Gray Whale Calves
An integral and incredibly important part of a Baja gray whale’s life takes place in the Mexican calving lagoons. The three most important are Scammon’s and San Ignacio Lagoons and Magdalena Bay. They have many similarities. When rainstorms and hurricanes erode quartz-rich sand out of the granitic Sierra Juárez, Sierra San Pedro Martír and more northern mountains it is carried to the Pacific. There it is transported south by the California Current and is deposited on beaches all the way to the tip of Baja California. Winter storms push the sand onto the land where it blown by the wind, and a long series of dunes form. Some of these develop extensive lagoons behind them. The main channels within these may be from 33 to more that 100 feet deep. The barrier of sandy islands breaks the big Pacific swells and shelters the protected lagoons that contain warmer water than the open ocean and numerous backwaters and channels that whales seek for solitude. These are perfect places for Baja gray whale mothers to give birth and nurse newborn calves that may weigh a ton and be up to 15 feet long.
Pregnant females lead the southward migration, no doubt because they need to make it to these calving lagoons before their calves appear. Photo identification of individuals shows they seem to prefer one lagoon over another, but sometimes they just can’t make it and turn into a more northern place to calve. Later when the calf can swim well, the pair will continue south to the lagoon that the female intended to be in. Calving starts in early January, but the peak occurs at the end of the month in Magdalena Bay. Scammon’s Lagoon is the largest and usually produces a little over half the calves each year. San Ignacio Lagoon produces the second greatest number. It has a wide entrance, is double-lobed with the northern half extending 16 miles inland and has up to 300 to 400 whales at one time. The total numbers that use the area is much larger, but they are not there simultaneously. The waterways of Magdalena Bay extend more than 100 miles. The northern segment contains narrow, convoluted channels lined with red and white mangroves. It has up to 200 whales at any one time. Boca del Soledad and the small town of Puerto Adolpho López Mateos are at the center of this area. Farther south, the central segment has two barrier islands, a wide entrance and a large bay called Magdalena Bay. It is important to ship traffic going to Puerto San Carlos. It has up to 225 whales at one time but usually far less. The southern segment has fewer whales.
It is in these lagoons that the slow process of feeding, training and nurturing begins. Mom has to support her calf for the first few breaths, but it can swim on a steady course after about 3 hours. It will take at least a month before the calf can face the big swells of the open ocean and the arduous journey north. For now they just need to press up against one of the two mammary slits, feel the nipple push out and accept more than a gallon of warm milk that’s forced into its mouth. The nourishing milk contains 50% butterfat. Fifty gallons a day will add 15 pounds to the calf every day for 7 to 8 months. During that time the calf will grow one foot a month and reach 11,000 pounds. It will be shy in the early days, but its curiosity will grow. When it is a month or so old it will have trouble containing itself, especially with the big floating objects that hum and have tentacles that splash. Sometimes the mother steers the calf away and at other times allows it to do anything it wants, even approach boats. San Ignacio Lagoon and the Magdalena Bay complex are the most popular whale-watching destinations. For most people, being close to a massive friendly whale with a gentle disposition is one of the greatest thrills in the animal world. The gray whale lagoons of Baja California offer the best possibility for this opportunity of anywhere in the world.