The Great Kiskadee appears like a much bigger version of the very familiar Lesser Kiskadee (in Guatemala and south to Argentina).
However, the Lesser Kiskadee prefers wetter areas like swamps and has a much thinner bill than its bigger brother.
In addition, the Great Kiskadee makes a sound like "kiss my rear" while the Lesser Kiskadee makes rather nasal, buzzy and slurred calls.

There are currently 10 recognized subspecies of the Great Kiskadee. 
This is Pitangus sulphuratus sulphuratus which is found in Surinam, the Guianas and north, west, central Amazonian Brazil, southeast Colombia and east Ecuador to southeast Peru.

1st photo: Manu Wildlife Center, Manu Biosphere Reserve, Peru, 28 June 2009
2nd, 3rd & 4th photo: Reserva Ecologica Taricaya, Puerto Maldonado, Peru, 10, 11 & 12 June 2009