Volume 20, No. 1

CAMERON W. BARROWS (Author)

DIETS OF FIVE SPECIES OF DESERT OWLS

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Common Barn-Owls (Tyto alba), Great Horned Owls (Bubo virginianus), Long-eared Owls (Asio otus), Western Screech-Owls (Otus kennicottii), and Burrowing Owls (Athene cunicularia) all occur as year-round or seasonal residents of southern California deserts. This species richness provided me an opportunity to compare the diets of these owls both within and between desert regions. Within-region comparisons allowed analyses in situations where all owl species had access to the same prey base, eliminating differential prey availability as a factor. Interspecific differences under these conditions might then be due to differences in predatory behavior or prey preferences. Additionally, I was able to follow month-to-month variation in diets of three sympatric owl species to determine if their dietary fluctuations were synchronous or independent.

BRIAN E. DANIELS, LOREN HAYS, DEBRA HAYS, JOSEPH MORLAN, DON ROBERSON (Author)

FIRST RECORD OF THE COMMON BLACK-HAWK FOR CALIFORNIA

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On 13 April 1985, Daniels and the Hayses found a Common Black-Hawk (Buteogallus anthracinus) at Thousand Palms Nature Conservancy Preserve, Riverside County, California, a lush California Fan Palm (Washingtonia filifera) oasis with a creek lined by Fremont Cottonwoods (Populus fremontii). They first saw the hawk at 0700 flying downstream about 50 yards away. A Common Raven (Corvus corax) whose nest was nearby harassed it. The hawk flew back over the observers (within about 50 feet) and disappeared into the palm trees. At about 0800 they saw it again about a half mile upstream. It flew past them and then circled higher and higher, disappearing toward the north. They observed the bird for a total of about 15 minutes. Efforts to follow it by car were unsuccessful. They, and others, searched for the hawk later that day, but did not find it.

WILLIAM I. BOARMAN (Author)

THE BREEDING BIRDS OF ALCATRAZ ISLAND: LIFE ON THE ROCK

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Grinnell and Wythe (1927) summarized the bird life of the San Francisco Bay region, paying particularly close attention to distribution and nesting sites. However, neither their report nor any other covering the area has mentioned the avifauna of one of the most prominent and well-known land features in the region: Alcatraz Island. The avifauna of Alcatraz is of interest because the island is only 1.6 km from a large city and a large number of people (an average of 2300 daily, R. Weideman pers. comm.) visit it year round.

Until recently, no ornithologist or natural historian had visited or at least had reported on any visits to the island. The only publications on the island’s birds are by Binford (1980), Howell et al. (1983), and Howell (1983). Here I summarize my observations of the birds breeding on Alcatraz. The data are based on many casual observations between May and August 1981 and between April and July 1982. All Western Gull nests were mapped during this period and on 10 and 30 May 1983.

RICHARD A. ERICKSON, JOSEPH MORLAN, DON ROBERSON (Author)

FIRST RECORD OF THE WHITE-COLLARED SWIFT IN CALIFORNIA

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At midmorning on 21 May 1982, Erickson and his birding companions Lynn C. Berner, Gary S. Lester, Gary J. Strachan, and Richard S. Tryon were near the spruce grove at Point St. George, Del Norte County, extreme northwestern California, when a swift caught their attention. Erickson’s first impression was of Black Swift Cypseloides niger, but Strachan noted white on its neck; soon the whole group focused on the bird. It was a large swift with tattered primaries that fed with a flock of swallows, including Barn Hirundo rustica, Cliff H. pyrrhonota, Tree Tachycineta bicolor, and Violet-green T. thalassina swallows, over the grassy headland northeast of the spruce grove. The morning fog was breaking up and lighting conditions were good. The observers watched the bird with binoculars and a 20 x telescope, as it approached them sometimes to within 15 m, for 20 to 40 minutes. The swift fed from a height of 100 m to within 8 m of the ground.

ASA C. THORESEN (Author)

NOTES: DIVING TIMES AND BEHAVIOR OF PIGEON GUILLEMOTS AND MARBLED MURRELETS OFF ROSARIO HEAD, WASHINGTON

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Data on the times and frequency of dives by Atlantic alcids have been reviewed by Bradstreet and Brown (1983), who pointed out the need for more such information for this family of birds. Scott (1973) presented data on diving times and depths for marine birds, including the Pigeon Guillemot (Cepphus columba), observed along the Oregon coast. Carter and Sealy (1984) found Marbled Murrelets (Brachyramphus marmoratus) in fish nets set at depths of 8 to 10 m, while Piatt and Nettleship (1985) recorded Black Guillemots (Cepphus grylle) caught in nets at 50 m and diving times for that species of up to 112 seconds in water 35 to 45 m deep.

STEPHEN F. BAILEY (Author)

NOTES: LEAST AUKLET IN CALIFORNIA

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During the afternoon of 15 June 1981 a distressed Least Auklet (Aethia pusilla) was found on Thornton State Beach in Daly City, San Mateo County, California, the first location southeast of Kodiak, Alaska, where the Least Auklet has been recorded. A park ranger rescued the bird and delivered it to the Peninsula Humane Society in San Mateo. Despite care the auklet died overnight. On 18 June I confirmed the identification and secured the specimen for the Museum of Vertebrate Zoology (MVZ), University of California, Berkeley.