Very few of the early scientific explorers in the Gulf of California had much to say about the land birds. There might be two reasons for this: first, the land birds in arid, desert regions are sparse and in general unbecoming, and second, the species encountered are by and large those seen in the much more accessible regions of southwestern North America. Chapter 1 introduced János Xántus, who is recognized as the pioneer ornithologist (or at least bird collector) in the cape area of Lower California, whose contributions (e.g., 1859, in which the first description of the Gray Thrasher, Toxostoma cinereum, was published) are appropriately commemorated in the Xantus Hummingbird, the most spectacular endemic on the peninsula. Lawrence (1860) first described the species as Amazilia xantusi (thence Hylocharis xantusii, and now Basilinna xantusii), and P. L. Sclater announced the discovery to Ibis readers in the same year. By the end of the nineteenth century, several ornithologists had collected in the southern peninsula and reported their findings (e.g., Baird 1870; Belding 1883; Bryant 1889; Ridgway 1896), but very little of this work referred to the islands in the gulf. Brewster’s (1902) report on the cape region avifauna was the most comprehensive of the earlier studies. Serious attention was first paid to the gulf island birds by Maillard (1923) and Townsend (1923), and the latter’s 1911 island-hopping trip in the Albatross served as a model for many similar expeditions later. The first distributional synthesis of their work, and especially that of Nelson (1921), Lamb (e.g., 1924), and Thayer (e.g., 1907), was published by Joseph Grinnell in 1928 in a monograph that is still the standard reference for the peninsula and gulf area. The last 50 years have seen little progress beyond the accumulation of further distributional records and the description of new subspecies (e.g., van Rossem 1929, 1932; Banks 1963a,b,c, 1964, 1969). The island birds remain rather poorly known; even species lists are likely to be incomplete, and ecological studies of the island populations have scarcely begun. In this chapter we report on the results largely of our own field work.