I blew up the picture of your snake and am second-guessing myself now. I was thinking "Ecuador" and not "Costa Rica." Looking at the Link I've now put in the corrected ID suggestion, I would say it is an Boa c. imperator, as the red-tail isn't found in Costa Rica. Sorry for the confusion and thanks for making me double check my suggestion. If I were you I'd write me a "nasty" comment telling me to be more accurate next time :-) Thanks Gilma.
Even as I'm looking at the differences, I found a site that gives a good description of the subspecies. It is making me question my call on your snake. I was thinking "Ecuador" not "Costa Rica." According to this site, the Red-tail isn't found in Costa Rica. I tried checking before and didn't find this information. Blowing up your picture and looking at the following site, I think the Boa constrictor imperator is probably the one you show. Sorry for the confusion and thanks for making me double check my suggestion. I would suggest changing the subspecies and sending me a "nasty" comment for my inaccuracy :-)
The Boa Constrictor's colors are generally light brown or tan with dark brown splotches. The darkness of the brown/tan varies as does the size of the splotches. In the Boa constrictor constrictor (Red-tail), the brown splotches on the tail become a bright chestnut or "reddish-brown color" while in the Boa constrictor imperator, they are the same dark brown the length of the snake and lack any reddish hue. One has been called "Red-tail" to differentiate it from the other. In the Ecuadorian Amazon we have the Red-tail, on the Ecuadorian coast they have the Imperator. Many pictures on the internet are mis-labeled. Here's a link that may show the "reddish" color better.
These are highly colorful snakes in the Aniliidae family. Although they only have two colors, those colors can vary. The black rings are always black, but the normally red bands can be bright red to dull orange. The longest one I have encountered was 106 cm. Most are somewhat smaller, 50-75 cm. They are ovovivíparos.
For the developers at New York start-up Networked Organisms, smartphones are the butterfly nets of the 21st Century. Their tool, Project Noah, lets people upload photos of plants and wildlife around them, creating a map of the natural world and contributing to scientific research in the process.
Bespectacled scientists of yore would carry around hefty field guides, made up of hundreds of pages of text and photos. But these days, smartphone owners have a lighter option: an app called Project Noah, which aims to help people identify plants and animals as well as collect data from "citizen scientists" about where certain species are located.
Project Noah enables us to be part of a more focused online community where we can learn more about wildlife around us and contribute to scientific research. It pulls participants into deeper, more meaningful engagement by enabling people to go on “missions” to collectively map changes based on sightings.
A modern invention that may also hold the key to saving species in the future. Project Noah is a global study that encourages nature lovers to document the wildlife they encounter, using a purpose built phone app and web community. In addition to the virtual "collection" of species, Project Noah encourages citizen science by linking up with existing surveys including the International Spider Survey and the Global Coral Reef Monitoring Network.