Cuban crocodiles are a spunky sort. Compared to other crocodilians, Cuban crocs are aggressive, distinctively colored, and amazing leapers. Unfortunately, rampant hunting nearly wiped them out last century, and today, poaching and habitat destruction continue to threaten their small populations. As a result, the species is now considered critically endangered.

Still, a more insidious danger looms: hybridization.  

American crocodiles living in Cuba are breeding with Cuban crocs. Over time, these courtships could squeeze out genetically pure populations of Cuban crocodiles, which are much more rare. Scientists estimate that just 3,000 of these crocs remain in the wild, where they live in Zapata Swamp on the Cuban mainland and Lanier Swamp on the Island of Youth.

Conservationists had suspected for some time that the two types of crocodile were coupling up. But DNA evidence would expose these match-ups for certain. So WCS scientists and partners collected samples from 89 wild Cuban and American crocodiles and two samples from zoo crocs. Their studies revealed that American crocodiles living in Cuba were more closely related to Cuban crocs than American crocodiles on the mainland.

The discovery means that the island’s crocs represent two distinct populations from the mainland reptiles. And though each population is evolutionarily significant, unfortunately, one could essentially extinguish the other, through breeding its cousins out of existence.

The study authors advise wildlife managers in Cuba to put the brakes on such reptile romances, for the crocs’ own good.

For more information, see press release.