period between 2008 and 2021. The human impact on tiger populations evidently cannot be underestimated. Moreover, it is not just poaching that harms tigers, but other means of death such as electrocution and road accidents as well.