Plethodon dunni Bishop 1934

A moderately sized, completely terrestrial salamander. The ground color is dark brown or black. A distinct broad yellowish to olive green dorsal stripe runs from the head to the tail, but does not reach the tip of the tail. Light spots occur on the sides. The belly is usually slate gray with white or yellowish flecks (Storm and Brodie 1970; Nussbaum et al. 1983; Petranka 1998). Occasional individuals and some populations are melanistic (black) (Stebbins 1985; Petranka 1998). Modal number of costal grooves is 15 (Petranka 1998). Adults measure from 5 up to 7.5 cm snout to vent length (10 - 15.5 cm total length), (Storm and Brodie 1970; Petranka 1998). Males have a relatively longer tail than females and also possess a mental gland, a raised region on the chin used in courtship (Storm and Brodie 1970; Petranka 1998). Juveniles are 13-16 mm SVL and have a brighter dorsal stripe with sharper edges (Storm and Brodie 1970; Petranka 1998). Plethodon dunni sometimes co-occurs with the similar P. vehiculum. These species can be distinguished using the stripe that extends all the way to the tail tip in P. vehiculum, but does not reach the tip in P. dunni.(Stebbins 1985).Melanistic populations in the area of Mary's Peak, Oregon, were described as a distinct species, P. gordoni (Brodie 1970). These populations are not genetically distinct from nearby P. dunni (Feder et al. 1978), and currently these are treated as P. dunni (e.g. Stebbins 1985; Leonard et al. 1993; Petranka 1998). See another account at californiaherps.com (http://www.californiaherps.com/salamanders/pages/p.dunni.html).

Plethodon dunni ranges from the Willapa Hills area in extreme southwestern Washington, south through the coast ranges and western slopes of the Cascade Mtns in Oregon, and into extreme northeastern coastal California (Del Norte, Co.) (Storm and Brodie 1970; Leonard et al. 1993). Among the western species of Plethodon, P. dunni inhabits some of the most mesic environments (Stebbins 1985), frequently semi-aquatic (Petranka 1998). In the rocky forest habitats preferred by this species, individuals may be found near seepages, streams, water falls, and other areas with rocky substrates (Nussbaum et al. 1983; Petranka 1998). At these sites animals will frequently be found in the splash zone or stream bank under rocks (Leonard et al. 1993). Populations also occur in moist talus slopes (Brodie 1970; Nussbaum et al. 1983; Leonard et al. 1993; Petranka 1998).

Like other members of the genus Plethodon, P. dunni 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). Females evaluate potential mates using both chemical cues and body size of the male (Marco et al. 1998). Courtship behavior has not been described, but general facts are known based on closely related species. Fertilization occurs by means of a spermatophore deposited on the substrate by the male and picked up in the cloaca by the female (Duellman and Trueb 1986). Mating may occur from October through April and eggs are laid in spring. The females attend the nest until hatching in the early fall (Dumas 1955; Petranka 1998). Clutch size ranges from 4 - 18 eggs, average 9.4 (Nussbaum et al. 1983; Petranka 1998). Seasonal activity depends on local climate. In warmer, coastal areas, Dunn's salamanders may be active year-round as long as the habitat remains moist (Nussbaum et al 1983). Animals are active primarily at night, when humidity is high, and retreat under cover objects during the day (Stebbins 1985). Surface activity is restricted in areas with cold winters or summer droughts (Petranka 1998). Diet consists of a large variety of small, terrestrial invertebrates including mites, annelids, isopods, millipedes, coleopterans, and dipterans (Altig and Brodie 1971; Petranka 1998). Adults occasionally eat juveniles (Riesecrer et al. 1996). Predators of P. dunni include Steller's Jay, and northwestern garter snake (Thamnophis ordinoides) (Nussbaum et al. 1983).

Some short term studies have suggested that P. dunni are not impacted by logging (e.g. Cole et al. 1997). Plethodon dunni are often abundant in forest stands of all ages (Corn and Bury 1991), however populations are more likely to be present in logged stands when mature timber is upstream than when stands upstream have been cut (Corn and Bury 1989). More research on the long term effects of logging on P. dunni and other forest-dwelling species is necessary.