Volume 2, number 4 of Western Birds, published 1971
Because of their migratory behavior and high mobility, birds frequently appear in areas far outside their normal ranges. Essential to understanding the significance of these extra-limital individuals is the accumulation of accurate data concerning their distribution and status (wild or non-wild).
Joseph Grinnell (1922) wrote, “it is only a matter of time theoretically until the list of California birds will be identical with that for North America as a whole.” This prediction is being rapidly fulfilled. However, the many records of “accidentals” obtained in California since 1922 suggest that we should reexamine the application of that term, particularly as applied to such species in California. Specifically we here ask whether the records of accidentals are without pattern, or whether they are in general predictable on the basis of zoogeographic and/or ecological characteristics of the species involved.
The fifth edition of the A.O.U. Check-list (1957) states that the Glaucous-winged Gull (Larus glaucescens) breeds from western Alaska south to Copalis Rocks, Washington. In the southern part of its breeding range (Vancouver Island to Copalis Rocks) it is sympatric with the northernmost populations of the Western Gull (L. occidentalis) (Pearse, 1946; Jewett et al., 1953). In the summers of 1969–1971 several pairs of Glaucous-winged Gulls nested on Yaquina Head, Oregon (44°40'N, 124°05'W), 300 km south of the previously reported southernmost breeding colony for this species. Approximately 60 ± 10 pairs of Western Gulls also nested on Yaquina Head. In addition, three L. glaucescens were paired with L. occidentalis in the colony (Fig. 1). In 1971, six known hybrids were banded from a total of three nests.
On the morning of 13 April 1971 while looking at birds in the vicinity of Imperial Dam with Bill Clow and Richard MacIntosh, I found an Olivaceous Cormorant Phalacrocorax olivaceus in breeding plumage. The bird was found among Double-crested Cormorants P. auritus on West Pond, situated about one quarter mile west of Imperial Dam on the California side of the Colorado River. During the two hours we had the bird under observation it was perched on a short snag in the pond with an adult and three immature Double-crested Cormorants. The close proximity of the bird to the Double-crested Cormorants enabled us to make a direct size comparison of the two species.
On 18 November 1967 a party of us, including Pierre Devillers, Alan Craig, and Cliff Lyons, were spending the afternoon checking for birds in the Tijuana River Valley to the south of Imperial Beach, San Diego County, California. At Windover Ranch, a small but well-watered avocado orchard situated just north of the Mexican border, I discovered a Wood Thrush Hylocichla mustelina.
On 12 June 1963 Eugene Kridler (1965) collected an adult female (USNM #479637) Tennessee Warbler (Vermivora peregrina) at Malheur National Wildlife Refuge Headquarters, Harney County, Oregon. This represented the first record of the species in the state. Kridler also banded and photographed (color transparencies on file at refuge H.Q.) an immature on 15 October 1963 at the same locality.
Although the Roadrunner (Geococcyx californianus) has long been known for its bird-catching propensity, there are few well-documented accounts of such behavior under natural conditions. Bent (U.S. Natl. Mus., Bull. 176:44-45, 1940) summarizes a number of observations, mostly concerning pet Roadrunners or juvenile prey, and Zimmerman (Condor, 72:475-476, 1970) details the capture of several adult passerines near a feeding station in New Mexico.
In a recent editorial comment (Calif. Birds 1:80, 1970), I uncritically repeated the Baja California record of a Nutting’s Flycatcher Myiarchus nuttingi inquietus from Catavina on 6 October 1930, quoted both by the North American check-list (A.O.U. Check-list of North American birds, 1957) and the Mexican check-list (Miller in Miller et al., A distributional check-list of the birds of Mexico, Part II, 1957). The bird was originally reported by Huey (Auk 48:429-430, 1931).