Professor Pei explains that there is a theory in natural resources management in which hunters should only hunt in a defined area, with surrounding areas off limits. When the animal populations in protected areas get excessive, animals naturally migrate into the hunting grounds, thus insuring that there will always be a supply of animals for hunt ing, with no danger of extermination.
裴老師解釋，自然資源經營理論中有所謂「沙漏效應」，獵人在特定的範圍狩獵，外圍則維持多處禁獵地，當動物繁衍超過容納量後，自然源源不斷往獵區擴散，因此獵區永遠不擔心缺乏獵物。