The Great Kiskadee appears like a much bigger version of the very familiar Lesser Kiskadee (not in Mexico but 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 guatimalensis which is found in southeast Mexico to central Panama.

Tapachula, Chiapas, Mexico, 27 April 2011