Science Proves Mountain Biking Is More Harmful Than Hiking

Mike Vandeman

The Impacts of Mountain Biking on Wildlife and People --
A Review of the Literature Michael J. Vandeman, Ph.D.
July 3, 2004

"Every recreationist -- whether hiker, biker, horsepacker,
or posey sniffer -- should not begin by asking, 'What's best
for ME?' but rather 'What's best for the bears?'" Tom Butler
"Will we keep some parts of the American landscape natural
and wild and free -- or must every acre be easily accessible
to people and their toys? … Mountain bikes' impacts on the
land are large and getting worse. … The aggressive push of
mountain bike organizations to build ever-growing webs of
trails poses serious problems of habitat fragmentation,
increased erosion, and wildlife conflicts. As interest in
extreme riding continues to grow, as trail networks burgeon,
and as new technology makes it possible for ever-more
mountain bicyclists to participate, even the most remote
wild landscapes may become trammeled -- and trampled -- by
knobby tires. … The destruction of wilderness and the
fragmentation of habitats and ecosystems is death by a
thousand cuts. Will introduction of mountain bikes -- and
their penetration farther into wilderness -- promote
additional fragmentation and human conflicts with the
natural world? Yes." Brian O'Donnell and Michael Carroll
"Some things are obvious: mountain bikes do more damage to
the land than hikers. To think otherwise ignores the story
told by the ground. Although I have never ridden a mountain
bike, I am very familiar with their impacts. For the last
seven years I have regularly run three to six miles several
times a week on a network of trails in the Sandia Mountain
foothills two blocks from my home. … These trails receive
use from walkers, runners, and mountain bikers; they are
closed to motorized vehicles. Because I'm clumsy, I keep my
eyes on the trail in front of me. I run or walk in all
seasons, in all kinds of weather. I have watched the growing
erosion on these trails from mountain bike use. The basic
difference between feet and tires is that tire tracks are
continuous and foot tracks are discontinuous. Water finds
that narrow, continuous tire tracks are a rill in which to
flow. Also, because many mountain bikers are after thrills
and speed, their tires cut into the ground. Slamming on the
brakes after zooming downhill, sliding around sharp corners,
and digging in to go uphill: I see the results of this
behavior weekly. … I regularly see mountain bikers cutting
off cross-country, even on steep slopes, for more of a
challenge. They seem blind and deaf to the damage they
cause. Admittedly, backpackers and horsepackers can cause
damage to wilderness trails. But this is a poor argument to
suggest that we add another source of damage to those
trails." Dave Foreman

"Studies show that bike impacts are similar to those of
other non-motorized trail users." Jim Hasenauer (professor
of rhetoric and member of the board of directors of the
International Mountain Bicyclists Association)

Introduction:

I first became interested in the problem of mountain
biking in 1994. I had been studying the impacts of
the presence of humans on wildlife, and had come to
the conclusion that there needs to be habitat that
is entirely off-limits to humans, in order that
wildlife that is sensitive to the presence of humans
can survive (see Vandeman, 2000). But what is the
best way to minimize the presence of people?
Restricting human access is repugnant, and difficult
and expensive to accomplish. It occurred to me that
the best way to reduce the presence and impacts of
humans is to restrict the technologies that they are
allowed to utilize in nature: e.g. prohibit bicycles
and other vehicles (and perhaps even domesticated
animals, when used as vehicles).

Having been a transportation activist for eight
years (working on stopping highway construction),
and having a favorable view of my fellow bicyclists
as environmentalists, I turned to them to help me
campaign to keep bicycles out of natural areas. Was
I ever surprised! I discovered that many bicyclists
(e.g. many mountain bikers) aren't environmentalists
at all, but are simply people who like to bicycle --
in the case of mountain bikers, many of them just
use nature, as a kind of playground or outdoor
gymnasium! (Of course, there are also hikers,
equestrians, and other recreationists who fall into
this category.) To my suggestion to keep bikes off
of trails in order to protect wildlife, they reacted
with hostility! (There is a degree of balkanization
among activists, where some transportation activists
ignore the needs of wildlife, and some wildlife
activists eschew bikes and public transit.)

In 1994 I attended a public hearing held by the East
Bay Municipal Utility (water) District to decide
whether to allow bikes on their watershed lands.
Mountain bikers were there asking for bike access,
and the Sierra Club was there to retain the right to
hike, while keeping out the bicycles. I said that I
had no interest in using the watershed, but that I
wanted to ensure that the wildlife are protected --
hence, I asked that bikes not be allowed. Afterward,
the EBMUD Board of Directors took a field trip to
Marin County, the birthplace of mountain biking, to
see the effects of mountain biking there. While they
were hiking along a narrow trail, a mountain biker
came racing by, swearing at them for not getting out
of his way fast enough. That helped them decide to
ban bikes. Today bikes are still restricted to paved
roads, and EBMUD is still one of the public agencies
most protective of wildlife.

It is obvious that mountain biking is harmful to
some wildlife and people. No one, even mountain
bikers, tries to deny that. Bikes create V-shaped
ruts in trails, throw dirt to the outside on turns,
crush small plants and animals on and under the
trail, facilitate increased levels of human access
into wildlife habitat, and drive other trail users
(many of whom are seeking the tranquility and
primitiveness of natural surroundings) out of the
parks. Because land managers were starting to ban
bikes from trails, the mountain bikers decided to
try to shift the battlefield to science, and try to
convince people that mountain biking is no more
harmful than hiking. But there are two problems with
this approach: (1) it's not true, and (2) it's
irrelevant.

I will examine (1) in a moment. But first, let's
look at relevance: whether or not hiking (or All
Terrain Vehicles or urban sprawl or anything else)
is harmful really has no bearing on whether mountain
biking is harmful: they are independent questions.
Such a comparison would only be relevant if one were
committed to allowing only one activity or the
other, and wanted to know which is more harmful. In
reality, hiking is always allowed, and the question
is whether to add mountain biking as a permitted
activity. In that case, the only relevant question
is: Is mountain biking harmful? Of course, it is.
However, since many people seem interested in the
outcome of the comparison, I will examine the
research and try to answer it.

The mountain bikers' other line of research aims to
prove that mountain bikers are just like hikers,
implying that they should have the same privileges
as hikers. (Of course, they already have the same
privileges! The exact same rules apply to both
groups: both are allowed to hike everywhere, and
neither is allowed to bring a bike where they aren't
allowed.) Using surveys, they have tried to show
that mountain bikers are really environmentalists,
lovers of nature, and deep ecologists. Of course,
surveys are notoriously unreliable: statements of
belief don't easily translate into behavior. I'm
going to ignore this research, since I am (and the
wildlife are) more interested in actual impacts, not
intentions.

The International Mountain Biking Association (IMBA)
has done me the favor of collecting all the research
they could find that seemed favorable to mountain
biking. Gary Sprung (2004) summarized it in his
carefully worded essay, "Natural Resource Impacts of
Mountain Biking". Gary says "the empirical studies
thus far do not support the notion that bikes cause
more natural resource impact". I will show that this
is not true; in fact, those studies, if their data
are interpreted properly, show the exact opposite:
that mountain biking has much greater impact than
hiking! Gary says that we should make "make
rational, non-arbitrary, less political decisions
regarding which groups are allowed on particular
routes". This is disingenuous. Mountain bikers (but
not bikes) are already allowed on every trail.

Impacts on Soil (Erosion):

Gary says "No scientific studies show that mountain
bikers cause more wear to trails than other users".
He cites Wilson and Seney (1994) and claims that
"hooves and feet erode more than wheels. … Wilson
and Seney found no statistically significant
difference between measured bicycling and hiking
effects". He quotes the study: "Horses and hikers
(hooves and feet) made more sediment available than
wheels (motorcycles and off-road bicycles) on
prewetted trails" (p.74).

This study is frequently cited by mountain bikers as
proof that mountain biking doesn't cause more impact
than hiking. But it has a number of defects that
call its conclusions into question. The authors used
a "rainfall simulator" to measure "sediment made
available" by the various treatments. They
"[collected] surface runoff and sediment yield
produced by the simulated rainstorms at the
downslope end of each plot", which they claim
"correlates with erosion" (they don't say what the
correlation coefficient is). This doesn't seem like
a good measure of erosion. For example, if a large
rock were dislodged, the very weak "simulated
rainfall" wouldn't be capable of transporting it
into the collecting tray; only very fine particles
would be collected. In fact, they admit that the
simulator's "small size … meant that the kinetic
energy of the simulated rainfall events was roughly
one-third that of natural rainstorms". Another
reason to suspect that the measurements aren't valid
is that "none of the relationships between water
runoff and soil texture, slope, antecedent soil
moisture, trail roughness, and soil resistance was
statistically significant".

The authors also ignored the relative distances that
various trail users typically travel (for example,
bikers generally travel several times as far as
hikers, multiplying their impacts accordingly) and
the additional impacts due to the mountain bike
bringing new people to the trails that otherwise
would not have been there (the same omission is true
of all other studies, except Wisdom et al (2004)).
They do say "Trail use in the last ten years has
seen a dramatic increase in off-road bicycles"
(p.86), but they don't incorporate this fact into
their comparison. In addition, there is no
recognition of different styles of riding and their
effect on erosion. We don't know if the mountain
bikers rode in representative fashion, or, more
likely, rode more gently, with less skidding,
acceleration, braking, and turning. There was also
no recognition that soil displaced sideways (rather
than downhill) also constitutes erosion damage. It
seems likely that they underestimated the true
impacts of mountain biking. I don't think that these
results are reliable. (Note that the study was
partially funded by IMBA.)

Gary next cited Chiu (Luke.Chiu@utas.edu.au)
and Kriwoken
(L.K.Kriwoken@utas.edu.au), claiming that there was "no
significant difference between hiking and biking trail
wear". I wasn't able to acquire this study, but it is
apparent from Gary's description of it that he (and
perhaps the authors) misstated the conclusions. If we
assume, as they claim, that bikers and hikers have the
same impact per mile (which is what they measured),
then it follows that mountain bikers have several times
the impact of hikers, since they generally travel
several times as far. (I haven't found any published
statistics, but I have informally collected 72 mountain
bikers' ride announcements, which advertise rides of a
minimum of 8 miles, an average of 27 miles, and a
maximum of 112 miles.)

Impacts on Plants:

Gary says "No scientific studies indicate that
bicycling causes more degradation of plants than
hiking. Trails are places primarily devoid of
vegetation, so for trail use in the center of
existing paths, impacts to vegetation are not a
concern." However this is a concern for plants that
try to establish themselves in the trail, and for
roots that cross the trail and end up being killed
or damaged.

He cites Thurston and Reader (2001), claiming that
"hiking and bicycling trample vegetation at equal
rates … the impacts of biking and hiking measured
here were not significantly different". Actually,
that is not true. Although overall impacts weren't
significantly different, "soil exposure [was]
greater on biking 500 pass lanes than hiking 500
pass lanes" (p.404). In other words, after 500
passes, mountain biking began to show significantly
greater impacts. Thus their conclusion, "the impacts
of biking and hiking measured here were not
significantly different" (p.405) is unwarranted.

The authors said "Bikers traveled at a moderate
speed, usually allowing bicycles to roll down lanes
without pedaling where the slope would allow." Thus
it would appear that the mountain biking that they
measured is not representative: it was unusually
slow and didn't include much opportunity for
braking, accelerating, or turning, where greater
impacts would be expected to occur.

The authors also said "Some hikers feel that bikers
should be excluded from existing trails" (p.397). Of
course, this is not true. Hikers are only asking
that bikes be excluded, not bikers. On page 407 they
admit the "possibility … that mountain bikers simply
contribute further to the overuse of trails". In
other words, allowing bikes on trails allows trail
use to increase over what it would be if bikes
weren't allowed. This is probably true, and deserves
to be recognized and researched.

They found that "One year following treatments,
neither vegetation loss nor species loss was
significantly greater on treated lanes than on
control lanes" (p.406). They conclude that the
recreation impacts are "short-term", and
experience "rapid recovery". This is unjustified.
Killing plants and destroying seeds modifies the
gene pool, and introduces human-caused loss of
genetic diversity, and evolution. Dead plants and
lost genetic diversity do not "recover" (see
Vandeman, 2001).

However, the greatest defect of the study and its
interpretation is that is that it doesn't consider
the distance that bikers travel. Even if we
accepted their conclusions that impacts per mile
are the same, it would follow that mountain bikers
have several times the impact of hikers, since
they are easily able to, and do, travel several
times as far as hikers. Try walking 25 or 50 or
100 miles in a day!

Impacts on Animals:

Gary cites Taylor and Knight (1993), claiming that
"hiking and biking cause [the] same impact to large
mammals on Utah island". First, as noted by Wisdom
et al (2004), this study lacked a control group, and
hence can't infer causation. Second, the authors
made the same mistake that all other researchers
made: they ignored the different distances that
hikers and bikers travel. I also wonder how
realistic it was to have all recreationists continue
past the animals without stopping to look at them.
(All of those researchers also failed to implement
blind measurement and analysis: the researchers were
aware, as they were measuring, which treatment they
were testing. Only Wisdom et al were able to carry
out their measurements (electronically) without any
people even being present.)

This is a very informative paper. The authors
"examined the responses of bison …, mule deer …, and
pronghorn antelope … to hikers and mountain bikers …
by comparing alert distance, flight distance, and
distance moved" (p.951). They noted, significantly,
that "Outdoor recreation has the potential to
disturb wildlife, resulting in energetic costs,
impacts to animals' behavior and fitness, and
avoidance of otherwise suitable habitat. … outdoor
recreation is the second leading cause for the
decline of federally threatened and endangered
species on public lands" (p.951). They also noted
that "Mountain biking in particular is one of the
fastest-growing outdoor activities, with 43.3
million persons participating at least once in 2000"
(p.952). However, they didn't draw on this fact when
they concluded "We found no biological justification
for managing mountain biking any differently than
hiking" (p.961).

The authors also surveyed the recreationists, and
found that they "failed to perceive that they were
having as great an effect on wildlife as our
biological data indicated. Most recreationists felt
that it was acceptable to approach wildlife at a
much closer distance (mean acceptable distance to
approach = 59.0 m) than wildlife in our experimental
trials would typically allow a human to approach
(mean flight distance of all species = 150.6 m). …
Of all visitors surveyed, 46%, 53%, and 54%,
respectively, felt that bison, deer, and pronghorn
were being negatively affected by recreation on
Antelope Island. … Visitors expressed little support
for allowing only one type of recreational use on
island trails, having fewer trails on the island,
for requiring visitors to watch an educational video
about the effects of recreation on wildlife, and for
allowing recreation only on the north (developed)
end of the island" (p.957). (Gary Sprung omitted
this information from his summary.)

They noted that the wildlife might habituate to the
presence of humans, but that exactly the opposite
happened with the pronghorn: they "in fact used
areas that were significantly farther from trails
than they had prior to the start of recreational use
on the island" (p.961). They also noted: "Because
flushing from recreational activity may come at the
cost of energy needed for normal survival, growth,
and reproduction …, and because it may cause animals
to avoid otherwise suitable habitat …, it is
important that recreationists understand that their
activities can flush wildlife and may make suitable
habitat unavailable" (p.961). I think that the
wealth of such information provided by the authors
makes this paper especially valuable.

They concluded "Our results indicate that there is
little difference in wildlife response to hikers vs.
mountain bikers" (p.957). I was present when Ms.
Taylor presented her findings at the Society for
Conservation Biology meeting at the University of
Kent, in Canterbury, England, in July, 2002. I
pointed out to her that she wasn't justified in
concluding, as she did, that "hiking and mountain
biking have the same impacts", since she only
measured impacts per incident. Since bikers are
able, and typically do, travel several times as far
as hikers, a more proper conclusion would be that
bikers have several times as much impact on wildlife
as hikers. That is why I am so disappointed to find
her later concluding in this 2003 paper, "We found
no biological justification for managing mountain
biking any differently than hiking" (p.961). If
mountain bikers can travel even twice as far as
hikers, and disturb twice as many animals, I would
think that that is biologically significant! It
isn't much help that she goes on to admit that
"because bikers travel faster than hikers, they may
cover more ground in a given time period than
hikers, thus having the opportunity to disturb more
wildlife per unit time" (p.961). She has still drawn
an unjustified conclusion, and it is certain to be
frequently quoted (out of context) by mountain
bikers, as they try to lobby for more trail access.

I also wonder about the accuracy of their
measurements of distance. Distance is notoriously
difficult to measure accurately, especially when
animals and recreationists may be hidden from view
("Due to the inherent errors in triangulating in the
steep canyon country, only ground visual locations
were used in the analysis" p.577). Bias may also
have been introduced by the fact that researchers
knew, as they were measuring, which treatment they
were measuring.

It is interesting that "when bighorn sheep did
respond to human activity, they noticed vehicles and
mountain bikers, on average, from twice the distance
they noticed hikers" (p.577). This would seem to
imply that, were hikers to remain on the trail where
the mountain bikers were, they might have equal or
lower impacts than the mountain bikers.

Sprung next cited Papouchis et al (2001), claiming
that "Hikers have [the] greatest impact on bighorn
sheep [in Canyonlands National Park] … because the
hikers were more likely to be in unpredictable
locations and often directly approached [the]
sheep". Actually, this is an artifact of the
experimental design, and not a result of research:
the researchers, for some reason, told the hikers
(who were research assistants) to approach the
sheep! So the study actually compared apples and
oranges: bikers who stay on a road, vs. hikers who
approach bighorn sheep! Nothing useful can be
concluded from such a study, except that people who
approach bighorn sheep disturb them. Of course,
there is nothing to prevent mountain bikers from
getting off their bikes and doing the same thing.
It's unfortunate that the opportunity was lost to
gain more valuable knowledge. I wrote the authors,
asking why they had done this, but I got no reply.
It would appear that the intention was to exonerate
mountain biking (this also applies to most of the
other studies).

It is also unfortunate that there was no control
group, so that they could determine the effect of
the presence of roads, with and without people on
them. They did note that "avoidance of the road
corridor by some animals represented 15% less use of
potential suitable habitat in the high-[visitor-]use
area over the low-[visitor-]use area. … human
presence in bighorn sheep habitat may cause sheep to
vacate suitable habitat" (p.573). This argues for
eliminating all recreation in the area, especially
since the absence of water forces recreationists to
bring motor vehicles carrying water and other
supplies: "mountain bikers frequently use the 161-km
White Rim trail, a 4-wheel-drive road. Caravans of
mountain bikers accompanied by support vehicles are
common. Day use along the Shafer and White Rim
trails exceeded 17,500 vehicles during the study
period, 1993-1994. This use was concentrated from
March to October, with peak use of 134 vehicles/day
in May" (p.575).

The authors conclude "Contrary to our original
expectations and the concerns of park managers, the
increase in numbers of mountain bikers visiting the
park does not appear to be a serious threat to
desert bighorn sheep, probably because mountain
bikers are restricted to predictable situations
such as the currently designated road corridors"
(p.580). For several reasons, this conclusion is
not justified: (1) as they reported, all
recreationists drive the sheep away from parts of
their habitat, causing loss of energy as well as
habitat; (2) permitting bikes causes the total
number of visitors to increase significantly; (3)
bikes can't travel alone -- they require motorized
support vehicles, further increasing impacts (e.g.
worsening air quality); (4) there is nothing to
prevent mountain bikers from getting off their
bikes and approaching the wildlife; if hikers do
that, so will mountain bikers; there is no reason
to exonerate mountain bikers.

They note, significantly, "However, these results
should not be extrapolated to other public lands
where mountain bikers are not confined to designated
trails and may surprise sheep in novel situations"
(p.580). Gary Sprung didn't mention this, thus
encouraging inappropriate use of this study's already-
questionable results.

I would like, however, to commend the authors for
stating "we recommend that park managers manage
levels of backcountry activity at low levels"
(p.580). The best policy would be to ban all
vehicles, including bicycles (as well as animals
used as vehicles). That would reduce human impacts,
without directly restricting who could go there
(perhaps occasional exceptions could be made for the
disabled).

Gary next cited Gander and Ingold (1997), claiming
that "hikers, joggers & mountain bikers [are] all
the same to chamois". But again, this is not an
accurate representation of the results: "They fled
over longer distances in jogging and mountain biking
experiments … carried out late in the morning"
(p.109). Also, "the three activities carried out on the
ground could have long-term consequences as they
prevent the animals from using areas near trails.
Thus, depending on the density of trails and the
intensity of recreational activities in a certain
area, animals may lose a large part of their habitat"
(p.110).

The authors conclude "Our results show that specific
restrictions on mountainbiking above the timberline
are not justified from the point of view of chamois"
(p.109). Once again (is there a pattern here?), this
conclusion is not justified. It ignores the fact
that mountain bikers are able to travel several
times as far as hikers, and thus negatively impact
several times as much wildlife. It also ignores the
fact that bicycles enable a large increase in
numbers of human visitors (note that this places the
blame on the bicycle, not the bicyclists -- my
argument doesn't depend on there being any
difference between hikers and mountain bikers). And,
of course, wherever the number of visitors
increases, there is pressure to build more trails,
destroying even more habitat. Once again, it would
appear that this study was undertaken with the
intent of excusing mountain biking.

Gary next cites a study of bald eagles by Robin
Spahr, that I wasn't able to acquire. "Spahr found
that walkers caused the highest frequency of eagle
flushing". However, this study is difficult to
interpret. Eagles don't congregate in large numbers,
like sheep. So it is hard to ensure that all
treatments are equally balanced. Gary doesn't
mention the numbers of eagles or recreationists. It
is hard to imagine that the conditions under
different treatments (or even within treatments)
were equal. Thus, I don't know if this was really a
controlled study. Spahr also found that "bicyclists
caused eagles to flush at [the] greatest distances",
which would tend to indicate bicyclists have greater
impacts. At best, these are mixed results. And, once
again, the greater distances that bikers travel are
ignored, as well as the greater visitor numbers that
the bicycle enables.

Gary concludes "Mountain biking, like other
recreation activities, does impact the environment.
On this point, there is little argument. But … a
body of empirical, scientific studies now indicates
[sic] that mountain biking is no more damaging than
other forms of recreation, including hiking [Gary's
emphasis]. Thus, managers who prohibit bicycle use
(while allowing hiking or equestrian use) based on
impacts to trails, soils, wildlife, or vegetation
are acting without sound, scientific backing." Au
contraire, as I have indicated, the very studies
that Gary and IMBA cite as support for mountain
biking actually show that mountain biking does much
more harm to the environment than hiking! Gary goes
on to fault "the wisdom of prohibiting [sic]
particular user groups". However, as I explained
earlier, mountain bikers are not prohibited from
using any trails. Bicycles are occasionally
prohibited. Mountain bikers are merely required to
follow the same rules as everyone else, and walk.

At the bottom of the same web page is the notice:
"IMBA wishes to obtain and incorporate into future
revisions of this document any new or additional
empirical science regarding the impacts of mountain
biking. IMBA welcomes input [my emphasis]. To offer
information, please contact the author at
gary@imba.com". On April 25 I emailed Gary (and Pete
Webber, pete@imba.com) the Wisdom et al study, which
demonstrates that mountain bikers have a greater
impact on elk than hikers. Not only hasn't this new
research been incorporated into his paper, but I
haven't even received a reply. It would appear that
IMBA isn't really interested in achieving a
scientific answer to this question.

In 2003, Jason Lathrop wrote an excellent "critical
literature review" on the ecological impacts of
mountain biking, raising some questions found
nowhere else. He quotes the BLM: "An estimated 13.5
million mountain bicyclists visit public lands each
year to enjoy the variety of trails. What was once a
low use activity that was easy to manage has become
more complex". He criticizes all of the studies for
not using realistic representations of mountain
biking. For example, on Thurston and Reader, he says
"this study's treatment passes at best loosely
approximate the forces exerted by actual mountain
biking. On real trails, riders possess widely
varying levels of skill, resulting in variant
speeds, turning, and braking. This study does not
address these variables." Lathrop also makes the
excellent point that "Direct mortality [of animals]
is virtually unstudied. I could find no references
to it in the literature. Anecdotal evidence
suggests, however, that small mammals are vulnerable
to impact and are not uncommonly killed."

And: "Taylor (2001) concluded that short-term
behavioral changes do not vary between bicyclists
and hikers on a per-encounter basis. However,
because bicyclists are capable of and, in most
areas, typically do travel much farther than hikers,
it is reasonable to conclude that they will create a
somewhat higher total number of encounters and
flushings."

Cessford (1995) did an oft-quoted review (which I am
including only because it is so widely cited) that,
like all others, uncritically accepts Wilson and
Seney (1994) as proof that mountain biking impacts
are no worse than those of hikers. His paper is
mostly speculation, based on few actual research
findings. He disparages negative information about
mountain biking by such devices as claiming that
problems are caused by a minority of mountain
bikers, exhibiting "poor riding habits", that
accidents involving hikers and bikers are "rare",
that hikers' dislike for being around bikes in the
woods, and feelings that bikes cause greater
environmental harm than hiking, are mere
"perceptions". He blames hikers for "misperceiving"
mountain bikers, claiming that "the two groups are
more similar than is generally perceived. … The
bicyclists … are basically hikers who are using
mountain bikes to gain quicker access to the
wilderness boundary". He speculates, without any
evidence, that "the degree of conflict with mountain
biking may diminish over time as other users become
more familiar with bike-encounters and riders
themselves". A more likely interpretation is that
hikers who dislike being around bikes simply stop
using trails that are open to bikes, thereby
lessening the conflict!

Finally, in 2004, Wisdom et al did a very well
controlled study comparing the impacts of ATV
riders, mountain bikers, and hikers on elk and mule
deer. They say we have an "urgent need for timely
management information to address the rapid growth
in off-road recreation. … Mountain biking [is] …
increasing rapidly". Recreationists were allowed to
stop for less than a minute to look at the animals.
All measurements were made electronically, using an
Automated Telemetry System and GPS, allowing control
measurements to be made "blind", with no humans
present! "Use of the automated telemetry system to
track animal movements, combined with the use of GPS
units to track human movements, provided real-time,
unbiased estimates of the distances between each
ungulate and group of humans [the recreationists
were in pairs]". He pointed out that direct
measurements, a la Taylor and Knight, tend to be
biased, because some animals can't be observed. The
area was entirely fenced, allowing researchers to
completely control human access.

They found: "Movement rates of elk were
substantially higher during all four off-road
activities as compared to periods of no human
activity. … For the morning pass, movement rates of
elk were highest during ATV activity, second-highest
during mountain bike riding, and lowest during
hiking and horseback riding. … Peak movement rates
of elk during the morning pass were highest for ATV
riding (21 yards/minute), followed by mountain bike
riding (17 yards/minute) and horseback riding and
hiking (both about 15 yards/minute). … By contrast,
peak movement rates of elk during the control
periods did not exceed 9 yards/minute during
daylight hours of 0800-1500, the comparable period
of each day when off-road treatments were
implemented. Interestingly, movement rates of elk
were also higher than control periods at times
encompassing sunrise and sunset for the days in
which an off-road activity occurred, even though
humans were not present at these times of the day.
These 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. In
particular, movement rates of elk at or near sunrise
and sunset were higher during the 5-day treatments
of mountain bike and ATV activity"
(p.111).

"Higher probabilities of flight response occurred
during ATV and mountain bike activity, in contrast
to lower probabilities observed during hiking and
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 from mountain bike and ATV riders.
In contrast to elk, mule deer showed less change in
movement rates during the four off-road activities
compared to the control periods" (p.7). (Perhaps
they seek cover, rather than running away.)

"The energetic costs associated with these
treatments deserve further analysis to assess
potential effects on elk survival. For example, if
the additional energy required to flee from an off-
road activity reduces the percent body fat below 9
percent as animals enter the winter period, the
probability of surviving the winter is extremely
low. Animal energy budgets also may be adversely
affected by the loss of foraging opportunities while
responding to off-road activities, both from
increased movements, and from displacement from
foraging habitat. … Our results from 2002 also show
clear differences in elk responses to the four off-
road activities. Elk reactions were more pronounced
during ATV and mountain bike riding, and less so
during horseback riding and hiking. Both movement
rates and probabilities of flight responses were
higher for ATV and mountain bike riding than for
horseback riding and hiking."

It is also instructive to note that only one pair of
ATV users were needed to cover the 20-mile study
area, but two pairs of mountain bikers and three
pairs of hikers were needed, to cover the distance
in the time allotted, underscoring the different
relative distances that the three groups are capable
of covering.

Summary:

Mountain bikers have turned to scientific research
to try to make mountain biking seem less harmful,
and in particular, to studies comparing it with
hiking. Although they have interpreted this data as
indicating that mountain biking impacts are no
greater than those of hiking, a more careful look at
these studies leads to the conclusion that mountain
biking impacts are actually several times greater
than those of hikers.

Some of the important characteristics of mountain
biking that have been ignored are: speed; distance
traveled; the increase in number of visitors that
bikes allow; increased trail-building, with its
attendant habitat destruction; the displacement of
soil (other than downhill); the killing of roots and
soil organisms and ecosystems; most effects on
wildlife; manner of riding (skidding, braking,
acceleration, turning, and representativeness); tire
tread; and noise (bikes are relatively quiet, but a
rattling chain may be perceived as "alien" to
natural surroundings).

In addition, measuring techniques need to be
described in more detail, "blind" measurements
should be considered (where the measurers don't know
what treatment they are measuring), controls need to
be added, and "intangibles"
(e.g. loss of feelings of safety and loss of the primitive
feel of natural settings) need to be taken more
seriously. The direct killing of small animals
deserves attention.

On the other hand, why do we need research to prove
what is obvious? We don't need any research to know
that we shouldn’t step in front of a speeding truck.
Or mountain bike.

References:

Butler, Tom, "Mountain biking in wilderness: What bears want
-- a wilderness view". Wild Earth, Vol.13, No.1, 2003,
http://www.wildlandsproject.org.

Cessford, Gordon R. (gcessford@doc.govt.nz), "Off-road
impacts of mountain bikes -- a review and discussion".
Science & Research Series No.92, Department of Conservation,
P. O. Box 10-420, Wellington, New Zealand, 1995, http://www-
.mountainbike.co.nz/politics/doc/impacts/index.htm.

Foreman, Dave, "A modest proposal". Wild Earth, Vol.13,
No.1, 2003, pp.34-5, http://www.wildlandsproject.org.

Gander, Hans and Paul Ingold, "Reactions of male
alpine chamois Rupicapra r. rupicapra to hikers,
joggers and mountainbikers". Biological Conservation,
Vol.79, 1997, pp.107-9.

Goeft, Ute and Jackie Alder, "Sustainable mountain biking: a
case study from the southwest of Western Australia". Journal
of Sustainable Tourism, Vol.9, No.3, 2001, pp.193-211.

Hasenauer, Jim (imbajim@aol.com), "A niche for bicycles".
Wild Earth, Vol.13, No.1, 2003, pp.21-22,
http://www.wildlandsproject.org.

Lathrop, Jason, "Ecological impacts of mountain biking: a
critical literature review". 2003, http://www.wildlandscpr.-
org/resourcelibrary/reports/mountainbikingreport.htm.

McCoy, Michael and Mary Alice Stoner, "Mountain bike trails:
Techniques for design, construction and maintenance".
Bikecentennial, P. O. Box 8308, Missoula, MT 59807, 1992.

O'Donnell, Brian and Michael Carroll, "Don't tread here".
Wild Earth, Vol.13, No.1, 2003, pp.31-33,
http://www.wildlandsproject.org.

Papouchis, Christopher M. (papouchis@hotmail.com), Francis
J. Singer, and William B. Sloan, "Responses of desert
bighorn sheep to increased human recreation". Journal of
Wildlife Management, Vol.65, No.3, 2001, pp.573-82.

Sprung, Gary (gary@imba.com), "Natural resource impacts of
mountain biking -- a summary of scientific studies that
compare mountain biking to other forms of trail travel",
2004,
http://www.imba.com/resources/scien...ct_summary.html.

Taylor, Audrey (audrey_taylor@fws.gov) and Richard L. Knight
(knight@cnr.colostate.edu) "Wildlife responses to recreation
and associated visitor perceptions". Ecological
Applications, Vol.13, No.4, 2003, pp.951-63.

Thurston, Eden and Richard J. Reader (rreader@uoguelph.ca),
"Impacts of experimentally applied mountain biking and
hiking on vegetation and soil of a deciduous forest".
Environmental Management, Vol.27, No.3, 2001, pp.397-409.

Vandeman, Michael J., "Wildlife Need Habitat Off-Limits to
Humans!" Presented at the Society for Conservation Biology
meeting, University of Montana, Missoula, Montana, June 10,
2000, http://home.pacbell.net/mjvande/india3.htm.

Vandeman, Michael J., "The Myth of the Sustainable
Lifestyle". Presented at the Society for Conservation
Biology meeting, University of Hawaii, Hilo, Hawaii, July
30, 2001, http://home.pacbell.net/mjvande/sustain.htm.

Wilson, John P. and Joseph Seney, "Erosional impact of
hikers, horses, motorcycles, and off-road bicycles on
mountain trails in Montana". Mountain Research and
Development, Vol.14, No.1, 1994, pp.77-88.

Wisdom, M. J. (mwisdom@fs.fed.us), Alan A. Ager
(aager@fs.fed.us ), H. K. Preisler (hpreisler@fs.fed.us), N.
J. Cimon (ncimon@fs.fed.us), and B. K. Johnson
(johnsobd@eou.edu), "Effects of off-road recreation on mule
deer and elk". Transactions of the North American Wildlife
and Natural Resources Conference 69, 2004, in press.

===
I am working on creating wildlife habitat that is off-limits
to humans ("pure habitat"). Want to help? (I spent the
previous 8 years fighting auto dependence and road
construction.)

http://home.pacbell.net/mjvande

S O R N I

Mike Vandeman wrote:

{42 KB's worth of hot air and cat scat}

Did you say something?

Bill "bwahaahhahahahahahahahahahha" S.

Stephen Baker

Mike "I've made up my mind, don't bother me with the Truth" V say:

<snip verbiage>

Isn't it strange that rabid folks only agree with the
literature that agrees with their viewpoint?

A mind is definitely a sad thing to waste, but a closed mind
really was wasted to start with...

Steve

Mike Vandeman

On Sat, 10 Jul 2004 00:42:55 GMT, "S o r n i" <sorni@bite-me.san.rr.com> wrote:

.Mike Vandeman wrote: . .{42 KB's worth of hot air and cat
scat} . .Did you say something? . .Bill
"bwahaahhahahahahahahahahahha" S.

Thanks for proving that mountain bikers aren't
interested in FACT.
===
I am working on creating wildlife habitat that is off-limits
to humans ("pure habitat"). Want to help? (I spent the
previous 8 years fighting auto dependence and road
construction.)

http://home.pacbell.net/mjvande

Mike Vandeman

On 10 Jul 2004 02:14:34 GMT, saildesign@aol.comnospam (Stephen Baker) wrote:

.Mike "I've made up my mind, don't bother me with the Truth"
V say: . .<snip verbiage> . .Isn't it strange that rabid
folks only agree with the literature that agrees .with their
viewpoint?

You didn't read it, did you? There are places you can learn
to read, even after you are too old for school.

.A mind is definitely a sad thing to waste, but a closed
mind really was wasted .to start with... . .Steve

===
I am working on creating wildlife habitat that is off-limits
to humans ("pure habitat"). Want to help? (I spent the
previous 8 years fighting auto dependence and road
construction.)

http://home.pacbell.net/mjvande

Gawnsoft

On Sat, 10 Jul 2004 00:02:31 GMT, Mike Vandeman
<mjvande@pacbell.net> wrote (more or less): ...
>Was I ever surprised! I discovered that many bicyclists
>(e.g. many mountain bikers) aren't environmentalists at
>all, but are simply people who like to bicycle
...

Why on earth did this surprise you?

--
Cheers, Euan Gawnsoft: http://www.gawnsoft.co.sr
Symbian/Epoc wiki: http://html.dnsalias.net:1122 Smalltalk
links (harvested from comp.lang.smalltalk)
http://html.dnsalias.net/gawnsoft/smalltalk

@

Wow, that was a really piss-poor essay.

Formal writing ... does not -- I repeat, does not -- have to
be ... punctuated with ... mental ellipses, Mr. Spock.

Mike Vandeman wrote: <ellipses

Tj

"Mike Vandeman" <mjvande@pacbell.net> wrote in message
news:vccue01qbn80dkkdovfqfnitgbevrfe2fm@4ax.com...
> The Impacts of Mountain Biking on Wildlife and People --
> A Review of the Literature Michael J. Vandeman, Ph.D.
> July 3, 2004
>
> "Every recreationist -- whether hiker, biker, horsepacker,
> or posey
sniffer --
> should not begin by asking, 'What's best for ME?' but
> rather 'What's best
for
> the bears?'" Tom Butler "Will we keep some parts of the
> American landscape natural and wild and
free --
> or must every acre be easily accessible to people and
> their toys? .
Mountain
> bikes' impacts on the land are large and getting worse. .
> The aggressive
push of
> mountain bike organizations to build ever-growing webs of
> trails poses
serious
> problems of habitat fragmentation, increased erosion, and
> wildlife
conflicts.
> As interest in extreme riding continues to grow, as trail
> networks burgeon, and as new technology makes it possible
> for ever-more mountain bicyclists to participate, even the
> most remote wild landscapes may become trammeled -- and
> trampled -- by knobby tires. . The destruction of
wilderness
> and the fragmentation of habitats and ecosystems is death
> by a thousand
cuts.
> Will introduction of mountain bikes -- and their
> penetration farther into wilderness -- promote additional
> fragmentation and human conflicts with
the
> natural world? Yes." Brian O'Donnell and Michael Carroll
> "Some things are obvious: mountain bikes do more damage to
> the land than
hikers.
> To think otherwise ignores the story told by the ground.
> Although I have
never
> ridden a mountain bike, I am very familiar with their
> impacts. For the
last
> seven years I have regularly run three to six miles
> several times a week
on a
> network of trails in the Sandia Mountain foothills two
> blocks from my
home. .
> These trails receive use from walkers, runners, and
> mountain bikers; they
are
> closed to motorized vehicles. Because I'm clumsy, I
> keep my eyes on the trail in front of me. I run or walk
> in all seasons, in all kinds of weather. I have watched
> the growing
erosion
> on these trails from mountain bike use. The basic
> difference between feet
and
> tires is that tire tracks are continuous and foot
> tracks are
discontinuous.
> Water finds that narrow, continuous tire tracks are a rill
> in which to
flow.
> Also, because many mountain bikers are after thrills and
> speed, their
tires cut
> into the ground. Slamming on the brakes after zooming
> downhill, sliding
around
> sharp corners, and digging in to go uphill: I see the
> results of this
behavior
> weekly. . I regularly see mountain bikers cutting off cross-
> country, even on steep slopes, for more of a challenge.
> They seem blind and deaf to the damage
they
> cause. Admittedly, backpackers and horsepackers can cause
> damage to
wilderness
> trails. But this is a poor argument to suggest that we add
> another source
of
> damage to those trails." Dave Foreman
>
> "Studies show that bike impacts are similar to those
> of other
non-motorized
> trail users." Jim Hasenauer (professor of rhetoric and
> member of the board
of
> directors of the International Mountain Bicyclists
> Association)
>
> Introduction:
>
> I first became interested in the problem of mountain
> biking in 1994. I had been studying the impacts of the
> presence of humans on wildlife, and
had
> come to the conclusion that there needs to be habitat that
> is entirely off-limits to humans, in order that wildlife
> that is sensitive to the
presence
> of humans can survive (see Vandeman, 2000). But what is
> the best way to
minimize
> the presence of people? Restricting human access is
> repugnant, and
difficult and
> expensive to accomplish. It occurred to me that the best
> way to reduce the presence and impacts of humans is to
> restrict the technologies that they
are
> allowed to utilize in nature: e.g. prohibit bicycles and
> other vehicles
(and
> perhaps even domesticated animals, when used as vehicles).
>
> Having been a transportation activist for eight years
> (working on stopping highway construction), and having a
> favorable view of my fellow bicyclists as
> environmentalists, I turned to them to help me campaign to
keep
> bicycles out of natural areas. Was I ever surprised! I
> discovered that
many
> bicyclists (e.g. many mountain bikers) aren't
> environmentalists at all,
but are
> simply people who like to bicycle -- in the case of
> mountain bikers, many
of
> them just use nature, as a kind of playground or outdoor
> gymnasium! (Of
course,
> there are also hikers, equestrians, and other
> recreationists who fall into
this
> category.) To my suggestion to keep bikes off of trails in
> order to
protect
> wildlife, they reacted with hostility! (There is a degree
> of balkanization
among
> activists, where some transportation activists ignore the
> needs of
wildlife, and
> some wildlife activists eschew bikes and public transit.)
>
> In 1994 I attended a public hearing held by the East Bay
> Municipal Utility (water) District to decide whether to
> allow bikes on their
watershed
> lands. Mountain bikers were there asking for bike access,
> and the Sierra
Club
> was there to retain the right to hike, while keeping out
> the bicycles. I
said
> that I had no interest in using the watershed, but that I
> wanted to ensure
that
> the wildlife are protected -- hence, I asked that bikes
> not be allowed. Afterward, the EBMUD Board of Directors
> took a field trip to Marin County,
the
> birthplace of mountain biking, to see the effects of
> mountain biking
there.
> While they were hiking along a narrow trail, a mountain
> biker came racing
by,
> swearing at them for not getting out of his way fast
> enough. That helped
them
> decide to ban bikes. Today bikes are still restricted to
> paved roads, and
EBMUD
> is still one of the public agencies most protective of
> wildlife.
>
> It is obvious that mountain biking is harmful to some
> wildlife and people. No one, even mountain bikers, tries
> to deny that. Bikes create
V-shaped
> ruts in trails, throw dirt to the outside on turns, crush
> small plants and animals on and under the trail,
> facilitate increased levels of human
access into
> wildlife habitat, and drive other trail users (many of
> whom are seeking
the
> tranquility and primitiveness of natural surroundings) out
> of the parks.
Because
> land managers were starting to ban bikes from trails, the
> mountain bikers decided to try to shift the battlefield to
> science, and try to convince
people
> that mountain biking is no more harmful than hiking. But
> there are two
problems
> with this approach: (1) it's not true, and (2) it's
> irrelevant.
>
> I will examine (1) in a moment. But first, let's look at
> relevance: whether or not hiking (or All Terrain Vehicles
> or urban sprawl or anything
else)
> is harmful really has no bearing on whether mountain
> biking is harmful:
they are
> independent questions. Such a comparison would only be
> relevant if one
were
> committed to allowing only one activity or the other, and
> wanted to know
which
> is more harmful. In reality, hiking is always allowed, and
> the question is whether to add mountain biking as a
> permitted activity. In that case, the
only
> relevant question is: Is mountain biking harmful? Of
> course, it is.
However,
> since many people seem interested in the outcome of the
> comparison, I will examine the research and try to
> answer it.
>
> The mountain bikers' other line of research aims to prove
> that mountain bikers are just like hikers, implying that
> they should have the same
privileges
> as hikers. (Of course, they already have the same
> privileges! The exact
same
> rules apply to both groups: both are allowed to hike
> everywhere, and
neither is
> allowed to bring a bike where they aren't allowed.) Using
> surveys, they
have
> tried to show that mountain bikers are really
> environmentalists, lovers of nature, and deep ecologists.
> Of course, surveys are notoriously
unreliable:
> statements of belief don't easily translate into behavior.
> I'm going to
ignore
> this research, since I am (and the wildlife are) more
> interested in actual impacts, not intentions.
>
> The International Mountain Biking Association (IMBA) has
> done me the favor of collecting all the research they
> could find that seemed favorable
to
> mountain biking. Gary Sprung (2004) summarized it in his
> carefully worded
essay,
> "Natural Resource Impacts of Mountain Biking". Gary says
> "the empirical
studies
> thus far do not support the notion that bikes cause more
> natural resource impact". I will show that this is not
> true; in fact, those studies, if
their
> data are interpreted properly, show the exact opposite:
> that mountain
biking has
> much greater impact than hiking! Gary says that we should
> make "make
rational,
> non-arbitrary, less political decisions regarding which
> groups are allowed
on
> particular routes". This is disingenuous. Mountain bikers
> (but not bikes)
are
> already allowed on every trail.
>
> Impacts on Soil (Erosion):
>
> Gary says "No scientific studies show that mountain bikers
> cause more wear to trails than other users". He cites
> Wilson and Seney (1994) and
claims
> that "hooves and feet erode more than wheels. . Wilson and
> Seney found no statistically significant difference
> between measured bicycling and hiking effects". He quotes
> the study: "Horses and hikers (hooves and feet) made
more
> sediment available than wheels (motorcycles and off-road
> bicycles) on
prewetted
> trails" (p.74).
>
> This study is frequently cited by mountain bikers as proof
> that mountain biking doesn't cause more impact than
> hiking. But it has a number of
defects
> that call its conclusions into question. The authors used
> a "rainfall
simulator"
> to measure "sediment made available" by the various
> treatments. They "[collected] surface runoff and sediment
> yield produced by the simulated rainstorms at the
> downslope end of each plot", which they claim
"correlates with
> erosion" (they don't say what the correlation coefficient
> is). This
doesn't seem
> like a good measure of erosion. For example, if a large
> rock were
dislodged, the
> very weak "simulated rainfall" wouldn't be capable of
> transporting it into
the
> collecting tray; only very fine particles would be
> collected. In fact,
they
> admit that the simulator's "small size . meant that the
> kinetic energy of
the
> simulated rainfall events was roughly one-third that
> of natural
rainstorms".
> Another reason to suspect that the measurements aren't
> valid is that "none
of
> the relationships between water runoff and soil texture,
> slope, antecedent
soil
> moisture, trail roughness, and soil resistance was
> statistically
significant".
>
> The authors also ignored the relative distances that
> various trail users typically travel (for example, bikers
> generally travel several times as
far as
> hikers, multiplying their impacts accordingly) and the
> additional impacts
due to
> the mountain bike bringing new people to the trails that
> otherwise would
not
> have been there (the same omission is true of all other
> studies, except
Wisdom
> et al (2004)). They do say "Trail use in the last ten
> years has seen a
dramatic
> increase in off-road bicycles" (p.86), but they don't
> incorporate this
fact into
> their comparison. In addition, there is no recognition of
> different styles
of
> riding and their effect on erosion. We don't know if the
> mountain bikers
rode in
> representative fashion, or, more likely, rode more gently,
> with less
skidding,
> acceleration, braking, and turning. There was also no
> recognition that
soil
> displaced sideways (rather than downhill) also constitutes
> erosion damage.
It
> seems likely that they underestimated the true impacts of
> mountain biking.
I
> don't think that these results are reliable. (Note that
> the study was
partially
> funded by IMBA.)
>
> Gary next cited Chiu (Luke.Chiu@utas.edu.au) and Kriwoken
> (L.K.Kriwoken@utas.edu.au), claiming that there was "no
> significant
difference
> between hiking and biking trail wear". I wasn't able to
> acquire this
study, but
> it is apparent from Gary's description of it that he (and
> perhaps the
authors)
> misstated the conclusions. If we assume, as they claim,
> that bikers and
hikers
> have the same impact per mile (which is what they
> measured), then it
follows
> that mountain bikers have several times the impact of
> hikers, since they generally travel several times as far.
> (I haven't found any published statistics, but I have
> informally collected 72 mountain bikers' ride
> announcements, which advertise rides of a minimum of 8
> miles, an average
of 27
> miles, and a maximum of 112 miles.)
>
> Impacts on Plants:
>
> Gary says "No scientific studies indicate that bicycling
> causes more degradation of plants than hiking. Trails are
> places primarily devoid of vegetation, so for trail use in
> the center of existing paths, impacts to vegetation are
> not a concern." However this is a concern for plants that
try to
> establish themselves in the trail, and for roots that
> cross the trail and
end up
> being killed or damaged.
>
> He cites Thurston and Reader (2001), claiming that "hiking
> and bicycling trample vegetation at equal rates . the
> impacts of biking and hiking
measured
> here were not significantly different". Actually, that is
> not true.
Although
> overall impacts weren't significantly different, "soil
> exposure [was]
greater on
> biking 500 pass lanes than hiking 500 pass lanes" (p.404).
> In other words,
after
> 500 passes, mountain biking began to show significantly
> greater impacts.
Thus
> their conclusion, "the impacts of biking and hiking
> measured here were not significantly different" (p.405) is
> unwarranted.
>
> The authors said "Bikers traveled at a moderate speed,
> usually allowing bicycles to roll down lanes without
> pedaling where the slope would allow."
Thus
> it would appear that the mountain biking that they
> measured is not representative: it was unusually slow and
> didn't include much opportunity
for
> braking, accelerating, or turning, where greater impacts
> would be expected
to
> occur.
>
> The authors also said "Some hikers feel that bikers should
> be excluded from existing trails" (p.397). Of course, this
> is not true. Hikers are
only
> asking that bikes be excluded, not bikers. On page 407
> they admit the "possibility . that mountain bikers simply
> contribute further to the
overuse of
> trails". In other words, allowing bikes on trails allows
> trail use to
increase
> over what it would be if bikes weren't allowed. This is
> probably true, and deserves to be recognized and
> researched.
>
> They found that "One year following treatments, neither
> vegetation loss nor species loss was significantly greater
> on treated lanes than on
control
> lanes" (p.406). They conclude that the recreation
> impacts are
"short-term", and
> experience "rapid recovery". This is unjustified. Killing
> plants and
destroying
> seeds modifies the gene pool, and introduces human-
> caused loss of genetic diversity, and evolution. Dead
> plants and lost genetic diversity do not "recover" (see
> Vandeman, 2001).
>
> However, the greatest defect of the study and its
> interpretation is that is that it doesn't consider the
> distance that bikers travel. Even if we
accepted
> their conclusions that impacts per mile are the same, it
> would follow that mountain bikers have several times the
> impact of hikers, since they are
easily
> able to, and do, travel several times as far as hikers.
> Try walking 25 or
50 or
> 100 miles in a day!
>
> Impacts on Animals:
>
> Gary cites Taylor and Knight (1993), claiming that "hiking
> and biking cause [the] same impact to large mammals on
> Utah island". First, as noted
by
> Wisdom et al (2004), this study lacked a control group,
> and hence can't
infer
> causation. Second, the authors made the same mistake that
> all other
researchers
> made: they ignored the different distances that hikers and
> bikers travel.
I also
> wonder how realistic it was to have all recreationists
> continue past the
animals
> without stopping to look at them. (All of those
> researchers also failed to implement blind measurement and
> analysis: the researchers were aware, as
they
> were measuring, which treatment they were testing. Only
> Wisdom et al were
able
> to carry out their measurements (electronically) without
> any people even
being
> present.)
>
> This is a very informative paper. The authors "examined
> the responses of bison ., mule deer ., and pronghorn
> antelope . to hikers and mountain
bikers .
> by comparing alert distance, flight distance, and distance
> moved" (p.951).
They
> noted, significantly, that "Outdoor recreation has the
> potential to
disturb
> wildlife, resulting in energetic costs, impacts to
> animals' behavior and fitness, and avoidance of otherwise
> suitable habitat. . outdoor recreation
is
> the second leading cause for the decline of federally
> threatened and
endangered
> species on public lands" (p.951). They also noted that
> "Mountain biking in particular is one of the fastest-
> growing outdoor activities, with 43.3
million
> persons participating at least once in 2000" (p.952).
> However, they didn't
draw
> on this fact when they concluded "We found no biological
> justification for managing mountain biking any differently
> than hiking" (p.961).
>
> The authors also surveyed the recreationists, and found
> that they "failed to perceive that they were having as
> great an effect on wildlife
as our
> biological data indicated. Most recreationists felt that
> it was acceptable
to
> approach wildlife at a much closer distance (mean
> acceptable distance to approach = 59.0 m) than wildlife in
> our experimental trials would
typically
> allow a human to approach (mean flight distance of all
> species = 150.6 m).
. Of
> all visitors surveyed, 46%, 53%, and 54%, respectively,
> felt that bison,
deer,
> and pronghorn were being negatively affected by recreation
> on Antelope
Island. .
> Visitors expressed little support for allowing only
> one type of
recreational use
> on island trails, having fewer trails on the island, for
> requiring
visitors to
> watch an educational video about the effects of recreation
> on wildlife,
and for
> allowing recreation only on the north (developed) end of
> the island"
(p.957).
> (Gary Sprung omitted this information from his summary.)
>
> They noted that the wildlife might habituate to the
> presence of humans, but that exactly the opposite happened
> with the pronghorn: they "in fact
used
> areas that were significantly farther from trails than
> they had prior to
the
> start of recreational use on the island" (p.961). They
> also noted:
"Because
> flushing from recreational activity may come at the cost
> of energy needed
for
> normal survival, growth, and reproduction ., and because
> it may cause
animals to
> avoid otherwise suitable habitat ., it is important that
> recreationists understand that their activities can flush
> wildlife and may make suitable habitat unavailable"
> (p.961). I think that the wealth of such information
> provided by the authors makes this paper especially
> valuable.
>
> They concluded "Our results indicate that there is little
> difference in wildlife response to hikers vs. mountain
> bikers" (p.957). I was present
when Ms.
> Taylor presented her findings at the Society for
> Conservation Biology
meeting at
> the University of Kent, in Canterbury, England, in July,
> 2002. I pointed
out to
> her that she wasn't justified in concluding, as she did,
> that "hiking and mountain biking have the same impacts",
> since she only measured impacts
per
> incident. Since bikers are able, and typically do, travel
> several times as
far
> as hikers, a more proper conclusion would be that bikers
> have several
times as
> much impact on wildlife as hikers. That is why I am so
> disappointed to
find her
> later concluding in this 2003 paper, "We found no
> biological justification
for
> managing mountain biking any differently than hiking"
> (p.961). If mountain bikers can travel even twice as far
> as hikers, and disturb twice as many animals, I would
> think that that is biologically significant! It isn't
much help
> that she goes on to admit that "because bikers travel
> faster than hikers,
they
> may cover more ground in a given time period than hikers,
> thus having the opportunity to disturb more wildlife per
> unit time" (p.961). She has still
drawn
> an unjustified conclusion, and it is certain to be
> frequently quoted (out
of
> context) by mountain bikers, as they try to lobby for more
> trail access.
>
> I also wonder about the accuracy of their measurements of
> distance. Distance is notoriously difficult to measure
> accurately, especially when
animals
> and recreationists may be hidden from view ("Due to the
> inherent errors in triangulating in the steep canyon
> country, only ground visual locations
were
> used in the analysis" p.577). Bias may also have been
> introduced by the
fact
> that researchers knew, as they were measuring, which
> treatment they were measuring.
>
> It is interesting that "when bighorn sheep did respond to
> human activity, they noticed vehicles and mountain bikers,
> on average, from
twice the
> distance they noticed hikers" (p.577). This would seem to
> imply that, were hikers to remain on the trail where the
> mountain bikers were, they might
have
> equal or lower impacts than the mountain bikers.
>
> Sprung next cited Papouchis et al (2001), claiming that
> "Hikers have [the] greatest impact on bighorn sheep [in
> Canyonlands National Park] .
because
> the hikers were more likely to be in unpredictable
> locations and often
directly
> approached [the] sheep". Actually, this is an artifact of
> the experimental design, and not a result of research: the
> researchers, for some reason,
told the
> hikers (who were research assistants) to approach the
> sheep! So the study actually compared apples and oranges:
> bikers who stay on a road, vs.
hikers who
> approach bighorn sheep! Nothing useful can be concluded
> from such a study, except that people who approach bighorn
> sheep disturb them. Of course,
there is
> nothing to prevent mountain bikers from getting off their
> bikes and doing
the
> same thing. It's unfortunate that the opportunity was lost
> to gain more
valuable
> knowledge. I wrote the authors, asking why they had done
> this, but I got
no
> reply. It would appear that the intention was to exonerate
> mountain biking
(this
> also applies to most of the other studies).
>
> It is also unfortunate that there was no control group, so
> that they could determine the effect of the presence of
> roads, with and without
people on
> them. They did note that "avoidance of the road corridor
> by some animals represented 15% less use of potential
> suitable habitat in the
high-[visitor-]use
> area over the low-[visitor-]use area. . human presence in
> bighorn sheep
habitat
> may cause sheep to vacate suitable habitat" (p.573). This
> argues for
eliminating
> all recreation in the area, especially since the absence
> of water forces recreationists to bring motor vehicles
> carrying water and other supplies: "mountain bikers
> frequently use the 161-km White Rim trail, a
4-wheel-drive
> road. Caravans of mountain bikers accompanied by support
> vehicles are
common.
> Day use along the Shafer and White Rim trails exceeded
> 17,500 vehicles
during
> the study period, 1993-1994. This use was concentrated
> from March to
October,
> with peak use of 134 vehicles/day in May" (p.575).
>
> The authors conclude "Contrary to our original
> expectations and the concerns of park managers, the
> increase in numbers of mountain bikers
visiting
> the park does not appear to be a serious threat to desert
> bighorn sheep, probably because mountain bikers are
> restricted to predictable situations
such
> as the currently designated road corridors" (p.580). For
> several reasons,
this
> conclusion is not justified: (1) as they reported, all
> recreationists
drive the
> sheep away from parts of their habitat, causing loss of
> energy as well as habitat; (2) permitting bikes causes the
> total number of visitors to
increase
> significantly; (3) bikes can't travel alone -- they
> require motorized
support
> vehicles, further increasing impacts (e.g. worsening air
> quality); (4)
there is
> nothing to prevent mountain bikers from getting off their
> bikes and
approaching
> the wildlife; if hikers do that, so will mountain bikers;
> there is no
reason to
> exonerate mountain bikers.
>
> They note, significantly, "However, these results should
> not be extrapolated to other public lands where mountain
> bikers are not confined
to
> designated trails and may surprise sheep in novel
> situations" (p.580).
Gary
> Sprung didn't mention this, thus encouraging inappropriate
> use of this
study's
> already-questionable results.
>
> I would like, however, to commend the authors for stating
> "we recommend that park managers manage levels of
> backcountry activity at low levels"
(p.958).
> The best policy would be to ban all vehicles, including
> bicycles (as well
as
> animals used as vehicles). That would reduce human
> impacts, without
directly
> restricting who could go there (perhaps occasional
> exceptions could be
made for
> the disabled).
>
> Gary next cited Gander and Ingold (1997), claiming that
> "hikers, joggers & mountain bikers [are] all the same to
> chamois". But again, this is not
an
> accurate representation of the results: "They fled over
> longer distances
in
> jogging and mountain biking experiments . carried out late
> in the morning"
> (p.109). Also, "the three activities carried out on the
> ground could have long-term consequences as they
> prevent the animals from using areas near
trails.
> Thus, depending on the density of trails and the intensity
> of recreational activities in a certain area, animals may
> lose a large part of their
habitat"
> (p.109).
>
> The authors conclude "Our results show that specific
> restrictions on mountainbiking above the timberline are
> not justified from the point of
view of
> chamois" (p.109). Once again (is there a pattern here?),
> this conclusion
is not
> justified. It ignores the fact that mountain bikers are
> able to travel
several
> times as far as hikers, and thus negatively impact several
> times as much wildlife. It also ignores the fact that
> bicycles enable a large increase
in
> numbers of human visitors (note that this places the blame
> on the bicycle,
not
> the bicyclists -- my argument doesn't depend on there
> being any difference between hikers and mountain bikers).
> And, of course, wherever the number
of
> visitors increases, there is pressure to build more
> trails, destroying
even more
> habitat. Once again, it would appear that this study was
> undertaken with
the
> intent of excusing mountain biking.
>
> Gary next cites a study of bald eagles by Robin Spahr,
> that I wasn't able to acquire. "Spahr found that walkers
> caused the highest frequency of
eagle
> flushing". However, this study is difficult to interpret.
> Eagles don't congregate in large numbers, like sheep. So
> it is hard to ensure that all treatments are equally
> balanced. Gary doesn't mention the numbers of
eagles or
> recreationists. It is hard to imagine that the conditions
> under different treatments (or even within treatments)
> were equal. Thus, I don't know if
this
> was really a controlled study. Spahr also found that
> "bicyclists caused
eagles
> to flush at [the] greatest distances", which would tend to
> indicate
bicyclists
> have greater impacts. At best, these are mixed results.
> And, once again,
the
> greater distances that bikers travel are ignored, as well
> as the greater
visitor
> numbers that the bicycle enables.
>
> Gary concludes "Mountain biking, like other recreation
> activities, does impact the environment. On this point,
> there is little argument. But . a
body of
> empirical, scientific studies now indicates [sic] that
> mountain biking is
no
> more damaging than other forms of recreation, including
> hiking [Gary's emphasis]. Thus, managers who prohibit
> bicycle use (while allowing hiking
or
> equestrian use) based on impacts to trails, soils,
> wildlife, or vegetation
are
> acting without sound, scientific backing." Au contraire,
> as I have
indicated,
> the very studies that Gary and IMBA cite as support for
> mountain biking
actually
> show that mountain biking does much more harm to the
> environment than
hiking!
> Gary goes on to fault "the wisdom of prohibiting [sic]
> particular user
groups".
> However, as I explained earlier, mountain bikers are not
> prohibited from
using
> any trails. Bicycles are occasionally prohibited. Mountain
> bikers are
merely
> required to follow the same rules as everyone else,
> and walk.
>
> At the bottom of the same web page is the notice: "IMBA
> wishes to obtain and incorporate into future revisions of
> this document any new or
additional
> empirical science regarding the impacts of mountain
> biking. IMBA welcomes
input
> [my emphasis]. To offer information, please contact the
> author at gary@imba.com". On April 25 I emailed Gary (and
> Pete Webber,
pete@imba.com) the
> Wisdom et al study, which demonstrates that mountain
> bikers have a greater impact on elk than hikers. Not only
> hasn't this new research been
incorporated
> into his paper, but I haven't even received a reply. It
> would appear that
IMBA
> isn't really interested in achieving a scientific answer
> to this question.
>
> In 2003, Jason Lathrop wrote an excellent "critical
> literature review" on the ecological impacts of mountain
> biking, raising some questions found nowhere else. He
> quotes the BLM: "An estimated 13.5 million mountain
bicyclists
> visit public lands each year to enjoy the variety of
> trails. What was once
a low
> use activity that was easy to manage has become more
> complex". He
criticizes all
> of the studies for not using realistic representations of
> mountain biking.
For
> example, on Thurston and Reader, he says "this study's
> treatment passes at
best
> loosely approximate the forces exerted by actual mountain
> biking. On real trails, riders possess widely varying
> levels of skill, resulting in
variant
> speeds, turning, and braking. This study does not
> address these
variables."
> Lathrop also makes the excellent point that "Direct
> mortality [of animals]
is
> virtually unstudied. I could find no references to it in
> the literature. Anecdotal evidence suggests, however, that
> small mammals are vulnerable to impact and are not
> uncommonly killed."
>
> And: "Taylor (2001) concluded that short-term behavioral
> changes do not vary between bicyclists and hikers on a per-
> encounter basis. However,
because
> bicyclists are capable of and, in most areas, typically do
> travel much
farther
> than hikers, it is reasonable to conclude that they will
> create a somewhat higher total number of encounters and
> flushings."
>
> Cessford (1995) did an oft-quoted review (which I am
> including only because it is so widely cited) that, like
> all others, uncritically accepts Wilson and Seney (1994)
> as proof that mountain biking impacts are no worse
than
> those of hikers. His paper is mostly speculation, based on
> few actual
research
> findings. He disparages negative information about
> mountain biking by such devices as claiming that problems
> are caused by a minority of mountain
bikers,
> exhibiting "poor riding habits", that accidents involving
> hikers and
bikers are
> "rare", that hikers' dislike for being around bikes in the
> woods, and
feelings
> that bikes cause greater environmental harm than hiking,
> are mere
"perceptions".
> He blames hikers for "misperceiving" mountain bikers,
> claiming that "the
two
> groups are more similar than is generally perceived. . The
> bicyclists .
are
> basically hikers who are using mountain bikes to gain
> quicker access to
the
> wilderness boundary". He speculates, without any evidence,
> that "the
degree of
> conflict with mountain biking may diminish over time as
> other users become
more
> familiar with bike-encounters and riders themselves". A
> more likely interpretation is that hikers who dislike
> being around bikes simply stop
using
> trails that are open to bikes, thereby lessening the
> conflict!
>
> Finally, in 2004, Wisdom et al did a very well controlled
> study comparing the impacts of ATV riders, mountain
> bikers, and hikers on elk
and mule
> deer. They say we have an "urgent need for timely
> management information
to
> address the rapid growth in off-road recreation. .
> Mountain biking [is] . increasing rapidly". Recreationists
> were allowed to stop for less than a
minute
> to look at the animals. All measurements were made
> electronically, using
an
> Automated Telemetry System and GPS, allowing control
> measurements to be
made
> "blind", with no humans present! "Use of the automated
> telemetry system to
track
> animal movements, combined with the use of GPS units to
> track human
movements,
> provided real-time, unbiased estimates of the distan