Some individuals respond to habitat degradation by dispersing to less degraded areas while others remain but display altered behaviours, potentially compensating for the habitat change. We examined the latter possibility by evaluating foraging behaviour and size of lesser snow geese over a period during which their habitat became severely degraded. We show that in this now-degraded habitat, adults spend more of their total time in motor activities and less time in vigilance and comfort behaviours. Goslings spend less of their total time foraging and more in comfort and other behaviours. The pecking rate of both adults and goslings while foraging increases, as do motor and searching behaviours of adults. These changes have not enabled the birds to keep pace with the loss of vegetation, and the size of goslings has continued to decline, likely leading to a reduction in reproductive success. The persistent use of degraded salt marsh is probably related to philopatry and will further damage the marsh.