Birds migrate for one of two reasons: to find more to eat or to find a place to nest. Many species of birds are migratory, but not all are long-distance migrators. Pectoral Sandpipers are one species of long-distance migrators and, like all long-distance migratory birds, they migrate each year from a higher region to a lower region but specifically to obtain more to eat, not to breed. In particular, they migrate from their breeding grounds in Siberia through North America to winter and feed in South America. Winter, especially winter in Siberia and North America, brings with it fewer insects and other sources of food, so birds must follow the food supply located in warmer regions. Some species of birds also cannot survive in cold temperatures, but the Pectoral Sandpiper is not one of those species. Instead, food supplies drive the Pectoral Sandpipers south for the winter.
Unlike some other species of long-distance migratory birds, Pectoral Sandpipers do not nest in South America. Instead, once winter is over, they migrate back north to their breeding grounds in Siberia.
Interestingly, not all Pectoral Sandpipers travel the Siberia to South America migrant pattern. Only half of Pectoral Sandpipers migrate from Siberia then through Alaska, Canada, and the US to South America and back up to Siberia. Other Pectoral Sandpipers migrate from their nesting grounds in Siberia through eastern Asia, which includes the Philippines, Taiwan, and Japan, to Southeast Asia, Australia, and New Zealand, where they winter instead.