Chico's Tyrannulet is one of the least known species of tyrant flycatchers. This tiny bird was completely unknown to ornithology until it was detected in 2009. Currently Chico's Tyrannulet is known only from a small area in south central Amazonian Brazil, where it occupies campina vegetation (low stature forest and scrub) on sandy soils. It is primarily frugivorous, often feeding, like other species of Zimmerius, on the small fruits of mistletoes. In appearance, Chico's Tyrannulet is extremely similar to Mishana Tyrannulet (Z. villarejoi) of northern Peru; these two species also are very similar vocally, but the calls and songs of Mishana Tyrannulet are slightly higher in pitch than are those of Chico's. The known distributions of Chico's and Mishana Tyrannulets are ca 1400 km apart, but it is possible that these, or other previously unknown tyrannulets, may occur somewhere in between.