Almost exclusively coastal in their range and are found in shallow bays and saltwater marshes. They nest in the wet, coastal tundra of the high Arctic. Their winter habitat is closely tied to the occurrence of sea grasses and marine algae.
Fast fliers with swept-back wings, Brant are usually found in a flock. They forage while wading, dabbling in shallow water, or while walking on mudflats or the shore. They display strong site-fidelity to both their wintering and nesting area.
Historically, Brant fed almost exclusively on eelgrass, which is still strongly preferred when available. Now they also forage on grasslands and have been able to diversify their diet in the absence of eelgrass, although their range is still closely tied to eelgrass. Brant also eat some aquatic invertebrates. (Source)