May 7, 2025
From Birth to Migration: A North Atlantic Right Whale Mother’s First Year with Her Calf
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BY: Uzezi Odharo
For North Atlantic right whale mothers, the journey to parenthood begins with a long wait. Females become sexually mature around age eight or nine and carry a single calf for about 12 to 13 months. After a year-long pregnancy, birth usually occurs between December and March in the warm, shallow waters off the coasts of Florida and Georgia in the United States (U.S.). And so begins a right whale mother’s first year with her precious calf.
The bond between a North Atlantic right whale and her calf
From the moment a North Atlantic right whale calf is born, it stays close to its mother — often touching her as they swim, surface and dive together. Their physical closeness is critical: it helps the calf stay safe and learn vital survival skills, such as breathing rhythms, diving behaviours, and navigating ocean currents. Despite a mother’s vigilance, danger is never far. Collisions with ships and entanglements in fishing gear remain the biggest threats to right whale mothers and their vulnerable calves.
Nursing and preparing for the journey north
North Atlantic right whales calves nurse in the warm waters off the southeastern U.S., where their mothers provide up to 150 milliliters of milk per day. Whale milk is high in fat — the perfect fuel for growing calves that need to build strength for their upcoming migration. After several months of nursing, mothers lead their calves north on a long and risky journey toward the rich feeding grounds off New England and Atlantic Canada. One critical stop along the way is Cape Cod Bay, a sheltered area teeming with tiny copepods that provide essential nourishment for hungry mothers and calves. For mothers that haven’t eaten much during the calving season, Cape Cod Bay offers a much-needed opportunity to feast and rebuild energy reserves. For calves, it’s their first experience in cooler waters and provides a glimpse of the feeding behaviours they will rely on for survival.
Reaching Canadian waters: new challenges for right whale calves
As spring turns to summer, North Atlantic right whale mothers and calves continue their migration north, often arriving in Canadian waters by late May or June. The Gulf of St. Lawrence has become an increasingly important feeding area for whales, offering abundant zooplankton. These conditions are critical for helping mothers replenish energy and giving young calves a chance to grow stronger before weaning. But these waters are also increasingly dangerous. The Gulf has become a hotspot for deadly entanglements in fishing gear and vessel strikes, as whales must navigate busy shipping lanes and a minefield of ropes attached to lobster and crab nets. Without stronger protections, the risks to North Atlantic right whale mothers and calves will continue to grow. Safeguarding these feeding grounds in Canadian waters is essential to giving these ocean travelers a real chance at survival and helping moms and their babies thrive.
The first year: how right whale mothers prepare calves for life
For the first year of life, a right whale calf rarely strays far from its mother’s side. While nursing can continue for up to two years, the bond is strongest during that first critical year, as the calf learns how to navigate, communicate, and feed independently — all under the constant guidance and protection of its mother. During this time, the mother guides her calf across thousands of kilometres of ocean, teaching it how to survive in waters filled with both opportunity and danger. Even after weaning, calves often stay near their mothers until they reach sexual maturity at around eight to nine years of age.
The first year of a North Atlantic right whale’s life is shaped entirely by the care and endurance of its mother. From a long 12-to-13-month pregnancy to milk-fueled growth in warm southern waters, and the high-risk migrations to places such as Cape Cod Bay and the Gulf of St. Lawrence, right whale mothers give everything to keep their calves alive.
But even the strongest mothers can’t shield their young from every threat. With only around 370 North Atlantic right whales left, protecting their migration routes and feeding grounds is critical for the survival of this species.
This Mother’s Day, let’s celebrate 11 incredible new moms that gave birth in the 2024-25 calving season. Each mother and calf is a symbol of resilience for a species that is still fighting for survival. Let’s honour their strength and sacrifice by demanding stronger protections and working toward a safer, healthier ocean where whales thrive.
Add your name and call for stronger protections for right whales in Canada here >>
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