Birding in California, 1960–2007

For several months during assembly and editing of this volume, Erickson, Hamilton, and photo editor Larry Sansone traveled weekly to Camarillo in Ventura County. The purpose of these pilgrimages was to review each record in the CBRC archives, which are housed in the chilly (but always friendly!) collections room at the Western Foundation of Vertebrate Zoology. The job naturally took longer than expected, but this exercise gave us perspective (for Erickson, a retrospective) on the Committee and its workings that we perhaps could not have gained with less effort. These trips also provided time to think about the recent history of birding in California and to examine the contributions of the California Bird Records Committee and its members.

Today’s birders may be surprised to learn that the CBRC once reviewed records of such routinely occurring species as the Laysan Albatross, Short-tailed Shearwater, Long-tailed Jaeger, Craveri’s Murrelet, Northern Parula, Clay-colored Sparrow, and Chestnut-collared Longspur. Californians would have soon discovered these birds’ true status even without a records committee, but the mere fact of their placement on the CBRC’s original review list speaks volumes about the number and size of the holes that existed in our collective knowledge of avian status and distribution in 1970.

In the 1960s, birders started employing bird-finding strategies new to western North America to detect an avalanche of first state records (see Figure 1 on page 32 and Table F on page 33). Much has been written about Guy McCaskie’s profound influence on field ornithology in California (e.g., Drennan 1992, Floyd 2005, Shuford 2005). We chime in here by noting that McCaskie provided documentation for more records treated in this book than did any other observer, probably by a factor of two or three. But Guy’s legacy is perhaps best reflected in how he changed the way observers went about their field work. When McCaskie moved to California from Great Britain in 1957, he came equipped with state-of-the-art methods for finding rarities and an intense desire to apply those methods to his new home. Demonstrating excellent field identification skills, boundless energy, an eagerness to share information, and an eye for productive migratory stopover sites, McCaskie revolutionized the way Californians watched birds (see Jehl 1980:105). A legion of recruits and converts, most notably Rich Stallcup, adopted his methods and adapted them to different parts of the state. By the mid-1960s new birds were being found across California, and many of the state’s now famous “vagrant traps”—from Furnace Creek Ranch to Pt. Reyes to the Tijuana River valley—had been discovered and were receiving regular observer coverage during peak migratory periods. The 1966 Annotated Field List of the Birds of Northern California that McCaskie prepared along with Paul DeBenedictis, and which Erickson and Joseph Morlan updated in 1979, captured much of the spirit of the times by updating the status of vagrants in that part of the state, and also by presenting new identification information on several difficult groups of species.

The other major development in the 1960s was the formation of the Point Reyes Bird Observatory. By 1968, PRBO—the first bird observatory founded in the United States—had established a permanent research station on Southeast Farallon Island, among the most storied vagrant traps in North America. Located about 29 miles west of San Francisco, the island had generated records of vagrant landbirds since the 1880s (Townsend 1885, Bryant 1888, Dawson 1911). Led by the likes of David F. DeSante, Phil Henderson, and Peter Pyle, PRBO biologists have by now banded a quarter-million birds on the island, including many species previously unrecorded in California (DeSante and Ainley 1980, Pyle and Henderson 1991, Richardson et al. 2003). Continuous coverage of this island through mist-netting and other methods has provided an invaluable means for gauging the status of many North American migratory bird populations (e.g., DeSante 1983, Pyle et al. 1994b, Pyle and DeSante 1994) while also providing a wealth of data on seasonal occurrence for many species difficult to locate and/or identify on the mainland (e.g., Empidonax flycatchers, Catharus thrushes, Oporornis warblers, Aimophila and Ammodramus sparrows).

That the 1960s was a unique period of discovery is easy to see—just look at Figure 1 on page 32. By 1970 birders’ minds were at work sorting out the patterns that they saw emerging from these non-random occurrences of “accidentals” and other “vagrants.” This year saw the start of the CBRC, and while the Committee as a group busied itself reviewing documentation and building up a database of peer-reviewed records, some individuals both inside and outside of the Committee set out to do something with the piles of data that were accumulating. Although this essay is essentially historical and sociological, we think it would be incomplete without a brief detour to touch upon a few ideas and observations borne out of examining patterns of vagrancy, particularly on Southeast Farallon Island.

In one of the earliest analyses, Paul A. DeBenedictis (1971) investigated various factors that contribute to the relative abundance of vagrant vireos and warblers in California. Among such factors, he identified only the size of the source population as having significant predictive value regarding the incidence of vagrancy to California (i.e., more common species were found to reach the state with greater frequency). He considered a weak positive correlation between the length of migration route and abundance in California likely to be a “spurious” reflection of “a tendency for species with short migration routes to be less common everywhere.” His analyses certainly contribute to our understanding of why some species reach California more often than others do, but with more years of data and further consideration, it is now clear that we must evaluate more than a species’ sheer abundance in addressing the question of vagrancy rates in California. For example, DeSante and David G. Ainley (1980) observed that the Palm Warbler occurs on Southeast Farallon Island more frequently than do the Red-eyed Vireo, American Redstart, and Ovenbird, despite having a smaller source population. And species with short migration routes are not universally uncommon. Among other potential explanatory factors investigated by DeBenedictis, he allowed that the angle of deviation from the normal migration route required to reach California “seems most likely to be influential.”

This last point was taken up by DeSante in his ground-breaking work at Stanford University, which culminated in his classic 1973 dissertation, An analysis of the fall occurrences and nocturnal orientations of vagrant wood warblers (Parulidae) in California (summarized by Jared M. Diamond in 1982). Building on left/right brain experiments by Corballis and Beale (1971), DeSante devised, explored, and experimentally tested the hypothesis of “mirror-image misorientation” among young wood-warblers undertaking their initial migratory flights. In this form of misorientation, a bird that should fly, for example, southeast mistakenly flies southwest at the same angle relative to true north. DeSante’s experiments and analyses provided multiple lines of evidence pointing to mirror-image misorientation as “the operative mechanism” responsible for most vagrant occurrences of parulids (and, presumably, other groups) in California. Later researchers have tended to view vagrancy as a more complex phenomenon with multiple underlying causes (see, e.g., Able et al. 1982), but mirror-image misorientation is now generally recognized as one of those causes (e.g., Berthold 1993, Tankersley 2004). DeSante’s theoretical and experimental work focused mainly on “Eastern” warblers—the Blackpoll in particular—but he also showed that the mechanism of mirror-image misorientation can accommodate patterns of vagrancy exhibited by “Southwestern” warblers, such as Virginia’s and Lucy’s. Other parulids whose patterns of fall vagrancy in North America appear to support DeSante’s hypothesis strongly include the Black-throated Blue, Palm, and Connecticut Warblers. Species whose patterns of routine fall vagrancy to California are not clearly explained by this mechanism include the Hooded Warbler and at least one non-parulid, the Painted Bunting.

A further nuance added by DeSante and Ainley (1980) is the observation that passerines with ten primaries (e.g., tyrant flycatchers, vireos, wrens, thrushes, and mimids) tend to stray far less often than do those with nine (e.g., wood-warblers, icterids, and finches). The explanation is elusive, but the relatively rapid and recent adaptive radiation of the nine-primaried oscine passerines throughout the world implies that their genome is more mutable, perhaps making them more prone to navigational errors. Furthermore, in the words of DeSante and Ainley, “by contributing to the establishment of new isolated populations, such vagrancy could, in fact, serve to enhance these species’ rapid and extensive radiation.” A later attempt by Steve Hampton (1997) to work out a mathematical formula for predicting the frequency of occurrence for rare migrants in California produced mixed results, but this exercise did provide general support for the hypotheses described herein, especially with regard to both mirror-image misorientation and the greater navigational acuity of species with ten primaries versus those with nine.

We conclude our detour into the theoretical by observing that several species of fairly common to common, short-distance migrants that breed and winter primarily in the eastern half of North America remain unrecorded or exceedingly rare in California. These include the American Woodcock, Red-headed Woodpecker, Carolina Wren (Thryothorus ludovicianus), Sedge Wren, Eastern Bluebird, Eastern Towhee, Field Sparrow, and Eastern Meadowlark (S. m. magna and S. m. argutula). Henslow’s Sparrow, a more localized species that otherwise fits in with this group, has been found no closer to California than northeastern New Mexico (NAB 58:119, 171). Most of these species are partially sedentary, and their migratory populations generally move no farther south than northern Mexico. Perhaps more importantly, their primary migration routes may lie close to the north-south axis, reducing the magnitude and hence the importance of any potential mirror-image misorientation effects. It appears that such factors greatly limit the potential of these species to reach California as vagrants. Consider also that the wren and bluebird are ten-primaried passerines, a factor thought to be correlated with navigational accuracy. As a mitigating factor, note that only the woodpecker tends to be both conspicuous and easy to identify (an Eastern Bluebird, particularly one other than an adult male, could easily be mistaken for a Western). Nevertheless, as indicated in the previous essay, each of these species seems likely to be found in California with the passage of time.

During the 1970s, as the CBRC took shape and defined itself, the central figures in California field ornithology included Pierre Devillers in San Diego and Laurence C. Binford in San Francisco. Arnold Small published The Birds of California in 1974, a title he would update two decades later in California Birds: Their Status and Distribution. Some of the most exciting areas of discovery in this decade involved sorting out identification challenges in notoriously tricky groups such as the Pterodroma petrels, boobies (Sula), Calidris sandpipers, and Empidonax and Myiarchus flycatchers. As field-identification problems previously thought to be intractable were solved, the new information and field techniques were disseminated to a growing community of birders through such outlets as Birding, Audubon Field Notes/American Birds, and California/Western Birds.

By the 1980s, maintaining even moderate growth of the state list required the concerted efforts of many more dedicated birders and banders than were active during the 1960s and 1970s. The most obvious and readily accessible hot spots had been discovered, explored, and popularized. Because of habitat degradation, modification, and loss, certain well-known areas—most notably the Tijuana River valley—were already in decline. The section of the collective learning curve that most recreational birders would consider the steepest and most exhilarating was already behind us. The Golden Age of California birding had passed.

Not all the news was bad, of course! Much of what had been learned by the few in those formative years was being consolidated and dispersed to the minds of the many in the form of books. The 1980s gave rise to several influential tomes of particular interest to California birders, starting with Don Roberson’s 1980 treatise on avian vagrancy from Alaska to California, Rare Birds of the West Coast. The following year brought Birds of Southern California: Status and Distribution, in which Kimball L. Garrett and Jon L. Dunn employed precise bar graphs and concise species accounts to synthesize the large body of information that had accumulated in the southern part of the state since the 1944 publication of Grinnell and Miller’s The Distribution of the Birds of California. In 1983, the National Geographic Society published the first edition of its Field Guide to the Birds of North America, with Dunn serving as a lead consultant. This guide and its later editions (fifth edition published in 2006) brought together in one place many advances made in bird identification and knowledge of bird distribution since the 1960s, and its coverage of many formerly obscure Eurasian species reflected the modern pursuit of vagrants, especially in Alaska. Surely it is no coincidence that, during the 1980s, most new additions to the state list (21 of 35 species; see Table F on page 33) involved birds from Asia, Alaska, or the Arctic. Field guides that focused on three particularly difficult groups—gulls (Grant 1982, 1986), seabirds (Harrison 1983), and shorebirds (Hayman et al. 1986)—and the banding guide by Pyle et al. (1987) represent the decade’s other major identification innovations.

Starting with the fifth CBRC report (Luther et al. 1983), the Committee began publishing its decisions annually. This report was the first to include color photos, and it started an upward trend in the level of detail provided in the CBRC’s discussions of the status, distribution, and identification of the vagrants under consideration. During the mid-1980s the Committee took perhaps its most important turn by deciding to review all pre-1970 records of review-list species. Members evaluated nearly 500 records per year during this period (more than double the average rate of review), and when the dust settled the CBRC’s database of peer-reviewed bird records was as complete as it could be. To a large degree, Roberson (1993) summarized the results of this effort in the oversized 14th Committee report.

Species taken off the CBRC review list in the late 1970s and 1980s included Murphy’s and Cook’s Petrels, Semipalmated Sandpiper, Barred Owl, Least Flycatcher, Eastern Phoebe, Hooded Warbler, Canada Warbler, Painted Redstart, and Nelson’s Sharp-tailed Sparrow.

The 1990s saw continuation of the trend in the annual reports to explain the Committee’s purpose and objectives better, to recommend proper procedures for documenting and submitting records of rarities, and to elucidate issues underlying the Committee’s decisions on individual records. This decade also witnessed the large-scale transition from handwritten or typed voting sheets to the use of computers. The attendant increase in productivity helped most members keep pace with an increasing volume of new records submitted for review, but the workload for the CBRC’s secretary—voting on records, keeping tabs on all data flow and paperwork, and chairing the annual meetings—was building toward critical mass. Finally, in 1997, the CBRC amended its bylaws to share the burden of leadership and organization between the secretary and the new position of chair, with the secretary becoming a non-voting position.

In examining records from the 1990s, the most obvious advance in the CBRC’s review process is the more frequent and reliable specification of age and sex information for records, a development linked directly to Peter Pyle’s regular participation on the Committee. The ornithological community’s collective understanding of these issues was boosted considerably by publication of his Identification Guide to North American Birds (Pyle 1997b, which built upon Pyle et al. 1987). The other marked improvement evident in records from the 1990s was in the quality and quantity of sketches, photographs, videotapes, and audiotapes submitted for review and archiving. The Committee’s evaluation of numerous important records, particularly those of pelagic species and large gulls, would have been crippled without the visual evidence provided by the many artists, photographers, and videographers who have graciously submitted their images for review and preservation. We trust that readers of this book will enjoy its striking images, many of them culled from the Committee’s archives.

The state list accrued 23 species during the 1990s, a 34% decline from the previous decade’s production. The contribution of seabirds increased substantially, while that of Asiatic/Alaskan/Arctic species dropped off somewhat. The CBRC stopped reviewing records of the Tufted Duck, Zone-tailed Hawk, Buff-breasted Sandpiper, Philadelphia Vireo, Red-throated Pipit, and Kentucky Warbler. Review of the pipit stopped after the Committee accepted a flurry of 1991 records involving at least 79 individuals. The warbler was excused following an unprecedented gust of 36 accepted records in spring and early summer 1992.

Also during the 1990s, the Committee took a fresh look at a limited number of its earlier decisions as new information on species’ distribution or identification became known, as previously anticipated patterns of occurrence failed to materialize, and as the Committee’s standards for acceptance evolved. Re-reviews have tended to be controversial, and at times acrimonious, but it is a testament to the abilities of earlier CBRC members that relatively few decisions have been overturned. Periodic review will always be necessary to maintain the CBRC’s high standards and to ensure that its decisions make sense in the dynamic context of ornithological knowledge and discovery.

Even the most stubbornly old-fashioned among us will admit that, for better or worse, the internet has revolutionized the means by which people share information. Web pages and e-mail alerts—particularly Calbirds but also a plethora of county and regional listservers—now keep birders abreast of rare bird reports, identification issues, and other topics. Among the most important California-centric sites have been Joe Morlan’s California Birding Pages, and Don Roberson’s Creagrus. A remarkable annex to the last site—A History and Chronology of the California Birding World, 1965–1989, with a Gallery of Who was Who—provides Don’s view of the California scene, including copious photos and lively commentary. The Searchable Ornithological Research Archive (SORA) provides free searchable access to back issues of several major ornithological journals, including Western Birds; Ornithological Worldwide Literature (OWL) compiles ornithological citations and abstracts from around the world; and the Cornell Lab of Ornithology and American Ornithologists’ Union have placed the Birds of North America series online for an affordable annual subscription. Christmas Bird Count data can now be quickly accessed and analyzed thanks to the National Audubon Society, and researchers seeking information on captive birds can start by checking the International Species Inventory System, or ISIS (discussed on page 48). Also exciting is searchable web access to some of the nation’s most important bird collections, either directly through those institutions or through the Ornithological Information System (ORNIS) database. Each of these services ranks among the most useful ornithological advances of the information age.

As new additions to the California list become harder to come by, field guides helpfully continue to improve. Landmark works relevant to California birding and published during the past decade or so include A Guide to the Birds of Mexico and Northern Central America (Howell and Webb 1995), Birds of Europe (Mullarney et al. 1999), The Sibley Guide to Birds and progeny (Sibley 2000, 2003a, 2003b), and the National Geographic Complete Birds of North America (Alderfer 2005). Continuing the trend started in the 1980s, numerous recent titles take aim at various taxonomic groups. Notable contemporary additions to this canon authored by past or present CBRC members include A Field Guide to Warblers of North America (Dunn and Garrett 1997), New World Blackbirds: The Icterids (Jaramillo and Burke 1999), Hummingbirds of North America: The Photographic Guide (Howell 2002a), and A Reference Guide to Gulls of the Americas (Howell and Dunn 2007). Finally, we note the advent of instructional birding video guides, which add dimensions of sound and motion not possible on the printed page. Among the progenitors of this promising new breed is the Advanced Birding Video Series, featuring CBRC member Jon Dunn.

Faced with the prospect of diminishing returns, we note with a measure of optimism that the 2000s have yielded accepted records of 15 species new to California (see Table E on page 30). The first part of this decade has seen the end of Committee review for the Reddish Egret, Yellow Rail, Ruddy Ground-Dove, and Painted Bunting, the start of review for the American Golden-Plover (which may be over-reported because of confusion with the Pacific Golden-Plover), and the resumption of review for the Rusty Blackbird, a species declining across most of its range.

Freeland (2002:462) noted that the CBRC’s “established by-laws and procedures [have] become models for the explosive expansion” of records committees that now operate in nearly all of the United States and parts of Canada. Birders hold mixed opinions about these deliberative bodies, but most seem to appreciate that any human system will have flaws and that the birding and scientific communities are better served with committees in place than without them. At a minimum, records committees perform a vital function simply by archiving the documentation that supports records of vagrant birds and making these materials, and written comments about each record, available for public review. With the publication of this book the CBRC demonstrates that, with the passage of time, the archived data and images can be mined and integrated into a powerful tool for birders, scientists, and others interested in the status, distribution, and identification of migratory birds.

We encourage readers intrigued by the information presented here to pay a visit to the Committee’s archives, housed at the Western Foundation of Vertebrate Zoology in Camarillo. And seriously, do remember to bring a jacket!