Vol. 38 No. 4 (2007) | Western Birds

JAY D. CARLISLE, GREGORY S. KALTENEKER, RYAN S. BRADY (Author)

STATUS OF THE BROAD-WINGED AND RED-SHOULDERED HAWKS DURING FALL MIGRATION IN SOUTHWESTERN IDAHO, 1995–2006

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Twelve years of counting raptors during fall migration near Boise, Idaho, yielded 214 Broad-winged and 9 Red-shouldered Hawks, revealing these species as much more frequent in Idaho than previously known. The Broad-winged Hawk is an uncommon, annual fall migrant in Idaho. The Red-shouldered Hawk is at least casual, possibly nearly annual, during fall migration. These data match increased sightings from other western states that have likely resulted from a combination of increased observer coverage and possible range expansions and/or numerical increases for both species in the West.

DAVID H. ELLIS, CHARLES T. LaRUE, JAMES K. FACKLER, R. WAYNE NELSON (Author)

INSECTS PREDOMINATE IN PEREGRINE FALCON PREDATION ATTEMPTS IN ARIZONA

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We compare two methods of collecting data on food habits (observations of predation attempts [n = 131] and analysis of prey remains at eyries [n = 809]) for Peregrine Falcons (Falco peregrinus) in Arizona. White-throated Swifts (Aeronautes saxatalis) were pursued in at least 38% of the predation attempts on birds but constituted 22% of the avian diet (by number) from prey remains. Insects constituted 1% of prey remains from eyries but were targets in 69% of observed attacks on prey. Insects, primarily cicadas (Cicadidae), were especially important numerically to breeding females guarding their nest cliffs. These observations suggest that insects may be much more important than formerly supposed in the Peregrine Falcon’s diet in other regions when and where large insects are aloft.

DARRELL L. WHITWORTH, HARRY R. CARTER (Author)

COLONIZATION OF THE BROWN BOOBY AT THE CORONADO ISLANDS, BAJA CALIFORNIA, MEXICO

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In 2005, we documented the colonization of Middle Rock, Coronado Islands, Baja California, Mexico by the Brown Booby (Sula leucogaster brewsteri)—a significant northern extension of the species’ breeding range possibly related to warming trends in the northeastern Pacific Ocean. Confirmed nesting in 2005 was preceded by an increase in sightings at sea along the northwest coast of Baja California and California in the 1990s and early 2000s and attendance at Middle Rock since at least 2002. In 2002, we observed Brown Boobies on Middle Rock in incubation postures attending two Western Gull (Larus occidentalis) nests containing one gull egg each. One of these gull nests was attended for at least 33 days at the exact site where a single Brown Booby nest was confirmed each year from 2005 to 2007. In 2005 the nest successfully fledged a chick but in 2006 failed for unknown reasons. In 2007, two nests fledged single chicks. Excluding juveniles, documented attendance of at least 6 boobies in 2002, 7 in 2006, 12 in 2006, and 35 in 2007 suggests that the colony will grow further.

PHILIP UNITT (Author)

AN APPARENT HYBRID BREWER’S × BLACK-CHINNED SPARROW

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An apparent hybrid between the Brewer’s and Black-chinned Sparrows, found in the Cuyamaca Mountains, southern California, in 2007, was closest in plumage to Brewer’s Sparrow but outside that species’ range of variation. It sang intermediate songs. The bird, and two other possible hybrids, occurred in areas extensively burned in 2002 and 2003. In these areas the numbers of the Black-chinned Sparrow increased spectacularly following the fires and Brewer’s Sparrow occurred in the breeding season sporadically, outside its historic breeding range.

JOSEPH R. JEHL, JR. (Author)

ADDITIONAL NOTES ON LEUCISTIC EARED GREBES AT MONO LAKE

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Blumin’s (2007) photograph essay on a leucistic grebe correctly identified it as an Eared Grebe (Podiceps nigricollis), which, incidentally, is an adult (red eye) and probably a male, judging by the apparent length of the bill (Jehl et al. 1998). Yet, 15 of 21 experts, perhaps relying on excessive caution regarding overlap in bill shape (Kaufman 1992), considered it to be a Horned Grebe (P. auritus). Actually, the bill shapes of the two species are quite different. In the Horned Grebe the culmen is strongly decurved for perhaps 25% or more of its length, whereas in the Eared it is essentially straight, slightly recurved, or occasionally very slightly downturned at the very tip. One of Blumin’s photos (figure 5) appears to show an Eared Grebe with a slightly decurved bill; the degree of curvature, if any, is not clear because the head is not shown in full profile.

THOMAS W. ANDERSON (Author)

CARCASSS SCAVENGING BY A BLACK-NECKED STILT AT THE SALTON SEA, CALIFORNIA

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The Black-necked Stilt (Himantopus mexicanus) is common at the Salton Sea year round with its abundance peaking annually during fall (Shuford et al. 2004). Several thousand stilts winter at the sea, with many remaining to nest in the variety of habitats surrounding the perimeter of this hypersaline lake (Patten et al. 2003). It is in highly productive habitats such as those found at the Salton Sea that they find their preferred invertebrate prey (Robinson et al. 1999).

JUAN PABLO GALVÁN (Author)

CALIFORNIA BROWN PELICAN NESTING ON ISLA ALCATRAZ, SONORA, MEXICO

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Numbers of the California Brown Pelican (Pelecanus occidentalis californicus) off southern California declined precipitously during the 1960s (Schreiber and Delong 1969, Gress and Anderson 1983). With the decline in dichlorodiphenyltrichloroethane (DDT) in the marine food chain along with efforts to preserve key habitat, Brown Pelican populations in southern California have increased (Shields 2002). Although patterns of attendance at each colony vary greatly from year to year, breeding populations farther south along the west coast of Baja California and in the Gulf of California have remained fairly stable (Everett and Anderson 1991, D. W. Anderson pers. comm.). In 2004 Brown Pelicans formed a small nesting colony on Isla Alcatraz, a small island located 1.4 km off the coastal town of Bahía de Kino Viejo in Sonora, México (28° 49′ N, 111° 55′ W). I monitored this colony throughout the 2006 breeding season to determine if it had expanded or declined in comparison to previous estimates of numbers of active nests. I also tried to determine the fledging success of the colony by monitoring 40 focal nests from early in the season in January to when nests were abandoned in May. Given its small size, short distance from a major human settlement, and high biodiversity, Isla Alcatraz should be considered an important site for research and conservation.

GARTH HERRING, HEIDI K. HERRING (Author)

COMMENSAL FEEDING OF GREAT EGRETS WITH BLACK-TAILED DEER

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Commensal foraging associations are defined as those in which one species aids the foraging of another while incurring no significant costs and receiving no benefits (Wiens 1989). A common commensal association comprises a “beater” species unintentionally flushing and thus making prey available for an “attendant” species (Wiens 1989). Commensal foraging is relatively common among birds, with most such associations between two or more species of birds (see Baker 1980, Robbins 1981, Hino 1998). Foraging associations between birds and mammals are somewhat less common but have been observed with Nine-banded Armadillos (Dasypus novemcinctus; Komar and Hanks 2002), West Indian Manatees (Trichechus; Scott and Powell 1982), Maned Wolves (Chrysocyon brachyurus; Silveira et al. 1997), human beings (Skutch 1969), other primates (Stott 1947, Boinski and Scott 1988, Ruggiero and Eves 1998), and, most frequently, ungulates (Heatwole 1965, Dinsmore 1973, Grubb 1976, Dean and MacDonald 1981, Burger and Gochfeld 1982, Källander 1993, Ruggiero and Eves 1998).

STEVE N. G. HOWELL (Author)

BOOK REVIEW: The Singing Life of Birds

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“Somewhere, always, the sun is rising, and somewhere, always, the birds are singing.” So begins the preface to this remarkable book, subtitled “The Art and Science of Listening to Bird Song.” Kroodsma’s ears and mind were opened to the world of bird sound over 30 years ago, when he started listening to and studying a Bewick’s Wren in his backyard. And so began a lifetime of inquiry, of discovery, and of wonder, much of which is conveyed in The Singing Life of Birds, originally published in 2005 as a hardback. This very reasonably priced paperback makes the singing planet even more accessible.

RON LeVALLEY, PETER PYLE (Author)

FEATURED PHOTO - NOTES ON PLUMAGE MATURATION IN THE RED-TAILED TROPICBIRD

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The Red-tailed Tropicbird (Phaethon rubricauda) is the most pelagic of the three species of tropicbirds. It ranges throughout the tropical Pacific and Indian oceans, nesting on islands. Young birds fledge alone, possibly with some postfledging parental care (Ainley et al. 1986), and most do not return to land for at least two years. During that time they wander, usually as single birds, well away from the sight of most observers. Most individuals return to breed at an age of 2–7 years. Although breeding at an age as young as 9 months, in a “near-adult like plumage,” has been reported (Schreiber and Schreiber 1993), we question this and wonder if the bird was older than suspected when banded the year before (see below). The majority of birds return by the age of 4 years, but those that reportedly return to breeding islands at 2 years of age (presumably in second basic plumage) are in almost full adult plumage (Schreiber and Schreiber 1993), and little is known about the species’ definitive molts and plumages. This uncertainty is compounded by year-round breeding in many populations, meaning that molts and plumes may not follow regular, season-based cycles at the population level. Individuals may undergo prebasic molts at intervals of less than one year (e.g., if a breeding attempt fails) or more than one year (e.g., if a breeding attempt was prolonged or skipped).

DAVE KRUEPER (Author)

PRESIDENT’S MESSAGE

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Lately, I’ve been thinking quite a bit about just what defines WFO is as an organization. To do this, I need to start with our base, the many diverse individuals who collectively constitute our membership. What is the membership base, what are their interests and experience level, where do they fall in the continuum between birdwatcher and hard-core science, and where do they call home? What are our strengths and weaknesses as an organization? Where are we going? From discussions with the membership, and looking into other resources, some interesting facts emerge that I would like to share with you.