Daniel Martínez drew my attention to a pair of Yellowish Flycatchers (Empidonax flavescens) that have chosen to nest underneath the small bridge that spans the Rio Guayabito at Santa Cruz. John Beer’s file photo of this pretty little bird was taken a little higher up at Calle Vargas:

Yellowish Flycatcher, courtesy of John Beer
I have found this bird just once at home in the garden even though it is supposedly common between elevations of 800 m to 2200 m. Generally, I encounter it almost immediately above 1600 m or so. The birds at Santa Cruz perch conveniently on a wire that runs parallel to the bridge. This spot is a good one for warblers during migration and also frequently has the resident Slate-throated Redstart, Common Chlorospingus and Silver-throated Tanager. These appear only very infrequently any lower down towards San Antonio.
Costa Rica has three resident Empidonax flycatchers, the Yellowish Flycatcher, the Black-capped Flycatcher (Empidonax atriceps), common in the highlands, and the White-throated Flycatcher (Empidonax albigularis). Only the latter species presents any identification problem, and then only when the four, highly confusing northern Empidonax migrants are present. It is said to be fairly common on the southern slope of the nearby Irazú Volcano. However, I have had no luck in the field so far and have recorded it only once, at the bird-banding station at CATIE.