Western Birds Journal

Volume 40, No. 3

Published July 1, 2009

Issue description

Volume 40, number 3 of Western Birds, published 2009

Articles

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    DANIEL S. SINGER, SCOTT B. TERRILL (Author)

    THE 33RD REPORT OF THE CALIFORNIA BIRD RECORDS COMMITTEE: 2007 RECORDS

    The California Bird Records Committee reached decisions on 285 records involving 92 species evaluated during 2007, endorsing 238 of them. New to California were Townsend’s (Newell’s) Shearwater (Puffinus auricularis newelli), Tristram’s Storm-Petrel (Oceanodroma tristrami), Lesser Frigatebird (Fregata ariel), Swallow-tailed Kite (Elanoides forficatus), Eurasian Kestrel (Falco tinnunculus), Wood Sandpiper (Tringa glareola), and Common Rosefinch (Carpodacus erythrinus). Adjusting for these changes brings California’s bird list to 640 species, ten of which are non-native.

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    MARY F. WILSON, GREY W. PENDLETON, KATHERINE M. HOCKER (Author)

    DISTRIBUTION, ABUNDANCE, AND SURVIVAL OF NESTING AMERICAN DIPPERS NEAR JUNEAU, ALASKA

    We studied the distribution of the American Dipper (Cinclus mexicanus) near Juneau, Alaska, from 2004 through 2008. An upper limit on the local abundance and distribution of dippers in our area resulted from several factors, including stream size and food abundance, nest sites, and territorial aggression. Dippers nested only along streams with an estimated flow in summer of at least 0.5 cubic feet per second and nested commonly only where flow exceeded 0.9 cubic feet per second. Large streams provided a greater average density and estimated total abundance of benthic macroinvertebrates. Although most territories were centered on typical fast, rocky reaches of fairly high gradient, a few were centered on low-gradient reaches with a sandy substrate where anthropogenic nest sites were available. Some nests were located along glacial streams, but no nests were located along streams originating in bogs. Nest sites were typically in locations protected from predators, floods, and other hazards. After each of three cold winters apparent survival was low, markedly reducing the number of occupied territories; survival analysis with the program MARK showed that apparent survival decreased with decreasing winter temperature. We suggest that if dippers are used as indicators of stream quality in our area, the research should either include multi-year and region-wide surveys of distribution and abundance to account for annual variation in survival or focus on the effects of stream pollution on dipper physiology and reproduction.

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    EDWARD R. PANDOLFINO, KIMBERLY SUEDKAMP WELLS (Author)

    CHANGES IN THE WINTER DISTRIBUTION OF THE ROUGH-LEGGED HAWK IN NORTH AMERICA

    We used Christmas Bird Count (CBC) data to demonstrate a shift in the winter distribution of the Rough-legged Hawk (Buteo lagopus) in North America from the late 1970s to the early 2000s. Data from nearly 300 CBC circles reveal decreases in the Rough-legged Hawk’s abundance on the east and west coasts and throughout the southern portion of this species’ winter range. Its abundance increased in the northern portions of the Great Plains. This distributional shift was associated with a decrease in the number of December days with substantial snow cover in the northern Great Plains and an increase in the winter abundance of the Red-tailed Hawk (Buteo jamaicensis) throughout most of the range of the Rough-legged Hawk. In addition, increasing human populations and associated loss of open country may have contributed to this shift.

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    ANTONIO GUTIÉRREZ-AGUILAR, ROBERTO CARMONA, ANDREA CUELLAR (Author)

    NESTING SUCCESS OF CALIFORNIA LEAST TERNS AT THE GUERRERO NEGRO SALTWORKS, BAJA CALIFORNIA SUR, MEXICO, 2005

    We studied a nesting colony of the Least Tern in the saltworks at Guerrero Negro, Baja California Sur, between 31 May and 23 July 2005. We marked the nests as they appeared and counted nests, eggs, and chicks daily. In a comparison of two periods of laying (31 May–13 June and 17 June–19 July) average clutch size of 15 nests (2.06 and 2.00 eggs/nest, respectively) did not differ, suggesting that in the year of our study food was not a limiting resource. We observed 36 chicks, 31 from the first period and five from the second. Incubation in the second period was interrupted by natural predation of nine nests (eight by coyotes and one by ravens). The hatching and fledging success of eggs laid during the first period were 100%, higher than for those laid in the second period (16% and 26%, respectively); the low values of the second period are attributable to a longer time during which the colony was exposed to predation. Though in an artificial habitat, the colony was not affected by human disturbance and enjoyed a high success rate overall. The problem of coyote depredation could be prevented with a fence, increasing the terns’ success further.

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    ENRIQUETA VELARDE, MARISOL TORDESILLAS (Author)

    SANDWICH TERNS ON ISLA RASA, GULF OF CALIFORNIA, MEXICO

    In North America the Sandwich Tern (Thalasseus sandvicensis) breeds locally along marine coasts and offshore islands primarily of the southeastern United States and Caribbean (AOU 1998). In these areas it commonly nests in dense colonies of the Royal Tern (T. maximus) and Laughing Gull (Leucophaeus atricilla; Shealer 1999). It winters along the coasts of the Atlantic Ocean and Gulf of Mexico from Florida to the West Indies, more rarely as far south as southern Brazil and Uruguay. It also winters on the Pacific coast, mainly from Oaxaca, Mexico, south to Panama (Howell and Webb 1995), occasionally to Colombia, Ecuador, and Peru (AOU 1998). As there are no breeding colonies on the Pacific coast, all birds wintering there are believed to represent migrants from Atlantic and Caribbean colonies (Collins 1997, Hilty and Brown 1986, Ridgely 1981, Ridgely and Greenfield 2001). Sandwich Terns have occasionally wandered as far north as eastern Canada (New Brunswick, Nova Scotia, and Newfoundland) and inland to Minnesota, Michigan, and Illinois (AOU 1998, Clapp et al. 1983). In the Pacific, vagrants are known from California and the Hawaiian Islands (Hamilton et al. 2007, AOU 1998).

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    CARROLL D. LITTLEFIELD (Author)

    CURVE-BILLED THRASHER REPRODUCTIVE SUCCESS AFTER A WET WINTER IN THE SONORAN DESERT OF ARIZONA

    Studies of avian reproductive success provide important clues about the relationship between a species’ population and its habitats. Although many species are hard to study because their nests are difficult to locate and assess, the Curve-billed Thrasher (Toxostoma curvirostre) is an ideal subject. Its open-cup stick nests are easy to find and often at a height convenient for observing nest contents. For the subspecies in southeastern Arizona (T. c. palmeri), the breeding season can begin in late January, but generally nesting does not increase sharply until late March, with a distinct peak from mid-April through mid-May (Corman 2005). The initiation of breeding, however, seems (in part) correlated with the amount of winter precipitation. Two or more wet months in succession lead to food resources sufficient to elicit early nesting (Smith 1971), but earlier clutches may be smaller than those laid later, as early in the season food supplies may be limited (Stahlecker 2003). As food supplies increase, clutch sizes increase (Smith 1971). On the other hand, the success rate of earlier nests may be greater, as important predators of eggs and nestlings, such as snakes, are less active early in the season (Tweit 1996). To assess the Curve-billed Thrasher’s nesting chronology and reproductive success after a period of abundant autumn–winter rainfall, I began a study of its nesting near Tucson, Pima County, Arizona, in late January 1979.

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    LUCAS H. DeCICCO, STEVEN C. HEINL, DAVID W. SONNEBORN (Author)

    FIRST NORTH AMERICAN RECORDS OF THE RUFOUS-TAILED ROBIN (LUSCINIA SIBILANS)

    The Rufoous-tailed Robin (Luscinia sibilans) breeds in Asia from the Altai Mountains and upper Yenisei River east to the Amur River basin, Ussuriland, and Sakhalin and south to Transbaikalia and Manchuria (OSJ 2000). Nearest to Alaska is an isolated population in central eastern Kamchatka in the Trukhnika River valley (Dement’ev and Glazkov 1954, Vaurie 1959). The species winters mainly from the Yangtze valley, in southern China, south to Hainan; it is a scarce or uncommon winter visitor in northern Thailand, Laos, and Vietnam (Vaurie 1959, Robson 2000). It migrates primarily over continental Asia and is of only rare and irregular occurrence in Japan, primarily in May along the west coast and on islands of the Sea of Japan (Brazil 1991). In Europe, the Rufoous-tailed Robin has been recorded once each in the fall at Fair Isle, Scotland (Shaw 2004), and in early winter at Białystok, Poland (Grygoruk and Tumiel 2006). This species has been reported three times from North America, all in Alaska.

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    RICH HOYER (Author)

    BOOK REVIEW: Bird Songs of the Pacific Northwest

    This set of five compact disks contains 931 separate recordings covering 316 species from the Pacific Northwest. This area is not defined, but to judge from a map on the back cover of the booklet it includes southwestern British Columbia, all of Washington and Oregon, the canyonlands of southwestern Idaho, and about a 100-mile swath of northern California. Each species receives its own track. Each track begins with the species’ name, and individual cuts within each track are separated by a brief pause.

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    ALAN CONTRERAS (Author)

    BOOK REVIEW: Memoirs of a Wildlife Biologist

    I decided to ignore the convention that discourages people from reviewing books by their friends because in this case there is some virtue in having a reviewer who knows the people and the subjects to a certain extent. I admit that I was a co-editor, with Dave Marshall and Matt Hunter, of Birds of Oregon: A General Reference. Marshall’s memoir, issued privately through the Audubon Society of Portland, is far, far more than a personal recollection. It is in effect a compact history of the wildlife refuge system in the Far West, told through the experiences of someone who helped build the refuges from scratch.

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    KURT A. RADAMAKER (Author)

    FEATURED PHOTO - JUVENAL PLUMAGE OF THE AZTEC THRUSH

    The monotypic Aztec Thrush (Ridgwayia pinicola) is endemic to Mexico (Howell and Webb 1995). It ranges from the mountains of central Chihuahua and Coahuila south to the Isthmus of Tehuantepec, favoring Madrean pine–oak woodland (Conservation International 2008) and pine forest from 1800 to 3500 m elevation (Howell and Webb 1995). Outside Mexico, it is casual in southeastern Arizona and southern Texas (AOU 1998). The secretive nature, irregular distribution, and nomadic habits of the Aztec Thrush make it difficult to study, leading to some uncertainty about its true status over much of its range. Also, little is known about its demography and life history; for example, the nests, eggs, and fledglings have rarely been observed.