Lots of ducks in the cold, cold Jordan River

I saw lots of ducks in the river. The air temperature was in the low teens (F), and the water must have been cold, probably in the high 30s or low 40s. I don't know how the ducks can withstand that cold water. I think their down has a natural oil that keeps the water away from their bodies, but their legs have no insulation and are in the cold water. Brrrrrr...