Apparently adult Tricolored Herons undergo a partial molt in spring, just prior to or perhaps early on in the breeding season. I'm not entirely sure about this as I can't quite make out what the literature is saying about their molts.

This individual clearly has adult plumage. And yet it was experience a molt in mid-May. Evidence is most notable in the wing where primary feathers seem intact while smaller wing feathers (secondaries?) appear not fully grown in. And he was definitely loosing lots of small downy feathers, some of which are stuck on his bill.

Location: Chincoteague National Wildlife Refuge, Va.