The Carib Grackle (Quiscalus lugubris) has recently extended its distribution to montane habitats in the Colombian Andes, including urban areas. Little is known about its reproductive biology in both natural and urban environments. We analyzed the relationship between morphological and morphometric external characters with sex, reproductive condition, and the annual reproductive activity of two groups of individuals that inhabit the city of Bucaramanga, Colombia. We aimed to know if there is a clear association between external features (including plumage/molting) and sex, maturity, and reproductive stage. We recorded the external morphology of these individuals (molt, iris color, and brood patch presence) as well as standard morphometric traits and classified these birds in reproductive stages according to morphology and histological analyses of their reproductive tracts. We found a clear sexual dimorphism between adults in morphometric features and plumage color. However, neither morphometric features nor iris and plumage color/molt pattern clearly indicates sexual maturity; some immatures can be mistakenly taken as adults due to the morphological characteristics obtained after they complete their pre-basic molt. Females reach maturity at different body masses and could reproduce asynchronically; therefore, the presence and type of brood patch is the only useful feature for the identification of female reproductive stages. Quiscalus lugubris has an extended breeding season throughout the year and a seasonal molting activity; at the end of the second rainy season (November) and during the driest time of the year (December?January), adults exhibited reproductive tracts in regression and were found in active molt.