Mexico’s Sea of Cortez is home to one-third of the world’s whale and dolphin species. Twelve species of annual whales live in these waters, including the blue whale (the largest animal in the world), humpback whales and gray whales. Gray whales are relatively large — about twice the length of an Orca (killer whale) and half the length of the enormous blue whale. Most adult gray whales are about ten to thirteen meters (35 to 45 feet) long, and weigh twenty-two to thirty-eight tonnes (20 to 35 tons), with females tending to be larger than the males. Named for their medium gray color beneath the water, which is marbled with lighter patches, gray whales appear to be a whitish-blue color at the water’s surface. Each whale has a unique skin pigmentation color which allows individuals to be identified, and these patterns often include round white markings that result from barnacles that have fallen off.

Undergoing one of the longest animal migrations in the world, gray whales inhabit the chilly waters of the Bering Sea (off the coast of Alaska) in the summer, and migrate to their annual birthing grounds in winter — the warm lagoons on the coast of Baja California Sur, Mexico, some 6,000 kilometers (4,000 miles) to the south. Exactly why the gray whale and many other whale species travel to warmer climes to breed and give birth is unknown. Yet, each year, gray whales depart from the Bering Sea in October, and by December, they are usually between Monterey and San Diego, where thousands of residents watch up to 200 whales a day stream past their shores. They reach the central coast of Baja by late December, where half of the females mate and the other half give birth. Each year, a few stragglers can be seen arriving as late as February. These slowpokes encounter northbound whales returning from Baja and often hit the brakes, turn around and join them.

Some gray whales round the tip of Baja Peninsula, swim past Cabo San Lucas and head north into the Sea of Cortez (Gulf of California) as far as Bahia de Los Angeles. A small number of grays give birth in the bays of Yavaros, Bahia Navachiste, Bahia Altata and Bahia Reforma (Santa Maria) on the Mexican mainland across the Sea of Cortez from the tip of Baja. However, most of the breeding takes place in four different bays along the coast of Baja: Guerrero Negro, Scammon’s, San Ignacio and Magdalena. Launching boats in these protected waters is not allowed, but joining a whale-watching tour on the outskirts of these whale calving areas is a truly incredible experience that no one should miss. Friendly gray whales will even approach tour boats and allow passengers to pet them. These are the memories of Mexico that most visitors say they will cherish forever.

The northernmost of these lagoons is Guerrero Negro, named after a whaling ship that sank there in 1858. As with many shipwrecks, local legend tells of a treasure aboard, but as it was just a whaling ship, the story is doubtful. Adjacent is the larger Scammon’s Lagoon, a huge complex that stretches forty-five kilometers (30 miles) into the Baja desert. San Ignacio Lagoon, known to locals in the 1940s as Ballenas Bay (Whale Bay), lies further south about 120 Kilometers (80 miles) from Scammon’s, and Magdalena Bay is another 270 kilometers (180 miles) south. Over half of all gray whale births take place in Scammon’s Lagoon. Magdalena Bay, in comparison, accounts for less than six percent.

The gestation period for gray whales is about 13 months, which means that whales impregnated in the lagoons one winter will return a year later to give birth. Most females give birth every other year, although birthing two years in a row happens in about one out of every 45 females. The peak gray whale births takes place around January 27th. Newborn gray whales are a very dark gray color which looks almost black in the water.

Female gray whales give birth to a single baby, although there have been rare observations of twins. Unlike most whales, baby grays are born headfirst. If a baby is born underwater, it instinctively swims to the surface to get its first breath of air, often with the anxious mother pushing it up. Baby grays are born fully developed, measure about four to five meters long (12 – 16 feet) and weigh 700 to 900 kilograms (1500 to 2000 pounds). The umbilical cord is short and rigid and snaps off easily. Newborns have fetal folds in the skin from being curled up in a fetal position inside the mother’s womb.

Females often let the babies ride on their backs for the first few days. In fact, the calves often use their mothers as huge playgrounds. Biologists Swartz and Jones noted, “They swim onto her rotund back and slide off, roll across her massive tail stock and pummel her with their leaping back-flops and belly-flops.” The calves sometimes mistake big tour boats for their mothers and attempt to rub against the boats, much to the delight of the passengers. After they get a bit bigger, the young calves like to lie at right angles to their mothers, with their heads resting across their mother’s broad backs. The young whales spend a lot of time playing, chasing each other, surfing on the waves and sometimes rapidly spinning in one spot at up to 60 revolutions per minute. They begin breaching (leaping out of the water onto their sides or their backs) within the first few weeks of life and will sometimes use objects in the lagoons, such as kelp, as toys. As the calves get older, up to twenty mother and calf pairs will assemble to play and socialize, the whale equivalent of human mothers with toddlers gathering in nursery schools. The nursery lagoon becomes a tranquil place where a gray whale mother can be seen stroking her baby with her broad flippers and rubbing her head against it tenderly. It is no wonder that in 1874, Captain Charles Scammon, the lagoon’s namesake, noted, “this species of whale manifests the greatest affection for its young.”