Many species of wading birds, such as egret, ibis and spoonbill, know to never over-fish. They know it instinctively and will leave a lagoon after feeding in it for a certain period of time.
Sometimes the tide works like a stopwatch and closes off the buffet for the waders. The birds will come back after their food had a chance to recuperate and the floods have receded.
That is why we can observe short-distance migration patterns between areas along the Gulf Coast or even between wetland habitats on Galveston Island.
It is also a reason why it is so important to have a string of habitats along the Gulf Coast and not just a few big sanctuaries.
If an area suffers from pollution, as with the current oil spill, there needs to be other reserves to accommodate a larger number of animals close by. This diminishes the bulk risk of killing off bird colonies with one single incident.