Are there any avid birders out there? I need help with the identification of a relatively common bird that I encountered in Costa Rica.

The bird in question was spotted amidst the undergrowth along the roadside in Turrialba Valley - not too far from Guayabo National Monument - about 3500 feet above sea level. Black and fairly small with no distinguishing characteristics to the naked eye, this bird had a relatively stout beak and was observed hopping up and down continuously while emitting a single plaintive note. By hopping up and down, I deduced that the bird was either trying to expose seeds on the ground or scare up some small insects for his next meal (part of the bird’s foraging behavior).

After referring to his bird book and after considerable hesitation, the young bird guide who had accompanied me from Guayabo National Moument claimed that the bird was a Variable Seedeater. I really wasn’t convinced as for such a common bird, an experienced bird guide should not have to refer to his bird book. After doing some investigation of my own – online and looking at my own Costa Rica Bird book – I think the mystery bird may have been either a Blue-Black Grassquit (most likely) or Blue Seedeater. What do you think?