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
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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, NW 1/4 of Kirk (this study) NW SE - 1/4 of 1/4 of sec 31, T3N, RIOE, W.M., Hood River County, Oregon; 450 42- DO" N, 121- 36- 55" W.
3. "Starvation Falls" Brodie (1970)
"at Starvation Falls" Burns (1962)
Starvation Creek vicinity, Holmes (1969) sec 3-4, TIN, R9E.
"Starvation Falls" Howard et al. (1983) Near abandoned portion of old Kirk (this and earlier Columbia River Scenic Highway studies) east of Starvation Creek Wayside, SE 1/4 of NE 1/4 of NE 1/4 of sec 4, T2N, R9E, W.M., Hood River County, Oregon; 450 41' 21" N, 121' 41' 14" W.
4. Approx. 1.5 miles east of Viento Holmes (1969) Creek, sec 36, T3N, R9E, W.M.
5. Viento Creek vicinity, sec 34-35, Holmes (1969) T3N, R9E, W.M.
6. Cabin Creek and Warren Creek Holmes (1969) vicinities sec 4, T2N, R9E, W.M.
-4- Table I (continued)
SITE NUMBER SITE DESCRIPTION SOURCE
7. 0.5 miles south of Wyeth Burns (1962)
Wyeth Highton (1962)
8. Near powerline east of abandoned Kirk (this study) quarry south of Herman Creek Rd., NE 1/4 of NE 1/4 of sec 3, T2N, R8E, W.M., Hood River County, Oregon; 45- 41" 22" M, 121- 48' OO` W.
Near abandoned quarry south of Kirk (this and prior Herman Creek Rd., E 1/2 of NW 1/4 studies) of NE 1/4 of sec 3, T2N, R8E, W.M., Hood River County, Oregon; 45- 41' 23" N, 121- 48- 13" W.
Talus slope southwest of abandoned Kirk (this study) quarry south of Herman Creek Rd., NW 1/4 SW 1/4 of ME 1/4 of sec 3, T2N, R8E, W.M., Hood River County, Oregon; 45' 41' 23" N, 121' 48' 13" W.
9. 1.5 miles N, 2.5 miles E Cascade Locks Brodie (1970)
10. Near new trail from Eagle Creek Trail Ostrand (1982) head to restrooms, NW 1/4 of SW 1/4 of sec 23, T2N, R7E, W.M.
II. About 1 mile along Tanner Creek Trail Ostrand (1982) "in" from powerline road, NW 1/4 of SW 1/4 of sec 27, T2N, VE, W.M.
12. "Ainsworth State Park along the old Burns (1962) Col umbi a Ri ver Hi ghway"
"Ainsworth State Park" Brodie (1970) "at Ainsworth State Park" Altig and Brodie (1971)
Western-most turnout on Scenic Kirk (this and prior Highway at Ainsworth State Park, studies) NW 1/4 of SE 1/4 of SW 1/4 of sec 3, TIM, R6E, W.M., Multnomah County, Oregon; 45' 35' 34" N, 121' 03' 27" W.
-5- Table 1 (continued)
SITE NUMBER SITE DESCRIPTION SOURCE
13. Horsetail Falls Howard et al. (1983) 14. Oneonta Gorge Brodie (1970)
"the vicinity of Oneonta Gorge" Altig and Brodie (1971) 15. West edge of rock slide 0.6 miles Kirk (prior studies) via Scenic Highway east of Multnomah Falls, SE 1/4 of sec 7, TIN, R6E, W.M., Multnomah County, Oregon.
16. "north slope of Larch Mountain, Burns (1954) three miles from summit, on Multnomah Falls Trail, Multnomah County, Oregon" [TYPE LOCALITY]
17. "150 feet below the summit of Larch Burns (1962) Mt. on Multnomah Falls Trail" 18. Wahkeena Falls Highton (1962) Wahkeena Creek vicinity, sec 18, Holmes (1969) TIN, R6E, W.M.
Rocky soil below Scenic Highway at Ostrand (1982) "Wahkeena Falls project"
19. 0.4 mi. west of Wahkeena Falls at Burns (1962) base of a basalt talus slope near U.S. Highway 30.
Talus slope at turnout 0.35 mi. via Kirk (prior studies) Scenic Hwy. west of Wahkeena Falls bridge, MW 1/4 of NE 1/4 of sec 13, TIN, R5E, W.M., Multnomah County, Oregon; 450 34' 30" N., 1220 07' 54" W.
20. Verbal report to Burns from "vicinity Burns (1964) of Three Links [sic] School on the Clackamas River, Clackamas County, Oregon."
Fthis report must be considered suspect; a number of herpetologists have searched in this area for P. larselli without success]
-6- 122-115- 122-1 CO. 121-1 45' 121,1 OREGON SIDE OF THE 30, COLUMBIA GORGE 8 VICINITY
45' 45' ICE SE SE E
Site. here P. 1-aLsolli ha. been observed by other, 3N
Sites here P. j_ar-elli has been observed by J. Kirk 7E
(D Sites of apparently ble P. i.rseiii 2N habitat se.rched by J.,it.Kirk finding P. i-L--elii BE
5E
4E IN
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Figure 1. Distribution of the Larch Mountain salamander (Plethodon larselli) in Oregon. Table 2. Sites in Oregon searched for Larch Mountain salamanders (Plethodon larselli) by J. Kirk.
SITE NUMBER SITE DESCRIPTION DATE SPECIES
1. Talus near downstream end of 10/23/82 no plethodontids railroad tunnel, NE 1/4 of sec 4, T2N, R11E, W.M., Hood River County, Oregon.
2. Talus slope south of I84 and east 10/23/82 no plethodontids of pond, NW 1/4 of sec 32, T3N, R11E, W.M., Hood River County, Oregon.
3. Talus slope south of I84, SE 1/4 02/12/83 no plethodontids of SW 1/4 of sec 33, T3N, RIIE, W.M., Hood River County, Oregon; 45- 41' 42" N, 121- 27- 10" W.
4. Talus slope south of I84 at east 03/13/83 no plethodontids end of pond, E 1/2 of SW 1/4 of SW 1/4 of sec 33, T3N, R11E, W.M., Hood River County, Oregon; 45' 41- 43" N, 121- 27- 22" W.
5. Talus slope south of I84 at mile 11/20/82 no plethodontids post 66.3, about 0.3 mile east of Koberg Beach Rest Area, sec 32, T3N, R11E, W.M., Hood River County, Oregon.
6. Slope south of I84 near Meno, 02/12/83 B. wrighti SW 1/4 of NE i/4 of sec 32, T3N, RIDE, W.M., Hood River County, Oregon; 45' 42' 06" N, 121' 35' 35" W.
7. East slope of Mitchell Point south 03/13/83 P. larselli of rock slide, NW 1/4 of SE 1/4 of -ff. @W-ri-ghti sec 31, T3N, RIDE, W.M., Hood River County, Oregon; 45' 42' 01" N, 1210 36' 43" W.
8. West slope of Mitchell Point, 03/13/83 P. larselli NW 1/4 of NW 1/4 of SE 1/4 of sec 31, 173N, RIDE, W.M., Hood River County, Oregon; 45' 42' 00" N, 121- 36' 55" W.
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(panULZU03) -Z aLqVi Table 2. (continued)
SITE NUMBER SITE DESCRIPTION DATE SPECIES
20. Talus slope at Camp Creek near 01/22/83 no plethodontids Herman Creek Trail, ME 1/4 of NE 1/4 of SW 1/4 of SW 1/4 of sec 10, T2N, R8E, W.M., Hood River County, Oregon; 45' 40' 05" N, 121' 48' 49' W.
21. Talus slope north of unnamed creek 01/22/83 no plethodontids near Herman Creek Trail, NE 1/4 of [warrants further NE 1/4 of SE 1/4 of sec 9, T2N, R8E, search] W.M., Hood River County, Oregon.
22. Talus slope west of Munra Point, 03/27/83 P. dunni SE 1/4 of sec 29, T2N, R7E, W.M., Multnomah County, Oregon; 450 37' 22" N, 121' 58' 12" W.
23. Western-most turnout on Scenic 11/12/66 P. larselli Highway at Ainsworth State Park, T. _cTu-nni NW 1/4 of SE 1/4 of SW 1/4 of T. '67s-chscholtzi sec 3, TIN, R6E, W.M., Multnomah County, Oregon; 45' 35' 34" N,; 04/16/72 P. larselli 1220 03' 27" W. 7. -Ju-nni T. iFa-crodactyl um
06/12/72 P. larselli 7. -du-in n 11/18/72 P. larselli T. _Tu@1n n
03/16/75 P. larselli 10/23/82 P. larselli 02/20/83 P. larselli 02/26/83 P. larselli 7. Tu @in n
03/27/83 P. larselli
24. Plateau near Multnomah Creek, 09/19/82 no plethodontids sec 17, TIN, R6E, W.M., Multnomah County, Oregon. -zi-
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(panULZU03) -3 @LqL)i Table 2. (continued)
SITE NUMBER SITE DESCRIPTION DATE SPECIES
31. South-facing talus slope south 04/03/83 P. dunni of Angel's Rest, S 112 of _E Tr@ighti SE 1/4 of SE 1/4 of sec 14, T1N, r. Ts-chscholtzi R5E, W.M., Multnomah County, Oregon; 45' 33' 44" N, 122' 08' 511, W.
32. Talus on right bank of Coopey 04/03/83 P. dunni Falls Creek near Angel's Rest Trail, NW 1/4 of NW 1/4 of NE 1/4 of sec 23, TIN, R5E, W.M., Multnomah County, Oregon; 45- 31- 40" N, 122- 09- 17" W.
33. Gully of small creek 0.1 mile 11/23/74 P. dunni west of Shepperds Dell bridge, 'ff. '51-ympicus NW 1/4 of sec 28, TIN, R5E, W.M., Multnomah County, Oregon.
34. Near top of Columbia Gorge on 02/26/83 P..dunni abandoned dirt road south of I84 and west of Vista House, SW 1/4 of sec 25, T1N, R4E, W.M., Multnomah County, Oregon.
35. Slope south of I84, west of 02/26/83 P. dunni Rooster Rock, east of railroad -9. -Wr'lghti tunnel, SE 1/4 of sec 26, TIN, R4E, W.M., Multnomah County, Oregon; 45- 32- 25" N, 122- 16' 09" W.
36. Slope south of I84 near east 02/26/83 P. dunni entrance to railroad tunnel, SE 1/4 of ME 1/4 of sec 26, TIN, R4E, W.M., Multnomah County, Oregon; 45' 32' 29" N, 122' 16' 22" W.
37. North-facing slope north of 11/22/74 no plethodontids Broughton Bluff, east of Lewis and Clark State Park, NE 1/4 of sec 25, TIN, R3E, W.M., Multnomah County, Oregon.
38. Timber sale area near Falls Creek 03/30/83 no plethodontids in Bull Run Reservation, SE 1/4 of sec 33, T1N, R7E, W.M., Multnomah County, Oregon.
-13- Table 2. (continued)
SITE NUMBER SITE DESCRIPTION DATE SPECIES
39. Timber sale areas near Falls 03/30/83 no plethodontids Creek, Bull Run Reservation, E 1/2 of sec 33, TIN, R7E, W.M., Multnomah County, Oregon.
40. Just east of junction of Rd. 1015 03/30/83 P..dunni and Bull Run River Rd., Bull Run Reservation, SW 1/4 of NE 1/4 of sec 4, T1S, R7E, W.M., Multnomah County, Oregon.
41. Talus slope on right bank of 03/30/83 E..eschscholtzi Falls Creek, Bull Run Reservation, NW 1/4 of sec 33, T1N, VE, W.M., Multnomah County, Oregon.
42. About 500 feet above north bank 02/26/66 B. wrighti of Three Lynx Creek, about 0.3 mile Tneides ferreus northeast of Three Lynx, SW 1/4 of sec 15 and E 1/2 of SE 1/4 of 10/13/68 P. dunni sec 16, T5S R6E, W.M., Clackamas F Ore;on. 'K: wrighti County, Terreus E. eschscholtzi
43. Talus on right bank of Salmon 04/09/83 P. dunni River, sec 22, T3S, VE, W.M., Clackamas County, Oregon;
44. Near abandoned quarry, NW 1/4 of 04/09/83 P. dunni sec 34, TH, VE, W.M., -i@riahti Clackamas County, Oregon. r. @7sChSCholtzi
45. Rocky rubble near Clackamas 04/09/83 B. wrighti County quarry north of county road, SW 1/4 of sec 24, T2S, R6E, W.M., Clackamas County, Oregon.
-14- Other Plethodontids
Searches for the Larch Mountain salamander usually revealed other plethodontids as well. Locality data for other species found during the course of this study are summarized in Table 2.
The distribution of the Oregon slender salamander (Batrachoseps wrighti) is of particular interest because it, like the Larch Mountain salamander, is protected under Oregon law. The known range of the Oregon slender salamander is considerably broader than that of the Larch Mountain salamander, but its distribution in the Columbia Gorge is not particularly well known. Figure 2 shows sites where I have found the Oregon slender salamander.
Rainfall
Information on accumulated rainfall provided by the Monthly Summary were supplemented by measurements taken at irregular intervals during the course of my field work. The results appear in Table 3 and are presented for comparative purposes in Figure 3, expressed as percentages of rainfall at the Ainsworth site.
Figure 3 shows that rainfall increases gradually through the Gorge from west to east, is heaviest in the vicinity of Ainsworth to Wyeth, and declines again farther east. A similar pattern is revealed by examination of total and mean annual rainfall data for the Monthly Summary stations.
The implications of rainfall on the range of the Larch Mountain salamander are included in the Discussion section under "Distributional Limits." 122-115- 122-1 00'. 121-1 45' 121-1,30' OREGON SIDE OF THE COLUMBIA GORGE a VICINITY
450 45'
IDE SE 9E 11 E
3N
B. h@@ Sit.s XLjShj hY h... b@.. obs.r@ed J. Kirk
TE
2N
BE
5E
E -T-
/Lb-
45 3c
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Figure 2. Distribution of the Oregon slender salamander (Batrachoseps wrighti) in the Columbia River Gorge. Table 3. Rainfall in the Columbia Gorge. These values, expressed in centimeters, were used to calculate the statistics presented in Figure 4. They are actually reliable to only 0.2 centimeter.
Hrmn Prtlnda Rstr Crk Hood The A. P. Trtdla Rock Answrth Bnnvlla Rd Viento Rivera Dallesa
03-10 Oct 82 1.8 1.8 2.7 5.5 5.5 5.6 3.2 2.1 0.7
10-23 Oct 82 3.3 2.5 2.8 5.0 5.7 5.2 4.0 2.5 1.1
23 Oct-14 Nov 82 7.8 2.7 13.4 19.1 8.6 17.9 13.2 12.0 4.7
14-20 Nov 82 3.9 4.2 5.6 8.6 7.5 9.1 7.4 3.9 1.9
20 Nov-18 Dec 82 19.0 19.9 25.5 34.5b 31.5 32.1 23.1 13.0 1.8
18 Dec 82-22 Jan 83 16.5 20.5 27.2 34.5b 38.9 34.5b 29.5 18.9 11.8
22-29 Jan 83 4.1 4.6 4.7 7.7 6.7 9.0 5.0 2.6 1.6
29 Jan-12 Feb 83 7.8 7.8 10.2 14.1 12.8 12.0 10.0 6.4 4.4
12-20 Feb 83 6.8 7.1 8.7 12.9 13.4 16.1 13.3 8.5 4.6
20-26 Feb 83 5.2 7.5 6.6 8.4 7.0 6.3 4.3 3.4 1.5
26 Feb-13 Mar 83 10.5 9.2 11.7 15.0 10.2 13.8 10.1 5.6 5.2
13-27 Mar 83 1.3 2.4 4.4 6.6 2.0 4.4 2.4 1.9 0.4
27 Mar-3 Apr 83 6.5 7.0 10.8 13.4 5.5 15.4 11.3 7.5 3.9
03-16 Apr 83 1.8 4.0 3.7 3.4 2.8 2.7 0.8 1.3 0.0
16 Apr-8 May 83 3.7 6.4 6.9 6.2 6.8 5.8 2.6 1.1 1.4
TOTALS 100.0 107.6 144.9 194.9 164.9 189.9 140.2 90.7 45.0
From Monthly Summary of Climatological Data for Oregon- see METHODS. Rain gauge overflowed; 34.5 cm is maximum capacity of the gauge. to periods of predicted surface activity. Pesticide applications and short-term surface disturbances could also be scheduled during periods when the salamander would not be active near the surface.
Distributional Limits
Eastern Limit
No plethodontids were found during four trips to sites of apparently suitable plethodontid habitat east of Hood River. Habitat and moisture conditions seemed ideal for the Larch Mountain salamander at several sites. Herrington has found the species considerably east of Hood River on the Washington side of the Columbia River (personal communication). Further searches east of Hood River on the Oregon side are warranted.
Holmes (1969) speculated that moisture may limit the distribution of the Larch Mountain salamander at the eastern and western extremes of its range. Herrington's discovery of the species in Washington well east of Hood River and an inspection of rainfall data (Table 3, Figure 3) suggest, however, that moisture is not a factor that would exclude the Larch Mountain salamander from the area east of Hood River in Oregon. I would expect the north-facing talus slopes of the Oregon side of the Columbia Gorge to retain moisture near the surface longer than the south-facing slopes on the Washington side. Assuming that rainfall is approximately the same on both sides of the Gorge at any given point, and assuming that moisture is the limiting factor, I would expect the species to occur farther east on the Oregon side than on the Washington side.
The Larch Mountain salamander's apparent absence from the Oregon side of the Columbia Gorge east of Hood River, may be due to a barrier imposed by the Hood River and its alluvial deposits. My failure to find any plethodontids east of Hood River suggests that the lower river and valley may be an effective barrier to all plethodontids. Richard Forbes has found the Oregon slender salamander (B. wrighti) east of the Hood River, but considerably south
-22- of the Columbia Gorge (Forbes, Portland State University, personal communication). The Oregon slender salamander presumably either made its way across the Hood River along its upper reaches or came around the south side of Mt. Hood.
Western Limit
A number of sites were searched west of the western limit of the Larch Mountain salamander's known range, and three species of plethodontids other than the Larch Mountain salamander were found (Table 2). Rainfall west of the western limit of the Larch Mountain salamander's range equals or exceeds that near the eastern limit of its range (Table 3, Figure 3). Moisture, therefore, is not likely to be a limiting factor to the west.
My subjective impression is that habitat west of the Larch Mountain salamander's known range is not optimal. Talus slopes are less common and less extensive. Fine mineral soil is a more common constituent of talus slopes in this area, and the small-sized, angular talus seemingly preferred by the species is uncommon or absent.
Limiting factors at the western extreme of the Larch Mountain salamander's range might include habitat quality and distribution, and possibly competition with Dunn's salamander (P. dunni).
Southern Limit
Virtually nothing is known regarding the southern limit of the Larch Mountain salamander's distribution. A number of people, myself included, have searched in the vicinity of Three Lynx in Clackamas County, Oregon, in the hope of verifying the report of the Larch Mountain salamander mentioned by Burns (1964). My recollection of Doug Burns' description of that report (personal communication in the early 1960's) is that it was a sighting by students at Oregon State University. Their description of a reddish belly led Burns to suspect the Larch Mountain salamander.
-23- Much of the area south of the Columbia Gorge is inaccessible by road. I searched the Bull Run Reservation on a limited basis, but did not uncover the Larch Mountain salamander. Plenty of talus slopes occur in the area, and more extensive and intensive searching is warranted. Many of the talus slopes on the Reservation appear to be accessible only on foot over rough terrain.
Some talus slopes between the Columbia River and the Bull Run and Hood River drainages can be approached by trail and should be searched. One problem in hiking to potential sites is the relatively high proportion of time spent in the transit and the need to revisit apparently suitable sites that do not yield the Larch Mountain salamander initially. Herrington searched repeatedly at several sites in Washington before he found the species (personal communication). I have often searched under apparently suitable temperature and moisture conditions at sites where the salamander occurs without finding a single individual. Thus, an adequate search of a particular site that can be reached only on foot, may require three or four separate, full-day trips under suitable weather conditions. Full knowledge of the southern limits of the Larch Mountain salamander's distribution is likely to accrue slowly at best.
Environmental Hazards
I did not set out to examine environmental hazards to the Larch Mountain salamander, but several casual observations merit reporting. Those observa- tions should not be used in making management decisions without verification.
Dense populations of the Larch Mountain salamander apparently will tolerate fairly intense collecting without being depleted. The sites shown in Figures 4 and 5 were heavily collected by amateur herpetologists during the early 1960's, but continued to yield salamanders. Population densities remain relatively high at these sites.
-24- The Larch Mountain salamander occurs in fair numbers on at least one transmission line corridor that has been treated with herbicide.
Unstable talus slopes may be a significant hazard for the species. Sites 2 (east slope) and 15 in Table 1 are immediately adjacent to active rock slides that apparently originated as a result of instability induced by quarrying activity at the bases of talus slopes. The slide area probably supported Larch Mountain salamanders before destabilization. A third slide adjacent to Larch Mountain salamander habitat may be the one just west of the Starvation Falls Rest Area. The slide on the east slope of Mitchell Point is particulary impressive because the quarry operations at the base apparently caused destabilization that now extends nearly to the summit 800 ft above. The Mitchell Point slide and adjacent Larch Mountain salamander habitat are shown in Figure 6.
RECOMMENDATIONS
The following recommendations are made to help direct future research and management activities for the Larch Mountain salamander in Oregon.
1. Searches in areas of suitable h@abitat should be continued, particularly to the south, to better delineate the distribution of the Larch Mountain salamander.
2. Research should be conducted into behavioral responses of the Larch Mountain salamander to changes in subsurface microclimatological conditions and the need for food.
3. Population densities, distribution, and composition should be monitored before, during, and after habitat disturbances when those disturbances can be anticipated.
4. Population composition and density should be monitored at several sites over a period of years to provide baseline data for evaluating the impact of habitat disturbances on the Larch Mountain salamander.
-25- Macgregor, H. and S. Sherwood. 1979. The nucleolus organizers of Plethodon and Aneides located by in situ nucleic acid hybridization with-It-n-OP-6s H-ribosomal RNA. Chromosoma 72(3):271-280.
Mizuno, S. and H. Macgregor. 1974. Chromosomes, DNA sequences, and evolution in salamanders of the genus Plethodon. Chromosoma 48(3):239-296.
National Oceanic and Atmospheric Administration (NOAA). 1982. Monthly summary of climatological data, Oregon. October-December 1982.
National Oceanic and Atmospheric Administration (NOAA). 1983. Monthly summary of climatological data, Oregon. January-May 1983.
Ostrand, W. 1982. Handwritten note on file at Columbia Gorge Ranger District, Mt. Hood Nat'l. Forest. U.S. Forest Service. 1 p.
-28- Appendix A: Bibliography of Plethodon larsellil
Altig, R. and E.D. Brodie, Jr. 1971. Foods of Plethodon larselli, Plethodon dunni and Ensatina eschscholtzi in the ColumbiaRiver Gorge, Mu Tt---m-ano 7 To-unty, Oregon. Amer. UTT.-Nat. 85:226-228.
Brodie, E.D., Jr. 1968. Observations on the mental gland clusters of western salamanders of the genus Plethodon. Herpetologica 24(3):248-250.
Brodie, E.D., Jr. 1970. Western salamanders of the genus Plethodon: Systematics and geographic variation. Herpetologica ?6 F4774-6197-516. Brodie, E.D., Jr. 1977. Salamander antipredator postures. Copeia 1977(3):523-535.
Brodie, E.D., Jr. and R.G. Altig. 1967. Morphological variation of the Jemez Mountains salamander, Plethodon neomexicanus. Copeia 1967(3):670-672.
Brodie, E.D., Jr., J.A. Johnson, and C.K. Dodd, Jr. 1974. Immobility as a defensive behavior in salamanders. Herpetologica 30(l):79-85.
Burns, D.M. 1962. A new subspecies of the salamander Plethodon vandykei. Herpetologica 10:83-87.
Burns, D.M. 1954. The taxonomic status of the salamander Plethodon vandykei larselli. Copeia 1962(l):177-181. Burns, D.M. 1964. Plethodon larselli. Cat. Amer. Amphib. Rept: 13.1.
Contolini, C. and K. Armstrong. (no date). Larch Mountain salamander habitat inventory and management recommendations. Typewritten manuscript, 8 pp., 6 maps. F.USFS Gifford-Pinchot N.F.].
Highton, R. 1962. Revision of the North American salamanders of the genus Plethodon. Bull. Florida State Mus. Biol. Sci. 6:235-367.
Holmes, C.O. 1969. A biological investigation of Plethodon larselli M.S. Thesis. Central Washington State College. vii +7Z p. Howard, J.H. and J.L. Larson. 1980. Habitat preferences of the salamander, Plethodon larselli. Amer. Zool. 20(4):775 (abstract). Howard, J.H. and R.L. Wallace. 1981. Microgeographical variation of electrophoretic loci in populations of Ambystoma macrodactylum columbianum (Caudata: Ambystomatidae). Copeia 1981(2):466-471.
1 This bibliography includes only reports of original research and publications that include new information on P. larselli. It does not include publications that merely summarize pr-(@-e-x-is-t-in-g-knowledge, such as field guides and identification manuals.
-29- Appendix A (continued)
Howard, J.H., R.L. Wallace, and J.H. Larsen, Jr. 1983. Genetic variation and population divergence in the Larch Mountain salamander (Plethodon larselli). Herpetologica 39(l):41-47.
Lotter, F. and N.J. Scott, Jr. 1977. Correlation between climate and distribution of the color morphs of the salamander Plethodon cinereus. Copeia 1977(4):681-690.
Macgregor, H. and S. Sherwood. 1979. The nucleolus organizers of Plethodon and Aneides located by in situ nucleic acid hybridization with-X@enopus 3H-r-iFo-somal RNA. Chromdsoma 72(3):271-280.
Maxson, L.R., R. Highton, and D.B. Wake. 1979. Albumin evolution and its phylogenetic implications in the plethodontid salamander genera Plethodon and Ensatina. Copeia 1979(3):502-508.
Mizuno, S. and H. Macgregor. 1974. Chromosomes, DNA sequences, and evolution in salamanders of the genus Plethodon. Chromosoma 48(3):239-296. Powders, V.N. and W.L. Tietjen. 1974. The comparative food habits of sympatric and allopatric salamanders, Plethodon glutinosus and Plethodon jordani in eastern Tennessee and adjacTnt-areas.--He-r-p-e-toTogica 30 T-2T--1-67-175.
Sever, D.M. 1976. Morphology of the mental hedonic gland clusters of plethodontid salamanders (Amphibia, Urodela, Plethodontidae). Jour. Herpetology 10(3):227-239.
-30-