The Point Arena mountain beaver's reproduction rate is 2-3 young a year. The gestation period is estimated at 28 to 30 days. All females ovulate at the same time during a period of five to seven weeks in mid or late winter. Breeding season is quite limited. The young are born naked, blind, and helpless.
Lactation probably occurs for the first two months after parturation.
The mountain beaver is very vigorous in defending its nests and burrows. The reasons for the mountain beaver's disappearance is habitat alteration or loss, development, cattle and sheep grazing, and farming. Private and county road construction have also disturbed the Point Arena mountain beaver's habitat and caused higher mortality rates through vehicular accidents. The construction of the tower would destroy the habitat and homes used by ten of the twenty animals at this site. The species also has a reputation as a burrower and forager in gardens, crop lands, and forests.