Common in agricultural areas and towns. Also found in marshes alongside BTGR. Usually in flocks, town roost gatherings can cause mayhem all night long with a deafening range of loud chuckles, wheezes and trills. ID: Very similar to BTGR but slightly larger and more angular with longer, diamond-shaped tail, flatter head, and larger bill. Where ranges overlap, GRGR has pale iris and BTGR dark iris. Ad ♀: colors as BTGR but averages darker on back. ♀: similar to BTGR but darker brown, with more contrasting face pattern. Juv: similar to ♀ with diffuse pale streaking on underparts. Imm ♂: shorter-tailed and duller than ad ♂. Imms can keep dark iris through first year of life.