The Elusive Blue-Spotted Salamander

by: John Gilhen
SPRING 1989

""I'll never forget the moment when I pointed my flashlight toward the first pond. It was 9:00p.m. and the shell ice was rapidly forming over the surface of the pond. There on the firm, red mud bottom was the first adult blue-spotted salamander I had ever seen in nature." ".


IMAGE: The blue-spotted salamander

Salamanders are by nature secretive creatures. Only during damp or rainy nights do most species venture out from their daytime retreats and unless you know and search their habitat, you will seldom see one.

The blue-spotted salamander is the second largest of our 5 native species of salamanders. Adult males range from 78 to 134 mm long while females are 95 to 140 mm. Adults are usually bluish-black in colour, although some individuals may be slightly paler underneath. Pale blue spots are found along the sides of the body and tails, as well as on the chin, abdomen and limbs. In some adults, particularly the males, the blue spots are so dense they form blue stripes along their sides.

The blue-spotted salamander was once considered rare in Nova Scotia. The few individuals that had been collected in the province were mistaken for Jeffersons' salamanders, a larger more southern species.

In 1964, Thomas M. Uzzell completed a study of all the specimens labelled as "Jeffersons' salamanders" from museum and university collections in eastern North America. He discovered that these salamanders could be separated into 2 major groups. those collected south of New York and New England had a broader snout, longer legs, greater body size, lighter colour and less spotting than those from the northeastern United States and Canada. The larger southern species retained the name Ambystoma jeffersonianum (Jeffersons' salamander) and the smaller northern species was renamed Ambystoma laterale (blue-spotted salamander).

Prompted by Uzzell's fascinating study and a request by our National Museum for living Nova Scotia blue-spotted salamanders, I began a study of these creatures. Although individuals had been collected in 7 widely separated localities in Nova Scotia, only 5 museum specimens were available. I needed more specimens.

The spring egg-laying season was over for 1968, so I decided to look for larvae in roadside cattail ponds between Halifax and Amherst. In the unvegetated shallows salamander larvae as well as northern spring peeper and wood frog tadpoles were common. When disturbed, they took shelter under cattail debris covering the bottom of the ponds. The larvae were easily collected by walking along the margin of ponds and using an aquarium dip net.

As there are no reliable keys to amphibian larvae, I had to collect a sample of all the salamander larvae from each pond and rear them beyond their transformation stage at the museum. The salamander larvae were placed in gallon jars which I had set up as semi-aquatic terraria. By the end of August all the larvae had absorbed their gills and moved out of the water inside the terraria. within days they changed from an olive-green colour to black. those with small metallic-yellow freckles scattered over the body and tail were yellow-spotted salamanders; those with small bright blue freckles were blue-spotted salamanders.

The results of this project were very encouraging. Blue-spotted salamander larvae were recovered from 5 ponds between West Wentworth and Oxford, Cumberland County. Since the exact location of the 7 previously reported breeding ponds was uncertain, these 5 ponds were very important. When I searched the woodlands adjacent to these ponds I found only slugs, earthworms and other small invertebrates - which salamanders prey upon - but no adults.

There was nothing else I could do until the following spring when adult salamanders would once again migrate to their breeding ponds. Over the winter, I reviewed the few published papers and reports on the amphibians of Nova Scotia.

Very little was known about the distribution of the blue-spotted salamander, and practically nothing about its local natural history. I knew that the blue-spotted salamander was the first of our 5 native species to breed in spring. Its cousin, the yellow-spotted salamander, migrates about April 15th in the Halifax area so I decided to start my survey for adult blue-spotted salamanders the first week of April.

That spring I visited the breeding ponds twice during the first week without any success. At dusk on April 11th I drove out to the bicentennial Highway and waited until dark. I had flagged trees adjacent to the ponds with reflector tape so that I could find them at night while driving along the highway. Searching the ponds from Halifax to the west side of the Shubenacadie river, I found no salamanders. Air temperatures dropped to freezing, but before calling it a night, I decided to check the next 4 ponds, between Enfield and Elmsdale.

I approached the first pond carefully. There on the bottom of the pond, in the beam of my flashlight, was the first adult blue-spotted salamander I had ever seen in nature. It was an adult male. Two other males were active on the bottom on the opposite side of the pond. In the next 3 ponds I found 4 more males and 2 females.

There were no salamanders in ponds north of Elmsdale on this night. However, on April 19 and 20, adults were found in 2 of the ponds between West Wentworth and Oxford.

Over the next 15 years I have travelled all over this province observing and collecting samples of amphibians. I begin on those first cold rainy nights in spring and finish during the cold rainy nights of late autumn. Over the years I have obtained a great deal of information on these shy amphibians.

The blue-spotted salamander seems to be less tolerant of the acidic soils and water found in the granite and slate bedrock areas of our Atlantic coast. Its distribution shows it to be most common in the red sandstone, conglomerate and shale areas of the province.

On land these salamanders prefer damp woodlands, particularly alder swamps next to ponds and slow-moving vegetated streams; however, breeding ponds have been located along roadsides near wooded areas.

Breeding begins about the 1st week of April near Caledonia, queens County; the 2nd week of April at Enfield and Elmsdale in Hants County; the 3rd week of April near Truro; and the last week of April near Lower Shinimicas, Cumberland County and Pomquet, Antigonish County. At Ingonish in Victoria county the salamanders may not begin breeding until the first week of May.

Female blue-spotted salamanders lay from 70-540 individual eggs each year on bottom materials such as cattail debris, pebbles and along the base of stones. Depending on water temperature, the eggs hatch in 1 to 2 weeks.

In Cumberland County large female blue-spotted salamanders up to 155 mm have been found. (These females are known as triploid because they have 3 sets of chromosomes instead of the normal 2 sets).

The gilled salamander larvae grow rapidly, feeding voraciously on small arthropods such as insect larvae. The larvae transform into air-breathing salamanders in late July and August. Then, on a rainy night, large numbers abandon their nursery streams or ponds, and , accompanied by transformed yellow-spotted salamanders, spread out to damp woodlands nearby. The young disperse quickly in a deliberate migration, while the juveniles (1 year old) and adults tend to linger on in the rain. The rain also stimulates juveniles and adults to explore again the surface of the forest floor and roadsides.

The young salamanders grow rapidly during the autumn and the following summer, reaching adult size near the end of their second summer. By the second autumn they are sexually mature and females are ripe with eggs as they retire for their second winter hibernation.

Soon after emerging from their subterranean hibernation in spring the salamanders begin feeding. Those that linger in the ponds after spawning eat a wide variety of insect larvae. Although the bulk of their food while on land consists of slugs and earthworms, various other small invertebrates are included in their diet.

Blue-spotted salamanders go about their daily lives in damp woodlands secluded from the view of people. As a herpetologist at the Nova Scotia Museum it is one of my most rewarding experiences to take interested people on field trips at night in spring to observe the salamanders migrating to breeding ponds. One naturalist tole me: "When you have searched for a blue-spotted salamander for years and have never found one, seeing many congregated in one pond is like being let in on a big secret".

I quietly walk the margin of the pond, and can now appreciate how useful salamanders are, and how fortunate we are to have these few nights in April to observe them in nature.