Monday, September 29, 2014

Adirondack Salamanders: The Red-Spotted Newt

800px-Notophthalmus_viridescensPCCA20040816-3983AEarly autumn is the time fog frequently shrouds valleys in the morning, and a heavy dew regularly coats unprotected surfaces for several hours after sunrise. As the atmosphere begins to cool with the change in seasons, moist conditions often develop at night and can continue well after dawn. This is ideal for our various terrestrial amphibians, which require damp surroundings for their survival. Among the members of these moisture sensitive vertebrates is the red-spotted newt, a unique form of salamander that goes on the move as the foliage changes color.

Unlike other amphibians, the newt is a creature that experiences a second metamorphosis during the course of its life. In early to mid spring, shortly after the ice goes out, adult red-spotted newts appear at some quiet, muddy-bottom aquatic setting ranging in size from large vernal pools and small beaver ponds to marshy sections of shoreline along sluggish rivers, or in sheltered bays and coves of a lake. In these shallow waters, hundreds of eggs are laid and hatch a month or two later, depending on the water temperature, into their larval or tadpole phase. After spending most of the summer in these waterways, the newt develops small legs, a long tail and a set of lungs as it metamorphosizes into its land dwelling stage, sometime referred to as the red eft. This 3 to 4 inch long salamander gets its name from its bright reddish-orange color.

In the period from Labor Day through Columbus Day, this conspicuously colored creature travels when the air is saturated to search for a place where it can spend the next 3 to 4 years. Heavily forested settings are particularly inviting to the eft, especially those in lowlands where the ground is often damp, even during periods of dry summer weather. Both evergreen and deciduous woodlands are inhabited, although this creature seems to prefer those areas containing a fair percentage of hardwoods to those composed of pure stands of conifers.

In these areas, the juvenile red-spotted newt prowls at night for almost any type of insect, spider, millipede or other bug that it can find. The rich assortment of invertebrate matter that exists in the layer of leaf litter covering the forest floor helps satisfy the appetite of this amphibian.

After several years, as it approaches maturity, the red eft experiences a second physical change that results in its forming a thicker and flatter tail and a skin that is an olive-green in color. The red-spotted newt now attempts to relocate to an aquatic setting in which to spend the remaining 8 to 10 years of its life. However, even though this amphibian often develops a life style like a green frog or bullfrog, it still retains its set of lungs as do these other aquatic creatures. In order to get oxygen, the red-spotted newt periodically comes to the surface for a gulp of air. Additionally, the skin of this organism is capable of absorbing some dissolved oxygen from the water that surrounds it.

Much of the longevity of the red-spotted newt can be attributed to the ability of its skin to release a highly toxic substance when threatened. All phases of this amphibian can yield a chemical known as tetrodotoxin, which functions as a fast-acting neurotoxin when introduced into the mouth of another animal. (The bright reddish-orange color of the eft is believed by naturalists to act as a warning sign to likely predators, much like numerous other poisonous creatures that occur in warmer, or tropical locations.) Biologists that study small predatory mammals, birds, and fish have noted the absence of the red-spotted newt in the stomachs of these carnivores, indicating that they have somehow acquired the knowledge of the effectiveness of its defense.

One of the main organisms to plague the red-spotted newt is the leech, as this lower form of life seems to be unaffected by this amphibian’s chemical weapon. In an attempt to rid itself of small leeches that parasitize it, the newt is known to climb out of the water during the day. When exposed to dry air, the leech hopefully will begin to experience problems with dehydration, before this amphibian does, and drop off.

Much of the active stage in the life of the eft and adult newt is carried out at night, however, this common Adirondack resident may be encountered on the trail or when launching a canoe or kayak on an overcast, or rainy day, or early in the morning in the autumn before the dew has evaporated. Anytime when the air is saturated, and the temperature is in the mid 40’s or higher, both forms of this amphibian remain active until the ground begins to freeze, or snow starts to accumulate on the forest floor.

Photo: Juvenile Eastern (Red-Spotted) Newt (Notophthalmus viridescens). Courtesy Wikimedia user Patrick Coin.

 


Tom Kalinowski

Tom Kalinowski is an avid outdoor enthusiast who taught field biology and ecology at Saranac Lake High School for 33 years. He has written numerous articles on natural history for Adirondack Life, The Conservationist, and Adirondack Explorer magazines and a weekly nature column for the Lake Placid News. In addition, Tom’s books, An Adirondack Almanac, and his most recent work entitled Adirondack Nature Notes, focuses on various events that occur among the region’s flora and fauna during very specific times of the calendar year. He also spends time photographing wildlife. Tom’s pictures have appeared in various publications across the New York State.




4 Responses

  1. Marisa Muratori says:

    During the summers, spending time at my family’s camp in Bolton… hundreds, thousands would show up all over the dirt road nearby after a rain. Very rarely see them anymore. Have their populations been in decline?

    • Tom Kalinowski Tom Kalinowski says:

      Hi Marisa: I do not know for sure, but I am of the opinion that their population has been in decline for the past few decades. I believe that acid rain has taken its toll on their numbers, but I have no real proof of that assumption. There may be several other factors that may also have influenced their decline, but again, I really don’t know for sure. Maybe someone that has read this article has more information regarding any population trends this amphibian has experienced in the Adirondacks.

  2. Kathy says:

    I still see them up at Hunt Lake at our family camp, just like we have for the last 45 years that I can remember. We also would go looking for bucket fulls after a rain. Seems to be a few less now than as a kid or maybe we just dont spot them as easily.

  3. Dave Gibson says:

    Tom, thank you. I have observed the aquatic form of the newt in our pond over the past three summers, slowly expanding numbers each year. None were observed the prior 26 summers, and I am in that pond swimming June-Sept. So, there seems to be some localized range expansion going on in my area.