Butterflies of Tamaulipas: Northern Prairie Wildlife Research Center listing of species reported in the state.
Gómez Farías Region and El Cielo Biosphere Reserve: Report on geography, flora and fauna, and cultural setting, from Smithstonian Institute's Centres of Plant Diversity.
Grutas de Bustamante (Caves of Bustamante): Overview and links to information about the huge cave system just outside of Bustamante.
World Institute for Conservation and Environment (WICE): List of resident and migratory birds, with common names in English and Spanish.