The White-winged Guan is endemic to a small region in northwestern Peru, in the equatorial dry forests of the western slope of the main Andean chain in the departments of Piura, Lambayeque, and Cajamarca. In the 19th-century, it was known from three specimens, the first one collected by Jean Stolczmann on 18 December 1876 on ‘La Condesa’ island, a mangrove-covered island at the mouth of the Tumbes River, near the Ecuadorian border, now at Warsaw Museum. The second specimen was collected by Konstanty Jelski at Hacienda Pabur, in the dry forests at the border between the provinces of Piura and Lambayeque, on 10 January 1877. This bird was a female and was found with two chicks, one of which died and the other was raised by Jelski, whereupon it became the third specimen, now held at The Natural History Museum in Tring. The female is held at the Museo de Historia Natural “Javier Prado” in Lima.
There were no further records in the 19th or early 20th centuries, and many authors speculated that this species had become extinct. The validity of albipennis was doubted, with some authors having speculated that the specimens represented partially albino Baudó Guans (Penelope ortoni) (Vuilleumier 1965).
Then, in a dramatic rediscovery, Gustavo del Solar and John O'Neill found the White-winged Guan just after a century with no records. It was 13 September 1977 when Solar and O’Neill, together with their guide Sebastian Chinchay, arrived at the San Isidro quebrada, where Chinchay had found a group of guans at the same site a few days earlier, and inform Solar about his finding. They found about eight guans. The rediscovery, which had come exactly 100 years after the last specimens had been collected, was filmed using an 8-mm camera by del Solar, helping to document ‘the rediscovery of the century’.
In fact, del Solar was looking for the guan since 1969, when he received the description from Maria Koepcke, when they met at the Museo de Historia Natural in Lima, while Koepcke was curator of the ornithology department. She asked if he had seen a black turkey-like bird with white in its wings. Solar answered negatively, but promised to look out for it. Although Delacour & Amadon (1973) believed that the species was already extinct, Koepcke maintained hope that the species might yet survive in the deep, forested, valleys of Piura and Lambayeque. Consequently, Solar started to spread the word among the local people of Olmos.
Following the rediscovery of the guan in 1977, it became clear that the taxon did indeed merit species rank (Eley 1982) and also, a series of extensive surveys were conducted of suitable habitat in river valleys in Piura and Lambayeque, and the guan was discovered at many additional sites.
The known northern distributional limit is at 5º25' S 79º55' W, and the southern limit is at 6º39'25" S 79º22'30" W (Diaz and del Solar 1997, Ortiz and Diaz 1997) within a strip of forests approximately 175–190 km long and 5–40 km wide. The original distribution of the White-winged Guan was continuous, but now it's distribution is interrupted by the Olmos-Jaen road (see Effects of human activity on populations), which subdivides the species into a larger northern population and a smaller southern population.
Across most of its range, the elevational range of the White-winged Guan is 500-1100 m, although occasionally it is reported as low as 300 m (Ortiz 1980). Recent research showed that the species can be found as high as 1385 m in the Quebrada Shambo of the Laquipampa Wildlife refuge (sharing at least 100 m elevation
of habitat with the Bearded Guan Penelope barbata) (Angulo 2008).