Wisdom, M. J., H. K. Preisler, N. J. Cimon, B. K. Johnson. 2004. Effects of Off-Road Recreation on Mule Deer and Elk. Transactions of the North American Wildlife and Natural Resource Conference 69: in press. http://bluewaternetwork.org/reports/rep_atv_forestservice.pdf

DESCRIPTION

This article reports first-year results of a manipulative, landscape experiment to measure effects of off-road recreation (ATVs, horses, mountain bikes, and foot traffic) on mule deer and elk.The study, begun in 2002 and scheduled to end in 2004, is being conducted in a 3,590 acre ungulate-proof enclosure at the Starkey Experimental Forest and Range in northeast Oregon. Objectives were to (1) document cause-effect relations of ATV, horseback, mountain bike, and hiking activities on deer and elk, using these off-road activities as experimental treatments and periods of no human activity as experimental controls; (2) measure deer and elk flight responses, resource selection, spatial distributions, and use of foraging versus security areas during experimental and control periods; (3) estimate energetic and nutritional costs associated with each activity and the survival; and (4) interpret results for recreation management. Off-road recreation, both motorized and non-motorized, is defined as that occurring on trails, primitive (unpaved) roads, or areas without trails or roads.

Procedure (pp. 2-6)

• A network of off-road transects was established and run in 2002, using ATV, horseback, mountain bike, and hiking activities as experimental treatments. Approximately 20 miles of transects were established over which traffic was experimentally applied from mid-April through October.
• Transects were located on flat or moderate terrain typically used by off-road activities. Primitive roadbeds, like those often established by off-road vehicles were included in the transects.
• For ATV travel, a pair of riders could easily cover the 20 miles of transects during a given morning or afternoon; a pair of mountain bike riders could cover about 50 percent of the 20 miles in a morning or afternoon; horseback riders and hikers could cover about 30 percent.
• To standardize the number of transect runs or "passes" (twice daily) among all four off-road activities, two different groups of mountain bikers, and three groups of horseback riders or hikers, were used to obtain complete coverage of transects for a given morning or afternoon.
• From mid-April through October, each 5-day period of off-road activity was followed by a 9-day control period, during which no human activities occurred in the study area. Throughout the experiment, all other human entry was prohibited.
• Twelve female mule deer and 12 female elk were radio-collared among a larger population of approximately 25 female deer and 100 female elk present in the study area in early April. Animal movements were monitored with the automated tracking system.
• Approximately two locations of each radio-collared animal were obtained every hour during no human activity control periods, to monitor areas of deer and elk use, habitat selection, movement rates, and flight responses in the absence of human activities.
• Both movement rate and probability of flight response were analyzed for use in estimating the energetic costs of animal reactions to off-road activities.
• Movement rate was defined as the speed of animal movement (yards moved/minute), as estimated hourly, 24 hours per day, for a given species.
• Flight response was any animal movement for a given hour of day that exceeded the 95th percentile of all deer or elk speeds calculated for that same hour of day during the paired 9-day control period that immediately followed a given 5-day period of off-road activity.
• Each estimated probability of a flight response for a given radio-collared animal was linked to the estimated distance between that animal and each group of humans conducting an off-road activity.

MAJOR FINDINGS

• Peak movement rates of elk during the morning pass were: (p. 6)
• ATV riding (21 yards/minute, or yd/min---metric rates reported in article),
• mountain bike riding (17 yd/min),
• horseback riding and hiking (both about 15 yd/min ).
• For the afternoon run, movement rates of elk were:
• ATV riding (13 yd/min),
• horseback riding (about 11 yd/min),
• hiking and mountain bike riding (about 10 yd/min).
• Peak movement rates during the control periods stayed below 8 yd/min during hours of 8 a.m. to 3 p.m., the comparable period of each day when off-road treatments were implemented.
• Higher movement rates near sunrise and sunset suggest that elk were displaced from preferred security and foraging areas as a result of flight behavior during the daytime off-road activities.
• Movement rates of elk at or near sunrise and sunset were higher during the 5-day treatments of mountain bike and ATV activity
• The estimated probability of elk flight from a human disturbance was highly dependent on distance. (p. 7)
• When elk and humans were close to one another, the maximum probability of a flight response was approximately 0.65 during ATV, mountain bike, and hiking activity, and about 0.55 during horseback riding.
• Probability of a flight response declined most rapidly during hiking, with little effect when hikers were beyond 550 yards from an elk. By contrast, higher probabilities of elk flight continued beyond 820 yards from horseback riders, and 1,640 yards (i.e., almost a mile) from mountain bike and ATV riders.
• Mule deer showed less change in movement rates during the four off-road activities compared to the control periods. During periods of off-road activities: (p. 7)
• Movement rates of deer during ATV riding were similar to rates during control periods.
• Movement rates of deerwere higher, as compared to control periods, during mountain bike riding, horseback riding, and hiking, especially in the morning.
• Movement rates near sunrise and sunset were particularly high during all four activities as well as during the control periods, suggesting that these times were peak foraging periods
• Deer did not exhibit the flight tendency as elk in relation to off-road activities.
• Deer may respond to an off-road activity by seeking dense cover, rather than running from the activity. Spending more time in dense cover could result in reduced foraging opportunities, and a subsequent reduction in opportunities to put on fat reserves during summer. (p. 7)
• Movement rates and probabilities of flight response for elk were substantially higher during all four off-road activities compared to control periods of no human activity. Consequently, these off-road recreational activities appear to have a substantial effect on elk behavior.
• The energetic costs associated with these treatments deserve further analysis to assess potential effects on elk survival. (p. 7)

QUESTIONS RAISED FOR THE THREE FORESTS

• Are you aware of: (1) off-road use rates and (2) off-road recreational equivalents (U.S. Department of Agriculture Forest Service. 2004. Managing the National Forest System: Great issues and great divisions. U.S. Department of Agriculture, Forest Service report, January 21, 2004, on file at Pacific Northwest Research Station, La Grande, Oregon.)?

• Are you taking into account the differences in effects from the same numbers of people pursuing different recreation forms (see following paragraph)?

RELEVANCE TO FOREST MANAGEMENT

For purpose of transportation/recreation analysis, the effects of ATV riding suggest that one group of ATV riders would exceed three groups of horseback riders or hikers and two groups of mountain bike riders.

For use in allocating recreational activities within and across watersheds, recreational equivalents need to be combined with other effects, e.g., road/trail density, comparative effects of each off-road activity on water quality, soil productivity, invasion of exotic plants, and other species sensitive to human activities.