The Tamaulipan Province stretches 55,000 square miles along the Tropic of Cancer, from the northernmost Mexican states of Nuevo Leon, Tamaulipus, San Luis Potos , and Veracruz all the way to southwest Texas. Home to such varied species as the ocelot and the prairie dog, as well as rare birds like the green-cheeked amazon and the crimson-collared grosbeak, it is one of the most diverse regions in North America--and one of the most threatened. The...