Twin Peaks Road Wildlife Linkages Research Project Rattlesnake

Twin Peaks Road Wildlife Linkages Research Project Rattlesnake Pass, Marana, Arizona

Town of Marana Environmental Engineering Division

Division Manager Jennifer Christelman

Prepared by:

Shawn F. Lowery, Research Biologist Arizona Game and Fish Department

Scott T. Blackman, Research Biologist Arizona Game and Fish Department

November 2007

Arizona Game and Fish Department, Research Branch 5000 W. Carefree Highway

Phoenix, Arizona 85086

Arizona Game and Fish Department 2007 Twin Peaks Road Wildlife Linkages Project Page ii

RECOMMENDED CITATION

Lowery, S. F., Blackman, S. T. 2007 Twin Peaks Road Wildlife Linkages Project Rattlesnake Pass, Marana, Arizona. Prepared for Town of Marana, Pima County, Arizona. Arizona Game and Fish Department. November 2007.

ACKNOWLEDGMENTS

We thank Jennifer Christelman and Corby Lust, in the Environmental Engineering Division of the Town of Marana, Arizona, for their role in project development. Thanks are also extended to Ray Schwiensburg, Arizona Game and Fish Department Research Branch, Contract Supervisor and Michael F. Ingraldi, Arizona Game and Fish Department Research Branch, Wildlife Research Biologist, for project administration, development and draft review. In addition, we would like to thank the White Stallion Ranch and Saguaro Springs for their cooperation and assistance with project logistics.

AMERICANS WITH DISABILITIES ACT COMPLIANCE

The Arizona Game and Fish Department complies with all provisions of the Americans with Disabilities Act. If you need this material in an alternative format or believe you have been discriminated against, contact the Deputy Director, Arizona Game and Fish Department, 5000 W. Carefree Highway, Phoenix, Arizona 85086; Telephone (623) 236-7900.

PROJECT FUNDING

Funding for project (No. 2001-52) was provided by the Town of Marana through a task order agreement for the Twin Peaks Road Wildlife Linkage Evaluation in the Town of Marana, Pima County, Arizona.

Arizona Game and Fish Department 2007 Twin Peaks Road Wildlife Linkages Project Page iii

TABLE OF CONTENTS

Executive Summary................................................................................................................................................... iv Introduction .................................................................................................................................................................1

Study Area...................................................................................................................................................................2

Methods .......................................................................................................................................................................3 Project Corridor Evaluation Areas ................................................................................................................3 Wildlife Evaluation Methods ........................................................................................................................3 Road Kill Evaluation..............................................................................................................................3 Track Scat Count Evaluation .................................................................................................................4 Existing Culvert Evaluations..................................................................................................................4

Results .......................................................................................................................................................................4 Twin Peaks Road Silverbell Road Wildlife Evaluation Segment .................................................................5 Herpetofauna Species Detections..................................................................................................................5 Mammal Species Detections .........................................................................................................................6 Avian Species Detections..............................................................................................................................6 Supplemental Track and Scat Counts............................................................................................................6 Cumulative Summary of Terrestrial Guilds ..................................................................................................6 Culverts .........................................................................................................................................................7

Discussion and Recommendations ..............................................................................................................................7 Multi- Species Mitigation Strategies by Landform and Habitat Overlap ....................................................................8 Lowland Mitigation Recommendations ........................................................................................................9 Upland Mitigation Recommendations.........................................................................................................10 Behavioral Mitigation Strategies..........................................................................................................11 Under Roadway Culvert Strategies .....................................................................................................12 Over Roadway Mitigation Strategies ...................................................................................................12 Structure Approach .....................................................................................................................................13 Structure Design..........................................................................................................................................13 Fencing........................................................................................................................................................14 Post Construction and Monitoring.............................................................................................................................14

Literature Cited.................................................................................................................................................... 15-19

Figures ............................................................................................................................................................... 19-27 Figure 1. Overview of Twin Peaks Road Evaluation Methods (Illustrating lowland barriers). ..................19 Figure 2. Amphibian Detections ................................................................................................................20 Figure 3. Reptile Detections........................................................................................................................21 Figure 4. Small Mammal Detections...........................................................................................................22 Figure 5. Carnivore Detections ...................................................................................................................23 Figure 6. Large Mammal Detections...........................................................................................................24 Figure 7 Avian Detections...........................................................................................................................25 Figure 8 Composite Model Results .............................................................................................................26 Figure 9 Twin Peaks Road Upland and Lowland Evaluation Segments .....................................................27

Appendices .......................................................................................................................................................... 28-32 Appendix A. Species List of Species detected during roadway evaluation.................................................28 Appendix A1. Summary Graph of total mortality detections along roadway evaluation segment.............29 Appendix B. Diagram of concrete multi-species barrier wall .....................................................................30

Appendix C. Value ranking for guilds represented in composite Model ....................................................31

Arizona Game and Fish Department 2007 Twin Peaks Road Wildlife Linkages Project Page iv

Executive Summary

The I-10 Santa Cruz River corridor, including Rattlesnake Pass, is one of many issues being addressed in order to adequately evaluate an identified Potential Linkage Zone between the Tortolita Mountains and the Tucson Mountains. The objective of this eleven-week project (July 2007- October 2007) was to evaluate wildlife presence data along the Twin Peaks road in order to identify concentration spots, or “hot spots”, where the roadway intersects with wildlife defined corridors. This information directs placement of applied mitigation strategies to ensure safe passage for wildlife. This wildlife evaluation project corridor included the entire Twin Peaks roadway easement from Silverbell Road and Valhalla Drive westward through Rattlesnake Pass to Quarry Road and Twin Peaks intersection. This traffic corridor intersects a northern extension of the Tucson Mountains which represent a contiguous area of environmentally sensitive lands or large habitat block suiting the needs of many species of the Sonoran Desert ecoregion.

In response to expected growth related to the Saguaro Spring Development, Empire Companies, the developer, and the Town of Marana will be converting the existing two-lane Twin Peaks Road into a four-lane, median divided road with incorporated design elements for safe wildlife passage (Town of Marana 2007).

Three methods of evaluation were used to identify presence of wildlife including road kill, track and scat counts and walking transects with culvert evaluation. As a result of the analysis of wildlife presence data there were fifty-five species detected. The utilization of a multi-guild additive model evaluation approach identified six hot spots encompassed in two different landforms described as Lowland and Upland in the project area. These areas have unique mitigation challenges based on species habitation. Four hotspots were identified in the Lowland areas west of Rattlesnake Pass. These hotspots were dominated by medium-small mammals and herpetofauna detections. Mitigation strategies for these groups of species are aimed at directing animals to appropriate sub-roadway crossing structures with applied barrier walls and to provide appropriate spatial arrangement of culverts to facilitate movement under the road. In addition, two hot spots were identified in the Upland area along the flanks of Rattlesnake Pass near the edge of the lowland transition. Mule Deer and tortoise detections in the Upland area define the unique challenges for mitigation in these areas. Application of appropriate fencing and barrier walls funneling wildlife toward culverts or land bridges have been successful elsewhere in developing permeable roadways for animal movement.

The results of this preliminary work will help integrate engineering designs with wildlife presence data and mitigation strategies. Ultimately the applied strategies, such as land bridges or large box culverts, will be dependant on final roadway engineering plans and efficacy of these mitigation strategies are dependant on long term commitments from all public and private land management groups within potential linkage zones. In addition, post construction monitoring is an essential element of any wildlife mitigation strategy.

Arizona Game and Fish Department 2007 Twin Peaks Road Wildlife Linkages Project Page 1

IntroductionUrban expansion into previously undeveloped lands and concurrent infrastructure development (e.g., roadway expansion), is causing an isolation of wildlife into habitat fragments. Roadways potentially affect vertebrate populations through collision mortality, barriers to movements, fragmentation of habitats, and disruption of gene flow. Barrier and fragmentation effects that diminish habitat connectivity are perhaps the most dominant impacts of roadways (Noss and Cooperrider 1994, Forman and Alexander 1998, Forman 2000, Trombulak and Frissell 2000, Farrell et al. 2002). Increasingly during recent years, state wildlife agencies along with local, state and federal transportation agencies have been addressing such problems associated with roadways and wildlife. Human-related developments and roadway traffic are increasing in Arizona leading to more new construction of paved roadways and the widening of existing highways, which ultimately creates a challenge to engineers and designers to enable wildlife to move safely across roadways.

The escalating issue of habitat fragmentation caused by development led to the collaborative Arizona Wildlife Linkage Workgroup (AWLW) spearheaded by the Arizona Department of Transportation and the Arizona Game and Fish Department. The AWLW initially utilized a Delphi (professional brainstorming) approach to identify important areas of habitat connectivity (Potential Linkage Zones) across Arizona, including many in Pima County. These Potential Linkage Zones were identified to provide regional collaboration in preserving the diverse wildlife communities and natural ecosystems in Arizona. The I-10 Santa Cruz River corridor, including Rattlesnake Pass, is one of many issues being addressed in order to adequately evaluate an identified linkage between the Tortolita Mountains and the Tucson Mountains. In May 2006, Pima County voters accepted and voted for the half-cent excise tax to fund the Regional Transportation Plan, a comprehensive transportation plan for Pima County. This plan includes 2.1 billion dollars for transportation planning throughout Pima County. A component of this funding is committed to address wildlife connectivity and linkage plans associated with roadway development within the county.

Methods exist to allow the passage of animals across highways ranging from relatively low-cost efforts (e.g., modifying the behavior of motorists and animals with warning signs, reflective lights and repellents) to expensive construction of new infrastructures (e.g., wildlife overpasses or underpasses). However, the success of these measures is strongly influenced by their placement (Clevenger and Waltho 2000, Gloyne and Clevenger 2001, Ng et al. 2004), and thus any effort to maintain safe passage for wildlife and reduce animal-vehicle collisions must first identify the location of problem areas, or “hot spots”. In addition, the high cost of many passage solutions requires that efforts be focused through applied research to produce maximum returns on any investment. The development of a comprehensive and efficient strategy for addressing the environmental, economic, and social costs of animal-vehicle collisions must be predicated on an understanding of where conflicts between wildlife and highway operation are most severe.

Wildlife vehicle collision and track locations along roadways are direct indicators of wildlife crossing points. This information can guide the design and placement of mitigation features intended to minimize vehicle related wildlife mortalities and increase wildlife permeability across roadways. To maximize effectiveness for wildlife crossing, the mitigation features


(currently based on storm water passage alone) must be located where animals cross roadways. Therefore, wildlife crossing structure placement should be based on animal movements. The purpose of this project was to collect wildlife species location data in order to identify concentration spots, or “hot spots,” where the roadway intersects with wildlife defined corridors. The results of this preliminary work will help integrate engineering designs with wildlife presence data and mitigation strategies. This information will also enable the development of strategies to reduce loss of wildlife along the roadway realignment corridor in Rattlesnake Pass.

Study AreaThe Twin Peaks Road transportation corridor consists of a two-lane road with traffic volumes of approximately 4200 (vehicles / 24 hour period, hereafter V/24Hr.) (PAG 2005). Subdivisions in this area have higher traffic volumes directed south towards the Tucson metropolitan area, with limited access to Interstate 10. The proposed development of the Twin Peaks I-10 traffic interchange and continued urban development in this area will result in higher traffic volumes through the Rattlesnake Pass Twin Peaks traffic corridor with 2030 estimates nearly doubling current traffic volume (Kimley-Horn and Associates 2005). Investigations into roadway mortalities have shown that roadkills are directly correlated to speed and volume of traffic (Fahrig 1995). The current development of the Saguaro Springs- Palo Verde community, which is north of Twin Peaks Road and west of Rattlesnake Pass, will bring 2500 new homes to the Marana area. The developer, Empire Companies, and the Town of Marana will be converting the existing two-lane Twin Peaks Road into a four-lane, median divided road with incorporated design elements for safe wildlife passage (Town of Marana 2007).

Twin Peaks Road is currently a non-divided arterial road that supports traffic from Silverbell Road into Avra Valley, Northern Marana and Pima County, Arizona. The Twin Peaks Road wildlife linkage research project corridor evaluation area included the entire Twin Peaks Road easement from Silverbell Road and Valhalla Drive westward through Rattlesnake Pass to Quarry Road and Twin Peaks intersection. The Twin Peaks traffic corridor extends through the northern spine of the Safford Peak complex of the Tucson Mountains. This northern extension of the Tucson Mountains represents a portion of a contiguous area of environmentally sensitive lands or large habitat block suiting the needs of many species of the Sonoran Desert ecoregion. This habitat block includes large tracts of land managed for open space including the Saguaro National Park West and Pima County Tucson Mountain Park and is dominated by the Upland Sonoran Desert Scrub vegetation community. The unique physiographic characteristics of this area are due to dramatic elevation changes, solar exposure and geology resulting in habitats rich in biodiversity. The lowland slopes are comprised of primarily Sonoran Lower Colorado River Subdivision with a Sonoran-Mojave Creosotebush-White-Bursage Desert Scrub association (Brown 1994). As elevation increases towards the upland pass the vegetation changes to Paloverde-Mixed Cacti Desert Scrub (Brown 1994).


Landscape Barriers:The Twin Peaks Road Wildlife linkages project identified many barriers in the study area. These barriers, although not evaluated for species resistance across the landscape, obviously restricted wildlife movements through the area. There are two distinct landforms present in the study area comprised of the Lowlands, which exist east and west of Rattlesnake Pass, and the Uplands, which contain the rocky extension of the Tucson Mountains at Rattlesnake Pass. Both of these areas contained natural and man-made barriers to the movement of wildlife.

On Twin Peaks Road, west of Rattlesnake Pass on the southern end of the Saguaro Springs Development is a storm water retention and distribution basin. This basin creates a 12-foot drop from the north edge of the road easement (Figure 1). This drop functionally disrupts north and south wildlife movement in the western lowland area. This imposed barrier will disrupt flow and potentially cause wildlife to bounce between it and the road in an attempt to negotiate the barrier. Where mitigation is applied in this area, wildlife friendly grades must be incorporated from applied mitigation into the retention basin on the north side of Twin Peaks Road.

MethodsProject Corridor Evaluation Areas:Road kill data was collected to reveal wildlife crossing spots (Malo et al. 2004, Waltho 2003). This evaluation corridor extended from the intersection of Silverbell Road and Valhalla Road through Rattlesnake Pass to the intersection of Twin Peaks Road and Quarry Road. This method adequately showed where animals failed to negotiate the road barrier, but does not illuminate how these species are approaching the perceived barrier of Twin Peaks Road. In addition to roadway evaluations, the project evaluation area extended approximately 400 meters north and south of this traffic corridor evaluating both scat and animal track surveys. This approach allowed for estimates of how larger wildlife negotiated the landscape for north-south movements along the Tucson Mountains.

Wildlife Evaluation MethodsRoad kill Evaluation:Walking surveys were used to determine road kill locations. The surveys were conducted for two consecutive days, every seven days, to estimate road kill counts within a 24-hour and weekly period. The project area was surveyed during an eleven week period from July 23, 2007- October 2, 2007. The road kill surveys covered a two-mile (3.2 km) paved traffic corridor and easement within the project corridor as described above. Two surveyors arrived 30 minutes prior to sunrise and walked the road and shoulder while additionally scanning the adjacent easement areas to 50 m beyond the road edge. Early morning surveys were utilized to detect mortalities prior to removal by scavengers. All animals, alive or dead, and all tracks detected along the paved roadway and shoulder were recorded as they were encountered. Specific locations were documented using a hand-held Trimble GeoExplorer, Geo XM pocket PC. The position relative to the road surface, shoulder or easement was also noted. To avoid double counting, all locations were marked with surveyor marking paint indicating the exact site on the road with a dot and a corresponding line along the side of the road and all detected tracks were erased. All data was collected into the developed data dictionary within the GeoExplorer memory and downloaded daily.


Track and Scat Counts:Track and scat counts were used to identify concentrated activity areas as well as larger movement corridors associated with the unpaved portion of the landscape around Rattlesnake Pass and the Twin Peaks Road traffic corridor. Graded track beds were placed along the north and south shoulder of Twin Peaks Road from Silverbell Road south to Quarry Road (Figure 1). In addition, track beds were developed north and south of Twin Peaks Road. The northern track bed extended from the eastern boundary of the Saguaro Springs development project southeastern storm water retention basin and continued eastward as far as the natural substrate allowed for track interpretation. The southern track bed was developed with cooperation from the White Stallion Ranch and extended from the Ranch headquarters east toward Rattlesnake Pass, south of Twin Peaks Road. Each track that entered the graded surface was categorized into taxonomic groups and to species when possible. After each track survey, the tracking beds were graded to prepare for the next reading. The track beds utilized natural substrate from on-site, and were graded with a 100 pound, six-foot wide surface grader pulled by an ATV. This produced an even, level surface comprised of sand clay loam with larger aggregate material effectively preserving tracks in wet and dry conditions. The supplemental track lines away from the road were developed to detect movements of larger species in the area. Due to the limited linear home range of smaller species in the study area and the scaled distance from the road, it was determined that only larger mammals would be recorded (Bissonette 2006). This included carnivores (Canids and Felids), Peccary (Tayassu tajacu), and Mule Deer (Odocoileushemionus).

Culvert EvaluationAll culverts existing in the current study area were evaluated for wildlife use. During the biweekly road kill walking transects each culvert was assessed for wildlife occupancy and tracks. There were two culverts applied to the study area to manage storm water discharge. The larger of the two culverts was along the previously constructed Silverbell Road. This culvert, which drains the southeastern segment of Rattlesnake Pass, receives discharge on the south side of Silverbell Road north of Valhalla Road and directs it northeast across Silverbell Road. This culvert has an existing 4-foot grade control structure upstream of Silverbell Road. The second culvert lies in the lowland areas of Twin Peaks Road west of Rattlesnake Pass. This 16” corrugated metal pipe reduces drainage issues on the south side of Twin Peaks Road at Belacani Avenue / North Sidewinder Lane.

ResultsData collected during the 11-week survey were summarized by partitioning the data spatially. All detections of road kill, tracks, and observed animals encountered within the road easement were included in this summation. The track data and walking surveys north and south of the Twin Peaks traffic corridor were utilized to generate a list of species assemblages detected on either side of the traffic corridor. All species encountered were partitioned into a segmented spatial histogram of detections, thus allowing for visual interpretation of “hot spots” throughout the evaluation area. All data collected in the Twin Peaks Roadway easement were summarized into 100 meter segments with relative numbers for each segmented cell highlighting where to apply mitigation based on guilds. These spatial histograms for each guild were further synthesized to produce a composite hot spot model for the terrestrial guilds represented within the project area.


Twin Peaks Road / Silverbell Road Wildlife Evaluation Segment During this evaluation period (July 23, 2007 - October 2, 2007) surveys were conducted on two consecutive days with five days between visits. This time period resulted in 21 survey days through the project corridor to collect data of direct mortality or secondary sign of presence in the form of tracks and scat. Utilizing this multi-species detection approach, 55 species were encountered in the Twin Peaks Road traffic corridor easement. These 55 species (Appendix A) were represented by 630 detections of which 529 were direct mortalities (Appendix A1), and 101 were secondary detections of scat or tracks within the road easement.

In comparison, during the 2006 Camino de Mañana Wildlife Evaluation project, 39 species were identified, accounting for a total of over 1200 detections. In addition, 60 percent of the total detections in the Camino de Mañana Wildlife Evaluation were amphibians that resulted in a large number of mortalities (Lowery and Blackman 2006). The change in total species detections between these two study sites illuminates the unique physiographic variability of the Rattlesnake Pass area that provides habitat requirements for these additional 16 species (primarily represented by reptiles and avian species detected).

Herpetofauna: Amphibians and Reptiles In the roadway easement of Twin Peaks Road 435 herpetofauna mortalities were detected. There were 16 reptile species and 5 amphibian species noted during the 11-week survey period. Of these detections amphibians comprised 60 percent of the total mortalities. The 5 amphibian species represented in the project area are summarized in Appendix A. Couch's Spadefoot Toad (Scaphiopus couchii), a lowland species attracted to open pools of water for breeding, dominated amphibian detections comprising 66 percent of all amphibians identified. Amphibians encountered during this project represent a guild of species that have an r-selected population strategy (i.e., producing many offspring with low survival rates in an unpredictable environment). It is difficult to understand what implications road mortalities would have on these population structures. Amphibian detections were locally abundant and scattered across the project area; however, the majority was away from Rattlesnake Pass and distributed along the lowland washes and depressions where water currently collects along the Twin Peaks Road shoulder (Figure 2).

Reptiles detected in the Twin Peaks Road evaluation corridor were comprised of 10 snake species, five lizard species and the Sonoran Desert Tortoise (Gopherus agassizii) (Appendix A). This impressive list of species encountered on a two-mile segment of road portrays the uniqueness of the study area (Figure 3). Western Diamondback (Crotalus atrox) was the most abundant snake species detected within the study corridor. All other reptile species represented less than five mortalities detected for each species during the evaluation period. On July 31, 2007, a Sonoran Desert Tortoise mortality was recorded on the western slope of Rattlesnake Pass. This individual, with a carapace length of 64 mm, would be categorized as a juvenile (Turner and Berry 1984).


MammalsSmall mammals accounted for 12 percent of the total mortality detections within the project area and are summarized in Appendix A. This group is primarily represented by kangaroo rats (Dipodomys spp.) wood rats (Neotoma spp.) pocket mouse (Perognathus spp.), lagomorphs; (Lepus spp., Sylvilagus spp.), raccoons (Procyon lotor) and skunks (Mephitis mephitis). In addition to these species, a brown bat (Eptesicus fuscus) mortality was recovered in the project corridor. Small mammal detections were evenly distributed across the lowland sections of the project corridor with only a few being detected in the upland segments of Rattlesnake Pass (Figure 4).

During the 21-day wildlife linkage evaluation, 65 large mammal movements were detected through the Twin Peaks Road traffic easement area. The category of large mammals includes Mule Deer, Javalina, and carnivores such as Bobcat (Lynx rufus), Coyote (Canis latrans), and Kit Fox (Vulpes macrotis). Carnivores, primarily represented by Coyote were locally abundant and distributed across the project corridor (Figure 5). Large mammals detected within the project corridor were concentrated in specific areas (Figure 6). During this same evaluation period a four point Mule Deer buck was found dead on the western slope of Rattlesnake pass. This was the only large mammal mortality detection in the project area.

AvianDuring the course of the study, 11 avian species were detected (Appendix A). This guild had the lowest mortalities of all other groups present in the project corridor. This guild had only three percent of the total detections, and no statistically significant mortalities to any single species group (Figure 7). Most detections were noted in the lowland areas west of Rattlesnake Pass.

Supplemental Track CountsTrack beds along the side of the road were evaluated as summarized above. In addition, tracks along routes north and south of Twin Peaks Road on the western most undisturbed portion of the project area were sampled. Evaluation of these supplemental track beds focused on larger mammals with increased mobility and larger home range size. Smaller species might be detected but due to limitation in these variables it would be unlikely that they would come into contact with the road barrier due to its distance from the supplemental track beds. The supplemental track beds allowed for interpretation of how animals navigated the barrier of Twin Peaks Road. There were no additional species detected through our supplemental track beds. Species in order of total numbers detected were: Coyote, Javalina, Mule Deer, Domestic Dog (Canis spp.),Bobcat, and Kit Fox. The southern supplemental track beds were developed through active cattle range on the White Stallion Ranch, yet all domestic cattle tracks were ignored.

Cumulative Summary of GuildsThe initial individual guild summary maps utilized a five category mortality distribution to identify hot spots for specific guilds. Classifying the mortality frequency data for each guild into the five equally distributed categories allows for the development of a value additive model to summarize all terrestrial guilds. This model applies a value of 0-4 to each 100m segment along the roadway dependent of the significance of that segment to a specific guild. The value ranking applied to each segment were ranked as 0, 1, 2, 3, and 4 with 0 indicating that the


roadway segment had low or no mortalities and 5 indicating a segment with the highest mortalities for the represented guild (see value ranking for all guilds Appendix C). This method eliminates the potential for high mortalities of a specific group driving the focus area for mitigation. After applying a value ranging to each variable category or guild a composite value additive map is developed showing the focus areas for mitigation along Twin Peaks Road (Figure 8). This model shows the aggregation of segment importance for all terrestrial guilds. Specifically it shows that the lowland mitigation segments priority areas are segments 17, 24, 26,and 32. These areas can be located by multiplying the segment number by 100m and measuring that distance west of Valhalla Drive and South Silverbell Road intersection. The upland composite model focus areas are on either side of Rattlesnake Pass at segments 5 and 12.

CulvertsThe focus during this investigation involved two culvert systems currently incorporated into the Twin Peaks Road. The larger of the two culverts at evaluation Segment 3 accommodated activity of javalina and coyote. The Silverbell culvert has a 48” grade control structure on the southern upstream side which prohibited the cross road movement for most species. Coyote was the only species to successfully negotiate the road by utilizing the culvert although Javalina tracks were recorded at the southern entrance. The second culvert at evaluation Segment 23 is a 16” CMP and was utilized by amphibian species only. This drainage culvert retained water after storms.

Discussion and Management Recommendations The issues related to roadway permeability for wildlife are paramount in the development of corridors through complex urban matrices. Developing the baseline data to guide research applied strategies toward roadway barriers is an initial step in evaluating methods to mitigate wildlife loss in biologically sensitive areas. In addition, development of mitigation strategies must have long term commitments from all public and private land management groups within potential linkage zones. Specifically, crossing structures are only as effective as the natural resource management strategies within the habitat blocks being connected. Mitigation strategies are only effective if habitat is present on both sides of the intended wildlife mitigation strategy (Barnum 2003, Cain et al. 2003, and Ng et al. 2004). In the development of potential linkage zones we must conscientiously apply strategies that will benefit areas with high biological value and those in immediate threat of development or loss. The Twin Peaks Road traffic corridor represents the most southern interruption of a potential passageway existing within the linkage area between the Tortolita Mountains and the Tucson Mountains.

Rosen and Lowe (1994) conducted roadkill surveys throughout Organ Pipe Cactus National Monument and concluded that Highway 85 (which dissects the National Monument) substantially effected the regional snake population with vehicle collisions accounting for 2000-4000 estimated mortalities over four years. Kline and Swann (1998) conducted roadkill surveys (for all species) in Saguaro National Park (East and West units) and estimated several thousand annual vertebrate mortalities from vehicle collisions. Vehicle collisions undoubtedly impact all species; however, the magnitude of this threat on population viability is less well understood. Long-lived and slowly reproducing individuals, such as the desert tortoise, are probably more severely affected by individual deaths when compared to species such as the spadefoot toads (which have punctuated reproductive episodes that are strongly associated with monsoons).


However, the high number of amphibian mortalities documented along both Camino de Mañana and the Rattlesnake Pass roadways may at least locally have a substantial impact on the viability of toad species. Despite the detection of only one desert tortoise vehicle collision mortality, this roadkill account, in a comparatively small sampling period, suggests that more collision fatalities undoubtedly occur at other times. This loss may be devastating to the local tortoise population, as wild individuals typically require many years (possibly decades) to replace one death (Averill-Murray and Klug 2000, Averill-Murray et al., 2002, Averill-Murray and Averill-Murray 2005). The high number of toad mortalities, coupled with the desert tortoise road kill, underscores the importance of implementing mitigation strategies in these respective hotspots.

Besides direct mortality through wildlife vehicle collisions, roads have been shown to create barriers influencing wildlife at a scale that extends beyond the road footprint. Wildlife may be influenced by or respond to roads through: direct mortality, area avoidance, changes in dispersal patterns, altered foraging movements and modification of seasonal migrations; of which all can be defined as a disruption in the horizontal ecological flow within the ecosystem (Fahrig 1995, Clevenger 1999, 2001, Mc Donald and St. Clair 2004). Conversion and fragmentation of natural landscapes through development and road construction by humans are leading factors contributing to the decline of biodiversity and extinction of plants and animals (Hudgens 2002, Palomares et al. 2000, Crooks 2002 and Forman et al. 2003). Wildlife use of crossing structures can exhibit species-specific preferences, although studies have documented many species using several different crossing structure designs (e.g., Clevenger et al. 2001, Mata et al. 2003). The flexibility of species regarding crossing structure design suggests that mitigation strategies, including barrier fencing, may prove successful where implemented.

Multi-Species Mitigation Strategies by Landform and Habitat OverlapThe interpretation of the segmented data by guilds shows specific areas where applied mitigation will benefit specific groups of species. A multi-species, multi-guild approach for applied mitigation allows for the best application and maximum return on limited development resources. The multi-species model is developed through further analysis of the five terrestrial guilds represented in the project area. As shown in the initial summary maps for these five terrestrial guilds most of the project area has recorded wildlife mortalities. It is unrealistic to apply mitigation across the entire project area to capture all of the potential mortalities. Therefore, through further analysis we can identify where to apply mitigation for the greatest return while utilizing amphibian walls and fencing to funnel ancillary wildlife into wildlife crossing points. The Twin Peaks Road traffic corridor bisects two distinct habitat types defined by the landforms present. These two landforms, described as Lowland and Upland, have unique challenges based on the species habitation of these areas. Current standards often rely on hydrology-based culverts to fulfill a habitat linkage role and direct connectivity for wildlife. For drainage culverts based on hydrology to fulfill a mitigation function as habitat connectors, strategies must be contemplated at various scales in order to accommodate multiple species. In this process mitigation strategies must be developed with this multi-species scale in mind. With this boarder approach, we must consider both the mean home range and median dispersal distance for an assemblage of animals in an area to determine correct spatial arrangement of applied mitigation. In consideration of spatial arrangement, this linear home range distance for multiple species becomes a function of managing for the minimum.


Correct spatial arrangement of applied mitigation will ensure maximum benefit for multiple species occupying the landscape at various scales (Bissonette 2006). Upland and Lowland landforms require different vegetative variables such as stem density, canopy closure, species composition and structural composition. Site-specific vegetative cover at the entrance of applied mitigation sites should be present to alleviate perceived stressors generated by the roadway including traffic noise, lighting and vibration (Clevenger et al. 2001; McDonald and St Clair 2004). At a site-specific level, measures are needed to keep wildlife from entering the road surface (e.g., highway shoulder fencing to funnel wildlife to crossing points). Correspondingly, culverts must be placed where animals are most likely to cross roadways at the landscape scale (Barnum 2003). Beyond the scale of the specific mitigation, structure and suitable habitat must be present throughout the linkage for animals to use a crossing structure. Obstacles other than roadways must be overcome if linkage strategies are to be effective. Development of wildlife crossings requires the consideration of many issues including crossing type, configuration in the landscape (i.e. spatial arrangement and habitat on both sides of the road), the inclusion of un-breached fencing (except for at the crossing structure), general maintenance, post monitoring of crossing effectiveness, and the adaptability to make management adjustments if necessary. Another point of concern in structure placement is urban development or high levels of human activity near crossing structures resulting in avoidance by animals. These factors decrease habitat quality and disrupt animal movements, particularly of large predators (Smith 1999, Clevenger 2001).

Lowland Mitigation RecommendationsA multiple species approach ensures that specific measures can be applied across the project area to mitigate wildlife vehicle collisions and benefit habitat connectivity. Creating crossing structures and fencing to aid in funneling wildlife to appropriate crossings are the cornerstone topics to consider when developing permeable roadways for wildlife. Again, for these strategies to work in Lowland areas along Twin Peaks Road we must direct animals to available habitat.

Application of these mitigation strategies are subject to barrier resolution along the Saguaro Spring southern water retention basin. The deadfall nature of the 12-foot vertical drop will need to be altered to accommodate a gradual transition into the retention basin in order to allow for north-south movements of wildlife. Flood retention basins can benefit wildlife but we must provide a means of egress and ingress with natural substrate, reasonable slope, and no vertical drops. These mitigation recommendations should be applied to those areas identified in the developed multi-guild composite model. The model results showed that the Lowland area hot spots were identified as segments 17, 24, 26, and 32.

In Lowland areas (Figure 8, 9) with the highest concentrations of herpetofauna and small-medium mammals, increase the road elevation above natural grade. This will allow for crossing structures below the road surface and has an overall effect of reducing road mortalities simply by changing grade and developing a barrier further from the road surface (Clevenger 2003). Along with the development of culverts for hydrology demands, culvert pipes or small box culverts should be developed above natural grade while maintaining natural substrate and vegetation components at entrances. The increased elevation prevents regular flooding of crossing structure and natural approach reduced the perceived barrier edge.


These additional mitigation culverts, centered on the identified hot spot, should encompass the entire 100m of the identified evaluation segment. Spatial arrangement in the identified hot spot segment should be alternating medium, small and medium culverts with 50m (150ft.) spacing with the small culvert centered in the evaluation segment, unless hydrology dictates larger dimensions. This inner-culvert distance will compliment the smallest linear home range of 0.02mi (48m) for Perognathus sp. present in the lowland areas (Bissonette 2006). Unfortunately, this data is not available for southwestern herpetofauna also present in the study area.

1. Small Culverts - Culverts measuring approximately 0.3 m (1.5 ft.) high, possessing vegetation cover for predation avoidance, and a distance of 50 m (150 ft) between each structure, were identified as the most effective mitigation strategy for small mammals and herpetofauna (Clevenger et. al. 2001, McDonald and St Clair 2004).

2. Medium Culverts - These culverts should be 1m (3 ft.) high with an Openness Index of 0.4 (Openness Index = (Culvert Height x Width) / Length). The larger distance of 100 m between medium culverts will accommodate larger mammals and carnivores movement preferences. This spatial arrangement applies to the multiple species approach. In addition, this strategy can utilize alternating lighted culverts (culverts with grates in roadway) and dark culverts (culverts with no grating in roadway) to accommodate variations in species behavior.

Between the above wildlife crossing structure, develop 1m (2.0-3.0ft) barrier wall structures to direct wildlife to appropriate crossings as defined in the Pima County Roadway Design Manual (Pima County 2003). This smooth faced concrete structure has low overall maintenance cost and can be applied utilizing currently developed curb forms. The ideal placement would be between sidewalk and natural grade on both sides of the roadway. (Appendix B) In Florida, construction of a barrier wall to guide animals into a culvert system resulted in 93.5% reduction in road kill for amphibians and reptiles. Applying a 4-6 inch overhanging lip could also increase its effectiveness. This would also provide a mounting platform to apply additional fencing strategies in newly developed hot spots during post monitoring. Reduction of lighting strategies in urbanized areas and roadway corridors which abut linkage zones. Allow animal movement areas to remain dark.In all culvert crossings keep grade control structures far enough away from the culverts to allow for animal escape into nearest habitat cover.Structures should be monitored for and cleared of obstructions such as detritus or silt blockages that impede movement. Manage human activity near each crossing structure. Separate human recreation from wildlife linkage areas. Apply fencing to driveways and apply cattle guards in appropriate large mammal crossing areas. Monitor and evaluate effectiveness of culverts as wildlife crossings and make appropriate adjustments if necessary (e.g., retrofit fencing or other modifications).

In addition, wildlife in the lowland areas represented by segments 3-5 would benefit from applied mitigation and renovations to the erosion control feature at the existing segment 3 culvert (e.g., removal, replace upstream or gradual grade transition) to facilitate greater wildlife passage.


Upland Mitigation RecommendationsThe approaches for wildlife permeability as it is applied to the Upland areas of Rattlesnake Pass are uniquely different than Lowland areas. Specifically, with the addition of Mule Deer detections concentrated on the western slope of Rattlesnake Pass, mitigation measures are now directed to managing for the largest species. This area includes Twin Peaks Road Evaluation segments 4-12 (see Figure 9), and is the only vicinity with collective detections of Tortoise, Mule Deer and Javalina. These segments encompass the northern spine of the Tucson Mountains and have geographic barriers unique to each of these species. This natural funneling due to topography of the area restricts movement of most wildlife species to either the eastern or western slopes. These areas intersect the Twin Peaks Road and can be identified as evaluation segments 5 and 12 (Figure 8, 9). Although segment 5 and the eastern slope of Rattlesnake pass did not generate any Mule Deer detections, anecdotal accounts generated during landowner conversations indicate that this corridor is occasionally utilized by deer. The abrupt escarpments in Rattlesnake Pass functionally funnel species of interest to specific areas or hot spots as seen in the composite summary maps and the Reptile, Carnivore and Large Mammal summaries. Prioritization of placement is critical and fencing should be placed between measures to allow for funneling of desired species to crossing structures.

The Upland area of Rattlesnake pass along the Twin Peaks traffic corridor provides a unique challenge for applied mitigation based on species present including Mule Deer. Solutions to this area are dependant on the completed Twin Peaks Road traffic corridor geometry and elevation. Due to the parallel nature of the traffic corridor and hydrology and slope of Rattlesnake pass, hydrology based culverts will be at a minimum. Ultimate design specifications for the completed roadway elevation allow for the largest range of possibilities of applied mitigation. The current roadway elevation in relation to natural grade could follow three scenarios for wildlife mitigation: 1) At Grade- The roadway will stay the same at natural grade and mitigation would include measures directed towards changing animal and motorist behavior in response to crossings. 2) Increased Road Elevation- Increasing the road surface elevation above natural grade would allow for the development of sub-roadway culvert type crossing. 3) Decreased Road Elevation- Excavation of the current road elevation in portions of Rattlesnake Pass to develop land bridges within the identified evaluation segments 10-12 ( Figure 8, 9) while following natural topography and maintaining adequate view shed across the top of the land bridge. A combination of these strategies should be applied through Rattlesnake Pass with a focus on segments 5 and 10-12.

Behavioral Mitigation strategies:At-grade crossings include a list of strategies directed at changing behavior at the intersection of wildlife corridors and roadways. Some strategies include a few of the following;

Animal warning systems or devices which detect vehicles and then warn animals with visual or auditory signals.Motorist alert systems provide flashing lights or signage when an animal is detected approaching a road.Roadway modification systems- these include sign deployment, changes in lighting, speed limit reductions, and most importantly the use of funnel fencing in order to guide animals to appropriate crossings.


For these systems to operate properly and reduce the incidence of mortality, many design and maintenance issues must be addressed including exact placement, weather conditions, motorist behavior, and non-target species interfering with the system’s function (Huijser 2003). Signage is a common approach to informing motorists when they are entering an area where the danger of wildlife collision is high. Romin and Bissonete (1996) report that most states have tried deer warning signs, hazing, reduced speed limits, and public awareness campaigns, but few states have conducted research to determine the effectiveness of these techniques. These strategies are generally species specific and do not allow for the safe passage of resident and incidental species which are less mobile and non-responsive to such measures.

Under Roadway Culvert Strategies: Increasing the road grade above the current elevation would allow for the application of a multi-species culvert approach much like the Lowland mitigation strategies. The addition of Mule Deer detection frequencies on the western slope of Rattlesnake Pass indicates the need for specific culvert structures that are taller in height (with larger cross-sectional areas and openness ratios).

The openness ratio determined to benefit Mule deer is 0.75 or greater calculated as follows (Reed 1975).Openness Index (OI): (Height x Width) Divided by Length = OIThe openness of a wildlife underpass or culvert influences the amount of light that penetrates the interior and the corresponding view shed of the other side. Evaluate culvert impacts on erosion, and riparian areas to ensure habitat integrity. As suggested by many studies, large mammals typically prefer large, open crossing structures, such as bridge underpasses and box culverts. Culverts and concrete box structures are used by many species, including mammals, amphibians and reptiles (Clevenger 2004; Ng et al. 2004). In addition to the specific requirements to allow permeability for Mule Deer, this increased roadway method allows for the application of the multi-species approach to cover additional species in the area. Increasing the road elevation on the east side of Rattlesnake Pass would allow for the development of additional culvert crossing structures in evaluation segment 5 to facilitate the movement of Javalina and carnivores in the area. No Mule Deer were recorded crossing on the eastern portion of Rattlesnake Pass during the evaluation period.

Over Roadway Mitigation Strategies:This scenario would be selectively applied to the identified hot spots in the Upland portion of the project corridor. The development of a land bridge which follows a natural grade on the western slope of Rattlesnake pass would have a multi-species benefit. Above grade land bridges have been shown to accommodate larger species and be effective as a multi-species mitigation tool (NCHRP 2002, Bissionette 2006). Use of a land bridge applied in evaluation segment 10 - 12 would allow for a safe, readily accepted mitigation strategy for Mule Deer. Only a handful of overpasses have been developed in the United States and these applied strategies are generally directed towards larger species such as Bears, Mule Deer and Big Horn Sheep while facilitating a connectivity function. When evaluating a solution to roadway permeability in Rattlesnake Pass multiple crossing structures should be provided through Rattlesnake pass uplands to allow functionality to this wildlife corridor within this potential linkage zone (Little 2003). Many carnivores prefer to have multiple crossing points along roadways yet also prefer a lower, more


obscured path (Foster 1995, Gloyne 2001). In Europe, it has been shown that when there is suitable habitat at and leading to the overpasses, it was found that the overpasses were effective for a wide variety of animals. The conclusions included the observation that structures at least 60 m (196.8 ft) wide were more effective than overpasses narrower than 50 m (164 ft), especially for larger mammals. It was noted that animal behavior on the overpasses was more normal on the wider structures (Pfister et al. 1999, USDOT 2002). In the United States the first overpass in North America was created for Mule Deer and Elk (Cervus elaphus) in Utah in 1975.

Establish multiple crossing points on either side of Rattlesnake Pass to facilitate carnivore movements through the area. Create “escape cover” around wildlife crossings by using dense native vegetation. Manage human activity near each crossing structure. Separate human recreation from wildlife linkage areas. Vegetated land bridge with native vegetation.Develop sidewalls on land bridge to keep wildlife contained and reduce light and noise disturbance.Apply fencing to driveways and apply cattle guards in appropriate large mammal crossing areas. Install wildlife crossing signs to inform motorists. Install small lighted culverts for smaller wildlife. Plant native vegetation in medians and other landscaping. Install walls to encourage reptiles and amphibians to use appropriate crossing structure.

Structure Approach: In upland and lowland mitigation strategies vegetation surrounding the approach to the structure is an important consideration when designing for multiple species. While some level of natural vegetation is important to maintain habitat continuity, the type of vegetation can play an important role in culvert use. Most small mammals, amphibians, and reptiles prefer low stature cover in the form of vegetation, rocks, and logs to protect them from predators. Medium and large mammals that are prey species (rabbits, deer) may be wary of using structures with extensive vegetation where predators can hide. Eliminating potential predator ambush opportunities, while providing good visibility for medium and large mammal prey species, will encourage use of a culvert.

Maintain native vegetation strategies with all plantings.Allow for nominal buildup of natural detritus material near entrances of culverts providing cover for small vertebrates. Maintain natural substrate within, and at egress and ingress points of culverts.

Avian species are influenced by the vegetation characteristics approaching roadways. The primary strategy for avian mitigation is to adjust their flight path when approaching the traffic corridor. Avian species following the contours of the landscape will alter their elevation in response to planted vegetation. For example, Florida DOT reported installing PVC pipe approximately 3 m (9.84 ft) in height perpendicular to the railing on the San Sebastian Bridge to keep bird flight patterns above the elevation of traffic (Egensteiner et al. 1998).


Structure Design: While considering the variety of internal habitats preferred by different animal groups, it is not surprising that specific design elements for particular species may be contradictory. For example, open-top culverts may provide favorable lighting, temperature, and moisture conditions for amphibians but may be too noisy for some mammals. Structures can be designed to facilitate multiple groups by incorporating design elements preferred by each. Alternatively, multiple structures in the same area could be incorporated to accommodate several groups. Large box culverts that accommodate large and medium mammals should be flanked by smaller crossing structures on both sides to accommodate smaller mammals, amphibians, and reptiles. This option addresses the need for different light, noise and moisture needs particularly well. Ultimately, there is no simple single approach. A variety of alternatives can and should be explored, with particular attention focused on local threatened and endangered species, and known wildlife migration corridors as identified hot spots. A structure that incorporates as many design elements as possible will most likely be the most successful at accommodating wildlife movement.

Utilize natural lighting in culverts when possible. Utilize natural substrate in culvert crossings. Eliminate deadfall zones due to head cutting at downstream end of culverts.

Fencing:Roadside fencing is arguably the most studied of devices implemented to reduce the incidence of deer-vehicle collisions. Most research has indicated that fences are not an absolute barrier to deer, and only serve to reduce the number of animals entering the roadway. Functionally, the fence must funnel the animal to an appropriate crossing area. In Arizona, this barrier concept in the form of boulder fields has increased the total number of species using culverts from 28 to 42 (Dodd et al. 2004). For Mule Deer, conventional fencing must be at least 2.4 m (7.7ft) high to limit the ability of deer to jump over it. This fencing or barrier method, when used with cattle guards at driveway entrances, has been shown to reduce deer access to roads by as much as 80% (Belant et.al. 1998).

Continue lowland barrier wall for herpetofauna through Rattlesnake Pass and attach fencing along top to increase needed height for larger mammal concentration areas. Utilize rip-rap bank stabilization to create greater disturbed edges where applicable. Place boulder barriers to direct large ungulates toward crossing feature. Eliminate unintended “hot spots” by maintaining complete barrier/fencing strategies between all culverts and driveways or arterial roads. Develop maintenance schedule for fencing.

Post Construction MonitoringFollowing installation of applied mitigation, there are several measures that can be taken to ensure continued effectiveness and use of the culvert by wildlife. These include:

Installation of traffic control measures (animal crossing signs). Monitor structures to ensure they are clear of obstructions such as detritus or silt that may impede movement. Develop a post monitoring project to identify measures of success. Monitor fencing to minimize any breaches that may compromise wildlife connectivity. Monitor and evaluate effectiveness of barrier walls, culvert wildlife crossing and make appropriate adjustments if necessary (e.g., retrofit fencing or other modifications).


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Appendix A.Species List Developed for Track Counts and Roadkill surveys along Twin Peaks Road Wildlife Linkages Research Project. July – October 2007

Guild Common Name Genus Species Guild Common Name Genus SpeciesMammals Amphibians

Bailey pocket mse Perognathus baileyi Bullfrog Rana CatesbeianaBanner tailed Kangaroo Rat Dipodomys spectabilis Couch's spadefoot Scaphiopus couchiiBig Brown Bat Eptesicus fuscus Red spotted toad Bufo punctatus

Blacktail jackrabbit Lepus californicusSonoran desert toad Bufo alvarius

Bobcat Lynx rufusWoodhouse'sToad Bufo woodhousii

Brush Mouse Peromyscus boylei Reptiles Coyote Canis latrans Coachwhip Masticophus flagellumDesert Kangaroo Rat Dipodomys spectabilis

CommonKingsnake Lampropeltis getula

Domestic Dog Canis domestic Desert Spiny lizard Sceloporus magisterHorse Equine caballas Gopher snake Pituophis cateniferJavalina Tayassu tajacu Long-nosed snake Rhinocheilus leconteiKit fox Vulpes macrotis Mojave rattlesnake Crotalus scutalatusMerriam Kangaroo Rat Dipodomys meriami Nightsnake Hypsiglena torquataMule deer Odocoileus hemionus Ornate Tree Lizard Urosaurus ornatus

Ord Kangaroo Rat Dipodomys ordiRegal Horned Lizard phrynosoma Solare

Pocket mouse Perognathus baileyi Sidewinder Crotalus cerastesRaccoon Procyon lotor Tiger Whiptail Aspidoscelis tigrisRound-tailed grd sqr Cetellus tereticaudus Tortoise Gopherus agassizii

Striped Skunk mephitis mephitisVariable Sand Snake Chilomeniscus stramineus

Wood Rat Neotoma albigulaWestern Banded Gecko Coleonyx variegatus

Avian WesternDiamondback Crotalus atrox

Cactus Wren Campylorhynchus brunneicapillWestern Thread Snake Leptotyphlops humilis

Gambels Quail Callipepla gambellii Large Arthropods Greater roadrunner Geococcyx californianus Centipede Scolopendra heroshooded oriole Icterus cucullatus Scorpion Hadrurus arizonensishouse finch Carpodacus mexicanus Tarantula Aphonopelma spp.Lesser Goldfinch Carduelis psaltriaMourning dove Zenaida macrouraNorthern Mockingbird Mimus polyglottos Phrrhuloxia Cardinalis sinuatusWhite-winged Dove Zenaida asiatica

e an

d Fi

sh D

epar

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t ild

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Link

ages

Res

earc

h Pr

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9

Amph

ibia

n R

oad

kill

Det

ectio

ns

050100

150

200

250

300

Bullf

rog

Cou

ch's

spa

defo

otR

ed s

potte

d to

adSo

nora

n de

sert

toad

Woo

dhou

se's

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d

No. Detected

Mam

mal

Roa

d K

ill D

etec

tions

024681012141618

Bailey

pock

et mse

Banne

rtaile

dKanga

rooRat Big

BrownBat

Blackta

iljack

rabbit Cac

tus M

ouse

Coyote

Desert

Kan

garoo

Rat Dom

estic

Dog

Merriam

Kanga

rooRat Mule de

er

OrdKan

garoo

Rat

Racoo

n

Round

-taile

d grd

sqr

Striped

Sku

nkWoo

drat

No. Detected

Avia

n R

oad

Kill

Det

ectio

ns

012345

Cactus

Wren

Gambe

ls Qua

ilGrea

ter ro

adrun

ner

hood

ed or

iole

hous

e finc

h Less

erGold

finch

Mourni

ng do

veNort

hern

Mockin

gbird

Phrrhu

loxia

White-w

inged

Dov

e

No. Detected

Roa

d K

ill D

etec

tions

Sum

mar

ized

by

Gui

ld

Am

phib

ians

Sm

all M

amm

als

Rep

tiles

Avia

nC

arni

vore

sLa

rge

Mam

mal

s

Rep

tile

Roa

d K

ill D

etec

tions

0246810121416 Coach

whip

Common

kings

nake

Desert

Spin

ylizard Gop

her s

nake

Long

-nose

d sna

ke

Mojave

rattle

snak

e Nightsn

ake

Ornate

Tree L

izard

Regal

Horned

Lizard Tige

rWhiptai

lTort

oise

Variab

le sa

ndsn

ake

Wester

nBande

dGecko

Wester

n diam

ondb

ack

Wester

n Thre

adsn

ake

No. Detected

App

endi

x A

1. S

umm

ary

of d

irect

mor

talit

ies t

otal

s det

ecte

d du

ring

Twin

Pea

ks R

oad

Wild

life

Line

ages

Res

earc

h Pr

ojec

t.

Ariz

ona

Gam

2007

Tw

in P

eaks

Roa

d W

Arizona Game and Fish Department 2007 Twin Peaks Road Wildlife Linkages Research Project Page 30

Appendix B: Diagram Schematic of Barrier wall placement.

Arizona Game and Fish Department 2007 Twin Peaks Road Wildlife Linkages Research Project Page 31

Appendix C: Value ranking for composite model of mortality frequency by guild.

.Variable Category Value Ranking

0Amphibians

3 - 6

17 - 10

211 - 15

316 - 20

421 - 48

0Reptiles

1234

01234

01234

01234

Large Mammals01234

0123 - 45 - 6

ySmall Mammals

01 - 23 - 56 - 89 - 10

Carnivores0123 - 45 - 6

Twin Peaks Road Wildlife Linkages Research Project Rattlesnake

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