Are gliders susceptible to bird strikes?
Gliders, as every other aircraft, are susceptible to bird strikes. This is a detached glider's tail after hitting a 10 kg vulture:




  The  accident  was  caused  when  the  crew  lost  control  of  the  airplane  following  the  loss
  of a part of the tail assembly after the vertical stabilizer on the airplane struck a griffon
  vulture head-on.


Some countries are more susceptible to this kind of accidents than others. In Spain, which has a large population of vultures, I routinely hear about fatal accidents due to bird strikes.