baby duck

by elese
(melbourne, victoria, australia)

i've recently adopted an orphaned baby duck, around 2 weeks old.
today though when i have moved him from outside to inside enclosure he just opens his mouth and shuts it again. i thought maybe he was hungry? but i'm wondering if its because my hands are hot and it's a warm day. he doesn't do it much when he's sitting in his enclosure.

appreciate some help :)