when i was youngER (still young.. just a teen). i heard stories that they could swim.. This was before anyone ever told me "They'll sink". so i put a hen i had in the pool with me.. Just in case she couldn't i stood next to her closely.. And she swam for about 20 seconds and slowly started to sink, after that i grabbed her and put her out of the pool.. So pretty much until the oil washes off their feathers they can swim.. But after that, They're goners.