Moose - Reproduction

Biology

Unlike species such as white-tail deer, moose do not reach maturity as calves. The age at which a cow will reach maturity is dependent on her body size which is influenced by climate, hereditary traits, and nutrition availability. When a cow does become sexually mature, usually between 16-28 months of age, her breeding season will begin in late September and continue through mid-October. May is the typical calving season.
 
Bulls usually become sexually mature the fall after their first birth but are unable to compete for mates due to their small body size in comparison to older bulls. The reproductive cycle for bulls begins in spring with the growth of antlers. Increased levels of testosterone cause the velvet to fall from the antlers.
 

Behavior

Moose are often split into two different categories: tundra moose and taiga moose. These two groupings implement different mating systems. Tundra moose follow a female-defense polygyny in which a group is formed from a dominant bull, many cows, and subordinate bulls. This type of system is characterized by large rutting groups in an open habitat. Rut occurs in late September to mid-October. During rut, bulls will scrape and urinate into depressions forming pit holes which attract females to the mating area. Bulls will also spar with their antlers. This action not only aids in forming a dominant hierarchy among males but the sound will attract females.
 
Taiga moose appear to be monogamous in which one bull will mate with one cow for a breeding season. This relationship is dominated by the cow and requires a nearly even sex ratio. Taiga moose will also form pit holes. These pit holes tend to be smaller because the bull does not have an established mating area.
 

General Behavior

 
Photo Credit:US Fish and Wildlife Service
 

Aggression

Invading the personal space of a moose can be a dangerous decision for both humans and animals alike. Moose will stand their ground more often and for longer than any other large ungulate. They have been known to take on trains, as well as cars and aircraft. However, the most frequent cause of moose-human attack is due to cows defending their calf’s space. There is also some evidence to suggest that bull and cow moose attacks may be the misidentification of humans as upright grizzly bears.
 

Communication

Moose can emit a variety of sounds that researchers have defined and linked to specific emotions or occasions. A ‘whining’ sound is used to attract other moose and may even be used as a friendly greeting. The distress call of a moose is a loud, nasal call that is used when approached by various threats such as predators or other moose whereas gnashing signifies a minor threat or an expression of pain. The maximum vocal threat is coined as a ‘roar’ and is used by animals that are either being trailed by other moose or humans. Moose will also use non-vocal sounds that serve mainly as an attractant. Antler clashing and scraping of the ground both attract the opposite sex to an area of an interest. Moose will also use gestures to communicate to predators as well as other conspecifics. When defensive, a moose will raise guard hairs on the neck and down the spine.