March 24, 1996

Sierra Club Board of Directors, Wild Planet Strategy Team, &

Off-Road Vehicle Subcommittee

730 Polk Street

San Francisco, California 94109

Re: "Harmless" Recreation Kills Wildlife!


It has been customary for people to assume that when we are not directly harming wildlife, we are not harming them. Besides being a convenient rationalization, this assumption is understandable: we assume that others, even members of other species, are like us. We don't feel very threatened by the presence of other species; we are, after all, the top predator. We also live surrounded by plenty; most of us can't imagine what it is like to go hungry for even one day. Wildlife, however, does usually feel very threatened by our presence, and many organisms exist on a very tight (food/energy) budget. Also, they often have much greater visual and auditory acuity than we do, and hence can be disturbed by sensations that we wouldn't even notice. Amphibians, for example, are extremely sensitive to vibrations.

"Traditionally, observing, feeding, and photographing wildlife were considered to be 'nonconsumptive' activities because removal of animals from their natural habitats did not occur.... nonconsumptive wildlife recreation was considered relatively benign in terms of its effects on wildlife; today, however, there is a growing recognition that wildlife-viewing recreation can have serious negative impacts on wildlife" (Knight & Gutzwiller, p.257).

Technology has made it much easier for people to reach wildlife habitat, including areas where access used to be difficult, such as cliff faces, caves, under water, and inhospitable climates. Roads, trails, ORVs, mountain bikes, high-tech camping gear, freeze-dried foods, and even waterproof maps are some of the tools that allow people to travel far into wilderness in great comfort. That and increasing population have squeezed and frightened wildlife out of its preferred habitat, both temporarily and permanently, depriving it of needed foods, shelter, and choice of mates. Roads are particularly pernicious, because they not only give humans easy access to wilderness, but they fragment habitat, because many cover-adapted species are afraid to cross them.

Speed is a big factor. Being encased in a motor vehicle greatly reduces the sensations that you experience. Thus in order to obtain the equivalent physical experience that a hiker acquires in a short walk through the woods (complete with sounds, sights, smells, tastes, and touch), you have to drive a great distance! Similarly, a mountain biker travels too fast to fully appreciate his/her surroundings, and thus soon gets bored with the trail and needs to experience another (and another and another). This is one reason why mountain bikers are never satisfied, no matter how many trails they have access to, and why they are exerting such tremendous pressure on land managers around the world to give them ever greater access. (I asked one of them if there were any limit to this process. He told me that no one would ever want to bike Mt. Everest. However, only a few days later I saw an advertizement for a mountain bike trip to Mt. Everest!)

Here are some of the damaging effects that the mere presence of a human can have on wildlife: When an animal is guarding a nest, it can be scared away ("flushed") for some time, at least while a human is present. Besides using up energy that may not be plentiful, eggs and young are left exposed to dangerous temperatures (hot or cold) and predators. The movement of the parent, or sometimes the odor of the human, can direct predators to the nest, causing the death of some of the young. Sometimes the parent in its rush steps on an egg or knocks it or its young out of the nest, leading to certain death for the offspring. Some parents may even abandon the nest or kill and eat the young, if they are frightened or startled enough. Young can get left behind when a parent flushes suddenly, get lost, and die of starvation or be eaten by a predator.

The stress of disturbance can increase energy needs, elevate heart rate (possibly leading to death), force the animal to temporarily or permanently abandon a feeding area, force it to become nocturnal, force it to spend a great amount of time watching for humans, interfere with reproduction, and in general decrease its productivity. Migratory birds, for example, have a limited amount of time to stock up on food before their trip. They often spend long periods flying over ocean, and can die if they don't have adequate nutritional reserves.

Because the Earth is losing some 100 species a day, worldwide, it is very important that we quickly become better informed, and stop mindlessly continuing "business as usual" in our approaches to wildlife and recreation.

Here are some relevant excerpts from Knight and Gutzwiller: "the notion that recreation has no environmental impacts is no longer tenable. Recreationists often degrade the land, water, and wildlife resources that support their activities by simplifying plant communities, increasing animal mortality, displacing and disturbing wildlife, and distributing refuse" (p.3); Boyle and Sampson ... reviewed 166 articles that contained original data on the effects of nonconsumptive outdoor recreation on wildlife. In 81% of them, the effects were considered negative" (p.51); "Nature viewing, by its very definition, has great potential to negatively affect wildlife. ... Predators learn to follow human scent trails to nest sites" (p.55); "activities [involving] nonmotorized travel ... [have] caused the creation of more ... trails in wildlands.... These activities are extensive in nature and have the ability to disrupt wildlife in many ways, particularly by displacing animals from an area" (p.56); "Recreational disturbance has traditionally been viewed as most detrimental to wildlife during the breeding season. Recently, it has become apparent that disturbance outside of the animal's breeding season may have equally severe effects" (p.73); "Birds can lose eggs and young when predators attack nests after parents are startled into flight" (p.133); "Human occupation and activity are clearly and directly correlated with declines in breeding populations of birds" (p.135).

"People have an impact on wildlife habitat and all that depends on it, no matter what the activity" (p.157); "Perhaps the major way that people have influenced wildlife populations is through encroachment into wildlife areas" (p.160); "a single visit to nest sites by people can cause nest abandonment" (p.161); "Some goslings got lost in the dense vegetation when parents headed for the pool, or parents swam off leaving goslings behind that could not follow" (p.162); "Pregnant animals suffered higher stress from wildlife viewers, causing some to abort" (p.163); "Outdoor recreation has been recognized as an important factor that can reduce biosphere sustainability.... Indeed, recreational activities, including many that may seem innocuous, can alter vertebrate behaviour, reproduction, distributions, and habitats" (p.169); "Human disturbance caused eagles to flush sooner than the other species, and eagles rarely returned to a carcass following disturbance" (p.170); "Juveniles that get displaced from familiar surroundings (e.g., home ranges) by recreationists may also be more susceptible to predation" (p.172).

"Displaced animals are forced out of familiar habitat and must then survive and reproduce in areas where they are not familiar with the locations of food, shelter, and other vital resources.... Hammitt and Cole ... ranked displacement as being more detrimental to wildlife than harassment or recreation-induced habitat changes.... Densities ... of 13 breeding bird species were negatively associated with the intensity of recreation activity by park visitors, primarily pedestrians and cyclists" (pp.173-4); "off-road vehicles can collapse burrows of desert mammals and reptiles" (p.176); "Compaction increases the mechanical resistance of the soil to root penetration and can reduce the emergence of seedlings" (p.184); "Soil compaction reduces the size of pore spaces, altering the soil fauna" (p.189); "several studies have shown the importance of contiguous, undisturbed habitat for many native species" (p.190); "Recreational activities clearly have substantial and generally adverse influences on terrestrial vegetation and soil, and on aquatic systems" (p.193); "researchers have documented an increase in heart rate in different species when approached by visitors, which can subsequently initiate other physiological effects of stress, including death" (p.206); "Indirect effects may also occur from development of trail networks and picnic areas, which not only remove habitat, but increase habitat edge ... [, opening] these areas for colonization by exotic ... species" (p.210); "Geese could not compensate for a loss in feeding time" (p.251); "The ESA defines harassment as 'an intentional or negligent act or omission which creates the likelihood of injury to wildlife by annoying it to such an extent as to significantly disrupt normal behaviour patterns which include, but are not limited to, feeding or sheltering'" (p.304).

"It is expected that outdoor recreational activity will continue to increase, while the amount of wild land where wildlife may seek refuge from disturbance will decrease" (p.327); "Recreationists are, ironically, destroying the very thing they love: the blooming buzzing confusion of nature.... The recreation industry deserves to be listed on the same page with interests that are cutting the last of the old-growth forests, washing fertile topsoils into the sea, and pouring billions of tons of greenhouse gases into the atmosphere" (p.340); "Tom Birch ... argues that wilderness managers, charged with incarcerating wilderness, are more concerned with the advancement of their careers through achieving quantifiable goals (number of park visitors, total revenues) and developing park and forest amenities (roads, 'scenic' turnouts, restrooms, paved trails, maps, campgrounds) than with perpetuating the land community of which they are a part" (p.344).

Ideally, we should be working to reduce all human access to wildlife habitat. But at the very least, we should eliminate mechanical access (with the exception of small compromises for wheelchairs).



Michael J. Vandeman, Ph.D.


Knight, Richard L. and Kevin J. Gutzwiller, eds. Wildlife and Recreationists. Covelo, California: Island Press, c.1995.