My 2 week old duckling has been panting when he lays down, he eats fine, drinks fine, runs around with the others, and swims and cleans himself just as much as the others. They go outside on beautiful days and come inside at night , they stay in a brooder with a heat lamp, but I put a 60 watt build instead of a 150 because it's been warmer. But when he's up and walking around or swimming he's fine, he only pants when he's laying down. Also he's about twice the size of my other 2 could it simply be his size?