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Trailing the Wildlife

Preliminary results of a new Bay Trail study suggest that recreational trails had "no appreciable effect" on the abundance and diversity of nearby shorebirds, and that habitat quality may be a more important determinant of bird use than whether humans jog, walk and bike by.

Whether public access and wildlife protection are compatible activities has been a hot topic among trail planners and resource managers of late, "but there has been very scant scientific data on this topic to date," according to Ceil Scandone of the Bay Trail and the Association of Bay Area Governments, which commissioned the independent study. "Most of the information in anecdotal."

Observers for the study monitored the number and species of birds on three Bay Trail mudflats between July 1999 and June 2000. Each location - Bothin Marsh in Marin, Redwood Shores in San Mateo, and Shoreline at Mountain View - had a trail site and a control site. Recreational activities at the three sites varied, ranging from cycling and jogging to in-line skating. Field observers visited sites on both weekends and weekdays to monitor both high and low levels of human use.

Based on summary data only - researchers have yet to analyze daily reports -lead scientists Jana Sokale and Lynne Trulio concluded that the study was functioning as designed, and that preliminary results suggest no pattern of relationship between human use of trails and overall bird abundance or species diversity in the foraging habitats studied.

This September, researchers presented these early findings at a national trails conference in Redding, California and at meetings of the Bay Area Open Space Council and the S.F. Bay Conservation and Development Commission(BCDC).

"They've done a great job, but they need to tease out the real results," says wetland scientist Mike Josselyn. "By combining a lot of data together in the summaries, they were unable to detect any differences from a statistical standpoint. Once migratory versus resident birds, and seasonal changes, are isolated, I think the conclusions may be different."

Final study results should help those planning or designing new trails in sensitive habitat. Others will look to the study for policy guidance - BCDC plans to update wildlife and public access policies in their Bay Plan by February 2001.

To this end, BCDC conducted a survey of 362 land managers in coastal and Great Lakes states nationwide earlier this year, asking them largely qualitative questions about their experiences with various measures taken to minimize wildlife impacts (43% responded). The survey gleaned a wide range of observations about whether flora and fauna benefited from such measures as creating buffers, boardwalks and viewing platforms to limit visitor intrusions into sensitive areas, or from restrictions on disruptive model planes, boomboxes, pets and the like. Although more than 72 respondents felt that walking/jogging had an immediate effect on wildlife at their sites (behavior such as alarm calling and flushing), an almost equivalent number (63) felt there was no effect at all, and only 12 felt there were long-term effects. BCDC survey manager Caitlin Sweeney notes that respondents were not asked to correlate such effects with the number of visitors at their sites.

Such correlations are more the purview of the Bay Trail Study, which could end up either contradicting or confirming some of the anecdotal information now swirling around the subject. This fall, the study won new grants to do another year's worth of field research. Sokale says they'll be adding three new control sites to better encompass what's left of the natural diversity of the Bay, doing more in-depth analyses to isolate seasonal and species differences, and soliciting others to examine the habitat quality and foodsupplies in their mudflat quadrants.

"It's gratifying how interested people are in the study," says Sokale. "But too many people are already taking the information and running with it, hearing what they want to hear. These are only very preliminary results, and we have a lot of analyses still to do. The study hasn't spoken yet." Contact: Ceil Scandone (510)464-7961 or Caitlin Sweeney (415)352-3600 ARO

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