Each year, from January through April, an estimated 17,000 Pacific gray whales mate and give birth in Baja's Pacific Coast lagoons and some areas of the Sea of Cortez.  Their yearly migration from Alaska's food-rich Bering Sea is one of the longest on record for any mammal.  Once spring arrives, the grays will head back north.  Cruising at 4-5 knots, they parallel the coastline for an estimated 5,000 miles (8,065 km) each way, feeding on plankton, frill, pelagic red crabs, eelgrass and kelp.

Gray whales get to be 40-50 feet (12-15 m) long and wigh 30-40 tons (27-35m).  At birth calves measure nearly 15 feet (5 m) and weigh almost a ton (1.1 m).  Their growth is rapid, sustained by a thick milk that contains nearly 55 percent fat.  Known for their high intelligence, these animals gained their description as "gentle giants"' by their tender demeanor among other whale's and in their encounters with humans.
  During mating, their slow courtship of playing and touching often involves two males and one female, and lasts several hours.  Their gestatiori period is believed to be between 12-13 months.

In the 15 foot (5 m) shallows, there is almost constant physical contact between mothers and calves.  The baby calf swims at its mother's side, watching and repeating all her actions.  When the mother stops to rest, however, the playful baby will cross back and forth over the mother's tail and head, pull itself onto her back, bump into her side and tease her until she plays.

These whales are quite gentle around humans and often enjoy having their heads and stomachs scratched.  It is an amazing experience to have one of these magnificent creatures nuzzling and nosing against you, slowly turning over to have her stomach rubbed.  After decades of slaughter, the gray whale has made a remarkable comeback, and in January 1993 it was taken off the endangered list.  The lagoons are now official sanctuaries, and no boats are permitted in certain lagoons.