User blog comment:BastionMonk/Name that snake/@comment-1791057-20130504201305/@comment-1791057-20130505053457

It is, but I've handled this subspecies enough to recognize one when I see it.

There's the possibility that, due to geography, it is a common boa constrictor - which lives in central America including Costa Rica, but the striping pattern in juvenile Commons are duller in coloration and blend into the rest of the scales better. Juvenile Red-Tailed Boas have very prominent striping. Common Boa Constrictor's striping doesn't get this prominent until adulthood, and even then, the scales on a Common are more golden than on a Red-Tailed.