Puerto Rico has a number of threatened, endangered, or extinct reptiles and amphibians. Among the most famous is the Golden Coquí (Eleutherodactylus jasperi; an ovoviviparous eleutherodactyline frog last seen in 1981) and the critically endangered Puerto Rican Crested Toad (Bufo lemur; a victim of fierce competition and predation from the ubiquitous invasive cane toad, Bufo marinus).
Also on the IUCN red list is the near threatened Puerto Rican Boa (Epicrates inornatus). Prior to my latest trip to Puerto Rico (with Luke Mahler in May), the only state in which I’d ever seen a Puerto Rican Boa was dead at the side of the road (as during this 2006 field trip with Butch Brodie).
However, in the karst region of northwest Puerto Rico it is still possible to see boas, sometimes several at a time, waiting patiently around cave mouths for the nightly emergence of tens of thousands of bats (and, hopefully, a warm meal).
These two great photos were taken by Luke at Mata de Plátano Reserve near Arecibo. The picture above is of two boas lying in wait, and the picture below captures the bat emergence in full glory (at least one snake is also visible in this latter photo, although it is more difficult to spot). Click on the image, above, to enlarge.