The chip call of the Eastern Wood-Pewee (Contopus virens) is a frequently cited feature of that species’ vocal repertoire, but similar calls of the Western Wood-Pewee (C. sordidulus) are usually overlooked. Differences in this call between the two species would aid in field identification of migrants, which rarely sing their diagnostic songs. Cross-correlations of audiospectrograms, comparisons of three audiospectrographic measures, and qualitative analysis of spectrograms show that most chip calls of the Eastern Wood-Pewee are not distinguishable from those of the Western Wood-Pewee, and Eastern chip calls are generally more variable than those of the Western. These analyses also show that the two wood-pewees are more similar to each other than they are to their respective sister taxa. This similarity raises questions about the role of chip calls in the behavior of Contopus species, especially as it relates to potentially shared functions and sources of selection in their nonbreeding ranges.
Identification in formative and basic plumage of two of the three subspecies of the Rock Sandpiper breeding in Alaska—Calidris ptilocnemis tschuktschorum and C. p. couesi—remains problematic, although a difference in the white wing stripe has been reported qualitatively. For all three of Alaska’s breeding subspecies, including C. p. ptilocnemis, I used three criteria to quantify the wing stripe on each of the inner primaries and on the outer and middle secondaries of numerous specimens and birds photographed. The white stripe is significantly more extensive in tschuktschorum than in couesi, and even more extensive in ptilocnemis, but there is overlap, especially near the zones of contact between the subspecies. The combined criteria can support subspecific identification, of at least some Rock Sandpipers, even in the formative and basic plumages.
A Tropical Parula (Setophaga pitiayumi) photographed and audio-recorded in Big Dalton Canyon, Los Angeles County, 12–14 May 2024 established a second record of the species for California and the first in spring or summer. Another sighting at the Switzer Picnic Area, 30.5 km to west but also within the San Gabriel Mountains, 4 July–26 September 2024, likely represented the same individual. Only the two northernmost subspecies of the Tropical Parula are partially migratory, S. p. nigrilora, which nests in eastern Mexico and north into south Texas, and S. p. pulchra, which is found along the Sierra Madre Occidental. The broad white wingbars, deep orange flanks, and pattern of the song identify the bird in the San Gabriel Mountains as pulchra. Narrower wingbars, paler flanks, and pattern of the song identify California’s previous Tropical Parula, at Huntington Beach, Orange Co., 5 January–14 February 2018, as nigrilora. Despite its relatively sedentary nature, the Tropical Parula has been detected as a vagrant in Colorado, Kansas, northern Texas, New Mexico, Arizona, and now at least twice in California.
We analyzed 175 calls of 91 individual Winter (Troglodytes hiemalis) and Pacific (Troglodytes pacificus) wrens by measuring characteristics such as peak frequency, frequency range, and complexity. We found considerable overlap in most measurements, but metrics such as peak frequency and trace shape are useful for distinguishing the two species. With these results, we recommend a standard for acceptance of extralimital Winter and Pacific wrens through evaluation of spectrograms quantifying the call’s peak frequency (higher in the Pacific, lower in the Winter), the shape and symmetry of the trace at the lowest frequency (more symmetrical in the Winter), and whether the lowest-frequency trace is tightly coupled with a second trace (favoring the Pacific).
The Winter Wren (Troglodytes hiemalis Vieillot, 1819) and Pacific Wren (T. pacificus Baird, 1864) are closely related species occurring primarily in eastern and western North America, respectively. Recent literature on the identification of these cryptic species has focused on vocal cues, but subtle differences in plumage have also been proposed since Spencer F. Baird’s original description of the Pacific Wren in 1864. The nature and consistency of these differences need quantification for plumage to be useful in identification. We analyzed 11 prospective characters, finding strong differentiation in 6: Winter Wrens show stronger pale markings on the chest, neck, mantle, and alula, and feature a paler throat and supercilium, on average, than Pacific Wrens. Two variables, relative width of pale and dark bars on the primaries and number of pale tips on the upperwing coverts, are moderately informative, whereas we found three variables—relative tone of pale barring on primaries and on secondaries, relative throat color, and crown color—to show no consistent differences. Although differences in plumage between Winter and Pacific wrens are subtle, consideration of the six informative characters should be of material use in identifying many individuals to species.
Because the relative threats to survival during each stage of the life cycle remain uncertain, understanding all aspects of the full annual cycle has become a priority for bird conservation. The time between the end of breeding and the onset of fall migration is poorly known in most neotropical migrants and may be fraught with peril as birds move away from accustomed breeding areas to find food sufficient to prepare for migration. Therefore, we explored the use by post-breeding adult Swainson’s Thrushes (Catharus ustulatus) of two bird-banding stations in southwestern Oregon over a combined total of 31 years. Though the stations are within the species’ breeding range it nests at neither. Of 547 nonbreeding adults captured, 15.5% (85) were molting flight feathers during at least one capture. On average, these molters arrived and left earlier (2 August–29 September) and stayed longer (18.5 days) than nonmolters (30 August–21 October; 7 days). Molters’ probability of being recaptured at the same site in subsequent years was higher. The estimated fidelity of molters was 0.35; that of nonmolters was 0.15. We infer that both categories represent short-distance movements of birds nesting nearby.
Analysis of 50 years (1974/75–2023/24) of 123 Christmas Bird Counts along the east and west coasts of North America and in the Great Lakes region reveals a substantial decline of the White-winged Scoter (Melanitta deglandi) along the more southern segments of its winter range. All 16 of the California count circles examined showed a decline, which from Sonoma County south averaged 8.5% per year over the 50 years. The segment from Washington to northwestern California saw a smaller but still significant decline of 2.2% per year, while on counts in British Columbia and Alaska White-winged Scoter numbers increased slightly, at rate of 1.4% per year. On the east coast, from New Jersey south to Florida, White-winged Scoter numbers declined 5.8% per year, as well as in 18 of the 22 count circles in that segment. The northern and central segments of the east coast showed smaller but significant declines of 1.4 and 0.6% per year, respectively. The Great Lakes host fewer wintering White-winged Scoters than does either coast; Christmas Bird Count data from that region showed no clear trend. It is unclear whether our findings reflect a decline in the White-winged Scoter’s population rangewide, a northward shift in the coastal nonbreeding range into areas not well surveyed by Christmas Bird Counts, or combination of the two. The increase in sea-surface temperatures on both coasts of approximately 1o C since the 1970s may be a factor.
Historical data suggest that over 100 pairs of the Peregrine Falcon (Falco peregrinus) were nesting in California prior to the mid-1940s. Because of the deleterious effects of DDE, a sharp decline began in the 1950s, and by 1970 only about 5% of the population remained. Following pesticide restrictions and aggressive management and recovery efforts using captive-bred Peregrines, the population rebounded rapidly and continues to increase into the 21st century. Although information necessary to enable the species’ conservation was circulated, few details on its historical and recent breeding status at either the statewide or regional level have been published. Here we report available details for breeding Peregrines in the eastern Sierra Nevada of Mono and Inyo counties. Data on seven suspected historical breeding locations are sparse. Since 2005, breeding has been verified or suspected at 14 locations, 11 spanning the length of Mono County and 3 at dispersed locations in Inyo County. Of these, four were newly identified in 2025. Despite the dramatic comeback, vigilance and monitoring are needed. Notably, Peregrine mortality from highly pathogenic avian influenza may be an important cause of population decline in many regions of North America, including California, since 2022. Although the effects appear to have been greatest in coastal areas, where the falcons depend heavily on shorebirds and waterfowl (known to carry avian flu), problems have surfaced inland, including possibly at the base of the eastern Sierra where these prey concentrate in spring and summer at saline lakes and freshwater reservoirs.
John Kirk Townsend introduced the Oregon Junco to science as Fringilla oregana, but since 1856 it has been classified in the genus Junco as Junco oreganus, Junco oregonus, Junco hyemalis oreganus, or Junco hyemalis oregonus. The change of spelling to oregonus is not justified under the current International Code of Zoological Nomenclature, and since 1901 oreganus has been used universally. Under the code’s articles 31 and 34 adjectival species-group names (both species and subspecies) must agree in grammatical gender with the genus with which they are combined. Under Article 30, Junco is masculine, whereas Fringilla is feminine. If oregana is an adjective, as it has generally been construed, it needed to be changed to oreganus to agree with Junco. But the termination “-a” is ambiguous, and in ambiguous cases the code prescribes that the word be construed as a noun in apposition that remains unchanged regardless of the gender of the genus in which the species or subspecies is classified. This case parallels other similar examples that have been treated inconsistently in recent literature. A comprehensive review of such cases at the level of both species and subspecies is needed.
Much noteworthy avian information has accrued since the publication of The Birds of Gambell and St. Lawrence Island, Alaska (Lehman 2019). These include first-time records as well as many new early arrival and late departure dates, high counts, and additional records of rare and casual species. From 2019 to 2025, 14 new species were recorded on St. Lawrence Island. Two, Pallas’s Grasshopper Warbler (Helopsaltes certhiola) and the Icterine Warbler (Hippolais icterina), were also firsts for North America. Another two species were new at the village of Gambell but had previously been recorded elsewhere on the island. In addition, the taxonomic splits of the Vega Gull (Larus vegae) and American Herring Gull (L. smithsonianus) from the Herring Gull (L. argentatus) and of the Siberian Pipit (Anthus japonicus) from the American Pipit (A. rubescens) were accompanied by the merging of Common Redpoll (Acanthis flammea) and Hoary Redpoll (A. hornemanni) into a single species. These discoveries and reclassifications bring the species total at Gambell to 303 and on St. Lawrence Island to 307.
Hawaiian wetlands provide habitat for seven indigenous waterbirds. Of the six endemic to Hawai‘i, the U.S. Fish and Wildlife Service has designated five as endangered and one as threatened; maintaining their populations requires control of introduced species of predators. Their susceptibility to depredation varies by life stage, and they should be managed strategically to offset vulnerabilities specific to each life stage. A review of the literature for life-stage-specific predators of the eggs, chicks, and adults of the endemic Hawaiian Duck (Anas wyvilliana, koloa maoli), Hawaiian Coot (Fulica alai, ‘alae ke‘oke‘o), Hawaiian Gallinule (Gallinula galeata sandvicensis, ‘alae ‘ula), and Hawaiian Stilt (Himantopus mexicanus knudseni, ae‘o) yielded 99 sources and identified 17 predators, encompassing birds, mammals, reptiles, amphibians, and fish. Eleven species of predators took eggs or chicks; only four took adults. Although some predators may have been reported taking only one of the waterbirds, it is likely they pose at least some risk to all four taxa. However, variation in behavior and habitat among the four waterbirds may lead to slightly different predation pressures. Aquatic predators likely have a propensity for the more aquatic duck, coot, and gallinule chicks. Managers of Hawaiian waterbirds will require many tools and resources to combat predators that occupy land, air, and water, but control should focus on the most devastating taxa—nonnative birds and mammals.
On 27 May 2024, Pohlen and Benter observed an adult female Oriental Honey-buzzard (Pernis ptilorhynchus) at Eareckson Air Station, Shemya Island, Aleutian Islands, Alaska—a first record for North America. The presence of six prominent primaries, cinnamon underside, and absence of dark carpal patches are diagnostic of this species and exclude the European Honey-buzzard (P. apivorus), a similar-looking congener unknown in North America.
Minor individual plumage variation in gulls is one of many factors confounding field identification of this notoriously difficult group. Plumage variation can sometimes take the form of more extreme anomalies such as leucism and albinism (Grant 1986). A well-known variant of the Heermann’s Gull (Larus heermanni) shows patches of white on the greater primary-coverts (Hubbs and Bartholomew 1951), as depicted, for example, by Sibley (2000); some individuals have additional white on other wing coverts, scapulars, or remiges (pers. obs.).
Edward C. Beedy, a >40-year WFO member, passed away suddenly on 28 March 2025 at the age of 75. Ted, as he was universally known, was a highly respected, dedicated, and visionary wildlife biologist, ornithologist, environmental consultant, conservationist, and birder who lived nearly his whole life in northern California.
Larry Allen, long-time WFO member and supporter and lead author of the Los Angeles County Breeding Bird Atlas, died on 3 April 2025.
The winter of 1996–1997 saw a major invasion of New Mexico by “winter” finches, particularly the Evening Grosbeak (Coccothraustes vespertinus) and Cassin’s Finch (Haemorhous cassinii, until 2012 known as Carpodacus cassinii). This event was well documented at Albuquerque (Bernalillo Co.) and Española (Rio Arriba and Santa Fe counties). Concomitant with this invasion, perhaps because of it, there was an epizootic of salmonellosis and mortality of finches that included as well the House Finch (H. mexicanus) and, to a lesser extent, the Red Crossbill (Loxia curvirostra).
Populations of California Black Rails (Laterallus jamaicensis coturniculus) have been drastically reduced in western North America over the last several decades (Repking and Ohmart 1977, Evens et al. 1991). The California Black Rail is listed as threatened by the California Department of Fish and Game and is considered a "species of concern" by the U.S. Fish and Wildlife Service (www.dfg.ca.gov/endangered/birds.html). In Mexico, the California Black Rail is listed as endangered (Diario Oficial de la Federación 2000).
In Pullman, Washington, to which the Lesser Goldfinch (Spinus psaltria) had spread by the late 1990s, regular observations of the species over four years revealed several notable insights. Seeds of the nonnative Tansy (Tanacetum vulgare) are a major and apparently preferred constituent of the bird’s diet at Pullman. There, as elsewhere in its range, the Lesser Goldfinch imitates other birds; within an interval of 30 seconds, one singing male imitated the sounds of 10 species, including the European Starling (Sturnus vulgaris), previously unreported as one of the goldfinch’s models.
We detail the occurrence of a Slate-throated Redstart (Myioborus miniatus) in an urban park in San Francisco from 29 July to 16 September 2024, establishing the first record for California and the northernmost for the species. The bird showed characters of the northern subspecies, M. m. miniatus. It may have reached this site as a late spring overshoot or possibly via a molt migration. This represents the 47th species of wood-warbler (Parulidae) recorded in California, and—remarkably—the 46th for San Francisco County.
