102 I n the chronicles of the discovery and con- quest of New Spain, stories abound about the biological riches in the extraordi- nary central region of what is today Mexico. In his letters to Emperor Car- los V, Hernán Cortés described in detail how when he arrived at Tla- macas (or Cortés Pass, as the low- est point between the Popocaté- petl and Iztaccíhuatl Volcanoes is today known), he witnessed a sight he could hardly forget: in the distance, at the bottom of that hydro- logical basin was one of the country’s most beautiful regions, rich in flora and fauna. There, five shallow lakes, the Zumpango, Xaltocan, Texcoco, Chalco and Xochimilco Lakes, covered more than 150,000 hectares, mixing crystalline waters with others cov- ered with aquatic plants like tules or cattails, ninfas and papas de agua, a kind of wild potato. Ducks, herons, tortoises, ajolotes and fish were also plentiful. In the center of the lakes was Tenochtitlan, the capital of the Aztec Empire. Down through the centuries, it was to become one of the largest, most highly populated metropolises on the planet. Today, Mexico City covers 100,000 hectares and has 20 million inhabitants. The environmental impact of the city’s growth has been devastating. The lakes, their fauna and their flora gradually disappeared, devoured by cultivated land and the advance of the city itself. In the twentieth century, enormous works of infrastructure, like the deep drainage and the grand canal, built to avert flooding, put an end to the last vestiges of the lakes. That silent crisis went almost unnoticed, even for scientists. Among the most profoundly affected species were the fish and the reptile known as the ajolote. Two types of ajolotes (Ambys- toma mexicanum and A. velasci), frogs (Rana tlaloci), and several kinds of fish including the white fish or shortfin silverside (Chirostoma humboldtiana), the mesa silverside (Chirostoma jor- dani), chubs (Algansea tincella, Evarra eigenmanni, E. thahuacensis and E. bustamantei) and mex- ECOLOGY Saving Endangered Species In Mexico City’s Chapultepec Park Gerardo Ceballos * Juan Cruzado** *Professor at UNAM’s Institute of Ecology, interested in the conservation of vertebrates. **Graduate student at the Institute of Ecology, working with vertebrate conservation. Photos courtesy of the authors.