Really, you can be anywhere and be a birder. The most prolific bird, seen multiple times each day on my trip down the Colorado River, was the Great Blue Heron.
Lifted from the National Park Service web page for birds of the Grand Canyon:
The lush vegetation and diversity of plant species along the riparian zone create many bird habitats in a relatively small area. Of the 373 bird species recorded in the greater Grand Canyon region, 250 are found in the Colorado River corridor. Only 48 bird species regularly nest along the river while others use the river as a migration corridor or as overwintering habitat. The Bald eagle is one species that uses the river corridor as winter habitat. The trout rich waters of the Colorado River provide a perfect food source for the eagles. Since the construction of Glen Canyon Dam, large numbers of waterfowl have begun using the stretch of river below the dam during the winter, peaking in late December and early January. Nineteen species have been regularly reported between Lees Ferry and Soap Creek, at a density of 136 ducks per mile.
See the National Park Service link above for a list of birds. Or swing over to amazon.com for a list of Grand Canyon birding books.
Photo courtesy of Utah Division of Wildlife Resources.