Walrus Gestation Period: How Long Is a Walrus Pregnant?

How long is a walrus pregnant?

A walrus carries her calf for an average of 460 days, or about 15 months. Counting from the breeding date, calving is normal anywhere from day 450 to day 480.

Key checkpoints across the 460-day walrus gestation, measured in days from breeding:

Estimate your walrus' calving date

Enter the breeding date for an estimated calving date at 460 days.

Walrus gestation stages, month by month

Signs a walrus is pregnant

• No visible change during the months of delayed implantation
• In managed care, hormone tests and ultrasound confirm pregnancy once the embryo has implanted
• A heavier, rounder body through the second winter
• Strong appetite and weight gain in the months before birth

Signs of approaching calving

• The female hauling out apart from the herd on the ice
• Increased protectiveness and restlessness shortly before calving
• Contact your vet if labour stalls, if the animal strains without progress, or if there is abnormal discharge before calving begins.

What affects walrus gestation length

• Walrus pregnancy lasts about 15 months in total, including a pause of several months before the embryo implants.
• This pause is called delayed implantation. After mating, the embryo floats free for a few months before attaching to the uterus, so active development takes roughly 11 months.
• Mating happens in late winter, and calves are typically born the spring after next, on the sea ice, around the time of the ice break-up.
• A newborn walrus calf weighs roughly 45 to 75 kg and can swim within hours.
• Calves nurse for around two years, so a female normally gives birth only once every three years or so, one of the slowest rates among seals and sea lions.
• Walrus mothers are known for being strongly protective, often holding the calf to their chest or carrying it on their back in the water.

Walrus gestation chart

Every fifth breeding date across the year with the matching calving date, calculated at 460 days. Find the row closest to the date the walrus was served; because normal gestation spans 450 to 480 days, plan for a window of a few days either side. Filter by month, or print the chart for the barn wall or breeding record: navigation, buttons and adverts are hidden on paper.

Sources for walrus gestation figures

Figures on this page are drawn from U.S. Fish and Wildlife Service Pacific walrus information, aquarium reproduction records and Arctic marine mammal field research, and checked against the references below. Averages describe healthy animals under normal management; individual animals vary, and nothing here replaces advice from your vet.

• U.S. Fish and Wildlife Service — Pacific walrus information
• Association of Zoos and Aquariums (AZA) — species husbandry and animal care manuals
• Smithsonian's National Zoo & Conservation Biology Institute — species fact sheets
• Published zoological studies of captive births