Bengal Tigers In India Suffer From High Stress Levels 

A New study of tigers in three Indian tiger reserves has found that they are about 20 per cent more stressed than the 200 Amur tigers roaming the Russian Far East. The team of researchers made up of both Indians and Russians measured the stress levels of the tigers by studying the metabolites present in tiger faeces.  The lead researcher says that tigers undergoing prolonged periods of increased stress will see their fitness and immunity affected.

Stress negatively impacts reproduction

Dr. Govindhaswamy Umapathy from the Laboratory for the Conservation of Endangered Species (LaCONES) at the Centre for Cellular and Molecular Biology (CSIR-CCMB), says that crucially elevated stress levels have negative implications for reproductive hormones in tigers which can result in reduced fertility and reproductive failure. It has been shown previously that elephants held in captivity display compromised reproductive cycles as a result of stress.

Stress markers

The tigers in India’s Kanha reserve had the highest levels of metabolites or stress markers whilst tigers from the Bandhavgrah reserve had the lowest level when compared to Russian Amur tigers. According to the researchers whilst there is a variation of metabolites in the tigers from all three Indian reserves there does not appear to be any significant difference in stress levels. The authors of the paper opine that perhaps the elevated stress levels in Bengal tigers may be the product of anthropogenic disturbance.

High population densities

Whilst Indian tiger reserves are typically smaller than those of Russia, anthropogenic disturbances are very high in India. The three Indian reserves also have higher population density compared with Amur tigers in Russia. Indian reserves have an average of 11.33 tigers per 100 square kilometres in comparison with 0.15 tigers in Russia.

Anthropogenic disturbances

A 2015 study by the same team found that tigers that had been re-introduced into an Indian tiger reserve experienced high stress levels because of anthropogenic disturbances. Not only was there high vehicular traffic but the tigers also had encounters with herders and villagers who visit the forest in order to graze their livestock or collect wood. This means the reproductive ability of the re-introduced tigers was reduced.

Successful reproduction

Unlike the other two reserves the Panna tiger reserve in India has far less anthropogenic disturbances. As a result of the five female tigers that were re-introduced to the Panna reserve, three produced multiple litters successfully over a period of four years. In contrast female tigers in the Sariska tiger reserve were only able to successfully breed once after four years.