The observations and descriptions included in the following pages have come to attention during detailed studies of the birds of the Isthmus of Panamá and their comparison with forms from other tropical areas. They are based in the main on the collections of the United States National Museum, with addition of specimens seen in the course of work at other institutions.
- Geographic variation in the Black Vulture, Coragyps atratus (Bechstein)
- The Crested Bobwhite, Colinus cristatus (Linnaeus), of western Chriquí (Colinus cristatus mariae subsp. nov.)
- An additional race of the Chestnut-backed Antbird, Myrmeciza exsul Sclater (Myrmeciza exsul niglarus subsp. nov.)
- The geographic races of the Silver-throated Tanager, Tangara icterocephala (Bonaparte) (Tangara icterocephala oresbia subsp. nov.)
- Additions to the recorded list of birds from the Republic of Panamá
- Additions to the list of birds known from Colombia