Volume 35, No. 2

MARTIN L. MORTON, MARIA E. PEREYRA (Author)

CLUTCH SIZES AND NESTING HABITS OF BIRDS AT TIOGA PASS

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We recorded clutch sizes for several birds, mostly passerines, during a lengthy study of vertebrate populations in the Sierra Nevada of California near Tioga Pass. Here we report frequencies of the various clutch sizes observed, descriptions of nest sites, and other natural-history notes. In at least three species, the Hermit Thrush (Catharus guttatus), American Robin (Turdus migratorius), and White-crowned Sparrow (Zonotrichia leucophrys), clutches in this montane setting tended to be larger than those reported for lowland regions. In the two species studied in greatest detail, the Dusky Flycatcher (Empidonax oberholseri) and White-crowned Sparrow, clutch size decreased through the breeding season with date of clutch initiation. We suggest that this commonly observed seasonal trend is cued by decreasing day length and that it is an expression of a gradual, as opposed to abrupt, onset of photorefractoriness.

Clutch size is probably the most commonly evaluated of all life-history traits in studies of avian reproduction. It is easily obtained and provides a measure of function that is broadly applicable to comparisons within and among species (Stearns 1992, Roff 2002). Furthermore, clutch size, along with the date of clutch initiation, is useful for understanding investment strategies of seasonal breeders that have broad geographic ranges.

KEVIN ELLISON, TIMOTHY BRUSH (Author)

HOODED ORIOLE NEST FAILURE ASSOCIATED WITH A NOVEL NEST SITE

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Ecological traps occur where species are attracted to use a resource that exposes them to greater than normal risk of mortality or reproductive failure. We observed complete failure of Hooded Oriole (Icterus cucullatus) nests in streetlights in a south Texas suburb where use of such nest sites was relatively common. This is of concern as streetlights functioned essentially as traps: orioles built their nests within them but all these nests failed, evidently because the eggs were exposed to lethal temperatures. Moreover, Hooded Oriole nesting success on all other substrates in this area was low (31%, n = 69). Therefore, sufficient time for multiple nesting attempts is an important component of the oriole’s reproductive success, and time lost to nesting attempts in streetlights, with no chance for success, imparts reproductive costs beyond egg losses. Deterring orioles from nesting in streetlights may increase the potential for subsequent nest attempts on more productive substrates. A simple screen installed as a barrier blocking the opening in the shades beneath the lightbulbs eliminates this unnecessary source of nest failure.

MARSHALL J. ILIFF, BRIAN L. SULLIVAN, TONY LEUKERING, BRIAN P. GIBBONS (Author)

FIRST RECORD OF THE LITTLE STINT FOR MEXICO

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A juvenile Little Stint (Calidris minuta) occurred at Estero Punta Banda, Baja California, Mexico, from 22 to 30 October 2002. The Little Stint breeds in the northern Palearctic and winters primarily in Africa and India. Since 1975 it has been found with increasing regularity as a vagrant in the New World, primarily in Alaska. The observation we report is the first record for Mexico and the first photographically documented record for Middle America.

The Little Stint (Calidris minuta) is one of seven small similarly plumaged arctic-breeding shorebirds known collectively in the United States and Canada as peeps and in Britain as stints. Members of this group pose considerable field identification challenges, the most difficult of which arise among the four small, black-legged species: the Semipalmated (C. pusilla) and Western (C. mauri) Sandpipers and the Little and Red-necked (C. ruficollis) Stints, all of which are similar in size, structure, and plumage.

CARROLL D. LITTLEFIELD (Author)

LOOSELY COLONIAL NESTING BY WESTERN KINGBIRDS IN NORTHWESTERN TEXAS

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The number of Western Kingbirds (Tyrannus verticalis) breeding on a farmstead in northwestern Texas increased from four pairs in 1990 to 13 pairs in 2001. In most cases, nests were located in large planted shade trees at this 0.6-ha farmstead. The earliest resident birds arrived on the mean date of 20 April (n = 12 years), and earliest observed nest building was on 10 May 2000; the first fledglings were noted on the mean date of 6 July (n = 11 years). Most clutch and nestling losses resulted from nest displacement (n = 7) caused by strong winds, with only two from other causes. Ten fledglings died, all from weather events. During the 1990–2001 study period, seven adults were known to have died. Territorial defense of only a small space surrounding the nest and dispersed foraging may have permitted such a large number of pairs to breed successfully in an area where nest sites were limited.

GORCONIO RUIZ-CAMPOS (Author)

NOTES: FIRST SPECIMEN OF THE NEOTROPIC CORMORANT FROM THE BAJA CALIFORNIA PENINSULA, MEXICO

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On 7 February 2003, during a fish survey in the Ojo de Agua at Río La Purísima, about 20 km upstream of Carambuche, Baja California Sur (26° 19′ 24.2″ N, 111° 59′ 09.7″ W, altitude 195 m), I observed and photographed a Neotropic Cormorant (Phalacrocorax brasilianus) resting on a small island in the center of the river (Figure 1). A day later, this same individual was found dead in a gill net placed in the river, along with 12 exotic cichlid fish (Tilapia cf. zillii). The bodies of two of the fish were mutilated, indicating that the cormorant had attempted to feed on them. The collected specimen, an adult male (total length 720 mm; wing span 960 mm; weight 1305 g), was deposited in the Bird Collection of the Facultad de Ciencias, Universidad Autónoma de Baja California, at Ensenada (UABC-1321, Figure 2). This individual constitutes the first known specimen of this species for the Baja California Peninsula.

AARON L. HOLMES, RUSSELL MORGAN (Author)

NOTES: WESTERN KINGBIRDS NESTING IN ASSOCIATION WITH BUTEO HAWKS

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Nesting associations between Buteo hawks and passerines have been reported in the literature for over a century (Sharp 1902, Cameron 1913, Bowles and Decker 1934, Bent 1937, Griffing 1974, McGillivray 1978). Reports involving passerine nesting associations with Swainson’s Hawks (Buteo swainsoni) and Ferruginous Hawks (Buteo regalis) have been anecdotal, and to our knowledge the importance of these associations has not been investigated. In their classification of nest defenses Collias and Collias (1984) recognized birds that use “protective nesting associations with formidable species.” These formidable species may include large birds of prey, colonies of seabirds, or aggressive insects. Konrad and Gilmer (1982) discussed a potentially mutualistic relationship between Western Kingbirds (Tyrannus verticalis) and Swainson’s Hawks, in which kingbirds may benefit from the presence of hawks in the form of protection from predators and additional food from insects attracted to the nest site by the presence of prey remains, dead hawk nestlings, or excrement. The raptors, in turn, may benefit from kingbirds feeding on pest insects and from their vigilance in alarm-calling and early detection of predators. We investigated nest-site selection of Western Kingbirds in sagebrush steppe of Oregon and provide support for the idea that this species prefers to nest in association with Swainson’s and Ferruginous Hawks.

PETER PYLE, ANDREW ENGILIS, JR., THOMAS G. MOORE (Author)

NOTES: A SPECIMEN OF THE NOMINATE SUBSPECIES OF THE RED-SHOULDERED HAWK FROM CALIFORNIA

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The Red-shouldered Hawk (Buteo lineatus) is a polytypic species with a disjunct North American breeding range. Four or five subspecies in two distinct groups are recognized (AOU 1957, Stresemann and Amadon 1979, Wheeler 2003a). Three or four of these (in one group) breed in the eastern half of North America, whereas one well-marked subspecies, B. l. elegans, resides along the Pacific coast, primarily in California, but also in southern Oregon, western Nevada, western Arizona, and Baja California (Wilbur 1973, Glinski 1982, 1998, Howell and Webb 1995, Marshall et al. 2003, Wheeler 2003b). The nominate subspecies, B. l. lineatus, is migratory, breeding primarily in the northeastern United States and migrating as far south as Florida and central Mexico (Stresemann and Amadon 1979, Howell and Webb 1995, Wheeler 2003b). Three other resident subspecies from the southeastern United States and northern Mexico have been recognized, texanus, alleni, and extimus; however, Wheeler (2003a) synonymized texanus with alleni.

SPENCER G. SEALY, HARRY R. CARTER (Author)

NOTES: ADDITIONAL NOTES ON THE SOUTHERN LIMIT OF THE ANCIENT MURRELET IN BAJA CALIFORNIA, MEXICO

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The Ancient Murrelet (Synthliboramphus antiquus) has been recorded six times in Mexican waters, five times off the northwest coast and once off the southeast coast of the Baja California peninsula. The first record, and the only specimen, was of a bird taken near Ensenada on 25 December 1927 (Grinnell 1928). The second record was of a group of five seen near Islas Los Coronados on 24 February 1980 (McCaskie 1980, Erickson et al. 1995, Howell and Webb 1995), not 1975 as given by Wilbur (1987). An apparently unhealthy bird in first-year basic plumage was photographed at close range in Ensenada harbor on 9 January 1994 (Erickson et al. 1995). The following year, a group of three was observed west of Punta Arena near the southeast tip of Baja California Sur on 21 December 1995. These birds had “black bibs with white [plumage] behind” (Erickson and Howell 2001:126), suggesting individuals in their second year or older. This record is the most southerly of the Ancient Murrelet on the eastern coast of the Pacific Ocean. Nearly three weeks later, on 8 January 1996, one Ancient Murrelet was seen just north of Ensenada at El Sauzal harbor. Last, an individual was observed at Ensenada on 3 January 1998 (Erickson and Howell 2001).

ROBERT W. DICKERMAN (Author)

NOTES: A REVIEW OF THE LITERATURE OF ACCIPITER STRIATUS PEROBSCURUS, WITH A REPORT OF SPECIMENS FROM CALIFORNIA, COLORADO, AND NEW MEXICO

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Snyder (1938) described a dark, rainforest subspecies of the Sharp-shinned Hawk (Accipiter striatus perobscurus) from Graham Island, Queen Charlotte Islands, British Columbia. This subspecies is darker dorsally and ventrally in all plumages than the widespread North American subspecies A. s. velox (Figures 1 and 2). Snyder gave its summer range as from southeastern Alaska (Yakutat Bay) south on the islands and adjacent coast of British Columbia to Vancouver Island, and its winter range as from the Queen Charlotte Islands to Vancouver Island “and apparently south to the San Francisco Bay region of California.” He also mentioned an inland record from the Okanagan Valley of British Columbia. The American Ornithologists’ Union added A. s. perobscurus to its check-list in the 19th supplement (AOU 1944), with its summer and winter ranges as delineated by Snyder. In this note I extend the winter range, clarify the characters of the subspecies, and suggest that migrants and wintering birds in other collections be reexamined.

Daniel S. Cooper (Author)

BOOK REVIEWS: Birds of the Salton Sea: Status, Biogeography and Ecology: by Michael A. Patten, Guy McCaskie, and Philip Unitt. University of California Press. 363 pages. 53 photographs (black-and-white), figures, maps. Hardback. $65.00. ISBN 0-520-23593-2.

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The avifauna of vast landscapes in the western U.S. is often surprisingly poorly known (e.g. the entire state of Nevada). Too often, these regions are suddenly faced with major threats—from urban sprawl, water diversions, a proposed military base expansion—each one sending conservationists scrambling for data to mine and experts to interview. The Salton Sea, a large region of brackish wetlands and agricultural habitat in southeastern California, is used by millions of individuals of more than 400 bird species each year. Yet, until the late 1990s, it too had all but fallen through the cracks, ornithologically speaking. With one fell swoop, the publication of Birds of the Salton Sea has turned the tide on this trend, synthesizing decades of taxonomic research and observational data on bird distribution—the raw material for conservation work.

Steve N. G. Howell (Author)

BOOK REVIEWS: The Birdwatcher’s Companion to North American Birdlife: by Christopher W. Leahy. 2004. Princeton University Press. 1039 pages, scattered line illustrations. Hardback. $39.50. ISBN 0-691-09297-4.

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The promotional blurb calls this Companion “both a practical handbook for amateurs and a handy reference for seasoned birders.” It is basically a reference manual of eclectic scope that covers topics related to North American birds (north of Mexico), with entries arranged alphabetically. Examples? Try “drake,” “Hutton,” “names, colloquial,” “skimmer,” “wreck,” and “xanthochromatism,” to name but six that my eyes lit upon in a random opening of pages. On page xii, the author explains his two-fold desires in writing such an encyclopedia: to have at his fingertips a book that could answer numerous technical to trivial questions about birds, and a longing for nontechnical accounts of the basic elements of birdlife that could be read for pleasure as well as information. An earlier iteration of the Companion was published in 1982, but this 2004 edition is greatly updated and expanded.

ALVARO JARAMILLO (Author)

FEATURED PHOTO: IDENTIFICATION OF ADULT PACIFIC AND AMERICAN GOLDEN PLOVERS IN THEIR SOUTHBOUND MIGRATION

Connors (1983) and Connors et al. (1993) confirmed that American (Pluvialis dominica) and Pacific (P. fulva) Golden-Plovers breeding in sympatry in Alaska are distinct species, a conclusion adopted by the A.O.U. (1993). Distinguishing these two species requires that the bird’s age or plumage class be determined first before the species can be identified. At any stage the identification requires close study, but adults in molt are the most difficult. In both species some prebasic molt takes place during fall migration. Because some field marks useful in juvenal or basic plumage, such as the color of the supercilium, do not apply to molting adults, many purported sightings of American Golden-Plovers have been questioned, and the distribution of adults in fall migration is uncertain. All or nearly all American Golden-Plovers occurring along the Pacific coast south of Alaska in fall migration are juveniles. In fact, there may be no certain records of adults in this region at this season (Paulson 1993). Because of uncertainty over published records, the California Bird Records Committee added the American Golden-Plover to its review list (Cole and McCaskie 2004), seeking documentation for all American Golden-Plovers in California from 2004 onward. This note is an attempt to focus attention on this issue in field identification.