Biology Reference
In-Depth Information
80
Mean
±
1.96* SE
60
Mean
±
SE
40
20
0
-20
-40
-60
-80
-100
0
> 500
1 to 300 301 to 500
Visitation Index
Fig. 10.7
Variation of fecal glucocorticoids (GC) in elk (
Cervus elaphus
) in Yellowstone
National Park in relationship to the number of snowmobiles entering the protected area
(Reproduced with permission from Creel et al.
2002
)
This investigation clearly demonstrated that the last generation of visitors is
aware of the consequences of vehicle use during wintertime in the parks and after
regulation a significant decrease of vehicle use has been experienced by commer-
cial guides.
Snowmobiles are a very intrusive source of noise in national parks and protected
areas. The regulation of these vehicles is achieved in many countries, but great
discussion persists against evidence that this device impacts animal life. Several
studies demonstrate that snowmobiles are avoided by white-tailed deer (
Odocoileus
virginianus
), mule deer (
Odocoileus hemionus
), reindeer (
Rangifer tarandus
), and
moose (
Alces alces
). Other investigations have discovered an increase in heartrate
in bighorn (
Ovis canadensis
) and white-tailed deer in the presence of human
disturbances. The physiological and behavioral responses to stress causes an
increase of glucocorticoids (GCs) secretion by the hypothalamic-pituitary-adrenal
axis. A long-duration high concentration of GCs produces reproductive suppres-
sion, ulcers, muscle wasting, and immune system suppression.
Analysis of fecal GC content, a good noninvasive method to evaluate the level of
stress, has been applied by Creel et al. (
2002
) on elk (
Cervus elaphus
)in
Yellowstone National Park (Fig.
10.7
) and on wolves (
Canis lupus
) in Yellowstone,
Voyageurs, and Isle Royal National Parks. The results confirmed the increase of GC
with the increase of snowmobiles when compared with other road vehicles. No
evidence was collected about the effects of snowmobiles on population dynamics,
however.
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