Technical Report #83-7-01 September DISTRIBUTION of the LARCH
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FISH & WILDLIFE REFERENCE LIBRARY Technical Report #83-7-01 September 1983 DISTRIBUTION OF THE LARCH MOUNTAIN SALAMANDER (PLETHODON LARSELLI) IN OREGON With Notes on Other Plethodontids 'A X Oregon Department of Fish and Wildlife Nongame Wildlife Program DISTRIBUTION OF THE LARCH 14OUNTAIN SALAMANDER (PLETHODON LARSELLI) IN OREGON With Motes on Other Plethodontids James J. Kirk Oregon Department of Fish and Wildlife Nongame Wildlife Program Technical Report #83-7-01 September 1983 CONTENTS AND TABLES FIGURES ....................................................... ii ABSTRACT 1 ................................................................. INTRODUCTION I ............................................................. STUDY AREA AND METHODS 2 ................................................... 3 RESULTS .................................................................. 3 Distributional Records .............................................. 3 Pitfall Trapping .................................................... 15 Other Plethodontids ................................................. 15 Rainfall ............................................................ DISCUSSION 19 ............................................................... 19 Habitat Requirements ................................................ Distributional Limits 22 Eastern Limit ............................................... 22 Western Limit .................................................. 23 .................................................. 23 Southern Limit ................................................. 24 Environmental Hazards ............................................... RECOMMENDATIONS 25 .......................................................... REFERENCES 27 ............................................................... APPENDIX 29 ................................................................. Appendix A: 29 Bibliography of Plethodon larselli ..................... i FIGURES Number 1. Distribution of the Larch Mountain salamander (Plethodon larselli) in Oregon 7 .......................................... 2. Distribution of the Oregon slender salamander (Batrachoseps wrighti) in the Columbia Gorge Oregon 16 River of ............... 3. Rainfall in the Columbia Gorge, 3 October 1982 to 8 May 1983 ......................................................... 18 4. Habitat occupied by the Larch Mountain salamander (Plethodon larselli) Ainsworth Park, Multnomah Countj 7. 20 at State ... .... 5. Habitat occupied by the Larch Mountain salamander (Plethodon larselli) east of Starvation Creek, Hood River CounE-y 21 6. East side of Mitchell Point, Hood River County, showing slide area and Larch Mountain salamander (Plethodon larselli) habitat to the .................... 26 left of the slide .......... TABLES Number 1. Sites in Oregon where Larch Mountain salamanders (Plethodon larselli) 4 occur .............................................. 2. Sites in Oregon searched for Larch Mountain salamanders (Plethodon larselli) by Kirk 8 J. .............................. 3. Rainfall in Columbia Gorge 17 the ............................... DISTRIBUTION OF THE LARCH MOUNTAIN SALAMANDER (PLETHODON LARSELLI) IN OREGON With Notes on Other Plethodontids; James J. Kirk ABSTRACT An inventory of the Larch Mountain salamander (Plethodon larselli) conducted between October 1982 and May T98T_re`su_T_t_e6'1n new site records for this species on the Oregon side of the Columbia River Gorge. These records extend the eastern limit of the species range in Oregon east of Hood River to the Mitchell Point vicinity. No salamanders were found farther east of Mitchell Point despite apparently suitable habitat and moisture conditions. Traditional habitat parameters were not suitable indicators for the Larch Mountain salamander, although the species was primariy associated with areas of small-sized, angular talus without heavy moss cover. All known distribution records for the Larch Mountain salamander in Oregon are summarized as well as records for other plethodontids located during this inventory. Recommendations are made for baseline monitoring of Larch Mountain salamander populations and studies to further delineate the species range and habitat requirements. INTRODUCTION The Larch Mountain salamander (Plethodon larselli) is endemic to the lower Columbia River Gorge in Oregon and Washington. In Oregon, it is apparently restricted to areas of talus between Bridal Veil at the west end of the gorge and Hood River to the east. The southern limit of its range has not been identified. Its limited distribution could make the Larch Mountain salamander susceptible to habitat disturbances. The species is classified as a Category 2 candidate species for listing by the U.S. Fish and Wildlife Service and as a protected species by the State of Oregon. In 1982, I conducted an inventory of the Larch Mountain salamander through the Nongame Wildlife Program of the Oregon Department of Fish and Wildlife. Study objectives were to locate previously unknown populations -I- within the known range of the species in Oregon and to delineate the southern limit of its range. Additionally, "indicators" of suitable habitat were to be developed from habitat data collected and evaluated from each site. STUDY AREA AND METHODS The study was conducted on the Oregon (south) side of the Columbia River Gorge from the vicinity of Troutdale in Multnomah County, east to the vicinity of Mosier in Wasco County, Oregon. I also searched south of the gorge along the Hood River drainage and on the Mt. Hood Mational Forest in eastern Clackamas County. Field work was conducted between October 1982 and May 1983, by manually searching for the Larch Mountain salamander in areas of apparently suitable habitat. In addition, I set one pitfall trap at each of three sites where the species was known to be abundant to determine if its presence could be detected using this trapping method. The traps were made of 3-pound coffee cans sunk to their rims in talus. Holes drilled in the sides allowed water to accumulate only to a depth of 3 cm. I have used traps of the same design extensively to trap shrews (Sorex spp.) and they regularly caught long-toed salamanders (Ambystoma macrodactylum) as well. The pitfalls were left in place for 42 nights during January, February and March, 1983. The Monthly Summary of Climatological Data (Monthly Summary) for Oregon, (NOAA 1982, 1983) provided daily precipitation amounts measured at the Portland Airport, Troutdale, Bonneville, Hood River, and The Dalles. To obtain additional data for areas between those stations, I put rain gauges at sites near Rooster Rock, Ainsworth State Park, Herman Creek Road west of Wyeth, and Viento State Park. The gauges had internal funnels to reduce evaporation, maximum depths of 34.5 cm and cross-sectional areas of 186 sq cm. I measured accumulated rainfall at irregular intervals during the course of other field work. Gauges were not calibrated against those from which the Monthly Summary data are derived, so systematic errors due to equipment differences probably occur in the data. -2- RESULTS Distributional Records The known distribution of the Larch Mountain salamander in Oregon is summarized in Table 1 and Figure 1. I concentrated my search efforts near the eastern and western-most sites where the species has been reported in hopes of more accurately delineating the eastern and western limits of its distribution. I found no Larch Mountain salamander west of the previously reported distribution. However, the species was found at several sites in the vicinity of Mitchell Point, east of the previously reported distribution. All sites searched for the I-arch Mountain salamander during this field survey are included in Table 2. Pitfall Trapping During 126 trap-nights, pitfall traps caught deer mice (Peromyscus maniculatus), shrews (Sorex spp.), and various invertebrates, but only one subadult Larch Mountain salamander, which I released alive. Bob Herrington has observed the Larch Mountai-h-salamander in captivity and thinks that it may be what I would call a 'Isit and wait" predator (Herrington, Washington State University, personal communication). The behavior may result in minimal surface activity, which may explain the poor performance of the pitfalls. Pitfall trapping during the breeding season might be more successful. Setting pitfalls deeper in the talus might also increase trap success. Traps have at least three substantial advantages, if they can be made to work: (1) salamanders could be detected at remote sites without an investigator being physically present during periods of surface activity; (2) more sites could be sampled in a given period of time than by manual searching; and (3) traps result in less habitat disturbance than manual searching. Development of a successful trapping technique for the Larch Mountain salamander should be pursued. -3- Table 1. Sites in Oregon where Larch Mountain salamanders (Plethodon larselli) occur. SITE NUMBER SITE DESCRIPTION SOURCE 1. "Hood River, Oregon" [probably Macgregor and Sherman should be construed to mean Hood (1979) River County] Hood River County Mizuno and Macgregor (1974) 2. Mitchell Point, northwest slope, Kirk (this study) SE 1/4 of NW 1/4 of sec 31, T3N, RIDE, W.M., Hood River County, Oregon; 121' 36' 53" W., 45' 42' 07" N. Mitchell Point, east slope, south of Kirk (this study) rock slide, NW 1/4 of SE 1/4 of sec 31, T3N, RIDE, W.M., Hood River County, Oregon; 45' 42' 01" N, 1210 36' 43" W. Mitchell Point, west slope,