Black-tailed prairie marmots are small rodents native to North America. They are tan, usually with slightly lighter bellies. Their tails have black tips, which gives them their name. Males are usually heavier than females, and can weigh up to 1.4kg. These animals are extremely social, and have the most complicated social system of all prairie marmots. Social groups are called “coteries” that live together in “towns” which can number thousands of individuals. The largest town ever recorded stretched for 65,000 sq km and housed 400 million prairie marmots! They are active all year long, though they spend more time underground in winter.