Eastern Bluebird (Sialia sialis) [XC481623]
by Richard E. Webster from Skidaway Island, Chatham County, GA USA, United States (call, song)
Eastern Bluebird (Sialia sialis) [XC545801]
by id from John James Audubon Center (near Audubon), Montgomery County, Pennsylvania, United States (call)
Subspecies
Occasionally hybridizes with Mountain Bluebird (Sialia currucoides). Geographical variation slight, and level of individual variation in morphology and behaviour within and between populations remarkably high. In addition, lack of a "prealternate" moult results in very worn birds in spring and summer, confounding racial analysis and attribution; bermudensis, grata and meridionalis possibly untenable. Proposed subspecies episcopus (southern coastal Texas, in USA, south to southern Tamaulipas, in north-eastern Mexico) considered indistinguishable from nominate.
The following 8 subspecies are recognised:
sialis (Linnaeus, 1758) - Southern and south-eastern Canada and eastern USA south to north-eastern Mexico. Non-breeding also northern Mexico and Bermuda.
fulva Brewster, 1885 - South-western USA (south-eastern Arizona) south through montane central Mexico.
grata Bangs, 1898 - South-western USA (southern Florida).
bermudensis Verrill, AH, 1901 - Bermuda.
nidificans Phillips, AR, 1991 - Caribbean slope of east-central Mexico.
guatemalae Ridgway, 1882 - South-eastern Mexico (Chiapas) and Guatemala.
meridionalis Dickey & van Rossem, 1930 - El Salvador, Honduras and northern Nicaragua.
caribaea Howell, TR, 1965 - Eastern Honduras and north-eastern Nicaragua.
BirdLife International Species Factsheet