We have two Khaki ducklings that we're hand raising (momma abandoned both) but they're about 3 weeks apart. The older duckling (a month old now) is like 3 or 4 times the size of the younger one (about a week old). We have them in clear plastic tubs (large enough for each to move about, with heat, food, water, etc.) adjacent to each other so they can see each other. They like to sit as close as they can to each other in their respective tubs, and they cheep to each other, but when we put them together for play the older one tends to nip at the younger one. Any idea how long this behavior tends to last before the older finally accepts the younger one? We'd like them to live together outside when they're old enough, so we're hoping they'll be friends soon. I figure the nipping will ease up as the younger one gets bigger, but any advice on facilitating the process will be much appreciated! Thanks!