Explanation here:
https://www.behindthename.com/bb/game/5161272
SO1: MOCH (Mountain Chickadee)
SO2: HUGO (Hudsonian Godwit)
DS: ROSA (Rock Sandpiper)
DS: VABU (Varied Bunting)
DS: MIKI (Mississippi Kite)
DD: COHA (Cooper's Hawk)
DD: ORJU (Oregon Junco)
DD: SUTA (Summer Tanager)
DS: PISI (Pine Siskin)