I was not able to see any markings but I really do believe they are sterling sliver,also they look like they are kind of old.so I dont know if they marked them back then.hope that helps :)
Without a US marking of ".925" the feathers are not sterling, sorry. Some handcrafted sterling is not marked but these are certainly manufactured. Just some info to save you problems. Did you know if they do not test positive for sterling, you have to refund the credits and pay return shipping to get them back? This is a reputable auction site and "guessing" is not allowed. Thanx