Our planet is now in its sixth mass extinction of plants and animals — the sixth wave of extinctions in the past half-billion years. We're currently experiencing the worst period of species die-offs since the loss of the dinosaurs 65 million years ago. Scientists estimate we are now losing species at 1,000 to 10,000 times the usual rate, with 

literally dozens of species going extinct every day

. It could be a scary future indeed, with as many as 30 to 50 percent of all species possibly heading toward extinction by mid-century. 

We have lost 97% of wild tigers in the last 20 years.

 The tiger is an example of what we call a keystone species because like the otters in the kelp forest, tigers play a crucial role in maintaining the ecosystem they live in. 70% of the remaining tigers in the world are found in India, where tigers live with humans within national tiger reserves. Project Tiger in India is working on the problem of the tiger extinction and we will use some of their data to try to solve the problem ourselves. 

Before 2006, tigers were allowed to die out even within some of the reserves in India. In 2008, 8 tigers were reintroduced to the Sariska Tiger Reserve and 9 were reintroduced in the Panna Tiger Reserve. Tigers in the Sariska Reserve did not have offspring for 4 years after the reintroduction. In Panna tigers successfully reproduced within the first year. 

Tigers generally have trouble reproducing when they are under stress. The Sariska Tiger Reserve (STR) has over 23 villages where people live among the tigers in the reserve. The scientists working with Project Tiger have come up with the hypothesis that the tigers are under stress because of their encounters with humans. As a group, analyze the data below to see whether it fits this hypothesis. Based on your conclusion, come up with a possible solution to the problem.

By tracking the tigers with collars the researchers also collected data on how many times each of these tigers came close to humans. In the study they counted each of these times as a 

To see how stressed tigers were, scientists looked at the amount of 

 in the tigers’ poop. These stress hormones are known as glucocorticoids and they were measured in nanograms (ng). The stress hormone data was averaged for all of the samples collected from that tiger in the year. The data was collected during the month of March in 2016.

1 Plot the data as a scatter plot using equal intervals. Include a title, axis labels, and units. Draw a line of best-fit.

2 Does the data fit the hypothesis that tigers encountering more human activity are more stressed? Explain using specific evidence. 

3 Based on the methods used for collecting data, what might be some limitations of this study? Is there anything you might have done differently? Explain. 

4 Based on the data you graphed and information we know about the tigers, what might be a possible solution to the problem of tigers being too stressed to reproduce in Sariska? Explain using specific evidence. 

Tigers are going extinct. Part of why tiger reintroduction is so difficult is because people often live within the tigers’ territories. In the Sundarbans, people are part of a tiger’s prey, but even in other parts of India, tigers attack cattle and sheep that may be a part of a family’s livelihood. Often, people that live in villages near tiger territories are poor and not well educated. They often lack the resources to move somewhere else outside of the tigers’ territory. 

5 How might we be able to save the tiger in a way that is fair to villagers and ranchers? Come up with a possible solution in your group and prepare to discuss it with the class. 

How might we be able to save the tiger in a way that is fair to villagers and ranchers? Come up with a possible solution in your group and prepare to discuss it with the class. 