ACTs Nature Corner: Spring Peepers, Frogs & Salamanders
Spring is here!!! Things are greening up everywhere here in Maine and the sounds of spring are all around us. From the call of the red wing black bird to the “meep meep” of the woodcock. My favorite sound is the Spring peepers. I was amazed the first time I saw one of these tiny guys. They are rarely seen since they are only about an inch long. How could something this small make all that noise? Let’s learn more about them. To understand what all the racket is about we need to learn about Vernal Pools the site of lots of amphibian spring action. We’ll look at three amphibians that come to the pools to reproduce. Amphibians are amazing, they begin their life hatching from eggs and live their early existence underwater with gills metamorphing as they grow legs and lungs and are able to live on land. It really is quite a miracle, and it all begins in vernal pools.
Vernal pools (vernal come from the Latin word for Spring), are a unique type of wetland habitat.
They are typically small, shallow, water bodies. They can be as small as a puddle or as big as a small pond. Unlike a pond or a lake, they have no permanent inlet or outlet. They are filled each spring by rain and snow melt, then usually dry up for a period of time during the summer. Most of these pools occur naturally but others are human-made. Sometimes even in the ruts and tracks left by 4 wheelers. Because they are not filled with water all year, fish cannot live in them. Without any fish to eat their young, it’s a great place for an amphibian nursery. In our area of Maine Wood frogs, the Spotted Salamander and the Blue Spotted Salamander among other spring pilgrims travel to these temporary pools. They return to the pools where they were hatched, to find a mate, fertilize, and lay their eggs before returning to their summer- winter habitats. This annual migration of hundreds of thousands of amphibians happens on the first warm, rainy nights in April and is called “Big Night”. It can be a very dangerous journey for these creatures, and many don’t make it. They are killed crossing roads or eaten by predators as they attempt to get to the vernal pool. There are a group of volunteers who attempt to help the frogs and salamanders safely cross some of the busier roadways. If you’d like to learn more use the link below. https://www.vernalpools.me/big-night/ . Avoiding impacts to significant vernal pools and their surrounding habitat is important. The loss of vernal pools can lead to local loss of amphibian species, a decrease in biodiversity, and a decline in food available for many other animals that live in these areas.
Spring peepers also use vernal pools but not exclusively. These very small tree frogs have smooth skin in shades of tan, brown, green, or gray, with lines that form an X-shaped pattern on their backs. Thus, their scientific name Pseudacris crucifer (Latin for cross).
Their bellies are white to cream-colored, and they have dark bands on their legs and a dark line between their eyes. Spring peepers are well camouflaged to look like tree bark and have some ability to make themselves lighter or darker in order to better match their surroundings. Although they are good climbers, they spend most of their time on the ground, often hiding under leaf litter during the day. Spring peepers are known for the males’ mating call, the peeping sound repeated about 20 times a minute. However, the faster and louder they sing, the greater the chances of attracting a mate. They often congregate near water and sing in trios, with the deepest-voiced frog starting the call. They begin breeding early in the spring and call on warm spring nights and during the day in rainy or cloudy weather. Females lay their eggs in vernal pools, ponds, and other wetlands where fish are not present. A female may lay anywhere from 750 to 1,200 eggs, which attach to submerged vegetation. Males fertilize the eggs as they are laid. Depending on the temperature, eggs can hatch within two days to two weeks. The tadpoles have gills to breathe underwater and tails to help them swim. Tadpoles transform into frogs over the course of 6 to 12 weeks. Spring peepers have rather short lives, living three to four years at most. They hibernate during the winter in soft mud near ponds, under logs, and in holes or loose bark in trees. They can withstand freezing during winter hibernation due to a natural “antifreeze” in their blood.
Wood frog songs are heard even before the Spring peepers. Their call is often compared with the sound of a quacking duck or a squawking chicken. They tend to repeat the call several times in a row when trying to attract females. Listen here and see if you recognize them. https://www.youtube.com/watch?v=db0siH_RHCI
Wood frogs live only in the United States and Canada. they range from 1 ¼ to 3 inches in size. Their skin colors re usually browns, tans, and rust, but they can also be found in shades of green and gray. They can be distinguished by a black "robber's mask" that extends over the tympanum (outer ear) to the base of the front leg. They also feature a white line outlining their upper lips. They have two back ridges on either side that extend from behind the eye, down the side of the back, and to the legs.
Females are much larger than males. Wood frogs breed every year from early March to May. Once mates are chosen and breeding occurs, females lay a globular egg mass in the water, most often in the deepest part of the vernal pool. Each egg mass can contain from 1000 to 3000 eggs. The masses are sometimes attached to a twig or grasses, or they can be left free-floating. After about a week the egg mass begins to flatten out, allowing it to rest on the surface of the water. The jelly around the eggs becomes green, creating a kind of camouflage. The mass then looks like a floating mass of green pond scum. The green color of the jelly is due to the presence of many small green algae.
The eggs hatch after 9 to 30 days and the tadpoles will undergo metamorphosis when they are 2 months old.
Male juvenile wood frogs grow into adults and are able to breed when they are 1 to 2 years old, while females take a bit longer and are not adults until they are 2 to 3 years old. Wood frogs also have a superpower, while subzero temperatures would kill most animals, the wood frog can survive freezing conditions for months without eating or releasing waste. During the wood frog’s hibernation, a special material called cryoprotectants, inside the frogs’ bodies, act like antifreeze, preventing ice crystals from forming inside their cells by lowering the body’s freezing point keeping their cells and tissues from freezing and bursting. If you were to find a hibernating wood frog, it would appear dead, cold, frozen, and stiff and yet when the spring come they are able to thaw out and continue as before with no apparent ill effects.
In addition to frogs, Maine has several salamanders that use the vernal pools as a nursery.
The spotted salamander is named for the two rows of yellow or orange spots along their dark black backs. They are large members of the mole salamander family. They grow to a length of 7-9 inches.
In early spring the spotted salamanders wake from their hibernation and migrate to the vernal pools where they were hatched each year. Thousands will be travelling at the same time during a “Big Night”. During the breeding period, females lay up to 200 eggs in a mass. The whole egg mass is then encased in a jelly-like coating. This coating helps protect the eggs from predators like frogs, birds, and turtles. The whole mass is usually attached to a twig in the pool. A salamander egg mass has many fewer but bigger eggs than a frog egg mass. The additional coating also make the mass look more solid and less fragile the frog egg mass.
A few weeks after being laid the eggs hatch. The tiny salamanders have feathery gills on the outside of their body. They live underwater for about four months before they grow legs, lose their gills, and climb on to land where they can live up to 20 years.
Although they are fairly common in the forests of Maine they are very hard to find. Grown salamanders spend most of the day hiding underground and under rocks and logs. At night they come out to eat insects, worms, and spiders or whatever they can catch. When they are threatened by animals like raccoons and skunks, hoping to make a tasty meal of them, the salamander secretes a sticky toxin from their back which convinces the predator to look for another meal.
You may find all of these creatures on your walk in the spring woods. In fact, if you take a look at the retention pond behind the Town Hall by the solar array you will find not only frog egg masses but a special surprise. I was there the other day with the kids from Arundel’s afterschool program run by Jenn Shea Director of Arundel’s Recreational Department. The children were excited to show me something I had nor ever seen before. Take a look.
Toad eggs!!!! Go check them out! You’ll soon be able to see frogs and toads from eggs to tadpoles with and without legs to young frogs that still have tails. Does it get any more exciting than this!!! While you are at the Town Hall go check out the trail. Jenn has installed a “Story Book Trail” you be able to walk the trails and stop along the way to read The Secret Pool a children’s book on vernal pools and those that live there. Thank you Jenn!!!!
Just remember not to disturb the egg masses. If you find some try to figure out if they belong to a frog or a salamander. Let me know what you find, take a picture, and send it to me at firstname.lastname@example.org . You may see it published in our next Newsletter. Until then get out and enjoy the woods. Spring is a time of fresh starts and rebirths not just for amphibians but all of us.
Last month we covered animal tracks and next month we’ll take a look at some beautiful early Maine wildflowers!