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High-speed, high-volume highways can result in lynx road-kills, fragment and restrict lynx habitat
<br />use. impair home range effectiveness, inhibit local and dispersing movements that may lead to
<br />reduced habitat connectivity, and the decline of some wildlife populations and species over time
<br />due to genetic isolation (Forman and Alexander 1998. C. Apps; Parks Canada and BC •
<br />Environment, pers. comm. June 17, 1998, 1999, in Thompson 2005a; Service 2000, 2003b;
<br />Alexander et al. 2004; Clevenger 2002; Forman et al. 2003). Highway mortality levels can
<br />increase drastically with relatively small increases in traffic volumes and speeds (Ruediger et al.
<br />2000). Lynx use may be further impaired along highways by adjacent human developments,
<br />including, but not limited to, suburban development (Service 2000, 2003b). Rare carnivore
<br />populations may be particularly susceptible to the effects of highways due to the large movement
<br />requirements of individuals and the natural low recruitment rate of juveniles into the breeding
<br />population (Ruediger 1996).
<br />Highways have resulted in lynx mortality from vehicular collisions, which can be detrimental to
<br />small populations (Ruediger et al. 2000). Introduced lynx are more vulnerable to highway
<br />mortality than resident animals because they exhibit more extensive movements through unfamiliar
<br />landscapes (Brocke et al. 1990, 1991, 1993). In an unsuccessful attempt to restore lynx to the
<br />Adirondack Mountains, 18 of 37 mortalities of translocated lynx were road-killed (Brocke et al.
<br />1990). Highway mortality was a primary cause leading to the extirpation of lynx in the White
<br />Mountain National Forest of New Hampshire (Brocke et al. 1993). While road-kills might not be a
<br />significant mortality source in resident lynx populations (Aubry et al. 1999, Ruggiero et al. 2000),
<br />it can be a significant mortality source in depleted or recovering populations until the population
<br />becomes viable.
<br />Eleven lynx released by the Colorado Division of Wildlife (CDOW) have been killed attempting
<br />to cross highways (Table 2, 2005c, 2005 in litt.). Roe and Poole (2004) observed that lynx
<br />highway mortality rates are decreasing with time despite an increasing number of lynx in the
<br />Colorado population. Five (2.5 lynx/yr.), 1 (0.5 lynx per yr.), and 1 (0.5 lynx per yr.) highway
<br />mortalities occurred in 1999-2000, 2001-2002, and 2003-2004 (to August 4), respectively. They
<br />speculate that this could be related to lynx becoming more resident and sedentary, as opposed to
<br />dispersing/ exploratory movements in an unfamiliar landscape, and to the CDOW's improved
<br />release technique that contributed to the high initial highway mortality rate. Based on results of
<br />the reintroduction attempts in New York and New Hampshire (Brocke et al. 1990, 1993), the
<br />CDOW anticipated that some highway lynx mortality could occur (Seidel et al. 1998). There are
<br />few records of lynx being killed on highways, but direct mortality from vehicular collisions may be
<br />detrimental to small lynx populations in the lower 48 states (Ruediger et al. 2000). In Colorado, 3
<br />lynx are known to have been killed on I-70, 3 on highway 550 north of the project area, and 1 each
<br />on Highways 17, 160 and 91, and 2 road kill mortalities in adjacent states (Kansas, New Mexico).
<br />Table 2a provides additional detail regarding the lynx mortalities, and includes the traffic volume
<br />associated with each road kill at the time the mortality occurred. Five of the 11 lynx carcasses
<br />were recovered in 2005 (Shenk 2005, in litt., and pers. comm. December 2005, also see Table 2a).
<br />With respect to highway traffic volumes and lynx crossings, Canadian studies suggest that 2,000-
<br />3,000 vehicles per day (VPD) are problematic and > 4,000 VPD are more serious threats to
<br />mortality and habitat fragmentation (Ruediger et al 2000). These numbers were based upon the
<br />general observations and professional judginent of Clevenger (Parks Canada) and Alexander
<br />(Univ. Calgary; November 15, 2004, pers. comm. T. Clevenger. Parks Canada), who have .
<br />conducted some of the most thorough studies (e.g., Cleven??er et al. 2002, Alexander et al. 2004)
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