Boat-billed Flycatcher (Megarynchus pitangua)

Nominate race has structurally very different daytime “rattle” call involving alternations of a very burry nasal note and a more whistled nasal note (latter flat or upslurred), without an obvious long note at end (score 2–3) (other taxa have burry or flat rattling notes ending with longer, usually emphasized note); chrysogaster fairly distinct, a short series of burry downslurred notes ending with longer note, quite similar to calls in W Mexico (“mexicanus group”); race mexicanus stands apart, with higher number of notes, shorter note length and faster pace (all scoring 2–3, giving total score of about 5)#R; more research needed on taxonomic implications. Trinidad birds described as race parvirostris, supposedly with smaller bill, but otherwise indistinguishable from South American birds. Some races seem readily distinguishable, others less so; populations of nominate from S Brazil and Paraguay appear somewhat larger and darker on average than those in N, but much individual variation; critical re-evaluation of races is needed. Six subspecies currently recognized.