Volume 26, number 4 of Western Birds, published 1995
Historically, the Glaucous-winged Gull (Larus glaucescens) has been considered an almost strictly coastal species in North America, only occasionally straying far inland. It breeds along the Pacific coast and on nearby inland lakes from Alaska south to northwestern Oregon, and wintersfrom the Bering Sea south to southern Baja California and the Gulf of California (A.O.U. 1983; Verbeek 1993).
The Inyo California Towhee (Pipilo crissalis eremophilus) is restricted to the southern Argus Mountains in Inyo County, California, on lands administered primarily by the Bureau of Land Management (BLM) and China Lake Naval Air Weapons Station (China Lake NAWS). The population is geographically isolated from other subspecies of P. crissalis and differs morphologically from P. c. carolae by having (on average) shorter wings, tail (males only), culmen, tarsus, middle toe, and possibly a grayer coloration (van Rossem 1935; Davis 1951; LaBerteaux 1989).
On 7 October 1994, we collected an adult female Gray Silky-Flycatcher (Ptilogonys cinereus) at Arroyo El Medano, also known as Arroyo Cantamar, about 1.5 km northeast of the town of Cantamar, Baja California, Mexico(32°14'10" N, 116°54'40" W; elevation 15 m). This species has not been previously recorded in Baja California (Grinnell 1928; Wilbur 1987), and the nearest known resident population is located in southeastern Sonora (28°20' N; Phillips 1991), approximately 750 km from the site reported here.
The pantropical Masked Booby (Sula dactylatra) is one of the most pelagic Pelecaniformes off the Pacific coast of Mexico. The Masked Booby breeds on Isla Clarión and Isla San Benedicto in the Revillagigedo group (Everett and Anderson 1991) and on Clipperton Atoll (A.O.U. 1983). It has been reported breeding at Las Rocas Alijos (24°57' N, 115°45' W) since 1925 (Hanna 1926, McLellan 1926), with a current breeding population of about 50 pairs (Pitman 1985).
Only three sighting reports exist for the Pacific coast of Baja California: one juvenile on 23 April 1988 at Islas Los Coronados, Baja California (Everett and Teresa 1988), and single adults on 18 December 1968 and 30 November 1980, both at Cabo San Lucas, Baja California Sur (Wilbur 1987).
Information on the breeding biology of Sabine’s Gulls (Xema sabini) is very limited. Parmelee et al. (1967) detailed the species’ life history on Victoria Island, northern Canada. Abraham (1986) quantified nesting and brood-rearing chronology and success, and noted a strong relationship between nesting Sabine’s Gulls and Arctic Terns (Sterna paradisaea). Additionally, Abraham and Ankney (1984) described partitioning of food resources by Sabine’s Gulls and Arctic Terns.
Patten et al. (1995) offered a stimulating overview of the current state of field ornithology in California since the publication of Grinnell and Miller’s (1944) classic The Distribution of the Birds of California. Nevertheless, we feel compelled to expand upon their views regarding the level of knowledge accumulated since 1944 and the direction we see field ornithology in California moving most profitably.
