Yeah there are two ways a glider can get "Lift". One is by thermals, ie. hot air rising, the other is "dynamic" or what is commonly referred to as Ridge Lift, where wind is blowing across the plains then runs into some type of ridge, like the Apelation Mts. and the air is forced upwards to go over the ridge, but it also comes back down on the backside, so you have to soar on the upwind side, obviously.

They have distance races to see who can ride the ridge the furthest...then when they run out of lift, they land in a field and call for their support crew to show up with the trailer, just like some of our catamaran distance races!

I don't know that I would follow a bird out over water in a glider, a large body of water lacks both ridge and thermal lift!