Assessing the Effects of Human Activities on Wildlife

1 Given the breadth of relevant humanactivities, the diversity of Wildlife speciespotentially affected, and the multitude ofways they may be affected, scientists andresource managers planning to assess theeffects of Human Activities on Wildlife mustbe careful to state their study objectivesexplicitly. In all cases, these objectivesshould specify the Human activity of inter-est; the timing,intensity (frequency,dura-tion) and spatial extent of the activity; thefocal Wildlife species of interest; and therange of ways that species might respond tothe activity that is, the objectives shoulddefine the disturbance context in whichthe Human Wildlife interaction occurs(Steidl and Anthony 2000).

2 Given well-defined objectives and a clear disturbancecontext, a measure that gauges the responseof the Wildlife species of interest to thehuman activity must be selected this paper, we provide a general clas-sification for the ways in which humanactivities can affect Wildlife , distinguishamong general types of relevant studiesbased on different objectives, and identifyappropriate measures for gauging wildliferesponse for different types of is to provide a conceptual frameworkto guide studying and monitoring Human Wildlife interactions, specifically thosederiving from non-consumptive recreation-al Human activitiesVirtually all Human Activities can affectwildlife populations either positively ornegatively.

3 Those Activities that are likely tohave adverse Effects can be divided intothose that function primarily by altering thephysical environment in a relatively perma-nent way and those that cause changes to ananimal s behavior. Activities that alter thephysical environment change the amount orthe suitability of habitat for a and large-scale examplesinclude Activities that directly alter thestructure and composition of the landscape,such agriculture, forestry, livestock grazing,and unregulated off-road vehicle use. InThe George Wright Forum50 Assessing the Effects of Human Activities on Wildlife Robert J.

4 Steidl and Brian F. Powell Human Activities THAT AFFECT Wildlife AND THEIR HABITATSare pervasive and increas-ing. Effects of these Activities are manifested at all ecological scales, from short-term changesin the behavior of an individual animal through local extirpations and global extinctions(Pimm et al. 1995; Chapin et al. 2000). Consequently, understanding the Effects of humanson Wildlife and Wildlife populations, as well as devising strategies to ameliorate these Effects ,is an increasing challenge for resource managers. Given the conflicting mandate to bothencourage Human use and to protect sensitive natural resources in national parks, develop-ing reliable strategies for Assessing and monitoring the Effects of Human Activities on naturalresources is essential to ensuring appropriate stewardship of these resources.

5 General, these are land use or land manage-ment practices that change the trajectory ofecological succession, including altering thedominant plant communities and the abiot-ic features of a site. The ecological Effects ofthese Activities on vertebrates are readilyapparent and have been relatively well stud-ied ( , Blair 1996; Spies et al. 1996;Lichstein et al. 2002).Perhaps less obvious in their ecologicalimpacts are those non-consumptive humanactivities that do not appreciably alter thephysical environment but nonetheless canaffect Wildlife adversely.

6 Examples includerecreational Activities such as hiking, Wildlife viewing,and boating all commonactivities for visitors in parks. As recreation-al use increases in wilderness and otherprotected areas, sensitive Wildlife speciesmay be increasingly affected by these activi-ties (Steidl and Anthony 2000). The magni-tude of Effects of recreational Activities onwildlife is influenced by many factors,including the type, duration, frequency,magnitude,location,and timing of the dis-turbance,as well as the particular species ofinterest.

7 Although Effects of these activitiesare typically of short duration, cumulativelythey can effect Wildlife populations adverse-ly in both the short- and long-term (Burger1981; Henson and Grant 1991; Fernandezand Azkona 1993; Holmes et ;Steidl and Anthony 1996, 2000; Swarthoutand Steidl 2001, 2003; Mann et al. 2002;Johnson et ).Observed Effects in-clude increased energetic stresses (B langerand B dard 1990),changes in activitybudgets (Steidl and Anthony 2000; Mannet al. 2002; Swarthout and Steidl 2001,2003), displacement from preferred envi-ronments (McGarigal et al.)

8 1991), andreduced productivity through abandon-ment and decreased survival of young(Tremblay and Ellison 1979; White andThurow 1985).Although there are Human activitiesthat cause physical changes to park environ-ments, such as construction of building androads, or vegetation destruction resultingfrom overuse of particular areas, mostwildlife-related impacts away from theseareas likely result from short-term recre-ational pursuits of visitors. We focus theremainder of our discussion on these typesof of studiesGiven the wide range of potential infor-mation needs and study objectives, we dis-tinguish between two fundamentally differ-ent kinds of studies: research and monitor-ing.

9 These can be classified primarily basedon their different objectives and secondarilybased on different stud-iesinclude an objective related to answeringspecific questions and are usually of rela-tively short duration (1 3 years). An exam-ple would be a study conceived to assess thedistance at which a population of birdsflushes in response to a particular visitoractivity, such as hiking or mountain biking( , Swarthout and Steidl 2001). The goalfor this type of study might be to reliablyestablish the distance at which birds flush inresponse to the activity so that the activitycan be restricted in particular areas toreduce disturbance frequency and mini-mize adverse Effects .

10 In contrast,monitor-ing studiesinvolve quantifying changes incharacteristics of resources over time, areusually not driven by particular questions,and are always intended to be undertakenover long-time periods (Steidl 2001). Thegoal for monitoring studies is almost alwaysrelated to quantifying changes in character-istics of resources over time. A third kind ofVisitor Impact MonitoringVolume 23 Number 2 (2006)51 study, which we only mention here, is ahybrid between research and assessment studiesare de-signed to measure the Effects of a plannedactivity or action within the context of a pre-viously established monitoring are often large-scale studies wherethe fundamental approach is to establish amonitoring program based on a series ofsampling sites.