Swainson's Thrush Catharus ustulatus
Flight call description A slightly rising, pure-toned, bell-like "pwee" or a burrier "whaai". Burriness, if present, is more pronounced toward the end of the call.
Fig.1. Minnesota September 1987 (WRE).
Perched bird.
Examples Nocturnal
Similar species Some variations of Veery are similar to burrier variations of Swainson's but are typically descending, whereas Swainson's is typically rising. Some Swainson's and Veeries may be indistinguishable. Rose-breasted Grosbeak is higher-pitched and sounds somewhat off-key. Bobolink's flight call is shorter, higher, and less musical. Typical call often likened to the call of the frog, Spring Peeper. See Hermit Thrush and thrush-like calls.
Behavior Primarily a nocturnal migrant. Diurnal onward migration occurs in spring in the Gulf coast region and presumably in the far northern latitudes. Rarely seen in redetermined migration, as this behavior apparently occurs to some degree prior to sunrise and may coincide with a characteristic early-dawn period of increased nocturnal flight call activity. Flight calls given commonly in nocturnal migration and also in diurnal onward migration. Perched birds may give flight calls at any time during the day but they do so particularly around dawn and dusk.
Discussion See Ball (1952).