I imagine that there are a few birders on the BC forum. Here is a list of what I encountered on this trip. My Costa Rica list is now in the mid-500s. I am not certain why, but it generally was quiet with not nearly as much avian activity as I remember from long ago. I really expected about twice this number of species but activity may have been suppressed due to the wet weather. My prior visits were during the dry season whereas this trip was in the middle of the wet. Those birds with an asterisk were lifers.
Little Tinamou Suena Azul
Great Tinamou Rara Avis, La Selva
Striated Heron Suena Azul
Great Egret -- Suena Azul, tranis
Neotropical Cormorant
Short-billed Pigeon Suena Azul, Rara Avis, La Selva
Red-billed Pigeon -- Volcan Arenal
Grey-chested Dove -- Rara Avis, La Selva, Volcan Arenal
Ruddy Ground Dove -- road to Rara Avis, La Selva
*Purplish-backed Quail-Dove Rara Avis
*Violaceous Quail-Dove -- Volcan Arenal
Great Currasow -- La Selva, Volcan Arenal
Crested Guan -- La Selva, Volcan Arenal
Bat Falcon Rara Avis, pair
Laughing Falcon Suena Azul, calling and in treetops
Roadside Hawk Rara Avis
White Hawk -- Rara Avis
Swallow-tailed Kite -- La Selva
Hook-billed Kite -- dark phase, Volcan Arenal
King Vulture one near Rara Avis, La Selva
Black Vulture
Turkey Vulture
Squirrel Cuckoo -- Suena Azul, Rara Avis, La Selva
Grove-billed Ani -- Suena Azul, La Selva
Spotted Sandpiper -- Suena Azul, Rara Avis
Amazon Kingfisher -- Suena Azul
Ringed Kingfisher -- La Selva
Green Kingfisher -- Suena Azul
Mealy Parrot -- Rara Avis, La Selva
Red-lored Parrot -- Volcan Arenal
White-crowned Parrot -- La Selva, Volcan Arenal
*Great Green Macaw -- La Selva
Crimson-fronted Parakeet -- La Selva, Volcan Arenal
Orange-chinned Parakeet -- Volcan Arenal
Spectacled Owl -- Rara Avis
Pauraque -- Suena Azul, La Selva, Volcan Arenal
Least Pygmy Owl -- Rara Avis
Long-tailed Hermit Suena Azul, La Selva
Little Hermit -- Rara Avis, VolcanArenal
Green Hermit -- Rara Avis, Volcan Arenal
Banded Barbthroat Suena Azul
Violet-headed Hummingbird -- Volcan Arenal
Rufous-tailed Hummingbird -- Suena Azul, La Selva
Blue-throated Goldentail -- Volcan Arenal
Purple-crowned Fairy -- Volcan Arenal
White-collared Swift -- Rara Avis
Grey-rumped Swift -- La Selva
Violaceous Trogon Suena Azul, La Selva, Volcan Arenal