Vol. 18 No. 3 (1987)

The Willow Flycatcher (Empidonax traillii) is a widely distributed species with a breeding range extending from southern British Columbia south to northern Baja California and east to the Atlantic coast. Small passerines with such wide ranges usually show some geographic variation, and several subspecies of E. traillii have been described by Oberholser (1918, 1932, 1947), Phillips (1948), and Aldrich (1951).

However, proof that the former "Traill's Flycatcher" is actually composed of two sibling species (Stein 1958, 1963), now known as the Willow (E. traillii) and Alder (E. alnorum) flycatchers, disrupted the study of intraspecific variation in this pair.

Alpine ecosystems occur as isolated islands on the highest of the Great Basin mountain ranges. These include the Wassuk, White, Humboldt, Toiyabe, Toquima, East Humboldt, Ruby, Grant, Schell Creek, Snake, Deep Creek, and Stansbury mountains (Cronquist et al. 1972). Like other altitudinally zoned ecosystems of Great Basin mountain ranges, alpine ecosystems have been neglected in the past because of difficult access and false impressions of biotic sterility (Johnson 1978). Recently, more attention has been directed to the scientific study of these unique environments and to their wise use and management (Ives and Barry 1974, Thilenius 1975, Billings 1978, Johnson 1979, Braun 1980).

Recent sightings of Common Ground-Doves (Columbina passerina) in Santa Barbara County and especially Ventura County, California, indicate that this dove is less rare in those counties than previously thought. This apparent change in status may not be due to inadequate past coverage, but rather may reflect a population increase caused by relatively recent changes in agricultural practices and dramatic increases in avocado acreage in Ventura and southern Santa Barbara counties.

On 30 June 1983, on South Plaza Island, Galápagos Archipelago, we observed a gull obviously different from the resident Swallow-tailed (Creagrus furcatus) and Lava (Larus fuliginosus) gulls of the islands. We initially found the gull in one of the abundant tide pools along the island’s rocky shore. From there, it flew a short distance to a sea lion carcass, where it supplanted a Lava Gull and fed on the maggots covering the rotting carcass. The gull then flew a few hundred meters to a pool where several members of our party took close-up photographs (e.g., Figure 1) that show the bird to have been a Ring-billed Gull (Larus delawarensis) in adult plumage.