Costa Rica Snake ID Request (1 Viewer)

I came across this snake on the trail behind the beach at PN Cahuita (southern Caribbean slope) last week. I'd guess it was roughly a meter long, and maybe a bit thicker than my thumb. Any thoughts of where to begin even? The entire back of the snake was black/navy....no stripes or anything. I couldn't tell if the yellow extended all the way to the tail or if it tapered off to black/navy at some point.

I´m no snake expert but it looks to me to be a Bird-eating Snake (Pseustes poecilonotus). Adults tend to be uniformly dark brown, olive, or blue-black above, with a yellowish to cream belly. They reach a total lenght of at least 200cm (79 inches). Its diet it´s mainly birds and their eggs, and occasionally bats.