Yellow-bellied Flycatcher Empidonax flaviventris, June 14. Empidonax species (“empids”) – a group of birds that are particularly difficult to identify – occur regularly on Sable, and the Yellow-bellied is among the most common. Since 1992, 112 Yellow-bellied have been recorded, and all were between May 25 and October 1. Other empids occurred during late May through early October. Numbers peaked in June, with a lesser peak in September.