Discovery of Cope's Giant Salamanders (Dicamptodon copei) East of the Oregon Cascade Range crest.
The Coastal Giant Salamander, Dicamptodon tenebrosus, in contrast, is more widespread in the Pacific Northwest (Good 1989). It is known from an isolated population 53 km east of the Cascade Range crest at Oak Creek-Springs in Wasco County (Nussbaum 1976). This is 36 km east of the Boulder Creek locality for D. copei. More recently, we discovered a 2nd site for Dicamptodon in the lower White River. Here, our objectives are to report on the history of this find and attempt to identify the new, isolated population.
Nussbaum (1970) used a defined set of characters to describe D. copei, including body proportions. We follow these definitions but compare only the 3 morphological ratios we believe most useful for identification. Further, Nussbaum (1970, 1976) only measured preserved salamanders [greater than or equal to] 65 mm SVL (snout-vent length) because smaller larvae could not be effectively distinguished based on proportions. We relaxed animals in MS-222 and immediately measured them. Euthanized individuals were preserved in 10% buffered formalin for a week, then washed and transferred to 70% ethyl alcohol for long-term storage. Those kept as vouchers have been deposited at the herpetology collection of Oregon State University and are waiting to be cataloged.
Biologists from the Prineville, Oregon Office of the Bureau of Land Management (BLM) made the initial observations of Dicamptodon in the lower White River area. In August 1991, J Sippel surveyed the White River canyon from the border of the Mt Hood National Forest downstream to the vicinity of Tygh Valley (town), about 25 km straight-line distance. The canyon area is mostly BLM land with surrounding uplands as private holdings or State hunting reserves (many leased from ranches). Near the lower end of the canyon, J Sippel located a spring on the south side of the river 350 m upstream and across from the mouth of Three Mile Creek. Here, he observed a large Dicamptodon moving in a shallow edge of the spring. On 25 October 1991, J Sippel brought R Demmer to the spring to confirm Dicamptodon presence. They found 1 larva, and photographed (Fig. 1) and released it. However, because of its small size (approximately 50 mm SVL) and the possession of an incomplete tail, the identity was ambiguous.
On 24 July 2013, RB Bury and a 3 person team visited this site with permission from Fred Justesen, one of the owners of the ranch. We caught 8 Dicamptodon larvae during a 2-hr search by 3 surveyors. We took tissue vouchers (tail clips) from all animals and released 3 larvae <45 mm SVL. We retained 5 larvae for museum specimens (Field tags RWN 13329-333; Fig. 2). Two were <45 mm SVL and were excluded from morphological comparisons. We measured three: 62.9, 66.1 and 67.5 mm SVL. Their relative body proportions match the descriptions of D. copei (Table 1).
The site is an unnamed spring-fed creek that is about 0.3 m wide, steep (approximately at 45[degrees]), and rocky. It flows to the north down a steep canyon wall and empties into the White River. Riparian vegetation includes Red Alder (Alnus rubra) and Water Birch (Betula occidentalis), which shade most of the creek. The new site is just upstream from where the White River opens up into a wider alluvial plain (Tygh Valley). The river, fed from the Palmer Glacier on Mt Hood, carries substantial glacial till and remains cool to cold year-round. We found larvae at this site from the mouth of the creek upstream for 50 m.
An earlier report (Steele and Storfer 2007) of D. copei was in Boulder Creek, which is 26 km upstream from our new site. Other unpublished observations of Dicamptodon exist in the upper White River and on forested slopes around Mt Hood (Foster and Olson 2014). These observations are all >20 km west or northwest of the locality at Justesen Ranch.
This new site is the southeastern-most record for D. copei and is just 9 km east of the mouth of the White River where it empties into the Deschutes River. The mouth of the White River is only 1.5 km downstream from the isolated population of D. tenebrous at Oak Creek. These 2 Dicamptodon sites are 7.6 km apart (straight line). Elevation is 250 m at the bottom of Oak Creek, which is 60 m lower than the White River site.
All the waters at Oak Creek-Springs are within the grounds of a Fish Hatchery operated by the Oregon Department of Fish and Wildlife. After flowing down the steep hillsides, almost all water is diverted into holding areas for fish. The Justesen Ranch site is a working ranch that also allows recreational activities (hunting and catch-and-release fishing in the White River area). No other apparent developments exist in the canyon (mostly BLM lands) upstream of the ranch lodge because of its steepness and rough lava rock substrate. Private lands on the uplands have flats and plains that are grazed or irrigated fields, with most water flowing from irrigation canals originating at the base of Mt Hood to the west.
Many of the seeps and creeks in this region are sources of water tapped for local irrigation or other uses. Currently, the aquatic habitats appear largely intact. Jones and Welsh (2005) pointed out that the Coastal Giant Salamander seems more resilient than other stream-associated amphibians in the Pacific Northwest and are likely to persist in streams that sustain moderate disturbance. However, special attention may be needed for isolated springs and creeks that feed the lower White and Deschutes Rivers because of a lack of proximate populations to re-colonize sites, if any salamander populations were lost.
Key words: biogeography, Coastal Giant Salamander, Cope's Giant Salamander, Dicamptodon copei, Dicamptodon tenebrosus, Oregon, range extension
Acknowledgments.--We are grateful to F Justesen for permission to visit the new locality, which is on his family ranch. AD Foster and DH Olson, PNW Research Station, provided unpublished records of salamanders in the region. We thank C Baggett, J Bracken, and GW Bury for field assistance.
CORKRAN CC, THOMS C. 1996. Amphibians of Oregon, Washington and British Columbia. Renton, WA: Lone Pine Publishing. 175 p.
FOSTER AD, OLSON DH. 2014. Conservation assessment for the Cope's Giant Salamander (Dicamptodon copei). Version 1.0. USDA Forest Service Region 6 and USDI Bureau of Land Management, Special Status Species Program. 57 p. Available at http://www.fs.fed.us/r6/sfpnw/issssp/species-index/fauna-amphibians.shtml.
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JONES LCC, BURY RB. 2005. Cope's Giant Salamander, Dicamptodon copei. In: Jones LLC, Leonard WP, Olson DH, editors. Amphibians of the Pacific Northwest. Seattle, WA: Seattle Audubon Society, p 46-49.
JONES LCC, WELSH HH Jr. 2005. Dicamptodon tenebrosus (Baird and Girard, 1852(b). Coastal Giant Salamanders. In Lannoo M, editor. Amphibian declines: Conservation status of United States species. Berkeley, CA: University of California Press, p 654-56.
NUSSBAUM RA. 1970. Dicamptodon copei, n. sp., from the Pacific Northwest, USA (Amphibia: Caudata: Ambystomatidae). Copeia 1970:506-514.
NUSSBAUM RA 1976. Geographic variation and systematics of salamanders of the genus Dicamptodon Strauch (Ambystomatidae). Ann Arbor, MI: Miscellaneous Publications of the Museum of Zoology, Number 149, University of Michigan, Museum of Zoology.
NUSSBAUM RA, BRODIE ED JR, STORM RM. 1983. Amphibians and reptiles of the Pacific Northwest. Moscow, ID: University Press of Idaho. 322 p.
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1410 NW 12th Street, Corvallis, OR 97330; clemmys@ gmail.com [RBB]; Bureau of Land Management, 3050 NE 3rd Street, Prineville, OR 97754 [RD, JS]; current address, 301 Dinosaur Trail, Santa Fe, NM 87502 [JS], Submitted 12 October 2013, accepted 15 May 2014. Corresponding Editor: Ryan O'Donnell.
TABLE 1. Comparison of selected body ratios of Dicamptodon (n = 3; RWN 13329-331) from the lower White River, Wasco County, Oregon. All preserved specimens. Abbreviations: SVL = Snout-vent length (from anterior angle of vent); Body length = SVL minus Head length. Nussbaum Nussbaum (1970) D. (1976) D. Ratio White River copei tenebrosus Head width / SVL 0.18-0.20 0.18-0.21 0.21-0.22 Head length / Body length 0.36-0.40 0.39-0.49 0.46-0.55 Maximum tail height / SVL 0.12-0.16 0.13-0.23 0.21-0.27
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|Title Annotation:||General Notes|
|Author:||Bury, R. Bruce; Demmer, Rick; Sippel, James|
|Publication:||Northwestern Naturalist: A Journal of Vertebrate Biology|
|Date:||Sep 22, 2014|
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