I'm also convinced that birds soar for pleasure as well as because they
might have to

Earlier this year sitting in my garden on a hot windless day, I watched a
Buzzard pick up a thermal over a small local wood and climb until it was a
speck in the sky. It then closed its wings and dived at great speed until it
was about fifty feet above the ground, pulled out and then proceeded to
climb again. It repeated the climb, dive, climb manoeuvre three times before
I went indoors. Surely that could not have been for anything other than
pleasure ?

DB