Does off-trail hiking affect elk?

ResearchBlogging.orgMuch of the work that I do is concerned about the impacts of off-trail hiking.  Specifically, I am most interested in impacts to vegetation and soil. However, when visitors leave the designated trail they have the potential to impact more than just plants; especially if they end up wandering into sensitive habitat.  Point Reyes National Seashore in northern California contains some areas that may be especially sensitive to recreation disturbance – the Tomales Point Elk Reserve. The Tomales Point Elk Reserve is home, year-round, to about 500 tule elk. The same area also receives approximately 350,000 visitors per year – many of which will wander from the designated trail and into the elk reserve.  Becker and colleagues were interested in finding out how tule elk might respond to the presence of off-trail hikers on the elk reserve.

Tule Elk at Tomales Point (photo by Wing-Chi Poon from wikimedia commons)

So what?

Wildlife species can response to recreation disturbance in a number of ways.  Some organisms will just ignore the recreationists while other will be attracted to them and still others will flee. Any alteration in normal behavior has the potential to influence the overall fitness of an individual. However, studies are inconclusive as to whether these potential changes in individual fitness translate to population level changes. Still, how wildlife respond to recreation disturbance is of concern to managers who are charged with protecting wildlife species – especially in areas of wilderness like the Tomales Point Elk Reserve.

Location of Point Reyes National Seashore

What did they do?

In order to determine if off-trail use was having any detrimental effects on the elk herd at Tomales Point, Brecker et al. designed an observational study. Observers were placed on the elk reserve near a hiking trail. The hiking trail did not actually cut through the observation area – so any visitor observed would be hiking off of the designated trail. The observers recorded elk behavior, herd size, and any source of disturbance.  The 6 behavior responses included: no response, the elk lifted their head up, standing about, moving away, running away, or sounding an alarm call. Observers also recorded if they saw any rutting behavior in the elk.  Observers recorded all responses by elk but only analyzed the most extreme reaction.  The study design also incorporated other potentially important variables by recording alternative sources of disturbance other than off-trail hiking and any other factors that might influence the elks’ behavior. These other variables included the presence of boats off shore, the time of day, length of survey, location, time of week, and the presence of rutting behaviors.  Various statistical models were used to determine which variables influenced the elk’s behavior and the direction of that relationship.

Male Tule Elk at Point Reyes National Seashore (used under wikiemedia commons license)

Do off-trail hikers influence tule elk?

The presence of off-trail hikers led to a 100% increase in disturbance response (186% increase for the occurrence of rutting behavior and 15% increase for the presence of boats).  Previous studies have supported the claim that less predictable activities (such as off-trail hiking versus on-trail use or boats) have a greater potential to cause disturbance to wildlife. In this study, it definitely appears as if off-trail hiking is having an impact on elk at Point Reyes National Seashore, but is the impact significant?  That is the question with every recreation ecology study examining wildlife response.  Does the changes in behavior that are observed have negative consequences for the elk herd?  Studies of the Yellowstone elk herd have shown that after disturbance from skiers, the elk moved to less desirable habitat to avoid recreationists but movement away from choice habitat does not seem to be happening at Point Reyes. To actually get at the significance of these results for elk herd health, and this is pointed out by the authors, there would need to be a study to examine any changes in fitness associated with the elk’s behavioral response.  However, Tomales Point Elk Reserve is also federally designated wilderness. Wilderness areas on public land receive the highest level of protection from resource degradation. The fact that researchers are observing negative wildlife response to human activity in a wilderness area should be of concern for managers at Point Reyes. Action may need to be taken to increase compliance with staying on the designated trail system in wilderness areas.

Reference
B.H. Becker, C.M. Moi, T.J. Maguire, R. Atkinson, & N.B. Gates (2012). Effects of hikers and boats on tule elk behavior in a national park wilderness area Human-Wildlife Interactions, 6 (1)

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