As the bird-watching calendar pushes further into spring, Oklahoma birders can look forward to the arrival of many migrating birds, including the whooping crane, a federally endangered bird whose wild flock numbers just over 500 birds. The spring migration is the first of the crane’s two annual migrations and consists of a 2,500-mile flight north to Canadian nesting grounds, with brief stops in Oklahoma expected in early April. The return journey to coastal Texas wintering grounds will take place in late fall, with Oklahoma stopovers expected in late October and early November.