whats up.
The first person to calculate the circumference of the Earth and coined the word "geography" was Eratosthenes. The man who successfully applied his scientific research to create an illustration of the first world map was Anaximander.
Answer:
It happens because the consuming is higher than the water drop rate, or even because there are too many people in a zone where there is not enough fresh water.
In the rocky communities of the Americal Pacific Coast which is an important predator. Hope this helps :)