Beluga whales can migrate freely between salt and fresh water, an ability that other cetaceans do not have.
The summer habitats of beluga whales generally include an estuary. Belugas show a high degree of philopatry, or site tenacity/ fidelity, with stocks returning to the same estuaries year after year. Genetic evidence also suggests that the stocks have been visiting separate estuaries for long periods, perhaps since glaciers receded at the end of the last Ice Age, with only limited exchange between the different groups.
Belugas migrate south as the ice pack advances in the autumn, leaving areas of broken pack ice and moving to shallow, brackish estuaries and river mouths in the summer. These patterns indicate that belugas possess an ability to move freely between salt and fresh water, an ability that most other cetaceans do not have.