Abstracts: Wildlife Impacts and Conservation Solutions
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Effects of Highways on Elk (Cervus Elaphus) Habitat in the Western United States and Proposed Mitigation Approaches
William (Bill) C. Ruediger (Email: firstname.lastname@example.org), Wildlife Biologist, Wildlife Consulting Resources (Retired USDA Forest Service), 1216 Creek Crossing, Missoula, MT 59802; and Ken and Robin Wall, Geodata Services, Inc., 104 South Ave. E., Missoula, MT 59801
Elk are an excellent species to use as a "terrestrial wildlife indicator" for highway impacts. First, they are widespread and exist in all western states as well as several midwestern and eastern states. They are prevalent on many National Forest lands, Bureau of Land Management lands, USDI Fish and Wildlife Service and National Park Service lands. Much elk habitat is on public lands in the western United States (Flathers and Hoekstra 1989, Peek undated, Thomas and Toweill 1982).
Elk are also one of the best studied animals in North America. This is particularly true in respect to the effects of roads on elk. Very few wildlife species have as much scientific literature directed at them. Information such as food habits, density, behavior, fecundity, migration patterns, home range sizes and other important scientific data also abounds.
Evaluation of Principal Roadkill Areas for Florida Black Bear
Stephanie L. Simek (Phone: 850-410-0656; Email: stephanie.simek@MyFWC.com), Sandra A. Jonker (Phone: 850-410-0656; Email: sandra.jonker@MyFWC.com), and Mark J. Endries (Phone: 850-488-6661; Email: mark.endries@MyFWC.com), Florida Fish and Wildlife Conservation Commission, 620 South Meridian Street, Tallahassee, FL 32399-1600
The high number of vehicle-bear collisions and the potential impact of these collisions on both humans and bears prompted a re-evaluation of principal roadkill areas for the Florida black bear (Ursus americanus floridanus). The Florida Fish and Wildlife Conservation Commission has documented an increasing statewide trend in the number of roadkill bears since 1976. Previous research indicates roadkills are concentrated in particular areas based on several habitat features (Gilbert and Wooding 1996). Additionally, Gilbert and Wooding (1996) suggest the areas with the largest bear populations (Apalachicola, Big Cypress, and Ocala) have accounted for the greatest number of roadkill, particularly Ocala National Forest. Most recently, Gilbert et al. (2001) prioritized "chronic" bear roadkill areas using roadkill data and habitat characteristics. A subset of black bear roadkill locations (May 2001-September 2003) was evaluated as part of a larger study focusing on several variables, including changes in patterns of principal roadkill areas. Using a simple density analysis (ESRI), principal roadkill areas were identified as those areas which have three or more roadkill instances within a distance of one mile. A one-mile buffer was established surrounding each of these identified areas to ensure that all roadkill locations were included. From the established criteria and analysis, principal roadkill areas were defined during the time frame May 2001 through September 2003. These principal roadkill areas were located in Apalachicola, Chassahowitzka, Ocala, and St. Johns. The majority of the principal roadkill areas, similar to previous research (Gilbert and Wooding 1996), were identified in Ocala. Although the results from the 2001-2003 analysis identified a number of principal roadkill areas documented by Gilbert and Wooding (1996) and Gilbert et al. (2001), several segments were no longer classified as principal roadkill areas, and a few new areas were documented. These new results prompted a re-evaluation of the data using the same time frame as Gilbert and Wooding (1996) as well as the full data set (1976-2004) to determine the causes of variation. These results identify trends in the occurrence of principal roadkill areas and determine re-occurring "chronic" areas. This evaluation provides information for managers and planners who must take direct management action in an effort to minimize road impacts on bears.
Modeling Highway Impacts Related to Grizzly Bear Core, Living, and Connectivity Habitat in Idaho, Montana, and Wyoming Using a Two-Scale Approach
Dr. Lance Craighead (Phone: 406-585-8705; Email: email@example.com), Executive Director, Craighead Environmental Research Institute, 201 South Wallace Avenue, Bozeman, MT 59715, Fax: 406-556-8189
To address highway impacts on grizzly bear movements and population persistence (and by inference other wildlife species) a two-tiered modeling approach was used. At a coarse scale, highway segments were ranked in importance based upon their relative effects on grizzly bear core and connectivity habitat. At a fine scale, influences were examined by including highway features such as jersey barriers and bridges in the modeling process.
Grizzly bears are widely considered an "umbrella" or "focal" species whose protection and persistence will benefit a broad assemblage of plant and animal species; in general, maintaining grizzly bears will maintain biodiversity and the health and function of natural ecosystems. Highways have negative impacts on grizzly bears, biodiversity, and natural ecosystems that can be mitigated to some degree by reducing the fragmentation effects of the highway. To address fragmentation effectively, highway segments need to be prioritized based upon their relative impact on grizzly bear habitat and movement. Highway mitigation efforts and habitat conservation efforts can then be guided to address the areas of greatest impact.
Factors found to affect grizzly bear movement and habitat quality are road density, building density, land cover type, habitat heterogeneity, and amount of forest-grassland edge habitat. Within a geographic information system (GIS), habitat quality was modeled and used to define core areas (large enough area for a small population to survive), living habitat (large enough for an individual to survive), and connectivity habitat (connections between core habitat).
Highway impacts on grizzly bear habitat and movement were estimated at the coarse scale by estimating the total length of highway intersecting: (1) suitable grizzly living habitat, (2) core grizzly habitat, and (3) connectivity habitat. Highways were weighted to reflect their overall impact, and lengths of highway segments were estimated to reflect the relative impact of each highway on grizzly bear habitat.
Highway impacts on grizzly bear habitat and movement at the fine scale incorporated data on building locations, road sinuosity, slope, and global positioning system (GPS) locations of highway features such as jersey and/or texas barriers, and presence of guardrails. These features tend to affect animal and/or motorist behavior during attempts at highway crossings. At the fine scale, areas of secure habitat were delineated based upon contiguous areas of high quality habitat encompassing 10 km2 or larger. A pilot modeling project was completed for the Bozeman Pass, Montana, area that should be applicable to other highway segments within potential grizzly bear habitat of Montana, Idaho, and Wyoming.
Our approach offers the ability to identify important areas at a coarse scale and then use fine-scale efforts to identify specific road segments of concern. Fine scale modeling should be done at all high-impact sites to help determine optimal locations where animals may attempt to cross highways. Additionally, other species may be modeled to examine locally important wildlife.
Monitoring Effects of Highway Traffic on Wild Reindeer
Bjřrn Iuell (Email: firstname.lastname@example.org), Environmental Section, Road Development Department, Directorate of Public Roads, Norwegian Public Roads Administration, Norway; and Olav Strand (Email: email@example.com), Norwegian Institute for Nature Research, Tungasletta 2, 7485 Trondheim, Norway
Some of the major wildlife problems associated with transport infrastructure development in Norway involve the negative effects on reindeer populations. Documented effects include barrier effects resulting in fragmented populations and indirect impacts on reindeer grazing caused by disturbance from road traffic and human activities in general.
Wild reindeer are sensitive to disturbance and are known to have high alertness ageinstagainsttend to be extremely shy of human activities. The disturbance caused by road traffic and human activities can reduce the reindeer h habitat use at relatively 's use of areas for large distances (several kilometreskilometers) on either side of roads. The result of this avoidance is a reduction in the available grazing resources, which during the winter consist mainly of lichens, in wide zones parallel to roads, and an equivalent increase in grazing pressure in a zone at some distance from roads in undisturbed areas. Because lichens needs 20–30 years to recover after periods of intensive grazing, the wild reindeer are regarded as especially vulnerable to barriers that reduce their possibilities to reach new grazing grounds.
At the Hardangervidda, the biggest mountain plateau in Southern Norway, the functional use of the wild reindeer area has probably changed from being a large-scale rotation in the use of the food resources and calving areas, to a more restricted use of a smaller and central area. become an overexploitation of a too small area. The northern parts of the Hardangervidda isparts of the Hardangervidda are, for example, functionally parted from the rest by Highway (Hw) 7 and the railroad. This situation is not unique to the northern parts of Hardangervidda, but appears to be a general problem for most of the edges, and many of the surrounding of the plateauareas that also happens to be most affected by humans and less are no longer used by the reindeer.
The Norwegian directorate for nature management has suggested closing down a stretch of about 40 km of Hw 7 crossing the Hardangervidda, during the winter months, hoping to . The aim is to resume reindeer habitat use in this partsthese parts of the areathe original use of the whole mountain plateau. Even if the road has very low traffic in the winter months (ADT 300-400), the suggestion has caused a lot of protests and discussions locally.
In 2002 scientists from the Norwegian Institute of Nature Research (NINA) were engaged by the Norwegian Public Roads Administration (NPRA) in a five-year study to undertake research on patterns of reindeer habitat use and utilization of the lichen grazing resources and on the movements of wild reindeer in the aareas believed to be influenced by the road close to the road. The main purpose of the project is to find out to which degree the road and/or the traffic generated by the road constitute a barrier for the wild reindeer, and if it has a repelling effect on the animals. The NPRA will draw up its recommendation to the Parliament on the future management of the road based on the results of the project.
The project has equipped a total of more than 20 animals with GPS transmitters, providing continuous detailed and accurate data on their habitat use and movementsposition. The GPS units are where programmed to register localize each animal every the localisation of the animal each third hour. The data are stored in the computer in the collar, which includes a possibility for remote data transfer, and the computer is programmed to deliver the data for the last two weeks every second week. The collar also sends out a VHF signal, so the animal can be tracked, and the data downloaded to a portable computer.
Since the expressed effects in reindeer behavior and habitat use are Because the fragmentation is the result of the cumulative effects of different disturbance sources, the project also aims to disentangle looks into the relative contribution level of disturbance to disturbance from other sources than road traffic, e.g.,xamples as such are pPower lines, the settlement of cottages and alpine resorts, and recreational use by skiers and snow scooters. all contribute to the disturbance of the wild reindeer.
Maps of the distribution of different reindeer the food resources (e.g., lichens) have been produced both by using field surveys and by the use of satellite imagesphotos. When the preliminary GPS data are compared with the distribution of lichen resources, in the area, it is very appears that clear that the animals do not use the areas richest in lichens: oin the outskirtsfringe of the plateau and in a zone 5 – 7 km from the road. This zone of avoidance also strengthens the barrier effect of the road such that the migration routes to and from the North are more or less cut off. This is both a problem of reduced genetic flow, and the availability of winter grazing resources.
The field work closes in 2005, and the results will be presented in 2006. The data will hopefully also also give us valuable information about the relative disturbance from other all the different disturbance factors, so that action can be taken based on the right factors.
Future research should focus more on the relative and cumulative effects of different disturbance factors, and whether placing selected stretches of the road in tunnels can eliminate or reduce the negative effects on reindeerthe disturbance from the road.
Addressing Habitat Fragmentation Impacts From Construction of a New Highway
Marion Carey (Phone: 360-705-7404, Email: firstname.lastname@example.org), Fish and Wildlife Program Manager, Environmental Services Office, Washington State Department of Transportation, Olympia, Washington
The purpose of this project was to develop methods to analyze impacts from and find solutions for habitat fragmentation resulting from the construction of a new highway across two military bases (McChord Air Force Base and Fort Lewis Army Base). The bases contain large blocks of rare terrestrial habitats. The need to maintain the security of the bases limits the ability to use on-site methods, such as underpasses and crossing structures.
In 2003, the Crossbase highway project, which had been a Pierce County-sponsored project, was identified as a new state highway, and thus became the Washington State Department of Transportation's (WSDOT) responsibility. The six-mile-long highway cuts through two adjoining military bases to connect a heavily developed urban/industrial area with Interstate 5. Both military bases have core areas containing airfields, housing, operational, and commercial areas that are surrounded by largely undeveloped natural habitats consisting of large wetlands, coniferous forests, rare oak woodlands, and rare native prairie areas. These natural areas are bisected by an extensive network of gravel and paved roads and are used for military training activities. These rare habitats support four federal candidate species, and one state-listed endangered species. Development activities surrounding the military bases have fragmented and eliminated much of the habitats outside of the bases.
The new highway is expected to result in three main ecological impacts: direct loss of rare habitat types, decreased use of surrounding habitat due to impacts associated with the operation of the highway (e.g., noise), and habitat fragmentation or isolation of habitats. While mitigation ratios exist to address the elimination of habitats such as wetlands, no ratios or methods exist to quantify impacts associated with operation impacts or habitat fragmentation. Working in conjunction with Washington State Department of Fish and Wildlife (WDFW), WSDOT developed a method to assess these impacts based on the level of function that would be lost. This method was used to determine what the total habitat enhancement and restoration package for the Crossbase highway should be.
The resulting habitat enhancement and restoration package that was developed consists of three parts: acquisition of a large parcel of rare habitat, restoration and enhancement of the acquired site, and providing funding for additional restoration, acquisition, and enhancement activities.
While construction of the highway has not begun, WSDOT is proceeding with acquiring the restoration and enhancement site and has provided funding for the additional acquisition, restoration, and enhancement activities. The developed method will be used on other new highway projects in the future.
Effectiveness of Rope Bridge Arboreal Overpasses and Faunal Underpasses in Providing Connectivity for Rainforest Fauna
Miriam Goosem (Phone: 617-40421467, Email: Miriam.Goosem1@jcu.edu.au) and Nigel Weston, Rainforest CRC, School of Tropical Environment Studies and Geography, James Cook University, P.O. Box 6811, Cairns, Queensland, 4870 Australia; and Sally Bushnell, Rainforest CRC, TESAG, James Cook University, Townsville, Queensland 4618 Australia
Rope bridge overpasses and faunal underpasses were effective in restoring rainforest habitat connectivity for many tropical rainforest species that suffer high levels of road mortality or that avoid large clearings, such as those for roads, and, therefore, suffer barrier effects.
Faunal underpasses furnished with logs and rocks to provide cover were constructed in 2001 at a hotspot for tree-kangaroo mortality. The narrow road and 120-m-wide strip of abandoned pasture divided two blocks of rainforest severing an important highland wildlife corridor through an agricultural landscape. No rainforest small mammals were recorded crossing the gap in six months of trapping prior to the road upgrade. During the upgrade, corridors of rainforest trees were planted through the pasture to connect with underpass entrances. Underpass use was monitored weekly using sand tracking beds complemented by infrared-triggered digital cameras. Weekly road kill data were collected for 12 months prior to construction and continues on two 0.5-km road transects in the vicinity of the underpasses and two transects along a highway dividing similar rainforest habitat 5km to the north. In 2004, bird and small mammal use of the planted corridors was investigated.
Many terrestrial rainforest species use the underpasses, including medium-sized and smaller mammals and terrestrial birds, together with two confirmed passages of the rare target species, Lumholtz's tree-kangaroo. Road mortality near the underpasses has remained low, whereas road kill rates are much greater along the narrow rainforest highway without underpasses. Community composition of rainforest birds within the corridors is approaching that of edge rainforest nearby, demonstrating effectiveness at this early stage of growth. However, although rainforest small mammals reside in the corridors, feral and pasture species still dominate, emphasizing the need for longer growth periods to encourage greater use by rainforest specialist mammals of the connectivity afforded by corridors and underpasses.
Several rope bridges erected 7m above narrow roads and designed for use by rare arboreal rainforest mammals have also proven effective and are regularly used by the obligate arboreal Lemuroid ringtail possum, which will not cross roads on the surface or via underpasses. Several other possums that rarely venture to ground level are also regular crossers. Structures also provide safe crossing routes for arboreal species that otherwise suffer road mortality. Monitoring using active infrared-triggered cameras, scat and hair collection, and spotlighting has shown all target rainforest ringtails and other possums using rope tunnel and cheaper rope ladder designs. Similar designs have since been installed elsewhere in Australia over four-lane highways. Subsequent rainforest studies will investigate use of longer rope bridges above a wide highway using mark-recapture and radio-tracking to determine home range and provide population information prior to construction, followed by systematic monitoring of the rope bridges.
Modeling the Effect of Roads and Other Disturbances on Wildlife Populations in the Peri-Urban Environment to Facilitate Long-Term Viability
Dror Ben-Ami, (Email: email@example.com) School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney 2052, Australia; and Daniel Ramp, (Email: firstname.lastname@example.org) School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney 2052, Australia
Roads and traffic exhibit a multitude of impacts on wildlife populations. Most road ecology research seeks to assess the quantity and diversity of fatalities from collisions with vehicles, while studies documenting the impact of roads on the structure and sustainability of wildlife populations adjacent to roads have been lacking. Populations of wildlife existing within the confines of fragmented reserves are particularly susceptible to fatalities on roads, especially those situated within peri-urban and semi-rural matrices.
We chose to examine the effects of disturbances, including fatalities on roads, using four case studies from Australia. These studies included a range of fauna, including the long-nosed bandicoot, the koala, and two studies of the swamp wallaby. To explore the impact of the various threats to wildlife living in peri-urban reserves, each case study utilized a population modeling approach. A combination of PVA modeling and sensitivity analysis was used to assess the impact of disturbances on the populations and identify appropriate management options to target disturbances. We discuss the utility of this approach in enabling conservation managers to assess the long-term viability of wildlife in these environments and in establishing management targets for improving viability in populations predicted to decline.
In all four cases road fatalities were a major disturbance, but the different landscape characteristics of each reserve and other threat levels altered the relative impact of roads. The findings suggest that the combination of a range of management options, such as road fatality prevention, control of predation, and improvements in immigration and fertility, are often necessary although the exact combination will be location specific.
Road management in the peri-urban environment can play a substantial role in ensuring the persistence of isolated populations in protected reserves that are surrounded by, and traversed by, roads. Given the broad geographic scale of roads, their effect on wildlife populations may be best understood from a landscape perspective, taking into account other disturbances that may be influencing population viability. We recommend the integration of PVA, sensitivity analysis, and GIS-based dispersion models as a suitable means for addressing both the temporal and spatial impacts of roads in order to successfully manage wildlife populations.
Taking the High Road: Treetop Bridges for Arboreal Animals (Formerly Titled, Walking at Height)
Hans Bekker (Phone: +31 15 2518470, Email: email@example.com), Program Manager, Infrastructure Environmental Affairs, Road and Hydraulic Engineering Institute, Directorategeneral of Public Works and Water Management, Ministry of Transport, Public Works and Water Management, P.O. Box 5044, 2600 GA Delft, The Netherlands
The major impact of habitat fragmentation results from the barrier effect caused by the construction and use of linear infrastructure of transportation systems. Habitat fragmentation can be described as the splitting of natural habitats and ecosystems into smaller and more isolated patches. Habitat fragmentation is recognized as one of the most important global threats to the conservation of biological diversity.
Fauna passages are constructed to minimize the negative effects of habitat fragmentation. However, there are only some vague ideas about measures for tree-living mammals (excluding bats). Some anecdotal stories, collected by this author from the international network and from discussion with interested people, helped to develop some thoughts for the design and construction of tree-bridges. There is some information about measures for squirrels, dormice, monkeys, possums, and pine marten. These species, for which such measures could be fruitful, are sometimes very common and well known by the public: e.g., squirrels; and sometimes rare and only known by specialists and biologists: e.g., several obscure possums.
Amphibian Road Kills: A Global Perspective
Miklós Puky (Phone: 00-36-27-345023, Email: firstname.lastname@example.org), Hungarian Danube Research Station of the Institute of Ecology and Botany of the Hungarian Academy of Sciences, 2131 Göd, Jávorka S. u. 14, Hungary
Transportation infrastructure is a major factor determining land use forms. As global changes in this factor are the most important for biodiversity, roads fundamentally influence wildlife. The effect of roads on wildlife has been categorized in several ways resulting in six to ten categories with road kill as an obvious and important component, and amphibians are greatly affected by this factor. As this animal group has been documented to decline from multiple threats worldwide, the study and mitigation of their deaths on roads has become an important conservation priority. It was also detected as a single cause of decline, and data have accumulated on related population fluctuations, isolation, decline, and extinction in several countries. Genetics studies greatly improve our insight into these processes, e.g., by repeatedly proving significantly low heterozigocy in populations of several species living near roads.
Amphibian road kills have been long documented and described due to their spectacular nature, but the overall effect of transportation infrastructure on amphibians was often underestimated due to contrasting research results. The speed of transport and the duration and timing of the surveys in which information was collected turned out to be decisive factors, causing differences of 5.5-16 times the number of road-killed amphibians recorded, mainly in connection with the low visibility and retention time of amphibians on roads. In light of such amphibian-related differences, the often cited national road kill estimates may well be considerably higher in practice, as well.
Amphibian road mortality studies have been conducted almost exclusively in developed countries, mostly in Europe and North America, and under temperate zone conditions. In general, all terrestrial and semi-aquatic amphibian species can suffer from road kills where they have populations near roads. However, different amphibian species are threatened to a different extent by traffic because of their specific life history characteristics. Besides amphibian-specific factors (amphibian movement types, length and direction of movement, velocity, temporal movement pattern, behavioural changes on roads), the spatio-temporal pattern of amphibian road kill is also influenced by habitat and transportation characteristics (especially aquatic habitats and vegation, road density, traffic intensity, vehicle speed, position and structure of roads, and awareness of drivers, respectively) and weather conditions (precipitation, temperature, wind). The effect of these factors must be understood before the need for mitigation can be evaluated and measures designed and built.
Many mitigation measures have been built since the first amphibian tunnels were created in 1969 near Zürich, Switzerland, and a high diversity of technical solutions successfully reduced amphibian road kills under different conditions. New research results have shown that amphibian tunnels can also be permeable for reptiles, such as snakes and small mammals. However, the lack of maintenance and construction deficiencies are common problems, which lower the efficiency of these measures worldwide.
Road kills also have socio-ecological importance. Successful road-kill related projects have the potential to improve the understanding of decision-makers regarding road-related problems, also leading to their support of more complex conservation projects, including, for example, habitat restoration or compensatory developments near roads. Using the media to educate the general public about conservation efforts to reduce road kill, such as setting up frog fences in the USA and toad saving campaigns in Europe, clearly helps to realise this aim by influencing support provided by various authorities.
Dissimilarities in Behavioral Responses of Snakes to Roads and Vehicles Have Implications for Differential Impacts Across Species
Kimberly M. Andrews (Phone: 803-725-0422, Email: Andrews@srel.edu) and J. Whitfield Gibbons, Savannah River Ecology Laboratory, University of Georgia, Aiken, SC 29082
Roads can act as a barrier to overland movement of animals by causing habitat fragmentation, disrupting landscape permeability, and having an impact on survivorship patterns and behavior. We conducted field experiments to determine how southeastern U.S. snake species with different behaviors and ecologies responded to roads. We attributed interspecific differences in how individual snakes responded to ecological and behavioral differences among the species tested. The probability that a snake would avoid entering the road rather than crossing it varied significantly among species. Smaller species showed high road avoidance behavior. We also observed significant differences in crossing speeds among species. Most nonvenomous species crossed more rapidly than venomous ones. Nonetheless, all species minimized road-crossing time by traveling at perpendicular angles. We also conducted field tests to determine how individual snakes respond to passing vehicles. We observed that most individuals of the three species tested became immobile when a vehicle passed, a non-adaptive behavior that would prolong roadcrossing time of an individual and further exacerbate a species' vulnerability when crossing roads. It is essential that the differential responses of snakes and other animals to roads be identified if the direct impacts of road mortality are to be incorporated into future mitigation plans that minimize road impacts in efforts to design more effective transportation systems.
Factors Influencing the Road Mortality of Snakes on the Upper Snake River Plain, Idaho
Denim M. Jochimsen (Phone: 208-244-1336, Email: email@example.com), Department of Biological Sciences, Idaho State University, ID 83209
This study documents the magnitude of road mortality on snake species that occur in sagebrush steppe habitat, provides insight into how susceptibility to this mortality differs among species as well as by sex and age class of individuals, and examines how different landscape variables influence road-kill aggregations using a logistic regression model. I collected data by road cruising a 183-km road loop on the upper Snake River Plain in southeastern Idaho from May through October of 2003. I conducted 56 total routes, traveling 10,248 km and encountering a total of 253 snakes (0.025 snakes/km) over the six-month survey period; 93 percent of these animals were found dead on the road surface (DOR). The majority of observations belonged to two species, with gophersnakes (Pituophis catenifer) comprising 75 percent of all road records, and western rattlesnakes (Crotalus oreganus) comprising 18 percent of all road records. Monitoring data from three of the largest snake hibernacula on the site indicate that rattlesnakes are the most abundant snake species, comprising 50 percent of all captures at trapping arrays since 1994. This suggests that gophersnakes may be more susceptible to road mortality due to higher vagility, or that our monitoring efforts do not effectively estimate their populations; this question remains to be explored. Overall, I documented more traffic casualties of adults than any other age class, the majority of which were males (64%). Road mortality varied seasonally by age and sex classes for both gophersnakes and rattlesnakes. More adult male gophersnakes were discovered DOR in May and June, while the death of adult females did not exhibit a trend. I documented a significant pulse of subadult mortality during the month of September. The seasonal trends in mortality of rattlesnakes differed from gophersnakes, but were not significant. This indicates that individuals may be more susceptible to road mortality during specific movements, such as mating or migration. The logistic regression indicated that increased cover of grass along roadsides, basalt piles, and mean distance to den were positively associated with gophersnake occurrence on roads. As most grasses on the site are invasive, this result implies that habitat change due to invasive species may be increasing susceptibility of gopher snakes to mortality.
Use of Low Fencing With Aluminum Flashing as a Barrier For Turtles
Kathleen Griffin (Phone: 406-544-9937, Email: firstname.lastname@example.org), Wildlife Biology Program, University of Montana, Missoula, MT 59812
I examined the effects of road mortality on a population of western painted turtles (Chrysemys picta belli) in west-central Montana; these turtles make up the majority of road mortalities in a section of highway that bisects the Ninepipes National Wildlife Refuge. The objective of my barrier fencing experiment was to determine whether turtles were able to breach fencing designed to direct turtles towards crossing structures and thereby keep them off the road. I constructed 45.7-cm-high turtle enclosures out of 2- by 5-cm fencing with and without 10- or 15-cm-high flashing attached at the top. Turtles were placed in the enclosures, and behavior was observed for one hour. Of 124 turtles, only four (3.2%) were able to climb to the flashing. No turtles climbed over the flashing within the time allowed. In enclosures without flashing, two (3.8%) were able to breach the fencing. The results of this experiment will help in the design of appropriate barriers to keep turtles off the road and direct them towards crossing structures.