This will mean the mother has fed them. Cottontail, one week old. Furry, eyes almost open. Fully furred, eyes open. Go to info sheet on jackrabbits and cottontails. . .
Birds are different.
They do not belong on the ground as a rule. However, there are ground nesting species like quail. These nests are not usually easy to see and a nestling that wanders into view should be left alone as long as there is no obvious injury. Other tree nesting species should be returned to the nest as soon as possible. Birds do not have a strong sense of smell and will NOT reject the baby as a mammal might.