Through the Lab's Birds in Forested landscapes program, participants learn the finer points of bird study while gathering important scientific data on woodland thrushes and raptors.

    Simply put, BFL is a continentwide study to look at the effects of habitat, and especially forest fragmentation, on the breeding success of thrushes and hawks. BFL focuses on seven species of North American thrushes--Wood Thrush, Veery, Swainson's Thrush, Gray-cheeked Thrush, Varied Thrush, Hermit Thrush, and Bicknell's Thrush and two forest raptors: Cooper's Hawk and Sharp-shinned Hawk. Because BFL is a breeding survey, fieldwork starts after spring migration and wraps up before migration starts again in late summer.

BFL is the natural outgrowth of Project Tanager, which was one of three National Science Experiments developed by the Cornell Lab of Ornithology. (The other two were the Seed Preference Test and Project PigeonWatch.) These experiments were designed to involve birders and amateur scientists across the continent in scientific research. Project Tanager studied the effects of forest fragmentation on four species of North American tanagers--Scarlet, Summer, Hepatic, and Western. Between 1993 and 1996, more than 1,500 groups of volunteers combed nearly 3,000 woodlots across the United States and Canada to find breeding pairs of these species.

    Forest fragmentation results when large, continuous forests are chopped into smaller blocks by roads, logging, agriculture, or development. Many researchers suspect that fragmentation of woodland habitat makes the birds that reside there more vulnerable to predators and nest parasites. They point out that open-country and edge predators such as jays, crows, and cats, as well as the parasitic Brown-headed Cowbird, can easily penetrate forests that have been dissected by roads or power-line cuts.

    Results from Project Tanager suggest that Scarlet, Summer, and Western tanagers are sensitive to the size of a potential habitat patch, and that the nature of the habitat surrounding a forest fragment can have just as significant an influence on the birds as the size of the fragment itself. In some locations, tanagers will nest in a small patch of forest--as long as the landscape surrounding that patch contains extensive amounts of forest.

    Ken Rosenberg, project director of BFL, discusses why Project Tanager was just the tip of the iceberg when it comes to studying forest fragmentation. "Two difficulties cropped up with Project Tanager. First, people couldn't find nests, because tanagers nest high in the forest canopy. So, although we received a lot of information about where the tanagers were, we had almost no information on how fragmentation might actually be affecting their reproductive success. And second, we weren't able to determine the actual rates of nest parasitism and predation."

    Thus, the idea for using the same protocol (sending volunteers out with sound recordings to take a targeted census at particular points, then measuring the habitat) on a different set of birds was born. The Lab chose thrushes because, like tanagers, at least one or more species can be found across most of North America. But, adds Rosenberg, thrushes nest on the ground or low in trees, making it easier for participants to find nests and thus enabling them to go one step further than Project Tanager, gathering vital data about rates of parasitism and nest predation in relation to forest fragmentation.

    Another issue surfaced once the Project Tanager data were analyzed. "We figured out the minimum size required for a woodlot that is likely to have tanagers, and it turned out to be very small--tanagers were found in woodlots of just a few acres. We worried that, by using tanagers, we were studying at a scale that was not large enough to capture a landscape-level problem with fragmentation," adds Rosenberg.

    To compensate, the Cooper's Hawk and Sharp-shinned Hawk were added to the group of species being studied by BFL, because, in theory, they require much larger areas of appropriate habitat than small songbirds to breed successfully. Additionally, BFL is studying large-scale features of the landscape, such as the percentage of forest in the 2,500 acres surrounding the census points and the distance to the next closest forest. In the end, BFL scientists will see which of these factors is most important in determining where these birds will be found.

    But there's something else about BFL that's just as important as the data. And that's the human quotient. The people at the Lab of Ornithology make these citizen-science projects work, because they're honestly excited and inspired by what they're learning. And they communicate their excitement to the participants. Ask members of the BFL team what they like best about this project, and they'll tell you two things: getting out into the field and working one-on-one with volunteers.

   Stefan Hames considers his involvement with BFL a "lucky break." Hames, who is a BFL research biologist, is also a graduate student pursuing a Ph.D. in Ecology and Evolutionary Biology at Cornell. In his thesis research, he is studying how birds of prey space themselves over the landscape--research that dovetails nicely with BFL. In addition to studying the effect of fragmentation on Cooper's and Sharp-shinned hawks across North America, Hames will compare large-scale patterns derived from BFL data with the results of his local research in Tompkins County, New York. "This combination should help us tease apart the mechanisms underneath the patterns we see," says Hames. "This type of research would not be possible without the participation of volunteers."

Hames is also enthusiastic about BFL's potential role in educating the public about woodland raptors and its potential for involving new participants in the Lab's citizen-science projects. Moreover, as a former volunteer at California's Golden Gate Raptor Observatory who "turned pro," he knows how seriously volunteers take these projects and how many good researchers are out there among the so-called amateurs. "From both a research and an educational standpoint, it's just exciting to be able to tap into that network," he says.

    If it sounds like BFL is a project for advanced birders only, think again. Jim Lowe, a Lab biologist since 1983, explains why BFL is within reach for all interested birders. "Even beginning birders are welcome to take part in the project, as long as they're willing to work a bit harder," says Lowe. "This is a fairly complex project that does entail more work than most citizen-science projects, but because you're working with a limited number of species, you don't have to be an expert birder. In most places, people have one, two, or maybe three thrushes they need to identify. If they can't identify these thrushes at the start, they can take our training tape and their field guides, and they can practice and learn just those few."

    As Lowe says, the birding portion of BFL is relatively simple. The habitat portion is more challenging, because it involves procuring accurate maps or aerial photographs, measuring habitat patches, measuring the distance to the next closest forest, and writing up detailed site information. Although this may seem intimidating, Sara Barker, the BFL project coordinator, assures me that help is available to all who request it. "We start by giving people a list of site coordinators, many of whom are with land management agencies and have access to accurate maps or GIS mapping systems," says Barker. "We also recommend checking the natural resources department of your local college for mapping assistance."

    "We talk to participants who feel overwhelmed," explains Lowe. "We encourage them to start small-pick just one site and practice this year, and if they feel good about it, they can turn in data next year." And Lowe's success rate? "After we talk, most people are willing to try."

    The time each participant spends on BFL is also manageable for most people. To monitor one or two sites, the fieldwork--not including the drive or hike to the site--takes about 30 minutes for each visit. Only two visits are required if you don't detect any thrushes or hawks at all. If you do find birds, you're encouraged to make extra visits to search for nests, check for fledglings, and look for signs of predators. The mapping portion takes an average of two hours per site. If you choose three or four sites, which is the average number of sites for BFL participants, your time involved might add up to two full days, but keep in mind that this time is divided into small portions from early spring until the data are due in September.

    After all BFL data are collected and analyzed over the next three to four years, what's next? Extending the project to include other species, perhaps, and to secure that most significant goal--developing conservation guidelines. Rosenberg shoulders the task of analyzing the field data and translating the analysis into conservation guidelines. "If an area is going to be fragmented, we'll recommend the minimum size needed for forest blocks to maintain these forest birds, how close the forest blocks need to be, and whether they need to be in a continuous block. We'll also make habitat recommendations--what kind of trees the birds require for nest sites, how tall the trees should be, and how to make smaller woodlots more suitable for these birds by maintaining a denser understory or adding fruit trees or a water source, for example.

    "Eventually," adds Rosenberg, "we'll be able to make recommendations to developers of state parks who would perhaps like to have Cooper's Hawks and a couple of species of thrushes on the property. At the largest scale, we'll be able to advise state and federal agencies how much forest is needed, at a county level, for instance, to maintain whole populations of these birds."

    For more information on Birds in Forested Landscapes, write to BFL, 159 Sapsucker Woods Road, Ithaca, NY 14850; call (607) 254-2465 ; or send e-mail to <forest_birds@cornell.edu>.