Northern Mountain Parks
Generally speaking there are four volcanic mountains dotting the northern third of Costa Rica. These include Tenorio Volcano, Miravelles Volcano, Rincon de la Vieja Volcano, and Guanacaste National Park. Of these four Miravelles Volcano has very little access and I do not have enough information to include it here. The Tenorio Volcano area is treated separately as the "Heliconias Lodge" area on my bird checklist. I treat Rincon de la Vieja and Guanacaste National Park separately here as northern mountain parks primarily because of their location close to the Guanacaste region of Costa Rica, making these two parks handy places to pick up a combination of both Guanacaste and Caribbean foothill specialties.
Guanacaste National Park
Guanacaste National Park has very little vehicle traffic and it has a reasonable road that runs around the circumference of the park which allows for a lot of stop-and-park birding. Since it is not a well-visited park, it's an easy birding spot for birders with an SUV. I have not visited the park in over 15 years, so updates would be appreciated.
In Guanacaste National Park, we had nice looks at Laughing Falcon, Gray-headed Chachalaca, Collared Aracari, White collared Manakin, Melodious Blackbird, Black-cowled Oriole, Violet-headed Hummingbird, and a variety of Caribbean-slope birds. Special hard-to-locate sparrows (Rusty, Botteri's, and Grasshopper sparrows) are found in the vicinity of Guanacaste National Park but seeing them requires serious work. I didn't pursue these sparrow specialties on my trip.
Rincon de la Vieja National Park
Rincon de la Vieja National Park is a more heavily visited park and has better trail access than Guanacaste National Park.
Birds in both of these parks are unlike birds in most of the lower areas of the dry Guanacaste province which includes the birds at Santa Rosa and Palo Verde national parks. The mountain foothills of Rincon and Guanacaste national parks contain large tracks of evergreen forest which run right to the edge of drier Guanacaste scrub habitat. The species diversity can be dependent both on the elevation and whether one is on the eastern or western side of the park.
Only two Costa Rica locations are really good places for trying to see the Tody Motmot which has a very limited range in Costa Rica. One is at the lower trail of Rincon de la Vieja National Park (where I saw it) and the other is in the Heliconias Lodge area (where it is seen more often, but where I have twice missed it).
In Rincon de la Vieja National Park, the lower trail (fairly easy hiking) provided us with observations of Thicket Tinamou, Great Curassow, Lesser Ground-Cuckoo (in scrub habitat), Long-tailed Manakin, Elegant Trogon, Pale-billed Woodpecker, Ruddy Woodcreeper, Northern Barred Woodcreeper, Bright-rumped Attila, Rufous-capped Warbler, Red-crowned Ant-Tanager, and Gray-headed Tanager.