The half coconuts I have which are filled with suet had been lasting for weeks as the birds gradually helped themselves. Occasionally the filling would fall out of one after it had shrunk during a particularly cold night. A couple of mornings ago I found two were empty where they had been half full the previous day. No sign of any fallen fillings on the ground. When I replaced them with a full coconut half I soon found out what was happening.
It doesn't take long for a large Rook beak to gobble it all up in a very short time:
An old coconut I have reused is one with only a quarter opening which was originally filled with suet. Now it is empty it is useful as a container for seed and suet treats:
Sometimes birds will spend a while trying to work out how to get at the food:
All in all Birdy Bistro Mk2 is very popular, especially with the cold temperatures hereabouts.