Fauna

Several avian and mammal inventories have been conducted in Ceibal and they have revealed that Ceibal has the most avian diversity of all southern Petén protected areas. In avian counting, six indicator species of primary forest have been identified (SEGEPLAN/PROSELVA, 2000): mealy Amazon (Amazona farinosa), ornate hawk eagle (Spizaetus ornatus), double-toothed kite (Harpagus bidentatus), slaty-tailed trogon (Trogon Massena), great black hawk (Buteogallus urubitinga) and white hawk (Leucopternis albicollis). Ceibal has more species of cannaries than Tikal National Park (SEGEPLAN/PROSELVA, Ibíd). In total, studies have counted 92 different avian species in Ceibal. Despite its small size, Ceibal plays an essential role in conserving several avian species. Recent studies on the migration patterns of the mealy Amazon parrot (Amazona farinosa) have demonstrated that the survival of the species is directly linked to the existence of the small protected areas in Southern Petén (Bjork, 2001, pers. com). There are also indications that threatened species like the scarlet macaw (Ara macao) could be using the area during parts of the year. These studies signal the importance Complex II has for the biological health of some species despite the fact that it is no longer in its pristine state.

There are reports of two mammal species which are indicators of primary forest: Mexican black howler monkey (Alouatta pigra) and Central American spider monkey (Ateles geoffroyi). In reality, mammals are not abundant in this protected area. In addition to the mentioned primates, there are reports of the existance of the Central American agouti (Dasyprocta punctata), kinkajou (Potos flavus), northern tamandua anteater (Tamandua mexicana) and Amazonian skunk (Conepatus semistriatus). Because of its small size, ecological isolation and continued human disturbances in the area, the large predators and the large herbivors have disappeared from the zone. Notable amphibian species include Muller's narrowmouth salamander (Bolitoglossa mulleri), which is regionally endemic (Campbell, 1998), and possibily another endemic salamander, Bolitoglossa odonnelli. And, the reptile, Morelet's crocodile (Crocodylus moreletii) has been reported on the banks of Pasión River.

Flora 

The forest is well-developed with many species. Within, there are three levels of the forest canopy. The lower level includes trees growing between 5 and 12 m. The medium level trees grow between 19 and 24 m. The trees in the upper canopy measure more than 25 m tall. Many trees have large and well-developed buttresses. The floristic composition of the forest is characterized by a great abundance of palms, including cohune palm (Orbignya cohune) and bay-leaf palm (Sabal morrisiana). There are 91 reported tree species (SEGEPLAN-AHT-APESA, 1994). Some worth mentioning, because of their abundance, are kapok tree (Ceiba pentandra), gumbo limbo (Bursera simaruba), cola de coche (Pithecelobium arboreum), jutahy (Dialium guianense), hog plum or jobo (Spondias mombin), angelica tree (Dendropanax arboreus), ramón (Brosimum spp), luin macho (Drypetes brownii) and luin hembra (Ampelocera hottei). Other common species are candelaria (Erblichia odorata), big-leaf mahogany (Swietenia macrophylla), Central American cedar (Cedrela odorata), and tigerwood (Astronium graveolens). Epiphytes are also common and there are numerous bromeliads and orchids. In addition, there are strangler plants, like Ficus spp. and Clusia spp