A recent survey indicated a consensus that the present Highway 133 shoulders are not a safe path for bicycle riders or walkers. Nevertheless, there is strong opposition to possible attractive off-highway routes for a trail. I find hunting, roadkill and human habitation of the rural/wild interface as major impacts on wildlife.
Data indicate that the impact of non-lethal recreation is likely to be insignificant compared to other factors.
Thus, Colorado Parks & Wildlife documents that nearly 500,000 animals were killed by hunters in 2015 (http://cpw.state.co.us/ thingstodo/Pages/hunt.aspx). Big numbers, similar to the prior five years: 44,852 Elk, 34,005 Deer, 16,390 Pronghorn Antelope, 153 Mountain & Desert Bighorn Sheep, 1,880 Moose, Bears, Goats and Lions, 130,800 Small Game (including Cottontail Rabbit, Coyote, Dusky Grouse & Pheasant), and ~ 269,000 Birds of all sorts.
None of the likely trail routes are in roadless areas.
Annual roadkill on Highway 133 reported to CDOT from 2007 to 2015 averaged 12 animals/year from Highway 82 to the top of McClure pass and 70 animals/year over the 68 mile highway. Animals who are hit and die off the highway are not included. It is a national problem. The Insurance Institute for Highway Safety reported that more than 1.5 million deer-vehicle collisions occur each year in the U.S. with ~150 vehicle occupant deaths and tens of thousands of injuries (Deer in the Headlights, EnCompass (AAA magazine), Nov-Dec 2016, p. 24.).
A 2014 Pitkin County buildout analysis indicated that the present number of dwellings in our valley is likely to nearly double in coming years: 435 ~800 dwellings in the the 14 percent of county land which is private and developable. Clearly, more people, pets and traffic will have a significant impact on wildlife.
A recent scientific review indicated that the global impact of non-lethal recreation on wildlife and biodiversity is about 10 percent of the impact of overexploitation. The hazard posed by climate change is a bit ahead of recreation.
More generally the authors summarize: “Of all the plant, amphibian, reptile, bird and mammal species that have gone extinct since AD 1500, 75% were harmed by overexploitation or agricultural activity or both . . .” (The ravages of guns nets and bulldozers. Nature: 11 August 2016, pp 143-145).
Finally, Colorado winters are tough on nutritionally stressed animals who typically lose 15 – 25 percent of their body weight. This weight loss is associated with a mortality of up to 24 percent in deer. Nevertheless, to support our diets we graze cattle and sheep in upland areas in our national forests during summertime. The latter conflicts with the need of wild ungulates to restore weight loss and energy deficits resulting from scarce winter food supplies In addition, a serious infectious disease was transmitted from domestic sheep to wild bighorns, resulting in a 74% decline in the bighorn sheep in our area. (~250 to ~65 bighorn sheep according to our USFS Wildlife Biologist.)
These are important discussions. I do find the opposition of Colorado Park & Wildlife personnel to off-highway routes particularly ambiguous even if deeply felt.