Spring Migration
SPRING MIGRATION ALONG LOUISIANA'S COAST
Each year millions of seabirds, waterfowl, wading birds, raptors, shorebirds, and land birds (such as hummingbirds, swifts, flycatchers, warblers, vireos, thrushes, and orioles) come to Louisiana’s coast as part of their annual flight north during spring migration. They are traveling from their winter homes in the West Indies, Mexico, and Central and South America to their summer homes in the United States and Canada. At these northern sites they nest and raise their families. Louisiana’s diverse habitats including swamps, marshes and forested wetlands provide food and shelter for migrating birds.
Some migrants make a relatively short flight; whereas others may fly many thousands of miles. For example, the tiny Ruby-throated Hummingbird may only fly 500 miles from Mexico’s Yucatan Peninsula across the Gulf of Mexico to southern Louisiana. This seems like a relatively short flight when compared to that undertaken by the American Golden-Plover. Thisplover may travel upwards of 10,000 miles one-way from southern Brazil to northern Alaska. Depending on the extent of their breeding and wintering ranges, individuals of the same species may fly different distances depending on how far north they nest and how far south they winter. Small songbirds are estimated to travel at approximately 30 mph; waterfowl and shorebirds at 60 mph. Most make the northward flight with few stops to rest and refuel. Flights between rest stops may be a couple of hundred miles (songbirds) to over a couple of thousand miles (waterfowl and shorebirds). Stops may be much longer if there are large ecological barriers (such as the Gulf of Mexico).
Some migrants traveling from the tropics north to Louisiana fly over land, but many others journey non-stop up to 600 miles across the open water of the Gulf of Mexico. And many are making this potentially perilous over-water journey at night. Some birds are exclusively nocturnal migrants (rails, warblers, vireos, thrushes). Others fly during daylight (hummingbirds, hawks, swallows); and still others migrate equally day or night (ducks, geese, shorebirds). Movements of most migrants often go unnoticed, flying at altitudes thousands of feet above the ground. Migrants generally move individually or in loose aggregations. When thousands of birds are generally moving in the same direction at the same time, these concentrations of migrants can be detected and tracked by Doppler weather radar. And, if it’s a quiet night, you can sometimes hear the calls of migrating birds flying high overhead.
Spring migration on the coast occurs over a longer period than what we typically define as “Spring,” beginning as early as January and ending as late as June. For example, the first Purple Martins arrive in January from their wintering sites in southern South America. In contrast, the first White-rumped Sandpipers nesting in the Arctic don’t arrive in Louisiana until mid- to late April, with their migration continuing thought mid June.
Some migrants remain in Louisiana to breed as summer residents and often arrive before migrants who are just passing through. For example, the peak arrival for Purple Martins who breed here is March; while other Purple Martins that breed farther north continue to move through Louisiana during April. They time their arrival at colonies in central Canada when the weather is more favorable for raising young. Louisiana is a great place to experience spring migration, especially along America’s WETLAND Birding Trail.