R e s e a r c h C o n t r i b u t i o n Research Contribution 33 April 2001 HABITAT USE BY SNAG-ASSOCIATED SPECIES: A BIBLIOGRAPHY FOR SPECIES OCCURRING IN OREGON AND WASHINGTON by Jennifer M. Weikel and John P. Hayes Photograph by Rebecca Goggans http://www.cof.orst.edu/cof/pub/home/rc/rc33.htm (1 of 2) [5/2/2001 3:33:38 PM] Habitat use by snag-associated species: a bibliography for species occurring in Oregon and Washington Jennifer M. Weikel and John P. Hayes Introduction Fifty-seven species of wildlife rely on or frequently use snags for breeding, roosting, or denning in Oregon and Washington. Several publications offer information on use of snags by wildlife, influence of management activities on snags and snag users, and approaches to managing snags to benefit wildlife. Because of the diverse information available and the variety of sources in which it is published, it can be difficult for a biologist or land manager to compile information needed to understand habitat needs of a given species. To help compile information on species in Oregon and Washington, that use snags, we developed a comprehensive bibliography of published literature on ecology of species of wildlife closely associated with snags. Here we present it in a user-friendly format. Methods used and scope of the database We searched seven bibliographic databases available through Oregon State University's Valley Library to compile our bibliography (Table 1). Additional information on the databases may be found at http://osulibrary.orst.edu. Although at times snags provide important habitat for many species, we limited our search to species of wildlife that are closely associated with snags and that occur in Oregon or Washington. We defined “closely associated species” as those species that require or very frequently use snags for breeding, roosting, denning, or foraging. Certain species that sometimes use snags but rely primarily on other structures for these activities were not included. We searched each database for citations matching either the common or scientific name of each species. For example, to find citations on hairy woodpeckers, we entered “hairy woodpecker or Picoides villosus.” This generated a list of citations that included either the common or scientific name anywhere in the citation (title, abstract, or keywords). Current common and scientific names were used as defined by the 7th edition of the American Ornithologist's Union checklist of North American birds (American Ornithologist's Union 1998) and Revised checklist of North American mammals north of Mexico, 1991 (Jones et al. 1992). For species whose common or scientific name had recently changed, we searched using old and new common and scientific names (e.g., the plain titmouse recently had been split into two, the juniper titmouse and the oak titmouse). We used two additional words in our search: "cavity-nesting" and "snag." These words helped us locate many citations that had pertinent information but did not list species names in the abstract, title, or keywords. Because the literature base on the ecology of the 57 species of interest is immense, we further stratified our search by developing secondary criteria for including or excluding citations. We established separate criteria for primary cavity-nesting birds and for other snag users. We defined primary cavity-nesting birds as those that excavate cavities for nesting or roosting in snags. We included the woodpeckers and nuthatches in this category. For primary cavity-nesting birds, we included papers on nesting, foraging, roosting, or habitat associations of the species. We defined other snag users as species that frequently use snags for breeding, roosting, denning, or foraging but that do not excavate cavities for nesting. Some of these species, such as chickadees, sometimes will excavate their own cavities, but more frequently nest in existing cavities. For other snag users we included citations only on the use of snags for nesting, roosting, or denning. We excluded papers that focused primarily on physiology, song patterns, identification, distribution or distributional records, dominance or social dynamics, use of bird feeders, or use of nest boxes. We did, however, include some citations regarding breeding biology of birds in nest boxes for species that have a limited base of literature on breeding biology in natural cavities. In addition, if a citation included information on multiple aspects of the biology of a species, including some of the criteria for exclusion, it was included if it appeared to provide substantive information on the topics of interest. When we were unable to determine whether a paper met our criteria for inclusion but suspected that it contained pertinent information; we included its citation in our bibliography. For example, we included many papers on habitat use by secondary cavity-nesting birds and mammals even though we could not ascertain whether the study actually included information on the use of snags as nesting, roosting, or denning sites. In addition to the organism-based citations, we also included citations that contained information on creation and management of snags. Additional citations not uncovered during systematic searching were added based on suggestions by anonymous reviewers and the authors’ personal knowledge. Selection of keywords After generating a list of citations, we downloaded them into ProCite© using Bibliolink© software, or entered them manually. We used our personal knowledge of the literature, information present in the downloaded citation, and in some cases the actual article to determine the content of each paper. We then characterized content of each paper based on a list of keywords (Tables 2-4). For each paper, we listed species of study, geographic location of the study, habitat type, and biological aspects studied. Species Species' common names were designated as keywords (see Table 2). Birds were further described by the keywords “primary cavity-nesting bird” or “secondary cavity-nesting bird.” Mammals were described by the keyword “mammal”, and bats were given the additional keyword “bat.” Geographic area Geographic areas were given keywords representing the continent and country where the research took place. North American areas were further subdivided by state or province. Areas within Oregon were given one of the following keywords: Coast Range, Cascade Range, Willamette Valley, Siskiyou-Klamath, C Oregon, NE Oregon, or SE Oregon. Areas within Washington were given one of the following keywords: Puget Sound-Olympic Peninsula, Cascade Range, NE Washington, SE Washington, or Columbia Basin. Habitat When possible, we characterized habitats in which the studies took place with one or more of the following keywords: conifer forest, hardwood forest, mixed conifer-hardwood forest, boreal forest, grassland, desert, scrub vegetation, agricultural area, and riparian forest. For North American temperate forests, habitats were given keywords representing the common names of the dominant tree species present (Table 3). Biological aspects We described the biological content of each paper by using one or more keywords Table 4. If we were not able to determine whether a certain biological aspect was actually examined in the paper, we listed the appropriate keyword followed by a question mark. Special fields We included two additional fields in our bibliography, one to note how the citation was located, and the other to note how the paper was described. Notes This Procite field shows how the citation was located. If it was located during a systematic search, “Search” was entered; if it was suggested by a reviewer and identified by our own personal knowledge, “Not found in search” was entered. Call number This Procite field shows how the paper was described. If we consulted the actual paper, “From article” was entered. If we used the title, abstract, or keywords from a bibliographic database to describe the paper, “From abstract” was entered. Using the Searchable Bibliography The user can search for citations and download them in one of the following format types: Procite©, Reference Manager©, or Endnote©. For users who do not have one of these programs, a copy of the database is available as text only, MS Word 2000© or lower, or as WordPerfect 8© or lower. You may obtain a copy by downloading it at http://www.fsl.orst.edu/cfer/snags/bibliography.html. The authors do not maintain a complete library of the citations listed in the bibliography and should not be contacted regarding distribution or locations of copies. Manipulating the search page You can search the database by keyword, authors’ names, title, year, and journal title. To search using a particular field, change the “Field to Search” button and enter the search criteria in “Data to Locate.” The bibliography is best searched through use of keywords or authors. It is important to realize that the list of keywords may represent an incomplete description of actual content of many of the papers. Because of this, we strongly advocate using a conservative search strategy using few keywords to obtain the most comprehensive list of citations. IMPORTANT: You must search in the “Advanced Search Mode.” When first entering the web page, the Advanced Search Mode will be the default. When searching, use the “Start Search” button and not the “Quick Search” button. Searching in the “Quick Search” will result in an inaccurate list of citations. If a keyword has more than one word, be sure to enter all words; failure to do so may result in an incomplete list of citations. If searching on an author’s name, enter the last name only. If searching on a title, you can enter either the entire title or a key phrase from the title. If you wish to search for titles based on multiple words in the title that do not appear consecutively, you should enter them on multiple lines on the search screen (see below).