Lagomorphs, the pikas, rabbits and hares of the world, are small-to-medium-sized herbivores. They are closely related to rodents and are distinguished by possessing small peg-like teeth, located immediately behind their large front incisors.

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The order Lagomorpha consists of two families, Ochotonidae (pikas) and Leporidae (rabbits and hares). There are roughly 30 species of pikas in the genus Ochotona. Pikas have hind legs not much longer than their forelegs, are small (75-300 grams), sport rounded ears as wide as they are long, and have no visible tail. Rabbits and hares, on the other hand, have hind legs longer than their forelegs, are larger, and have long conspicuous ears. The 32 species of hares (jackrabbits) are the largest lagomorphs, have the longest hind legs and ears, and are all classified within a single genus, Lepus. Rabbits are the most diverse lagomorphs – approximately 30 species of rabbits are classified into 11 genera, seven of which contain a single species. The largest group of rabbits are the Western Hemisphere cottontails, found in the genus Sylvilagus.

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While there is a preconception that all lagomorphs “breed like rabbits,” the reality is that many lagomorphs are among the rarest and most endangered of all mammals (see Red List). Lagomorphs frequently play important roles in ecosystems: they serve as prey for many avian and mammalian carnivores, are often keystone species or ecosystem engineers that promote biodiversity in select ecosystems, and serve as game animals for hunters or sources of sustainable harvest for local people. Because many lagomorph populations are susceptible to disease epidemics, they are useful research models for the study of disease in natural and artificial ecosystems. Last, as many Lagomorphs appear to be impacted by global warming, declines in their populations may be early harbingers of the effect of climate change.