Plethodon vandykei

A small terrestrial salamander. Stocky with relatively long legs, adults range in size from 4.5 to 5.8 cm snout to vent length (9.5-10.5 cm total length). Modal number of costal grooves is 14. Males are slightly smaller than females and have a mental gland, a raised area on the chin used in courthip. There are indistinct paratoid glands on the back of the head, and the feet are broad and slightly webbed (Brodie and Storm 1970; Petranka 1998). Hatchlings are 15-18 mm snout to vent length (Nussbaum et al. 1983).Three color morphs occur and populations often have 2 or, rarely, all 3. The dark phase is dark brown to black dorsally with a yellow,orange, green, or red stripe that extends to the tip of the tail. The venter is dark and the throat is yellow. The yellow morph has a tan or yellowish ground color dorsally and ventrally, and the rosemorph is similar with a pinkish to salmon coloration over the body (Brodie 1970; Nussbaum et al. 1983).

Plethodon idahoensis was formerly included within P. vandykei, sometimes treated as a subspecies, but mitochondrial data reveal deep divergence between the two (Carstens et al. 2004). Genetic work throughout the range of these forms has supported suggestions that populations in the Rocky Mountains be regarded as a separate species from populations in western Washington (Highton and Larson 1979; Collins 1991; Howard et al. 1993).

This species has a patchy distribution in western Washington with populations in the Willapa Hills, the Olympic peninsula and Mt. St. Helens/Mt. Rainier in the Cascade range. Preferred habitats are conifer forests with average annual rainfall >150 cm. The most aquatic species of Plethodon, animals are frequently found in seepages and splash zones of waterfalls and in rocky areas along streams (Brodie 1970). Populations may also be associated with talus, and away from streams individuals can be found under an assortment of cover objects (Nussbaum et al. 1983; Petranka 1998).

This species can be found in Willapa Hills, and Olympic and Cascade mountains, Washington, USA; disjunctive centres in the Willapa Hills, on the Olympic Peninsula, and in the southern Cascade Ranges are separated by glacial and alluvial deposits that might limit the regional distribution (Wilson et al. 1995). Coexists with Dunn salamander southeast of South Bend, Pacific County, Washington (Stebbins 1985). It generally occurs in small isolated populations.

endemic to a single state or province

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (5000-200,000 square km (about 2000-80,000 square miles)) Willapa Hills, and Olympic and Cascade mountains, Washington; disjunct centers in the Willapa Hills, on the Olympic Peninsula, and in the southern Cascade Ranges are separated by glacial and alluvial deposits that may limit the regional distribution (Wilson et al. 1995). Generally occurs in small isolated populations.

Length: 12 cm

Habitat and Ecology

Systems

• Terrestrial

Comments: Van Dyke's Salamander is primarily associated with streams and seeps (Leonard et al. 1993, Wilson et al. 1995), but also occurs in upland forest (Slater 1933), talus (especially well-shaded, north-facing slopes) (Herrington 1988), lake shores (C. Crisafulli, personal communication) and cave entrances (Aubry et al. 1987). It can be found under bark, in and under logs, and in leaf litter in wet weather. The species is often most abundant in old forest stands that have complex stand structure and moderate to high levels of woody debris and colluvial rock present (Hallock and McAllister 2002).

Few clutches have been found. One nest was under a moss covered stone; eggs were in the usual grape-like cluster and attached to the stone by a single gelatinous thread, as in other Plethodon (Nussbaum et al. 1983). Another clutch was in a moist, partially rotted log along a stream in old-growth forest (western red-cedar/Douglas-fir/western hemlock/grand fir) in Washington (Jones, 1989, Herp. Rev. 20:48). Large decaying conifer logs near streams appear to be important habitat for nests (Blessing et al. 1999, Hallock and McAllister 2002).

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 81 - 300

Comments: Approximately 96 occurrences have been documented since 1982 (Washington Department of Fish and Wildlife reptile and amphibian database, Olympia, WA. Retrieved October 2002).

In the Cascades, the Washington Herp Atlas (Hallock and McAllister 2002) mapped approximately 28 sites for years prior to 1979 and only about 8 sites for 1979-2001 (map symbols difficult to count).

2500 - 100,000 individuals

Comments: Total adult population size is unknown but likely exceeds several thousand. Generally uncommon.

Sympatric with P. DUNNI and P. VEHICULUM in some areas.

Comments: Most surface activity takes place in the spring after snowmelt and before summer drought and in the fall after the onset of fall rains and before temperatures approach freezing (Hallock and McAllister 2002).

Terrestrial breeder. Nests found on the Olympic Peninsula (elevations below 700 meters) were laid in early May; development was completed by early October (Hallock and McAllister 2002). Females brood and guard the eggs during development.

Year Assessed

Assessor/s

Reviewer/s

Contributor/s

Justification

United States

Rounded National Status Rank: N3 - Vulnerable

Rounded Global Status Rank: G3 - Vulnerable

Reasons: About 96 isolated populations occur in three regions in Washington; less than 25% of occurrences have high viability; not very threatened, though industrial forestry could be detrimental by degrading required habitat conditions.

Intrinsic Vulnerability: Moderately vulnerable

Comments: Low reproductive rate.

Environmental Specificity: Narrow. Specialist or community with key requirements common.

Comments: Habitat affinities are poorly understood. Although usually associated with streams and seeps, it has been found in a variety of habitats (Leonard et al. 1993). This would suggest a generalist. However, its distribution is spotty across its range and it does not occur in many areas that appear to have suitable habitat (Wilson et al. 1995). This suggests that the species may have narrow ecological tolerances (Wilson et al. 1995).

Like other members of the genus Plethodon, P. vandykei is completely terrestrial through all stages of its life history; courtship, mating, and egg deposition occur on land. There is no free living larval stage, and juveniles hatch completely metamorphosed (Stebbins 1985; Petranka 1998). Courtship behavior has not been described in detail for this species, butis probably similar to the closely related species P. idahoensis. Fertilization occurs by means of a spermatophore deposited on the substrate by the male and picked up in the cloaca by the female (Lynch and Wallace 1987). Courtship occurs in spring and perhaps fall. Oviposition takes place in the spring. Females attend the eggs until hatching in the fall (Nussbaum et al. 1983; Jones 1989). Clutch size ranges from 7-14 (Stebbins 1951; Jones 1989). Eggs are cream-colored and measure about 4-5 mm in diameter (Blessing et al. 1999). Each clutch is suspended by one or two gelatinous threads attached to the walls of the cavity (Blessing et al. 1999).

Only six nests of Van Dyke's salamanders have been discovered. The first was described as a "grape-like cluster" attached by a common pedicel to a moss-covered stone in a damp location (Noble 1925) and the second was located inside a partially rotted log (85 cm in diameter and 5 m in length) in an old-growth forest on a north-northeast facing slope, near a small headwater stream (Jones 1989). Four additional nests were found in logs near undisturbed or protected streams during the summer of 1997, in the Olympic Peninsula (Blessing et al. 1999). Three of those four nests were located in old-growth forest (western hemlock and Pacific silver fir), while one was located inside a buffer of old trees in a clear-cut area. The four clutches were all found in cavities in sapwood, 6.5-7.0 cm below the surface of large decaying moss-covered conifer logs, and were each attended by an adult salamander (likely female). Clutches were left in the logs and took 144 days of observation to hatch, a much longer period than reported for other species of Plethodon (generally about 45-90 days, according to Petranka 1998).

Not much is known about the natural history of this species. Adults are most active in the spring and fall months, but individuals are not commonly encountered (Petranka 1998).

Population

Population Trend

Global Short Term Trend: Relatively stable (=10% change)

Comments: Stable to slight decline over past 20 years (J. Flackenstein, pers. comm., 1997).

Global Long Term Trend: Decline of 30-50%

Comments: Populations have probably declined in the last 200 years (Wilson et al. 1995).

Degree of Threat: High - medium

Comments: The species is relatively sedentary, with narrow ecological tolerance that limit its ability to survive in or colonize disturbed habitats. Approximately 60% of the occurrences are in areas where timber has been harvested within 1 kilometer of the element observation and where additional harvests are probable. Although no definitive studies have been published to document losses from specific threats, timber harvest activities, especially clear-cutting, seem intrinsically detrimental for a species that requires cool temperatures and wet habitats. Clear-cutting has the potential of eliminating populations in areas where woody debris is the primary source of surface shelter and nesting sites (Wilson et al. 1995). The level of impact timber harvest will have on a population is expected to vary, depending on the level of disturbance to the microhabitats and microclimate (Welsh 1990). The Cascade Range populations are also threatened by volcanic activity. However, some populations survived in the blast zone of the 1980 eruption of Mount St. Helens (Zalisko and Sites 1989) (the number of populations lost is unknown).

Patchy distribution and apparently low population densities suggest that this species should receive conservation attention. Populations are at risk from logging and intense management of forests (Welsh 1990; Petranka 1998). This species has limited ability to survive in disturbed habitat (Hammerson 2004). It occurs in two protected areas, Mt. St. Helens National Monument and Olympic National Park (Hammerson 2004).

Major Threats

Conservation Actions

Biological Research Needs: Research is needed on seasonal habitat affinities and the effects of roads and forest practices on the species' habitat and its populations (Hallock and McAllister 2002).

Global Protection: Many (13-40) occurrences appropriately protected and managed

Comments: The habitat condition for most occurrences in the Willapa Hills is degraded, due to timber harvest activities. Habitat condition for occurrences on the Olympic Peninsula and Cascade Mountains varies from degraded (on lands managed for timber) to excellent (in the National Parks). Adequately protected in Mount St. Helens National Monument (6 occurrences), Olympic National Park (11 occurrences), Department of Natural Resources' Natural Areas (3 occurrences) and Long Island National Wildlife Refuge (3 occurrences).

Needs: This species likely will benefit from existing/planned habitat protection for spotted owl (Thomas et al. 1993). It is important to protect riparian zones and leave adequate upland buffers next to them. Large woody debris, in various stages of decay, should be maintained near streams (Hallock and McAllister 2002).