Dear Brian.  All very interesting.  All I can offer is one year I recall finding a Mangrove Kingfisher nesting in the hole of a tree in the middle of Gede Forest. It was going to the edge of the forest (thick bush) and taking food back to the young.  Certainly not crabs !!

Remember the one ringed at Ngulia on 01 December 2003.  Long way from any crabs for sure.

Worth calculating in a straight line how far that was from the nearest known locality at the coast.

Best wishes
Don