Bay Trail Wildlife & Public Access Study
Developing public access trails that offer a spectacular shoreline experience without impacting wildlife is central to the Bay Trail's mission. Yet, many have asked: can we build a shoreline trail while protecting wildlife, sensitive habitat, and the natural environment?
This delicate balancing act has been the subject of continuing debate in the Bay Area and worldwide. Many resource managers and environmental advocates are concerned that the presence of humans (and their pets) on trails may be deleterious to shoreline wildlife. These concerns often lead to heated controversy and can sometimes create roadblocks for trail implementation. On the other end, policymakers are frustrated because there is little scientific data to support expressed concerns about the potential impacts of public access trails on wildlife.
To begin to find answers to these questions, the Bay Trail Project initiated a study to look at if and how recreational trail users impact shorebirds. The Wildlife & Public Access Study, launched in 1996, is being led by an independent research team. Specifically, the Study is examining the potential effects of non-motorized recreational trail use on the diversity, abundance, and behavior of shorebirds and waterfowl that use mudflat foraging habitat along the Bay Trail. The Study will build a foundation of statistically valid data that can begin to guide the development and management of trails in a manner that respects and protects wildlife.
The research team has completed two years of field research, and preliminary findings based upon summary data are available. The preliminary findings indicate that the study functioned as designed and suggest that there is no general relationship between trail use and either bird abundance or overall species diversity in foraging habitat in the San Francisco Bay area. However, there are many caveats, and much more to learn from the detailed data sets and statistical analyses. The team will continue to enter the "raw" data and perform statistical analyses during the summer and fall of 2003, and a final report is expected to be available early in 2004.
The Study has generated great and broad interest, and funds for a third year of research have already been secured by the Bay Conservation and Development Commission (BCDC) from the The National Oceanic and Atmospheric Administration (NOAA) through the Coastal Impact Assistance Program. The specific question for this next phase of research has not yet been defined. Many new questions have sprouted from the Study to date, and the final results are likely to uncover many more.
More studies will be needed to develop
enough statistically valid data to fully address wildlife and public access
in a scientific manner. While continuing the research and dialogue, trail
and resource managers can utilize a variety of environmentally sound trail
siting, design, and management practices. BCDC's
Public Access and Wildlife Compatibility Report provides an excellent
summary of these practices.
Study Design & Research Question
The basic research question of the Wildlife and Public Access Study is "does trail use affect wildlife." The study more specifically asks, "what are the potential effects of non-motorized recreational trails on the diversity, abundance, and behavior of shorebirds and waterfowl that use mudflat foraging habitat adjacent to the Bay Trail."
After extensive field review, three locations were used for the study: Bothin Marsh in Mill Valley (Marin County), Redwood Shores (San Mateo County), and Shoreline at Mountain View (Santa Clara County). At each location, paired trail and non-trail (control) sites were selected and 100-foot by 100-foot study quads were set up. Paired sites were ecologically and physically similar; in each case, the sites were on levees adjacent to a tidal wetland where mudflats are exposed at low tide.
Data were collected for 24 months at paired sites in the three locations. Observations were made four times a month in four-hour observation periods simultaneously at both the trail and control sites, on two week days and two weekend days.
Three types of data were collected at
each site. The first compares the abundance and species diversity of shorebirds
found at sites that have developed shoreline trails with those observed
at similar undeveloped control sites. The second data set records shorebird
behavioral responses to various types of trail users relative to behavior
at undisturbed control sites. Finally, data are collected on the type
and intensity of recreational use at the three locations.
Through the Wildlife and Public Access Study, the Bay Trail Project hopes to accomplish the following general objectives:
Specifically, the Study will:
Dr. Lynne Trulio, Associate Professor and Chair, Department of Environmental Studies, San Jose State University