From Yucatán Wildlife:

Welcome to the world of nature in the Yucatan peninsula! This area is well known for the beach resorts of Cancun and the Mayan Riviera. But few nature lovers know that there are many exciting opportunities for watching wildlife, which are only hours away from the tourist hotspots of Cancun, Playa del Carmen and Cozumel.

The Yucatan Peninsula has incredible bio-diversity. It is home to 50% of all the birds living in Mexico, several of them endemic, 25% of Mexican mammals, and 10% of Mexico´s flora

Yucatán Wildlife has photos and descriptions of mammels, birds, reptiles, fish, and more.