Yes I would keep most of these birds under cover . Basically its protection from preditors. We have issues with owls,ravens,hawks,and even eagles .Some people can keep ducks and geese out on the ponds and not have any issues , but not us . We do keep most of our geese , and swans not under cover , only because it would be very costly to net all the ponds . But we have lost geese and swans to the preditors too . Most of our waterfowl either are in the warm barn , or a cold barn . The warm barn stays above zero all the time . Some of the species that are smaller go inside . Some birds are kept in the cold barn , which can get quit cold , but its completely out of the wind and snow . Some of the ducks are perfectly fine in the cold barn , and will have access to the outside during winter. As long as they have access to water , and food at all times they can handle the cold quit well . If you need to know what birds can handle what , just e-mail me , I can let you know .