A small number of animals, which have a broad diet, can reproduce rapidly, and don't have any preferences about heat and humidity are able to "keep in step" with human development.
三、四十年前，平地乾淨的溪流、溝渠還可以看見水獺抓魚；走在大台北的路上都能「撿」到分佈在台灣北部的台北赤蛙，而水獺與赤蛙今天都已芳蹤難尋。