COS 60-3
A test of wintering waterfowl habituation to recreation in San Francisco Bay: Implications for waterfowl conservation

Wednesday, August 13, 2014: 8:40 AM
Regency Blrm B, Hyatt Regency Hotel
Lynne Trulio, Department of Environmental Studies, San Jose State University, San Jose, CA
Heather R. White, ICF/Jones and Stokes, San Jose

As outdoor recreation increases in popularity, so does concern about its impact on wildlife species.  Migratory waterfowl may winter in areas where they are exposed to recreational features, such as trails.  Animals often respond to human presence as they would to predators, but some individuals and species that experience non-threatening activities associated with people will become habituated to human presence.  Whether waterfowl can habituate to trail use requires study.  Waterfowl exposed to regular trail use might learn that human activity in this context is not threatening.  Alternatively, since many waterfowl species are hunted, waterfowl may always view humans as a threat and never habituate to human presence.  To test these competing hypotheses, we exposed wintering, migratory waterfowl to experimental trail use at six pond sites adjacent to trails and eight pond sites without trails around the San Francisco Bay, California.  We tested whether waterfowl numbers, species richness and behavior varied in response to trail walkers based on trail type (trail versus non-trail conditions), hunting season, or numbers of trail users.


At non-trail sites, where we exposed naïve birds to experimental trail use, we found far fewer birds after our walks than before as far into the ponds as 120 m.  Birds stayed an average of 107 - 170 m from the levee during our walks.  Results at trail sites, where we tested whether waterfowl would habituate to regular, non-threatening trail use, showed that overall they did not habituate.  Both before and after our walks there were very few birds adjacent to trail sites. In fact, ducks responded to walkers at trail sites no differently than if they were naïve birds exposed to trail walkers for the first time.  We also found the number of birds did not vary based on numbers of trail users, indicating that whether trail use was heavy or light, birds always regarded humans as a threat. These results indicate that, at pond sites adjacent to trails, waterfowl may not habituate to trail use and birds could experience reduced habitat and increased disturbance compared to areas without trails.  These impacts may contribute to decreased populations. When managing for waterfowl, managers should consider the significant impact that adjacent trails may have on these species.