Currently, females within the Southern Resident killer whale population raise approximately one healthy calf every 10 years. Most females reach sexual maturity in their early teenage years, while males don’t begin breeding until age 25. One of the most fascinating aspects of killer whale biology is that females undergo menopause at roughly 40 years of age. This has only been documented for humans and several other species of cetaceans. Given these life-history traits, a 60-year-old Southern Resident killer whale female may produce five offspring during her lifetime.

Comparatively, Bigg’s Killer Whales have been in the midst of a notable baby boom in which healthy females are producing one calf every three to five years. This demonstrates the stark difference in reproductive output and overall health between these two geographically similar populations.

Sadly nearly 70% of Southern Resident killer whale pregnancies are miscarried (lost) before the calf reached full term and is born alive; of those who are born alive, up to 50% die within the first 12 months of life. Luckily, if a calf can make it to their first birthday, their chances of survival increase markedly.

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