“Salamanders: Unseen, Unheard, but NOT Unimportant” presented by Fred Schueler/Mike Oldham, Bishops Mills Natural History Centre
Salamanders are keystone inhabitants of local streams and forests: A lecture report by Fred Schueler
The Mississippi Valley Field Naturalists (MVFN) 2011-12 natural history lecture series in Almonte continued recently with the 4th talk: Salamanders: Unseen, Unheard, but NOT Unimportant. Originally to have been given by Mike Oldham (MNR), stormy weather on lecture night forced Mike to turn back to Peterborough, and so Dr. Fred Schueler, scientist and local naturalist graciously stepped in and presented an excellent lecture. Dr. Schueler’s lecture report which follows provides an overview of salamanders, and a focus on local salamander species. The full report by Dr. Schueler is posted at mvfn.ca.
Salamanders retain the long-tailed, four-limbed shape of primitive land-dwelling vertebrates, overlaid by a wide range of specialized adaptations. They diverged from the tailless frogs some time before the earliest known salamander fossils, from the Middle Jurassic, 164 million years ago. There are now about 550 species of salamanders in the world. Among provinces, Ontario has the greatest number of species, probably because it is closest to the southern Appalachian region, which is the world centre of salamander diversity. Our salamanders range from 35 mm to almost half a metre in length, and show remarkable variation in life histories and habits. Some spend their entire lives in the water, others live on the land but breed aquatically, and some have an entirely terrestrial existence. Salamanders may breathe via gills, lungs, and skin, or can be lungless and breathe only through their skin. Moisture is thus a very important factor regulating their distribution, and they tend to be active on the surface mostly on rainy nights, when potential observers tend to seek shelter.
Salamanders are elusive, and in addition to being rarely seen at the best of times, and on the formerly ploughed and trampled lands of eastern Ontario, they’re often much rarer than they were before settlement, though because of their effectiveness as predators they are often regarded as ‘keystone predators’ in intact forest ecosystems of eastern North America.
Thirteen species of salamanders are known from Ontario, including six that are legally listed as ‘at risk’ either federally or provincially. Eastern Ontario is not a particularly diverse area for salamanders, but the seven the species found here have a variety of different life histories and are among our most poorly known vertebrates.
The Mudpuppy (Necturus maculosus) is Ontario’s largest salamander, reaching a foot or more in total length. These salamanders are permanently aquatic and have feathery gills behind the head, and other features of larval morphology that other species lose when they mature. Mudpuppies occur in larger rivers and lakes throughout southern Ontario, as far north as Thunder Bay and the upper Ottawa River, though their distribution is poorly known due to their permanently aquatic habits. They’re known from the Rideau, Mississippi, and Madawaska rivers, on the basis of only a few records. The one place they can be easily seen in eastern Ontario is during the winter at Mudpuppy Night in Oxford Mills – http://pinicola.ca/mudpup1.htm – where many Mudpuppies from an abundant population are out in the open during their winter activity period.
The salamanders with the least surprising life history are the Ambystoma ‘Mole Salamanders’, so called because they spend much of their lives underground – like frogs these live on land and come to ponds to lay eggs in the spring, which hatch into larvae which, like tadpoles, transform to leave the water to live on land until they come back to breed in ponds as adults.
The Blue-spotted salamander (Ambystoma laterale) is the most frequently encountered species in our area, often wandering into basements or garages, or turned up under wood. Photo Amelia Argue
The Blue-spotted Salamander (A. laterale) is the most frequently encountered species in our area, often wandering into basements or garages, or turned up under wood that has been resting on the ground. Adults are about 13 cm in total length; they are black or dark brown with variable amounts of bluish spots or flecks. This species is closely related to the Jefferson Salamander, which does not occur in eastern Ontario, and the two species hybridized historically to produce unisexual polyploids which contain multiple sets of chromosomes from both the Jefferson and Blue-spotted Salamanders and are almost indistinguishable from the parental species except through genetic testing. These polyploid populations are almost entirely female and usually must mate with a male of one of the parental species to reproduce, though usually rejecting the chromosomes from his sperm.
At one time the polyploids occurring in eastern Ontario were called a separate species, Tremblay’s Salamander, larger and less spotted than ordinary Blue-spots, with two sets of Blue-spotted genes and one of Jefferson genes; but since it doesn’t reproduce sexually it is no longer considered a separate species. Our other Ambystoma is the Yellow-spotted Salamander (A. maculatum). This large, blackish Salamander has two rows of large yellow spots on its head and along its back and tail. It can grow to over 20 cm in length. It’s fairly common on the Shield, including Lanark County, but is restricted to mature woods on sandy dunes in the limestone country of easternmost Ontario. The large, slow-hatching, jelly-swathed egg masses are conspicuous in woodland breeding ponds in the early spring.
The red colour of the terrestrial stage of the red-spotted newt serves as a warning to predators that it is poisonous. Efts such as this one photographed during MVFN’s 2010 bioblitz near Almonte, are the only salamanders you’ll see wandering around in daylight.Photo by Karen Thompson
The Eastern or Red-spotted Newt (Notopthalamus viridescens) has a life-cycle that differs from any other Ontario salamander – the larvae transform into a terrestrial stage known as the ‘red eft’ and spend 2-4 years on land in the woods. They then return to the water to become mature aquatic adults. Adults have expanded tail fins, and are dark above, often a greenish-brown colour, with prominent black-ringed red spots on their sides; efts are orange-red, with the same red spots, but narrow tails. The red colour serves as a warning to predators that the eft is poisonous, and efts are the only Salamanders you’ll see wandering around in daylight. In eastern Ontario the distribution of Newts is very scattered, and they may be declining.
The final and largest family of Salamanders is the lungless Plethodontidae. We have two specialized uncommon species, and one that is widespread and relatively abundant. The species with the most specialized habitat is the Four-toed Salamander (Hemidactylium scutatum). In May the females leave their woodland habitat and form cavities in moss, typically Sphagnum, overhanging water, where they lay their eggs. When the larvae hatch they wriggle down through the moss into the water where they live until they transform. Although the Four-toed Salamander has only four toes on its hind feet while similar Salamanders have five, the tiny toes are not a particularly useful identification character – better are the constriction at the base of the tail and the underside which is bright white with bold black spots, quite unlike the greyish underside of the Red-backed Salamander, with which it could be confused. Undoubtedly the species is more common in eastern Ontario than very few old records indicate – you have to go to bogs or other moss-banked ponds or ditches during the breeding season to have the best chance of finding them.
Another small, slender Plethodontid Salamander is the Two-lined Salamander, Eurycea bislineata, almost always found in or very near running water or gravelly seepages. This species is generally gold-coloured with two dark longitudinal stripes down its back. Eggs are laid beneath flat rocks in streams and the larvae live in the stream until they metamorphose. The best way to find them is to flip over rocks just at the edge of a stream or lake. Two-lined Salamanders are not found in southwestern Ontario, but are locally common in a band from Georgian Bay, across Algonquin Park to Quebec, and south to the St. Lawrence River, though they are found east of the Shield in Ontario only in a very few sites where water flows into streams through seepages of clean gravel. Lanark County is part of this range where the species is fairly common; there used to be a population below the dams in Almonte, but the new hydro station has been built over the site where they occurred.
The Eastern Redback Salamander, Plethodon cinereus, is usually regarded as the most abundant vertebrate in the forests of northeastern North America. These Salamanders act as keystone predators to regulate the invertebrates of the forest floor community, and through them the character of leaf litter decomposition, soil, and nutrient cycling in the forest. Red-backed Salamanders are an exception to the rule that our amphibians lay their eggs in water, since they lay their eggs in moist spots inside or beneath rotten logs and the entire larval stage of the salamander occurs inside the egg, as they are attended by the mother. The Small Eastern
Colour morphs of Plethodon cinereus: Left, a redack morph (Photo Joe Crowley) and right, a leadback morph (Photo Bev Wigney), both on Earthworm castings.
Plethodon Salamanders, like several other common vertebrates in our forests (Ruffed Grouse, Screech Owls, and Redbelly Snakes), have distinct reddish and greyish colour forms. Rufous and ashy are plausible colours for cryptic forest creatures, as the colours of freshly dead and decayed leaves . . . In Plethodon these morphs are ‘leadback’ – unpatterned and charcoal gray, and ‘redback’ with a reddish dorsal stripe. In New England leadbacks are more frequent in warmer localities, and it has been found that the morphs forage at different temperature . . . Across most of southern Ontario populations are mixed, with leadbacks rarely frequent, but in eastern Ontario south of Ottawa and east of the Frontenac Axis there are no redbacks. You can collaborate with Dr. Schueler’s efforts to find out how abundance or colour morph ratios are changing by helping re-sample places where Plethodon have been collected in the past (http://pinicola.ca/thirty/pcin_2012.htm).
[One group of animals has been particularly detrimental to salamanders, i.e. Earthworms.] Pleistocene ice sheets wiped out any native Earthworms that had lived in Canada, leaving North American species . . . only where glaciation was incomplete, on Vancouver Island and the Richardson Mountains of the Yukon. [However, European earthworms were later introduced and where these invaded old growth forests all but the most recently fallen leaves have been pulled underground and consumed, leaving minimal leaf litter.] The missing leaf litter was home to complex communities of everything from snails to nematodes to springtails to centipedes to beetles to salamanders, and to the extent that their habitat is gone, the fauna must be gone from the forests with minimal leaf litter. The invasion of wooded areas by non-native earthworms can also lead to the decline in some native plants, such as rare woodland orchids that depend on a rich humus layer, as well as facilitating the invasion of wooded areas by non-native plants.
The most important thing those interested in contributing to salamander research and conservation can do is to archive sightings of salamanders and other species. This is perhaps even more important for common species not yet listed as ‘at risk’ because such species are not adequately monitored. Canadian agencies such as the Natural Heritage Information Centre [nhic.mnr.gov.on.ca] are only concerned with species at risk and rare habitat. Salamanders have what Schueler referred to as a ‘boom and bust’ economy. While many years in some habitats may offer great conditions for salamanders, often the habitat can’t support any population at all and so suitable areas with a source of dispersing individuals are also vital for species survival. When you are out and discover these creatures, record where and when and what you see and share the information with the Ontario Herpetofaunal (Amphibian & Reptile) Summary Atlas (OHS) at http://www.ontarionature.org/protect/species/herpetofaunal_atlas.php