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Disappearing act: study investigates reasons for recent tiger extinctions

1/19/2018

Prachi Thatte
PhD student, National Centre for Biological Sciences, Bangalore, India

Sal, mahua, teak, tendu and several others, deciduous trees of varying heights characterize the tropical dry forests of central India. Light filters in through the uneven canopy and enables the growth of shrubs, lush grass and climbers in these forests. Such tropical dry forests constitute the largest habitat for the tiger, making up nearly 50% of its current habitat. At the same time, the tropical dry forest ecosystem also supports high human population densities.

Tropical dry forest, Panna Tiger Reserve. Photo by Rohan Jahagirdar

With fertile soil and agreeable climate, this ecosystem provides favorable conditions for
agriculture and human settlement. Clearing of land for agriculture has resulted in extensive
deforestation of this ecosystem over years. Human activities are considered the largest threat to this ecosystem. Panna and Sariska, where tigers recently went extinct and were re-introduced, are both tropical dry forests. Poaching was established as the main reason behind the extinctions.

Tiger in a tropical dry forest. Photo by Kaushal Patel

For better management of tiger populations in the future, it was important to identify other factors that may have contributed to the extinction. In a recent study, researchers have found that the type of forest and the size of the protected area can also contribute to the vulnerability of predator extinction.

Dr. Raghunandan Singh Chundawat and co-authors examined whether tigers in some habitats are more vulnerable to extinction than others in a study published in the journal Biological Conservation in 2016. They also investigated if the size of a protected area contributed to its vulnerability of extinction.

It's figs all year round for Bilaspur bears

1/6/2018

Prachi Thatte
PhD student, National Centre for Biological Sciences, Bangalore, India

Bilaspur is an agriculture dominated district in the north western part of the state of Chhattisgarh. It is known for the aromatic Dubraj variety of rice. Nearly 65% of the land area of Bilaspur is under agriculture. What remains is covered by villages and towns, industries and fragments of forests. The forest fragments are mainly found on hillocks and around boulders. Inspite of the patchy distribution of forests, sloth bears thrive in this landscape.

Harendra Singh Bargali and co-authors carried out a study to understand more about these sloth bears living in the agriculture dominated landscape. They wanted to investigate what sloth bears ate in this fragmented landscape.

Following sloth bears to observe what they eat can be challenging and not always feasible as they are active at night. How else could they study what sloth bears ate?

Sloth bear (Melursus ursinus). Photo by David V Raju, via Wikimedia Commons

Examining fecal samples (scat) is a common technique used in research to understand feeding habits of wild animals. Remains of food found in the scat are identified using reference collections of potential food samples. For example, the feces of animals that eat fruits often contain seeds of the fruits. A reference collection of seeds is used in that case to identify what fruits the animal has eaten. For carnivores, the hair and bones in the diet are used to identify the prey species.

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