Scrub Euphonias (Euphonia affinis) sound similar to their congens, the Yellow-crowns, but the call is higher in pitch and delivered rather faster. This specimen was recorded in a mimosa about a third of the way up the mountain to Monteverde (Costa Rica).
Olive-backed Euphonias (Euphonia gouldi) have this distinctive call, which, to me, sounds a bit like an old "Selectric" typewriter! This one was recorded at La Selva (Costa Rica).
Olive-backed Euphonia (Euphonia gouldi). Here's an example of their mixed call/song, at El Gavilan lodge, Puerto Viejo de Sarapiqui (Costa Rica), 6/18/99. (A very Vireo-like thing to do!)
Olive-backed Euphonias (Euphonia gouldi) have this distinctive call, which, to me, sounds a bit like an old "Selectric" typewriter! Here's another example, from La Selva (Costa Rica).
The Yellow-crowned Euphonia (Euphonia luteicapilla) produces some of the purest tones I've recorded in any bird. This one was at Manuel Antonio (Costa Rica) in June, 1998.