Excavation of burrows by fiddler crabs are a crucial component of functional dynamics in mangrove ecosystem. Eleven burrow characters of rosy fiddler crab Uca rosea (Tweedie) were compared between two biotopes in Indian Sundarbans, throughout the year. Substratum qualities and mean shore level were estimated monthly. Mean density and sex ratio was calculated. Multivariate analysis of variance revealed significant differences (P < 0.05) in burrow morphology in different size classes of the species and in different seasons. Nine out of eleven characteristics differed between male and female fiddler crabs including burrow diameter (mm), burrow volume (cm3), total burrow length (mm) and depth (mm), chamber diameter (mm), burrow neck height (mm) etc., being larger in males than in females. These can be attributed to the presence of large chelipeds in males. Although, the two sites were different regarding the substratum composition, percent organic carbon and organic matter content, soil pH and shore level, the burrow morphology of rosy fiddler crab followed a fixed pattern that did not change even in different habitat. © 2015, The National Academy of Sciences, India.