I have two Indian Runner ducklings that hatched 3 days apart. They are currently 7 and 4 days old. The older duckling constantly pecks at her siblings beak and mostly feet. Sometimes she'll go for the wing. I can see that the younger duck is annoyed because she always tries to get away. I have them separated in the brooder most of the day with a glass pane so they can see each other, but we let them out to run around with each other at night for awhile. I don't trust the older duckling just yet. Will this behavior eventually subside?