This year, a certain breed of salamander in Canada will hopefully be enjoying a safer spring migration. This is because the City of Burlington, Ontario, has closed a portion of King Road in order to protect the endangered Jefferson salamander, Ambystoma jeffersonianum, during its annual egg-laying migration.
An Introduction to the Jefferson Salamander
The Jefferson salamander, also known as Jefferson’s salamander, is a North American amphibian, whose range includes the Niagara peninsula of southern Ontario and sections of the northeastern United States.
The creature’s colour scheme is grey through brownish black on the dorsal side, but with a lighter underbelly. The limbs and flanks may have bluish flecks.
Adults may be from twelve to twenty centimetres long, although the tail accounts for about half the total body length. The larvae appear as small adults, except for the fact that they are missing the colour highlights and they have gills for breathing underwater.
The habitat requirements of the Jefferson salamander seem simple: a deciduous forest with leaf litter, fallen logs or moist but friable soil. However, they also need pollution-free breeding ponds that remain full until at least midsummer, when the larvae lose their gills and adapt to breathe air. These salamanders use “vernal pools”, or ponds that arise every spring but usually dry later in the summer.
The females lay clumps of eggs and attach them to underwater vegetation. The eggs hatch into larvae within six weeks.
Adult Jefferson salamanders eat worms and insects. The larvae prey upon aquatic insects and other immature amphibians.
During the winter, Jefferson salamanders hibernate under the soil.
Threats Facing the Jefferson Salamander
The major threat to the Jefferson salamander’s existence is loss of habitat. Since they live in colonies of only a few hundred members, any one location may be destroyed by a housing development or changes made to a drainage system. Conservation efforts generally involve maintaining a clean, unspoiled wooded environment.
The city of Burlington, Ontario, has recognized a different problem for the critter, which, in this part of Ontario, crosses the King Road in order to move from its winter locations to its breeding and feeding ponds.
During 2011, a voluntary road avoidance program failed to protect enough of these amphibians. In order to provide greater protection for their amphibious residents, researchers from Conservation Halton recommended the three-week road closure.
The Endangered Status of the Jefferson Salamander
Ontario protects the Jefferson salamander under its Endangered Species Act.
The International Union for Conservation of Nature (IUCN) categorizes the Jefferson Salamander’s status as “of least concern” because it has a fairly widespread habitat in portions of the states of New York, Pennsylvania, Ohia, Indiana, Kentucky and Virginia. The IUCN does note that many of the sampled individuals are hybrids that have cross-bred with related species A. texanum or A. platineum.
The hybrids are fertile female triploids: their DNA has three times the haploid number of chromosomes that would be found in pure-bred Jefferson salamanders. (The “haploid number” is the number of chromosomes in a sperm cell or egg cell; this is one-half the number in a typical cell in the animal’s body.) These triploid females mate with pure-bred Jefferson males to produce new triploid females.
The IUCN recognizes that “[s]ome local populations incur heavy road mortality during migrations to and from breeding sites”. Fortunately for Canadian Jefferson salamanders, the city of Burlington’s temporary road closure mitigates this risk.
City of Burlington, “King Road closed to protect Jefferson salamander“, March 7, 2012, referenced March 13, 2012.
Ontario Ministry of Natural Resources, “Jefferson salamander (Ambystoma jeffersonianum)“, 2008, PDF referenced March 13, 2012.
Geoffrey Hammerson, IUCN Red List of Threatened Species (Version 2011.2), “Ambystoma jeffersonianum“, 2004, referenced March 13, 2012.
Ohio Dept. of Natural Resources, “Jefferson Salamander“, referenced March 13, 2012.
Dorland’s Medical Dictionary for Health Consumers, “Haploid“, 2007, referenced March 13, 2012.