The reserve is home to extensive mangrove wetlands, and rich in birds and other wildlife.

Freshwater from the peninsula's extensive aquifer has outlets in the reserve, mixing with the salt waters of the Gulf of Mexico in the wetlands.

[2] The reserve is home to large and diverse populations of migratory and resident birds, with over 300 species identified.

Bird species present include the American flamingo (Phoenicopterus ruber), jabiru (Jabiru mycteria), wood stork (Mycteria americana), Muscovy duck (Cairina moschata), snail kite (Rostrhamus sociabilis), orange oriole (Icterus auratus), hooded oriole (Icterus cucullatus), least tern (Sternula antillarum), crane hawk (Geranospiza caerulescens), common black hawk (Buteogallus anthracinus), black hawk-eagle (Spizaetus tyrannus), Yucatan amazon (Amazona xantholora), bat falcon (Falco rufigularis), ferruginous pygmy owl (Glaucidium brasilianum), least bittern (Ixobrychus exilis), reddish egret (Egretta rufescens), blue-winged teal (Spatula discors), northern pintail (Anas acuta), American wigeon (Mareca americana), lesser scaup (Aythya affinis), king vulture (Sarcoramphus papa), and hen harrier (Circus cyaneus).

[2] In 2008 the Mexican government nominated the Los Petenes and adjacent Ría Celestún reserves as a World Heritage Site.