VOCALIZATIONS OF SELECTED BIRD SPECIES
OF KLAMATH MOUNTAINS MIXED EVERGREEN FORESTS
Bruce G. Marcot, Richard W. Lundquist, Valen Castellano
INTRODUCTION
Most of the methods of surveying or censusing birds in the field involves counting individuals from precribed routes or points (e.g., see papers in Ralph and Scott 1981). Typically, surveys entail counting birds heard as well as those seen. In forested or semi-closed habitats, the bulk of observations of birds is usually from aural detections. For example, some 70-90 percent of birds counted during variable-radius circular plot surveys conducted in northwestern California were detected aurally only (B. Marcot, unpub. data). (The actual percentage depended on how visually open the habitat was.) Including aural detections in surveys is desirable for greatly increasing sample sizes per unit survey effort. However, the risk of misidentification or uncertainty of identification of species may bias the observations and result in misleading summaries of presence of or relative abundances among species.
A number of published field guides and species accounts provide terse descriptions of bird sounds for western U.S., including songs, calls, and drumming (see References Cited below). Many of these references, however, lack detailed descriptions of some sounds, especially calls, for many species encountered in the coastal and inland forested areas of the Pacific Northwest. This report was prompted by the need for a catalogue of bird sounds for use in the mixed evergreen forests of the Klamath Mountains Physiographic Province of northwest California and southwest Oregon. Our general aim is to combine descriptions of bird sounds found in the birding guides and to supplement these descriptions with our own observations made over many hundreds of hours of surveying birds in the field. However, this is not, and is not meant to be, an exhaustive coverage of all geographic and individual variations of vocalizations.
The sounds listed herein are those likely to be encountered during field surveys of birds in Douglas-fir (Pseudotsuga menzeisii) forest. We believe this report will also prove useful in similar habitats of other locales.
ACKNOWLEDGMENTS
Thanks to Linda Doerflinger for helping develop and edit early drafts of the text descriptions in this report. Thanks also to John Brack, Stanley Harris, and Ron LeValley for providing valuable comments on subsequent text drafts, and for helping teach identification of bird vocalizations. Pat Hall provided comments on Accipiter vocalizations. Selected species desciptions were condensed and used in an ancillary report on bird vocalizations (Carey et al. 1990).
The sound files embedded in the descriptions were recorded in the field in interior northwestern California mostly by Valen Castellano, Richard Lundquist, Bruce Marcot, and Martin Raphael during 1979-1983, and were transferred to computer format by Bruce Marcot in 1993-94 (see Technical Descriptions elsewhere in this report). Additional recordings of forest songbirds used in this report were made in the same geographic area by Ron LeValley and colleagues (LeValley et al. ca. 1981). Most of the recordings of Northern Spotted Owls and Barred Owls used in this report were made by Tom Hamer and Sharon Sime in Mt. Baker-Snoqualmie National Forest, northern Cascades Mountains, Washington. We deeply appreciate and acknowledge their labors in obtaining these recordings.
To provide a more complete set of sounds, we also borrowed from the National Geographic Guide to Bird Sounds recording for a few of the songs or calls of the following species: Great Horned Owl, Common Nighthawk, Anna's Hummingbird, Allen's Hummingbird, Scrub Jay, American Crow, Chestnut-backed Chickadee, White-breasted Nuthatch, Swainson's Thrush, Hermit Thrush, Hutton's Vireo, Purple Finch, and House Finch.
STUDY AREA
This report focuses on birds of the Mixed Evergreen Forest in northwestern California (Küchler 1977). The Mixed Evergreen Forest occurs mostly inland and is floristically and structurally diverse. Three successional stages of Mixed Evergreen Forest referred to in this report include grass/forb, shrub/sapling, and forested stages (Marcot 1985).
The grass/forb stage includes previously forested areas recently clear-cut. Grass/forb sites are dominated by a variety of species, including low canyon live oak (Quercus chrysolepis) shrubs, bull thistle (Cirsium vulgare), low tanoak (Lithocarpus densiflora) shrubs, and berries (Rubus spp.), with groundsel (Senecio spp.), skeleton weed (Stephanomeria virgata), and California harebell (Campanula prenanthoides) also occurring frequently.
The shrub/sapling stage includes sites reclaimed by heavy brush cover following timber harvesting. Shrub/sapling sites are commonly dominated by tanoak, Douglas-fir, Pacific madrone (Arbutus menzeisii), ceanothus (Ceanothus spp.), canyon live oak, gooseberry (Ribes spp.), and elderberry (Sambucus spp.), as well as a number of grass and forb species.
The forested stage is dominated by Douglas-fir, with subdominants of tanoak and Pacific madrone. Additionally, California black oak (Quercus kelloggii), canyon live oak, ponderosa pine (Pinus ponderosa), Jeffrey pine (P. jeffreyi), sugar pine (P. lambertiana), bigleaf maple (Acer macrophyllum), Oregon white oak (Quercus garryana), white fir (Abies concolor), golden chinquapin (Castenopsis chrysophylla), and insence cedar (Libocedrus decurrens) occur less frequently.
FORMAT OF DESCRIPTIONS
Text Descriptions
Bird sounds are described in text according to the following format. Understanding this format will greatly aid in the use of this report for identifying species in the field.
1. Birds are listed in taxonomic order. Common and scientific names are included, according to the American Ornithologists' Union (1983) and updates.
2. Under each species' name, different lower-case letters denote different call, song, or other sound types. Alternate descriptions of the same call or song may appear, especially if they complement each other and provide a fuller understanding of the particular sound.
3. Sounds are listed in the order of calls, songs, drum sounds, and vocalizations of juvenile birds, where applicable.
4. Additional comments on sounds and frequency of occurrence may be found following each set of descriptions.
5. References used in the descriptions of vocaliztions are: F - Farrand 1983, H - Heintzelman 1982, L - Larrison and Sonnenberg 1968, N - National Geographic Society 1983, P - Peterson 1961, R - Robbins et al. 1983, U - Udvardy 1977. These are denoted by single upper-case letters following each description (also see References Cited, below). Unreferenced statements are original descriptions by the authors.
Sound Files
We recognize the long-acknowledged difficulty in describing bird sounds with words or phrases alone (Jellis 1977). Sound spectrograms are vastly superior to words for denoting durations, frequencies, harmonics, and overtones. However, they are difficult to obtain for as full a set of sounds as offered in this report and are substantially less mnemonic than are the more subjective written descriptions and actual recordings.
To aid description, a number of recordings made in the field in northwestern California were transferred into computer-compatible format (see Technical Descriptions elsewhere in this report). These individual calls or songs are embedded in the appropriate text descriptions under each species. By clicking with a mouse on the sound file descriptive line (if the user is viewing the files on a computer set up with sound-producing hardware), the actual recording can be heard. In this way, the mnemonic text descriptions can be coupled with actually hearing particular sounds. The combination of text and sound should greatly help the user learn and compare the various vocalizations and sounds.
In some cases, several examples of a song or call are given, where vocalizations are variable but still based on the same sound structure. In other cases, several versions of a song type are presented if they seem substantially different in structure. We have not quantitatively analyzed the sound spectrograms or behavioral contexts of examples and version. However, visual inspection of the sound signature (see Technical Information) and differences in the phrasing, pitch, or quality of the sound, suggested the several versions that are identified. Mostly, we present examples and variations as a means by which to identify the range of variation in some vocalizations. In addition, partial songs of some of the immature songbirds are also presented.
The main reason for including sound files in this publication is that many of them are seldom-recorded call notes, particularly of the warblers and sparrows, which are not included on commercially available tapes or CDs (e.g., Peterson, Borrer, others), which typically focus on main song types. In addition, there are no commercially available recordings of sounds of birds in the Klamath Mountains Physiographic Province in northwestern California and southwestern Oregon. Thus, the sounds presented herein are intended to complement existing recordings to aid in field training for bird surveys and identification of individual sounds.
To our knowledge, this is the first "publication" of its type in which descriptive text and actual sound recordings have been combined in one "document." We hope it inspires other innovative approaches to cataloging and describing the biology and ecology of wildlife.
OCCURRENCE OF SPECIES BY SEASON AND HABITAT
Table 1 presents the occurrence by season and habitat of bird species included in this report. Table 1 was developed from extensive surveys of birds in Mixed Evergreen Forest of northwestern California (Marcot 1985). Surveys were conducted during summer 1980 and year-round from June 1981 through April 1983.
IDENTIFYING SPECIES
This report can be used to help identify species heard in the field in the following ways. First, if you suspect a particular species, use the table of contents and taxonomic ordering to find the species, and read the descriptions and listen to the sounds. Second, use the comparison tables (see main contents) as a quick guide to distinguish among similar-sounding species. Third, check the occurrence table (Table 1) to determine likelihood of a species being found in a particular season or habitat.
REFERENCES CITED AND BIBLIOGRAPHY
References preceded with a single capital letter are those specifically cited in the descriptions of bird sounds.
American Ornithologists' Union. 1983. Check-list of North American birds. 6th edition. Allen Press, Lawrence, Kansas.
Benkman, C. W. 1993. Adaptation to single resources and the evolution of crossbill (Loxia) diversity. Ecol. Monogr. 63:305-325.
Carey, A. B., V. E. Castellano, C. Chappell, R. Kuntz, R. W. Lundquist, B. G. Marcot, S. K. Nelson, and P. Sullivan. 1990. Training guide for bird identification in Pacific Northwest Douglas-fir forests. USDA Forest Service Gen. Tech. Rpt. PNW-GTR-260. Portland OR. 28 pp.
(F) Forrand, J., Jr. 1983. The Audubon Society master guide to birding. 3 vols. Alfred A. Knopf, New York.
Groth, J. G. 1988. Resolution of cryptic species in Appalachian red crossbills. Condor 90:745-760.
Groth, J. G. 1993. Evolutionary differentiation in morphology, vocalizations, and allozymes among nomadic sibling species in the North American red crossbill (Loxia curvirostra) complex. Univ. of Calif. Pub. in Zool., Vol. 127. Univ. of Cal. Press.
(H) Heintzelman, Donald S. 1982. A guide to hawk watching in North America. Keystone Books, The Pennsylvania State University Press, University Park and London. 284 pp.
Jellis, R. 1977. Bird sounds and their meaning. Cornell University Press, Ithaca, New York. 256 pp.
Küchler, A. W. 1977. The map of the natural vegetation of California. University of Kansas, Lawrence.
(L) Larrison, Earl J., and Klaus G. Sonnenberg. 1968. Washington birds and their location and identification. The Seattle Audubon Society, Seattle, Washington. 258 pp.
LeValley, R., M. G. Raphael, K. Rosenberg, J. Brack, and K. Taylor. ca. 1981. Bird calls from northwestern California's Douglas-fir forest, Humboldt, Trinity, and Siskiyou Counties. Unpub. audio cassette tape.
Marcot, Bruce G. 1985. Habitat relationships of birds and young-growth Douglas-fir in northwestern California. Ph.D. Dissertation, Oregon State University, Corvallis. 282 pp.
(N) National Geographic Society. 1983. Field guide to the birds of North America. The National Geographic Society, Washington, D.C. 464 pp.
(P) Peterson, R. T. 1961. A field guide to western birds. Houghton-Mifflin, Boston, Massachusetts. 309 pp.
Ralph, C. John, and J. Michael Scott. 1981. Estimating numbers of terrestrial birds. Studies in Avian Biology No. 6.
(R) Robbins, C. S., B. Bruun, and H. S. Zim. 1983. A guide to field identification: birds of North America. Golden, New York. 360 pp.
(U) Udvardy, M. D. F. 1977. The Audubon Society field guide to North American birds: western region. Knopf, New York. 854 pp.