Yellow-eyed Ensatina

Ensatina eschscholtzii xanthoptica

Summary 2

Ensatina eschscholtzii (commonly known by its genus name, Ensatina) is a complex of plethodontid (lungless) salamanders found in coniferous forests, oak woodland and chaparral from British Columbia, through Washington, Oregon, across California (where all seven subspecies variations are located), all the way down to Baja California in Mexico.

Life History & Ecology 3

Ensatinas are terrestrial lungless salamanders with direct development (Stebbins 1954; Petranka 1998). Females lay and attend from 3-25 eggs (usually 9-16) in typical aestivation sites at the end of the rainy season (Stebbins 1954; Petranka 1998). Nest sites are often associated with logs (under or within a log, or underneath moss or loose bark on top of the log; summarized in Olson 2006), but may also include rock fissures in seepage areas (Stebbins 1954), animal burrows (Storer 1925) and cavities up to 0.8 m deep (Nussbaum et al. 1983). Juveniles hatch after 114-143 days and appear at the ground's surface at the beginning of winter rains (Stebbins 1954; Petranka 1998).

Ensatinas are usually common where present, with density estimates of 1730/ha for E. e. xanthoptica (Stebbins 1954) and 2833/ha for E. e. oregonensis (Gneadinger and Reed 1948).

Ensatinas are active during the winter rainy season on very local home ranges, 6-41 meters in width (Stebbins 1954; Staub et al. 1995). During the dry summer, they aestivate in underground retreats such as root cavities and rodent burrows (Stebbins 1954). This species has been shown to mark, recognize, and defend home areas in the laboratory outside the breeding season, suggesting territoriality (Wiltenmuth and Nishikawa 1998).

Coloration in Ensatina shows wide geographic variance, and distinguishes the seven subspecies, as delineated above (see Description). Coloration also serves to deter predators, via crypsis, aposematism (vivid warning colors, associated with toxicity), or mimicry of another species' warning colors. Crypsis via background matching is seen in three Ensatina subspecies: E. e. oregonensis, E. e. picta, and E. e. eschscholtzii (Stebbins 1949); crypsis by way of disruptive coloration is exhibited by another three Ensatina subspecies: E. e. platensis, E. e. croceater, and E. e. klauberi (Stebbins 1949); and Batesian mimicry of aposematic coloration in toxic newts (genus Taricha) is used by E. e. xanthoptica (Kuchta et al. 2008). Subspecies with disruptive coloration (blotching or spotting) are associated with forested areas, usually closed-canopy forest (Stebbins 1949).

Stebbins (1949) proposed that the vivid orange and yellow coloration of E. e. xanthoptica might be mimicry of the highly toxic newts Taricha torosa and Taricha granulosa, both of which are sympatric with E. e. xanthoptica. Kuchta et al. (2005) first tested this hypothesis, and showed that painted clay model salamanders with coloration matching that of E. e. xanthopticawere attacked significantly less often than brown morphs, despite both being equally visible on a white paper base. In experimental trials, Western Scrub-Jays presented first with a newt (Taricha torosa) were significantly less quick to attack and consume the presumed newt mimic E. e. xanthoptica than to attack and consume the cryptically colored E. e. oregonensis(Kuchta et al. 2008). Since jays were observed to eat E. e. xanthoptica tail and all, with relish and without ill effect, E. e. xanthoptica is apparently edible, making its resemblance to the highly toxic Taricha a case of Batesian mimicry rather than Müllerian (Kuchta et al. 2008).

Ensatinas lack traditional amphibian mucous glands as well as lacking typical, acidic mucus, instead secreting neutral mucus via specialized, derived granular glands (Fontana et al. 2006). The toxicity of E. e. xanthoptica has not been evaluated; high concentration of granular glands are found in Ensatina tails, and secretion under stress of a milky, sticky glutinous substance with an astringent taste has been observed (Kuchta et al. 2008). However, since Western Scrub-Jays are able to eat Ensatinas without any apparent ill effect, these salamanders appear not to be particularly toxic (Kuchta et al. 2008). The birds did spend considerable time scraping their beaks during and after consumption of E. e. xanthoptica (Kuchta et al. 2008). The stress-induced, sticky white mucous secretions may actually be an antipredator defense by virtue of being extremely adhesive, enabling Ensatinas to avoid being consumed by predators such as Western Terrestrial garter snakes (Thamnophis elegans; Arnold 1982).

Read more at AmphibiaWeb.

Hastings NHR Notes 3

Ensatina has been documented with voucher specimens from several places in and around the Reserve. However, no recent observations have been made for this species since 1993!

Need observations to confirm their continued presence.

Sources and Credits

  1. (c) Michelle S. Koo, some rights reserved (CC BY-NC-SA),
  2. Adapted by Michelle S. Koo from a work by (c) Wikipedia, some rights reserved (CC BY-SA),
  3. (c) Michelle S. Koo, some rights reserved (CC BY-SA)

More Info

iNat Map

Iucn status Least_Concern
Taxonomy:family Plethodontidae