Wood Frogs Thawing Out
It won’t be long before you see or hear a Wood Frog (Lithobates sylvaticus), one of the first frogs to emerge in the spring from its dormant state of brumation (similar to hibernation in mammals). Unlike most other frog species that have to overwinter underwater or below the frost line, Wood Frogs are able to survive just inches below the surface of the leaf litter.
The reason they can tolerate freezing temperatures is that their liver produces antifreeze-like glucose which is concentrated in vital organs and prevents ice crystals from forming that would injure the frog. Thanks to this adaptation, up to 65 % of the water in their body can freeze. Their heart stops beating, their brain and kidneys stop functioning, their respiration ceases and they become as solid as a rock during this period. However, with the onset of spring the frozen frogs start thawing and regain consciousness within 24 hours. Soon thereafter they head for their breeding pools.
N.B: For readers in the Northeast, tomorrow, Saturday, April 1, it’s supposed to be rainy and if it’s 40 degrees or milder conditions will be perfect for the”Big Night,” when Wood Frogs, Peepers, and mole salamanders migrate to breeding pools.
Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.
Amphibians On The Move
According to Jim Andrews, Director of the Vermont Reptile and Amphibian Atlas Project (https://www.vtherpatlas.org), the recent warm rain triggered a significant movement of many amphibians in the Lake Champlain Basin as they left their hibernation sites and migrated towards their breeding grounds. Blue-spotted Salamanders (& hybrids), Four-toed Salamanders, Spotted Salamanders, Eastern Red-backed Salamanders, Eastern Newts, Spring Peepers and Wood Frogs were among those seen emerging from their hibernacula.
Keep your eyes peeled on warm (40°+), rainy evenings and see if you discover a popular amphibian road- crossing location. Check local resources to see if there is a local volunteer group that assists these slow-moving migrants across the road. If not, you could start one yourself – be sure to wear reflective clothing, have a flashlight and report your findings to a local nature center or conservation organization. (Photo: Blue-spotted Salamander by Erin Talmage)
Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.
Spring Has Sprung!
March is the absolute high point in anyone’s life who anticipates and celebrates the annual celebration of the arrival of spring. For this reason, it is the first chapter in my book “Naturally Curious” – every day brings confirmation that no matter what is going on in the human world, you can depend on the natural world to observe the rites of spring.
Mourning Cloak butterflies emerge from behind loose bark, migrating American Woodcock probe the mud, sleepy Eastern Chipmunks appear above ground, Red-winged Blackbirds return, Beavers see the sun for the first time in perhaps months, buds swell with newly accessible sap, Red Fox kits emerge from dens, Wild Turkeys mate, Spring Peepers peep, Painted Turtles emerge from hibernation and bask in the sun, Ruffed Grouse drum and Skunk Cabbage blooms.
For at least a few minutes a day, we can lose ourselves in the natural rhythm of life that surrounds us.
Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.
Spring Peepers Peeping
The peeps of male Spring Peepers can be heard fairly consistently this time of year. Unlike in the spring, these calls are coming not from bodies of water, but from the woods nearby. And they are single peeps coming from individual peepers, not the chorus of “sleigh bells” one hears in the spring. This phenomenon occurs so regularly in the fall that herpetologists have given it a name – “fall echo.” They speculate that the calling of peepers is spurred by light and temperature conditions that mimic those that occur in the spring, during Spring Peeper mating season.
Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.
Big Night Approaching
Every spring there comes a day when the temperature approaches or exceeds 45 degrees, and a gentle spring rain occurs and extends into the night.* These conditions signal the impending nocturnal migration of many amphibians to their breeding pools. Spotted Salamanders, Jefferson/Blue-spotted Salamanders, Wood Frogs, Spring Peepers and an occasional American toad rise from their state of hibernation to crawl out of the dirt and make their way to wetlands (often vernal pools) where they will breed and lay their eggs. So many migrate en masse that the first night that this migration takes place has been dubbed “Big Night.”
It goes without saying that in many cases, roads have to be crossed when going from hibernaculum to breeding pool. This poses a major threat to the frogs and salamanders that are on the move, and roads often become slick with their carcasses due to unwitting automobile drivers. If you are out driving on the first warm, wet evening this spring, drive slowly while keeping an eye out for lumps in the road, and if you see them and have a flashlight or head lamp handy (to find the frogs and salamanders, as well as to announce your presence in the road to other drivers), stop and lend them a hand (usually there are concentrated areas where crossings occur). (Perhaps a group of well-marked volunteers could gather to monitor and assist migrating amphibians at major road-crossing locations in your town.) It should be obvious which direction the frogs and salamanders are all headed in, and they can be placed well off that side of the road. (Photo: left to right, Wood Frog, Spring Peeper, Spotted Salamander)
*With one to two feet of snow on the ground and vernal pools still frozen over in many parts of northern New England, this event will most likely not occur with the impending warm, rainy weather, but will happen in the next few weeks.
Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.
Big Night!
A magical migration awaits all who take note of the first rainy spring day (in the 40’s) when the rain continues into the night. Last night these conditions resulted in what herpetologists refer to as “Big Night.” While snow still covers parts of the forest, there is ample bare ground that has warmed up enough to waken hibernating frogs and salamanders at this time of year. As if silently communicating with each other, thousands and thousands of these amphibians emerge from their subterranean hibernacula on the very same night and migrate en masse to their ancestral breeding pools, known as vernal pools. They avoid the lethal sun by travelling at night, in the rain. Unfortunately, many die, as they often must cross hazardous roads in order to reach the pool where they breed every year. If you are driving in these conditions, please keep an eye out for these jaywalkers and try to avoid them. Roads can quickly become slick with their squashed bodies.
How many Spring Peepers, Wood Frogs and Spotted Salamanders can you find in this photograph taken on Big Night? (There are six.) Thanks to the unbelievable generosity of Naturally Curious readers, this photograph was taken with my new camera and lens. I cannot tell you how deeply touched I am by your kindness and generosity.
Naturally Curious is supported by donations. If you choose to contribute, you may go to https://naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.
Young Spring Peepers Appearing
Every year in late July or August a young Spring Peeper crosses my path and I cannot resist photographing it. At this time of year they are roughly the size of a Japanese Beetle, and during early mornings and late afternoons can be found in shrubbery where they intermittently rest in the shade and feed on insects even smaller than themselves. If you live near a pond where it sounded like sleigh bells were ringing last spring, keep an eye out for these irresistible frogs that are no bigger than your tiny finger nail.
Feathered Fishermen
Using their keen eyesight and sense of hearing, Barred Owls typically sit and perch on a branch, surveying the ground beneath them for whatever morsel appears, small mammals and birds being at the top of their list during the winter, with more emphasis on amphibians, reptiles, fish and invertebrates during the warmer months.
Several times I have observed a Barred Owl taking advantage of a vernal pool that was teaming with life, specifically Wood Frogs and Spring Peepers. Perched in a nearby tree, the owl kept an eye out for any sign of movement in the water. When ripples appeared near the shore it would swoop down to the water’s edge in an attempt to grasp a frog with its talons. Although it met with repeated failure, success was inevitable due to the plethora of distracted mating frogs.
Because they lack hair and feathers, frogs may be underestimated when scientists dissect owl pellets to see what Barred Owls eat. Given the frequency with which I have observed these feathered fishermen, I would think that might be very likely.
Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.
Amphibians Migrating
Vermonters were witness to a record-breaking (early) amphibian migration in the Champlain Valley last week on March 1st, when night temperatures were in the low 50’s. Not only did it occur a week earlier than any other previous major migration, but records show that migration for the earliest amphibians in Vermont is now approximately two to three weeks earlier than it has been during the last decade. (as reported by Jim Andrews, www.VtHerpAtlas.org).
Spotted Salamanders, Four-toed Salamanders, Eastern Red-backed Salamanders, Blue-spotted Salamanders, Jefferson Salamanders, Spring Peepers, Wood Frogs and even an American Toad were on the move. According to Andrews, “this is a concern if the weather turns really cold and the ground and ponds refreeze. If that happens, many of the early migrants (that are not freeze tolerant) could freeze and die. If the weather stays relatively mild, with only short cold snaps, they should be fine.” Weather since these sightings has been unseasonably cold, and one can only hope they survived. (Photo: Spotted Salamander, Ambystoma maculatum)
Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.
Spring Peepers Dispersing
If you live near a pond where you heard loud “peeping” in late April or May, now is the time to keep your eyes peeled for young subadult Spring Peepers in the woodlands near the pond, for they are just completing metamorphosis and moving onto land. Thanks to their enlarged toe pads, peepers are good climbers but are usually found on the ground or low in shrubbery. The best time to look for young peepers is in the early morning hours and in the late afternoon, when they tend to feed. Even if your timing is right, it can be challenging to find one — a full grown peeper is only ¾” to 1 ¼” long, and recently metamorphosed individuals are not much longer than ¼”, about the size of your baby fingernail. You’ll know it’s young because of its diminutive size and its snub nose!
Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.
Green Frogs Mating & Laying Eggs
The loose banjo string call of the Green Frog is a familiar sound near wetlands this time of year. Males (to the right in photo, with bright yellow throat) have been busy serenading females (to the left in photo, with white throat), in an attempt to breed with one. Female Green Frogs select their mate, a choice which is based partially on the suitability of the male’s territory (underwater plants are a plus). After inspecting several males’ territories at night, the female chooses one and slowly approaches him, turning to face away from him as their bodies come in contact. External fertilization takes place as he clasps her while she lays her eggs (known as “amplexus”).
Unlike Wood Frog eggs that are laid in clumps, or Spring Peepers’ individually-laid eggs, Green Frog eggs are laid in a loose cluster that often floats on the water’s surface (see photo) or is draped on underwater plants. Each cluster usually consists of 1,000 to 5,000 eggs that hatch in three to five days. Females sometimes return to breed a second time with a different mate, in which case the second egg clutch is usually smaller, consisting of about 1,000 to 1,500 eggs.
The larval, or tadpole, stage of a Green Frog lasts from 3 to 22 months, which explains why you might have already seen large Green Frog tadpoles this summer.
(Outstanding theories were submitted on yesterday’s mystery. Be sure to read comments!)
Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button
Effects of Cold Weather on Breeding Amphibians
With spring peepers (pictured) and wood frogs just coming into voice, and some salamanders also having recently emerged from hibernation, there is concern for their welfare due to the erratic weather we are having. According to Jim Andrews, Director of the Vermont Reptile and Amphibian Atlas, the effects of this meteorological fluctuation depend on the exact climatic conditions experienced, as well as the species affected.
Wood frogs and spring peepers, as stated in a recent post, are well equipped to survive the cold weather. However, egg-laying has already taken place in some locations and if the eggs are exposed to the air, as opposed to being attached to a submerged branch or vegetation, and it’s cold enough, long enough, they will freeze.
Many of the mole salamanders, including spotted, Jefferson, and blue-spotted, are in the middle of migrating to or from their annual breeding pools. Faced with freezing temperatures, they retreat temporarily into the leaf litter and thawed soil beneath, a sheltered environment where they spend all of their life except the breeding season. An extended period of cold that freezes the ground would pose problems for these creatures, although Andrews has witnessed the survival of a blue-spotted salamander that sought shelter under rocks that were on top of frozen ground.
Many factors are involved in the effects of this phenomenon – how warm it was before the cold spell arrived (long enough for hibernating amphibians to emerge?), how low temperatures go, how long it remains cold, the species of frog or salamander, and where it is in its breeding cycle. The peeping and quacking we briefly enjoyed has been silenced, but not permanently and hopefully not for very long.
Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.
Wood Frogs & Spring Peepers On The Move
Although the temperature hovered around 32°F. last night in central Vermont, wood frogs and spring peepers were on the move. Usually it is above 40° or 45° before you see the earliest of our breeding amphibians, but a few hardy souls ventured forth to their breeding pools and ponds under cover of darkness and rain yesterday. Those that breed in vernal pools are in a hurry to take advantage of every day, as the eggs they lay must complete metamorphosis by the time their pool dries up, often in mid- to late summer.
Both of these species of frogs are freeze tolerant. Wood frogs are coming out of a state in which they haven’t taken a breath and their heart hasn’t beaten for several months. Prior to hibernation they convert glycogen in their bodies into glucose, a form of antifreeze that helps prevent the water within their cells from freezing, which would kill them. However, the water outside their cells does freeze. Amazingly, wood frogs can survive having up to 65% of this water frozen, yet when warm weather arrives, they thaw and move about in a matter of hours.
If you rescue these woodland amphibians that are crossing roads (where so many of them get run over at night) during their migration to their breeding pools, take note of the temperature of their body. Often they are still quite cold to the touch — colder than the air, even – which fortunately makes it difficult for them to move fast enough to escape your helping hands. (Photo: Amorous wood frogs getting a head start as they cross a road to get to breeding pool.)
Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.
Spring Peepers Peeping
The sound of a peeping Spring Peeper in December (yes, this occurred in Vermont this week) conveys to one and all that climate change is not a figment of our imagination. Amphibians are extremely sensitive to small changes in temperature and moisture due to their permeable skin and shell-less eggs. Certain species, including Spring Peepers, Grey Tree Frogs, Wood Frogs, American Bullfrogs and American Toads, are emerging and mating earlier in the year than they did historically. Causal relationships have been found between irregular climate conditions (drought, increasing frequency of dry periods and severe frosts) and decreasing (extinction in some cases) of certain amphibian species.
Behaviorally and physically, warming temperatures are having an impact on amphibians. A recent laboratory study investigated changes in amphibian metamorphosis time due to pond desiccation and whether amphibian immune systems become compromised as a result of these changes. They found that amphibian immune responses became increasingly weaker and white blood cell counts were increasingly lower with higher desiccation. As a result of climate effects, immune systems are weakened, making it more difficult for amphibians to fight off diseases.
Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.
Spring Peepers Calling
The peeps of male Spring Peepers can be heard fairly consistently this time of year. Unlike in the spring, these calls are coming not from bodies of water, but from the woods nearby. And they are single peeps coming from individual peepers, not the chorus of “sleigh bells” one hears in the spring. This phenomenon occurs so regularly in the fall that herpetologists have given it a name – “fall echo.” They speculate that the calling of peepers is spurred by light and temperature conditions, when fall climate conditions are similar to those of spring.
Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.
Spring Peepers Metamorphosing
Roughly two months ago Spring Peepers (Pseudacris crucifer) could be heard calling from temporary as well as permanent ponds, as males sang to attract mates. After mating took place, the females each laid hundreds of eggs, attaching them singly or in packages of two to three eggs to vegetation.
After hatching, it takes roughly two to three months for peepers to metamorphose into tiny, four-legged, land-dwelling adult frogs. They are now finding their way to shrubby growth and woodlands near ponds, where they are fairly well hidden in the leaf litter or on the lower leaves of shrubs. Here, in the shade, they feed on small insects and spiders. Roughly one-quarter-inch long at this stage, these small treefrogs will only reach one or one-and-a-half inches when fully grown. (For scale, Spring Peeper is sitting next to two red honeysuckle berries.)
Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.
Young Spring Peepers Now The Size Of Your Baby Fingernail
It takes roughly two months for Spring Peeper tadpoles to metamorphose into adults, and unlike other frogs, they don’t complete this process in the water. Young Spring Peepers leave their ponds at an earlier stage of development than most frogs – they have four legs and lungs when they come out of the water, but most of them also still have a tail which is absorbed shortly after they become land dwellers. Adult Spring Peepers measure roughly ¾” (males) to 1 ½” (females) in length. As you can see in this photograph, this fully metamorphosed young Spring Peeper is hardly bigger than a Japanese Beetle, and it has completely lost its tail, so it was even smaller when it hopped out of the water!
Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.
Spring Peepers Mating & Laying Eggs
The mating season for spring peepers lasts two months or more, and judging from the sound that is coming from ponds and woodlands these days and nights, it is in full swing. Once a singing male is successful in attracting a female, he mounts and clasps her while depositing his sperm on her eggs. She lays up to 800 eggs, either singly or in small groups, on plants within the male’s territory. The frogs remain joined (a position known as “amplexus”) for up to four hours. After egg-laying and fertilization is completed, the female peeper returns to the woods; the male remains at the pond and resumes singing.
Spring Peepers Emerging
Sitting on top of the snow, still as a statue, a spring peeper gathers strength to make the long trek to open water, where, if it is a male, it will exercise its voice for the first time in many months. Like the gray treefrog and wood frog, spring peepers can freeze as solid as a rock for several months during hibernation and then, on a warm day, thaw out in a few hours and resume a normal, active life. The formation of glucose and ice crystals that form outside of cells enable this phenomenon to occur. Once hibernation has come to an end, peepers seek out wetlands, vernal pools and ponds to breed and lay eggs before they return to their home on the forest floor.
Naturally Curious with Mary Holland 
What Other Naturally Curious People Are Saying