A little more than a year ago, this correspondent trekked to the eastern coast of Costa Rica to chronicle the spread of the invasive Puerto Rican anole, A. cristatellus. Introduced to the Caribbean port city of Limon many moons ago, we found that the crested anole has made its way down the coast to the vicinity of the Panamanian border, and speculated that it may also have crossed the bridge to the Land of the Canal. In addition, it has spread inland to the west, as far and as high as the town of Turrialba and, at lower elevations, to Siquirres, 60 km from Limon. However, 37 km further west, we failed to find it in Guapiles, though our visit was late in the day. Given its widespread occurrence at low-to-mid elevations, we predicted that the Puerto Ricans may some day advance far to the north and west, trampling through the Tortuguero area to Nicaragua and who knows how far westward?
Taking advantage of our herpetology class sojourn to Costa Rica, I led an intrepid expedition comprised of a freshman, a sophomore, and a graduate student to head eastward from the La Selva Biological Station to determine just how far these lizards have advanced. Unfortunately, the heavens were against us, as the day was completely overcast, quite cool, and on-and-off raining. We backtracked from Puerto Viejo, near the field station, to Guapiles and environs nearby, stopping periodically to survey. No cristatellus were found and we couldn’t decide whether we were happy or sad to fail to document further spread of the invader. In any case, given the weather, we can’t really conclude much from our failure to find any.
However, we did find quite a few brown basilisks, Basiliscus vittatus, as well as some A. limifrons at the edge of thicket lining a stream (in the palacial grounds of a dentist’s office, that included a swimming pool and an outdoor x-ray machine, but that’s another story). These observations lead to a number of thoughts:
1) A. limifrons is a cool-adapted, forest interior species, so the fact that it was active doesn’t say anything about cristatellus. However, brown basilisks seem to be sun lovers; does the fact that they were out and about suggest that, if cristatellus were present, it should have been active, too?
2) Brown basilisks are substantially larger than crested anoles, and probably eat the same fare. Is competition between the two an important factor? More importantly, I suspect that a crested anole would make a delicious meal for a brown basilisk. Could the combined effects of competition and predation by basilisks limit the occurrence or cristatellus, or have other effects on their ecology and behavior? I should note that we saw the two species in seemingly happy sympatry in the vicinity of Cahuita on the Caribbean coast.
3) And what about the effects of cristatellus on the native limifrons? Just as basilisks may devour crested anoles, cristatellus is known to consume other anoles and probably would delight in consuming a limifrons or two. Smaller and substantially slighter, limifrons would be no match for male cristatellus.
Clearly, much remains to be learned about the invasion of cristatellus and how it is interacting with the locals.
One last note: in two days at the Pacuare Nature Reserve, between hanging out at night with the nesting leatherback turtles, we searched to no avail for cristatellus, which apparently has not made it to this area, just south of Tortuguero.
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