Not the tree itself, but the stringly "grass" in the pot. I have no idea what this is made of--does anyone know if this is going to hurt them? I keep shooing them away from it but of course I can't watch them 24/7.
If that's what I think it is, it would be either Spanish Moss or Sphagnum Peat Moss, both natural products, but I would think they would be courting a blockage by eating too much of it. Do you have some cat grass for them? If they have access to such it might make the moss less attractive.