This is yet another heron that we saw on our recent wildlife boat trip in Palo Verde National Park. I am sorry that I do not know the exact species. My guidebook on the birds of Costa Rica has photos of 252 species, but there are more than 860 species of birds in Costa Rica, more than the USA and Canada combined.
Maybe someone more knowledgeable about birds than I am will know the type of heron in this photo. Regardless, I like the black and white pattern of its feathers.