Figure 1. Photo made in early morning, poor light, no flash. Exposure time 1/9 sec (!), f/2.8, ISO 800, from a hide.

The bird on the photo was probably only a few months old. I saw it at the waterhole together with two adult White-browed Guans. The latter tried several times to chase the young bird away, but it insisted and continued in their company.

The Rusty-margined Guan is described in the literature as having the upper wing coverts and the secondaries edged rufous or ochraceous (Blake 1977, Mata et al. 2006, Sick 1997). In comparison with the nominate race, the rufous on the wing feathers of subspecies jacupemba is usually paler (Blake 1977). But the individual on the photo has the wing feathers edged whitish, with only a faint touch of rufous on some feathers (hardly visible on photo).

So far, I have no information about the normal appearance of the Rusty-margined Guan in our region. There seems to be quite some variability, though. For example, I have seen photos of a Rusty-margined Guan from Piaui with a rusty (and not white) superciliary. I am not certain whether the bird on the photo is representative of the local population; the white on the wings could also be a color aberration.

See Teixeira and Sick 1998 for color aberrations in other Cracidae species.