These loud, large birds were fairly common but rather wary and tended to forage high in the canopy making photography difficult. They were most active at dawn and dusk.
Some authors call this bird the Purple or Purplish Guan. It has also been classified under the name P. cristata which is a synonym.
This is the nominate race found in Mexico and adjacent Central America. Two other smaller races with less white markings range south into South America.
Digiscoped with Panasonic DMC-LZ5 | Nikon FieldScope III | 30XWA | hand-held (no adapter)