1. On March 23 last year, Huan Huan delivered her first set of quadruplet ligers.

2. In contrast to ligers, tigons are often relatively small in comparison with their parents because of reciprocal gene effects.

3. Ligers may grow to exceed 10 feet [3 m] in length and can weigh over 1,000 pounds [500 kg].

4. Male ligers also have the same levels of testosterone on average as an adult male lion, yet are azoospermic in accordance with Haldane's rule.