Cattle Egret possibly feeding on a European Pond Terrapin (1 Viewer)

Would welcome comments on this behaviour. There are some photos of the activity as well as it went on for longer than shown in the video. To me this looks like the egret is attempting to find food on the body of the terrapin, especially around/under the shell (and maybe succeeding?).

What do you think and is anyone aware of this being documented before?
https://youtu.be/djBbjattwqM

I'd guess just looking for parasites (ticks, leeches, etc.) which Cattle Egrets are well-known for, or just other food that happened to be hitching a lift on the terrapin (water snails and suchlike). Seems to me pretty much the same as a Cattle Egret would treat any large animal (like cattle), except that normally I'd have thought the terrapin would have felt threatened and dropped off straight into the water.

Thanks. This is exactly my thinking just not sure it's ever been documented for terrapin!