Spring Migration Wave Theory
Graphic provided by Julie Rossman/Audubon
Research by BSBO has identified major movements of passerines (songbirds) that occur roughly the same time each year. These "waves" of migrants, are associations of species that migrate the same time each year. Day-length is the primary driver of spring migration with weather "tweaking" actual arrival dates. Each wave generally has two pulses each approximately a week apart. Normal weather patterns include low pressure cells crossing the southern part of the continent with large movements in Ohio when the cell is in Oklahoma-Arkansas. This results in tropical warm fronts rotating warm winds up the Mississippi and Ohio River valleys. It generally takes a pressure cell about a week to cross the country. Expected large neotropical waves arrive in three general movements (al. 1985; Krementz & Ankney 1987). Adequate stopover habitat may play an important role in delivering migrating passerines to their breeding grounds with sufficient energy reserves to successfully nest.
The first wave dominated by male White-throated Sparrow, Hermit Thrush, male Myrtle Warbler, and male Ruby-crowned Kinglet occurs around 25 April. Sub-dominant warblers include the Black-throated Green, Black-and-white, and Nashville. This first wave has been named the "overflight" wave as several more southern species of warbler get caught up in strong southwest winds and over shoot their normal range (Louisiana Waterthrush, Kentucky Warbler, Worm-eating Warbler), resulting in a gradual filtering back to the south.
The second wave, known as the big wave, occurs 7-13 May and is represented by the greatest species diversity of the spring and is dominated by female White-throated Sparrow, Swainson's Thrush, female Myrtle Warbler, female Ruby-crowned Kinglet, and male Magnolia Warbler. The second pulse of this wave coming five to seven days after, usually has the largest volume and contains the same species dominants.
The third wave normally comes around Memorial Day weekend and is dominated by female Magnolia Warbler, American Redstart, Mourning Warbler, vireos, and flycatchers.
The first wave dominated by male White-throated Sparrow, Hermit Thrush, male Myrtle Warbler, and male Ruby-crowned Kinglet occurs around 25 April. Sub-dominant warblers include the Black-throated Green, Black-and-white, and Nashville. This first wave has been named the "overflight" wave as several more southern species of warbler get caught up in strong southwest winds and over shoot their normal range (Louisiana Waterthrush, Kentucky Warbler, Worm-eating Warbler), resulting in a gradual filtering back to the south.
The second wave, known as the big wave, occurs 7-13 May and is represented by the greatest species diversity of the spring and is dominated by female White-throated Sparrow, Swainson's Thrush, female Myrtle Warbler, female Ruby-crowned Kinglet, and male Magnolia Warbler. The second pulse of this wave coming five to seven days after, usually has the largest volume and contains the same species dominants.
The third wave normally comes around Memorial Day weekend and is dominated by female Magnolia Warbler, American Redstart, Mourning Warbler, vireos, and flycatchers.