I just adopted 2 females mallards Monday. I was told they were born this past spring. They are certainly fully feathered. I gave them access to a pool today and they swam like crazy but stayed soaking wet! It is only 32 degrees in Southern Oregon tonight. They are in a crate to be introduced to my existing flock. The crate has deep straw and a tarp over it. I hung a heat lamp outside but is there anything else I can do to make sure they will be OK tonight? Indoors is not an option