When herded or chased they tend to run in a tight group, whereas, caribou are often scattered. These traits are the result of domestication. In Eurasia reindeer are classified as either domesticated or wild. Only in North America are wild reindeer called caribou. Some female calves on the Seward Peninsula conceive at five months of age and calve as yearlings.
Bulls usually don t breed until they re three years old.
Their life expectancy is about eight years, usually ending as a result of their final breeding attempt. Breeding takes place in August and September with calving peaking around April 24th. However, reindeer and caribou can interbreed. Most likely, breeding would be between a male caribou and female reindeer, because caribou are usually dominant. Substantial growth of calf and female antler can be obtained with good nutrition.