Volume 12, number 4 of Western Birds, published 1981
The official state bird list for Oregon has not been updated since 1940 when Gabrielson and Jewett published their monumental work, Birds of Oregon. Since that time many additional birds have been recorded in Oregon. Others have significantly changed their status and distribution. The need for a revision of the official state list has prompted the publication of this paper.
Many recent quantitative studies of avian population ecology have used strip transect methods to estimate bird densities (see Emlen 1971, 1977). These methods, and indeed all census methods, suffer from complications and limitations, some of which pertain to the observation conditions (e.g., weather and time of day). Traditionally the bias introduced by diurnal variations in bird detectability has been met by limiting censusing to early morning “when birds are most active” (Pettingill 1970). However, recent findings that detectability may vary inversely with time of day in winter, but directly with time of day in summer (Anderson and Ohmart 1977, Shields 1977), or in some species (Robbins 1981), emphasize the need for further studies.
Since 1978 we have been intensively censusing bird communities along a 2600-m altitudinal gradient in California’s Santa Rosa Mountains, using the narrow strip transect method (Merikallio 1946, 1958). In order to sample all of our transects monthly, we have had to census at various times of day. Our early results suggested that, in the open desert habitats of our study region, time of day had little influence on census results, provided air temperature was below about 35 C. Indeed, midday censuses seemed to yield density estimates comparable to those obtained at sunrise. To examine this further, we censused two desert habitats ten times each, twice daily — once around sunrise and once at midday — between 25 March and 9 April 1980.
Although the marshes associated with Bear Lake, the Bear River and the Great Salt Lake are noted for providing habitat for large concentrations of waterbirds, the status of the shorebirds (Charadrii) has not been well-documented in northern Utah. Because of their location in the arid Great Basin, these extensive marshes may be a critical staging area for many migratory shorebirds; in addition, they support substantial breeding populations of several species. As human demand for the limited water resource increases, information about the seasonal use of the wetlands by shorebirds becomes more urgent for consideration in water management decisions. This paper presents new information on the phenology of migration and nesting, and on the numerical status, of shorebirds in northern Utah.
For at least 9 days during May 1980 a Sandwich Tern (Sterna sandvicensis) was present near Imperial Beach, San Diego Co., California. All sightings were made at the Elegant Tern (S. elegans) breeding colony located in the saltworks at the south end of San Diego Bay. I first saw the Sandwich Tern the afternoon of 11 May with a group of about 150 Elegant Terns, 50 Forster’s Terns (S. forsteri) and 6 Least Terns (S. albifrons) which were foraging in an outer evaporating pond on numerous small (2–10 cm) fishes, mostly Topsmelt (Atherinops affinis) and Longjaw Mudsuckers (Gillichthys mirabilis).
On 9 January 1977 James A. Gast of Arcata, California, picked up a dead Pied-billed Grebe (Podilymbus podiceps) at the mouth of Maple Creek, Humboldt County, California. Because there are relatively few documented cases of natural mortalities in birds, I present some information on this one.
The grebe, a robust male, weighed 564 g, and had a wing chord of 142 mm. A Prickly Sculpin (Cottus asper) protruded outward between the bird’s mandibles (Figure 1). The sculpin, a female, was 131 mm standard length (tip of snout to base of caudal fin), 153 mm total length, and weighed 42.4 g (preserved wet weight). It had large ovaries weighing 5.3 g, with maturing ova which caused the abdomen to bulge. The preopercular spine of each gill cover protruded slightly and appeared to be lodged in the gular skin of the grebe just posterior to the base of the mandibles. The entire gular region was examined for hemorrhaging, or obvious internal injuries. As none were discovered, I assumed the cause of death to be suffocation. Both bird and fish were in fresh condition.
At 1230 on 26 August 1980, while making counts of Band-tailed Pigeons (Columba fasciata) at an artificial bait site, I observed an albinistic bandtail near Evergreen, Jefferson County, Colorado. This pigeon was with four normally-colored bandtails and landed in a tree approximately 40 m from my vehicle. I viewed the aberrant pigeon through a 15–60x spotting scope and recorded its general appearance. The feathers on the head, back and dorsal side of the wings and tail were buff-yellow to cream-colored (Smithe 1975). The tip of the tail was lighter but the terminal band was indistinct. The nape was purple-iridescent but the neck crescent was absent. The breast feathers were buff-colored. The pigeon had spectrum yellow legs and feet but a glaucous bill, and appeared similar in size to another nearby immature bandtail.
The buff-yellow plumage of this bandtail was almost certainly caused by loss of pigment or schizochroism (Harrison 1963). In Rock Doves (C. livia), “yellow” plumage refers to a dilute erythristic form. Both the normal eumelanin and phaeomelanin pigment concentrations were probably reduced in the plumage of the observed pigeon. It could be classified as a nonmelanic schizochroic (Harrison 1966).
