At first glance this might look very similar to a North American migrant Empidonax such as Yellow-bellied or Pacific-slope (which does not get to Costa Rica), but this is a Yellowish Flycatcher. Yellow-bellied is a wintering bird here, but they do not nest in CR and this one is nesting as the images will show. We heard the vocalizations of this bird which I was familiar with from the mountains of Chiapas and we soon spotted the adult pair and soon after their nest with three young. It was a delightful setting in the forest and the birds were actively feeding the young with little concern about our presence.

Savegre Lodge,
Costa Rica
7 February 2016
9.5500
-83.8055
7420 ft elevation