Roads generate a variety of influences on wildlife populations; however, little is known about the effects of roads on endemic wildlife on islands. Specifically, road-kills of island foxes (Urocyon ...littoralis) on San Clemente Island (SCI), Channel Islands, California, USA are a concern for resource managers. To determine the effects of roads on island foxes, we radiocollared foxes using a 3-tiered sampling design to represent the entire population in the study area, a sub-population near roads, and a sub-population away from roads on SCI. We examined annual survival rates using nest-survival models, causes of mortalities, and movements for each sample. We found the population had high annual survival (0.90), although survival declined with use of road habitat, particularly for intermediate-aged foxes. Foxes living near roads suffered lower annual survival (0.76), resulting from high frequencies of road-kills (7 of 11 mortalities). Foxes living away from roads had the highest annual survival (0.97). Road-kill was the most prominent cause of mortality detected on SCI, which we estimated as killing 3-8% of the population in the study area annually. Based on movements, we were unable to detect any responses by foxes that minimized their risks from roads. The probabilities of road-kills increased with use of the road habitat, volume of traffic, and decreasing road sinuosity. We recommend that managers should attempt to reduce road-kills by deterring or excluding foxes from entering roads, and attempting to modify behaviors of motorists to be vigilant for foxes.
Recently, island fox (Urocyon littoralis) populations on 4 of 6 California Channel Islands (USA) were greatly reduced by colonizing golden eagles (Aquila chrysaetos) and a suspected outbreak of ...disease, creating concern for subspecies on all islands. Consequently, efforts of live-trapping foxes for research, monitoring, and vaccination has increased. Despite increased trapping efforts, evaluation of factors that influence capture success has not been conducted. We examined capture success of island foxes at 85 random trapping locations on San Clemente Island during 170 trap-nights during 2006–2007. We captured 98 island foxes, and found that traps placed ≤10 m from primary roads had higher overall capture success (i.e., 1.52 times more likely to capture foxes) than traps placed at random locations throughout the study area. We found no evidence to suggest that the density of edges between land-cover types (i.e., sum length of edges per 100-m buffered area m/m2), nightly temperature, proportions of land-cover, or type of attractant tested (n= 3) affected capture success. All attractants captured similar proportions of sex and age classes of foxes. Our findings suggest that future trapping efforts would have the most success if conducted along roads.
Because mule deer (Odocoileus hemionus) and white-tailed deer (O. virginianus) cause extensive and costly damage to orchards, nurseries, shelterbelts, and ornamental plantings in Colorado, we ...evaluated 3 concentrations (0.062, 0.62, and 6.2%) of Hot Sauce Animal Repellent® (Hot Sauce), habanero peppers, Tabasco® sauce, Ani-spray®, and liquid MGK® Big Game Repellent (BGR) as browsing deterrents on tame mule deer from 31 December 1991 to 25 January 1992. While consumption of apple twigs treated with Anispray and the 0.062% concentration of Hot Sauce did not differ (P > 0.05) from the control (tap water), a 6.2% concentration of Hot Sauce (100 times the concentration labeled for deer) and BGR reduced (P < 0.05) consumption relative to the control and other repellents. Although the 6.2% concentration of Hot Sauce and BGR were the most effective browsing deterrents, their effectiveness may be relatively short lived if deer are continually exposed to them.
We studied the effect of group size on survival of black-tailed prairie dogs (Cynomys ludovicianus) relocated to 12 experimental plots in Colorado to determine success of reintroductions. Six groups ...of 10, 3 groups of 30, and 3 groups of 60 prairie dogs were randomly assigned and released from July to October 1990 in 6 1-, 3 3-, and 3 6-ha plots, respectively, in former prairie dog colonies that were extirpated by sylvatic plague (Yersinia pestis) during fall 1988. We recaptured prairie dogs in plots during September-October 1990, February-March 1991, June 1991, and September-October 1991 to estimate survival. We used capture-recapture models to estimate survival and recapture rates. Daily survival rates between release release and first recapture were different for 10- (0.9767, SE = 0.0044), 30- (0.9854, SE = 0.0023), and 60-animal groups (0.9914, SE = 0.0016) (P < 0.001) and were directly related to group size (P < 0.001). The number of progeny captured per animal released was greater in the 60- (x̄ 0.79, SE = 0.06) than in the 10- (x̄ = 0.28, SE = 0.21) animal plots (P = 0.028), but did not vary between the 60- and 30-animal plots (x̄ = 0.62, SE = 0.09) (P = 0.333) or between the 30- and 10-animal plots (P = 0.156). The 60-animal groups attracted more immigrants than the 10- or 30-animal groups. Ratios of the number of prairie dogs 1 year after release (survivors and progeny) to those released varied (P = 0.018) among the 10- (x̄ = 0.46, SE = 0.21), 30- (x̄ = 0.81, SE = 0.09), and 60- (x̄ = 1.17, SE = 0.08) animal groups and were related linearly (P = 0.006) but not quadratically (P = 0.750) to the number of animals released. One year after release, only the 60-animal groups had more survivors and progeny than the number of prairie dogs released. We recommend releasing a minimum of 60 animals/site in areas with potential immigrants.
In western North America, large concentrations of elk (Cervus elaphus) can have detrimental effects on aspen (Populus tremuloides) regeneration and clone survival. In some situations, management ...intervention to protect aspen sprouts is needed. We conducted an experiment to evaluate the effectiveness of Hot Sauce Animal Repellent® (HS) and Deer Away® (DA) in deterring elk from browsing aspen sprouts during summer. We examined the responses of elk browsing on aspen sprouts at 3 levels of HS (0.062%, 0.62%, 6.2%) and 1 level of DA at 2 time periods (2 and 5 weeks postapplication). High concentration HS (6.2%) and DA were the most effective repellents; browsing on aspen sprouts was reduced by 45% with HS and 27% with DA compared to controls. Elk browsing on aspen sprouts decreased linearly (P < 0.001) with increased concentration of HS. Levels of elk browsing on aspen sprouts were similar (P = 0.249) for repellent treatments applied 2 and 5 weeks prior to exposure to elk. We conclude that HS (6.2%) and DA will provide protection of aspen sprouts from browsing by elk for at least 5 weeks during the growing season, but current economic costs limit the practicality of large-scale use of these repellents.
Relative preference of captive cow elk for repellent-treated diets Andelt, W.F. (Colorado State University, Fort Collins, CO); Baker, D.L; Burnham, K.P
The Journal of wildlife management,
(Jan 1992), 19920101, 1992, 1992-01-00, Letnik:
56, Številka:
1
Journal Article
Recenzirano
Because of the extent and cost of elk (Cervus elaphus nelsoni) damage in Colorado, we tested the repellency of MGK® Big Game Repellent (BGR), chicken eggs, coyote (Canis latrans) urine, Hinder®, Hot ...Sauce Animal Repellent® (Hot Sauce), Ro·pel®, and thiram on tame cow elk there from December 1990 to February 1991. At the concentrations used, coyote urine and BGR performed better than the other repellents for deterring elk from feeding on cubed alfalfa hay. Consumption of rations treated with odor repellents (BGR, chicken eggs, coyote urine, and Hinder) increased from day 1 through day 5 of the trial, but consumption of rations treated with thiram (a taste repellent) decreased. In a second trial, hungry elk consumed significantly more repellent-treated apple twigs (Malus domestica) than did elk that were maintained on an ad libitum diet. Hot Sauce, applied at 100 times (6.2%) the labeled concentration for deer (Odocoileus spp.), deterred all 9 satiated elk and 7 of 9 hungry elk from browsing on apple twigs, but the labeled concentration (0.06%) failed to deter most elk fed ad libitum and all elk when hungry. Coyote urine, at 10% and 100% concentrations, failed to deter hungry elk, but the 100% solution moderately deterred elk fed ad libitum from browsing on apple twigs. Thiram applied at the labeled concentration and at 10% of the labeled concentration for deer failed to deter any elk when hungry and most elk when fed ad libitum. In a third trial, Hot Sauce at concentrations of 0.06%, 0.20%, and 0.62% did not deter any of 9 elk fed 50% of their average daily intake, but the 2.0% and 6.2% concentrations deterred 2 and 6 elk, respectively. Hot Sauce, at concentrations of 6.2% and 12.4%, and 100% coyote urine were not phytotoxic to apple trees.
Because studies of coyote (Canis latrans) density have lacked standardization and estimates of variance, we conducted a mark-resight study of 17 coyotes on the Rocky Mountain Arsenal (RMA), Colorado, ...to provide the basis for recommending survey design. Radiolocations of some coyotes on and off the study area verified that geographic closure of the population was violated. Thus, we estimated coyote population size with an estimator that allows for immigration and emigration. Using program NOREMARK (a mark-resight program; Neal et al. 1993), we estimated that a daily population of 50 (95% CI = 34-81, 0.71/km2) coyotes and a total population of 73 (95% CI = 50-121) coyotes used the study area during December 1990-January 1991. With Monte Carlo simulations in program NOREMARK, we demonstrated that if ≥20% of the population is marked and observed during each survey, it is more cost effective to decrease bias and improve precision by conducting additional surveys rather than capturing and marking more coyotes. We recommend conducting simulations with program NOREMARK to determine the best way to decrease bias and improve precision while minimizing cost of a coyote mark-resight study.
We tested the repellency of chicken eggs, MGK® Big Game Repellent (BGR), coyote (Canis latrans) urine, thiram, Hinder®, bars of soap, and Ro·pel® on tame mule deer (Odocoileus hemionus) in Colorado ...during May and June 1989. Chicken eggs, BGR, and coyote urine performed better than the other repellents for deterring deer from feeding on pelleted rations. Consumption of rations treated with odor repellents increased from Day 1 through Day 4 of the trial, but consumption of thiram-treated rations decreased. The repellency of eggs, BGR, and coyote urine was reduced when apple twigs were sprayed with 7 cm of water to simulate heavy rainfall. When the deer were moderately hungry, even the best performing repellents failed to deter browsing.
Mortalities from collisions with vehicles have created concern for the welfare of the San Clemente Island fox (Urocyon littoralis clementae); 1 of only 6 genetically distinct subspecies of island ...fox. To find possible solutions for minimizing these mortalities, we compared 9 characteristics of roads and roadsides at kill-sites and control-sites to ascertain whether certain features were associated with risk of collisions. We found that kill-sites were positively associated with the volume of traffic, and negatively associated with the distance of motorists' visibility, which had not been previously identified for island foxes. Additionally, visual obstructions along roadsides (i.e., steep ditches and tall vegetation) showed some evidence of increasing mortalities. We also found that gravel mounds, a possible pseudo-barrier along roadsides, were associated with reducedmortalities. Speeds of vehicles, presence of drainages, cacti, and culverts, and seasonality showed minimal effects on road-kills. Our findings suggest that efforts to reduce mortalities should focus on roads with high volumes of traffic and high amounts of visual obstruction for motorists. Possible methods for reducing road-kills include installing signs and speed bumps on curves of roads, regular mowing of roadsides, constructing gravel-mound barriers along edges of roads, and educating motorists.
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