Northern Two-Lined Salamander
General Description
The Northern Two-lined Salamander is a small and slender species which can attain a total length of about 12cm.[1] The salamander has a yellowish olive colored stripe down it's back bordered by 2 black lines.[4] Yellow or mottled pigmentation extends down it's sides, with small legs attached to the pale yellow belly.[5] As an adult they have 13-16 costal groves as well as a laterally compressed tail.[1] This species occupies a wide range stretching throughout most of the Northeast U.S and up into Southern Canada. The species can be found as far West as Ohio, as far south as Virginia, and all the way up to Eastern Ontario and Quebec.[1]
Taxonomy
| Kingdom | Phylum | Class | Order | Family | Genus | Species | |
|---|---|---|---|---|---|---|---|
| Classification | Animalia | Chordata | Amphibia | Urodela | Plethodontidae | Eurycea | E.Bislineata |
Habitat
This salamander dehydrates more easily than other lungless salamanders and is generally found in close proximity to streams.[4] This species inhabits moderate to fast flowing rocky streams, tiny creeks to actual rivers, and either deciduous or mixed forests.[4] As a juvenile the salamanders tend to spend more time in the water, and as an adult they prefer woodland or open habitats with sufficient cover provided by leaf litter, logs, and rocks.[5] The species is somewhat tolerant of urbanization; this tolerance has allowed the Two-Lined Salamander to replace the Dusky Salamander in areas of Southwest Connecticut where the two once coexisted.[2]
Conservation Status
Under the IUCN Northern Two-lined Salamanders are listed under Least Concern, and in New York state their population is listed as secure. The salamanders are doing well but in order to continue their populations success we must help conserve water purity, adequate above ground habitat, and refrain from using toxic fertilizers, herbicides, and insecticides.[2]
Diet
Adult Salamanders feeds on insects, annelids, arachnids, sow bugs, mites, and even an occasional salamander.[2] The larvae eat primarily aquatic benthic invertebrates.[1] Larvae eat crustaceans and copepods as well as the aquatic larvae of midges, mosquitoes, caddisflies, stoneflies, and beetles.[5] The larvae act as opportunistic generalists up until the developmental point where their jaw size can accommodate larger prey items.[5]
Defense Mechanisms
Northern Two-lined Salamanders utilize their tail to their advantage, the tails regeneration allows it to be bait of sorts for predators. The Salamander assumes a defensive posture when attacked by predators such as shrews or blue jays where the tail is elevated and moves up and down. [6] In lab, 10 of 11 salamanders attacked by shrews were first bitten on the tail and the shrew backed away wiping its mouth, giving the salamander time to escape.[6] This defense mechanism is not successful with predators like garter snakes, in response to snakes the salamanders will either run or remain immobile. In a testing chamber for garter snake predation 90% of the salamanders with tails survived, as tailed individuals can run faster. [6] Tail autonomy can increase the chanes of the salamander escaping, but once tail-less it's more susceptible to future predation. [6]
Reproductive Biology
The salamander starts it's life in the water as an aquatic larvae for two to three years before transforming into semi-terrestrial juveniles.[5] Due to this lengthy larval period, different age classes of salamanders are often found within the same stream.[2] Approximately a year after metamorphosis, they will reach sexual maturity.[4] The species primarily breeds in the spring and exhibits a complex courtship behavior. A male salamander uses his head to nudge a potential mate and encircles the female's head with the front of his body.[5] The male scratches the females skin with his teeth to allow secretions from his mental gland to enter the females bloodstream.[5] It's hypothesized that the male's secretions may stimulate courtship behavior in the female.<sup[5] Eventually the female presses her chin to the males glandular area at the tail bases and they engage in a "tail straddling" walk.[5] During this walk the male will release a spermatophore which is picked up by the female in her cloaca.[5] The female will lay up to 200 eggs in the spring on the underside of submerged rocks.[4] The female normally will stay with the eggs until they hatch in 1-2 months.[4]
References
[1] Canadian Herpetological Society. 2023. Northern Two-lined Salamander. https://canadianherpetology.ca/species/species_page.html?cname=Northern%20Two-lined%20Salamander
[2] Connecticut Department of Energy & Environmental Protection. 2016. Northern Two-lined Salamanders. https://portal.ct.gov/DEEP/Wildlife/Fact-Sheets/Northern-Two-lined-Salamander
[3] Poston, et, al. 2023. Northern Two-lined Salamander. https://www.paherps.com/herps/salamanders/twolined_salamander/
[4] Ontario Nature Organization. 2020. https://ontarionature.org/programs/community-science/reptile-amphibian-atlas/northern-two-lined-salamander/
[5] Vanwormer, E. Eurycea bislineata Northern Two-lined Salamander. https://animaldiversity.org/accounts/Eurycea_bislineata/
[6] Sever, D. Eurycea Bislineata. 2023. https://amphibiaweb.org/cgi/amphib_query?where-genus=Eurycea&where-species=bislineata&account=lannoo