Identifying Amphibian Species

The Myth of the "Big Night"

There is this old unique myth of the big night; after a long, snowy, cold winter, spring arrives and it finally starts to rain and all on one night the amphibians come out of their winter burrows and migrate to vernal pools to lay their eggs. While this myth is partially true, he amphibians do not migrate only on one specific night because it is entirely weather dependent. 

There are three things that are needed for these migrations to occur. There needs to be thawed ground with minimal to no snow cover. The nighttime temperature has to be above 40 degrees as these species are mainly nocturnal, 40 degrees is the threshold for a low temperature but 45 degrees or above is the prime temperature. Lastly, for it to be raining that night is ideal but, there may still be migrations if there is a drought if it is humid and foggy one night. 

Image of a vernal pool.
By Yuvalr - Own work, CC BY-SA 4.0

     Vernal pools are critical for amphibians to use as breeding grounds. A vernal pool is a woodland wetland that forms in depressions in the forest floor from snow melt and rain fall. They are temporary pools which is crucial because throughout spring and summer the sun evaporates the water or it soaks into the ground meaning that fish cannot sustain there giving the eggs a much higher rate of survival. Salamanders tend to go back to the same site every year again and again, typically the one that they were born at. What happens at the breeding site is that the males arrive first and congress. What this means is that the males are hanging out with one another in the pool saying 'hi' to everyone while they wait for the females to arrive. When one does, a male will go up to her and rub chins 'dancing' to see if they like one another, if she approves then she will sit on his back along his spermatophores which fertilizes her eggs. The females typically lay their eggs along a stick of a twig or the leaves on the bottom of the forest floor under the water. They take 6-8 weeks to hatch which is why it is important that they lay their eggs where there is not fish living there feeding on them. These pools are already 'fast food oasis's' for other spring wildlife in New England but the eggs and larvae that do survive can live up to 20-30 years. 

Spotted salamander.
Image by myself.

 Identifying Salamanders

In Keene, New Hampshire, the main salamanders that will be seen migrating are the spotted salamander, Jefferson salamander, Blue-spotted salamander, and the Jefferson/blue-spotted salamander hybrid. Spotted salamanders can be identified by their coloring, they are black bodied with bright yellow polka dots on their backs which makes them easily distinguishable. They are typically 6-8 inches long and are known for their mouths being in a smile. They also spend 95% of their lives underground. 

Jefferson salamanders, Ambystoma jeffersonianum, are a type of mole salamander. They are 5-7 inches in length with long toes. Their distinctive features of its brown/blackish coloring with some small blue spots along its back. The Blue-spotted salamander, Ambystoma laterale, have bright blue spots along its back. There is also now a hybrid between these two species, the Jefferson/blue-spotted hybrid. This species can only be distinguished 100% by its DNA. The mother salamander preforms kleptogenesis, where she basically clones herself forming a hybrid of the two species. 

There are also a few other species of salamanders in Keene that we might come across but they are not truly migrating to the vernal pool sites. They consist of the red eft, the Eastern newt, red backed salamander which is the most numerous salamander, four-toed salamander, and the two-lined salamander. 

Spring peeper
By brian.gratwicke. CC BY 2.0.

     Frogs are the other amphibian that is prominent at these crossings. The wood frog, Lithobates sylvatica, is one of the first amphibians that comes out of hibernation when the ground thaws. They survive winter by freezing completely, their heart, lungs, bodies, everything so once the ground is thawed they come back to life again. They are smaller than the palm of your hand and have a dark coloring behind their eyes. Males sign to the females to signal them to come to the pools and breed. Spring peepers, Pseudacris crucifer, are also very common at the sites. They are a type of tree frog the size of the tip of your thumb with tan coloring and suction cups on their toes. There are also other frog species such as the gray tree frog, Pickerel frog, green frog, bull frog, and the American toad that are frequently seen.