Archives of The Cold Blooded News

The Newsletter of the Colorado Herpetological Society

Volume 29, Number 8;   August, 2002

Spring Frenzy

by Mark Tegges

I had visited this same area two nights ago, but there was not a sound. Upon arriving tonight, however, I am not disappointed. The noise is so intense, it is almost deafening. Standing by the edge of this pond, barely an acre in size, I observe hundreds of tiny frogs "calling" from the floating vegetation. These minute frogs, barely an inch long, are appropriately named spring peepers. The males can easily be seen with throats extended, making their characteristic high-pitched peeping sound.

Spring peepers belong to a group of amphibians known as tree frogs, which have toe pads or small suction cups located on the ends of each toe. These pads enable the peeper to climb and inhabit areas not obtainable to most frogs. The ability to climb gives tree frogs an added advantage in chasing their favorite food item, insects.

To find a spring peeper at any other time of the year is like looking for a needle in a haystack. During the summer months they disperse into the surrounding woods and live among the moist leaves of the forest floor. Basically brown in color, with a darker brown or black "cross" marking on its back, this frog is difficult to find. But now, these tiny amphibians appear in large numbers around the pond. The sole purpose behind this large gathering is for the reproduction of the species.

The peepers, however, are not the only visitors this night. Wood frogs, in large numbers, appear in the deeper, center portion of the pond. Wood frogs are the earliest frog breeders and are known to lay their eggs while ice is still on the pond. The males were here earlier, but tonight they have decided to make their presence known. The lowpitched, quacking sound produced by the males is in sharp contrast to the peep of the spring peepers.

Wood frogs are members of the "true" frog family and in appearance resemble the frogs we all recognize. They vary in color from shades of light to dark brown and sometimes gray. They all have the characteristic dark masks around the eyes and their body length varies from two to three inches; females are generally larger.

The males of this species arrive first to the pond. They group together in a central area in prime egg-laying sites and begin calling to attract females. When a female arrives within reach, the male actually pounces upon her and mounts onto her back. This is known as amplexus. Nature has provided the males with suction pads (known as nuptial pads) along the sides of the front legs, which aid the male in holding on. The pads are quite visible and are only found on males during the breeding season. The female usually deposits her eggs within hours after amplexus and the eggs and sperm are shed simultaneously.

Wood frogs are community egg layers. A single egg mass consists of hundreds of eggs surrounded by a single jelly-type mass. A community egg laying site may contain twenty or more separate egg masses grouped together to form one huge mass of eggs; sometimes eight to ten feet in diameter. Tonight, wood frogs can be seen laying eggs within inches of one another, forming this large community egg mass.

This egg laying behavior is quite different from the spring peeper's method. The males will amplex the females similarly, but peepers produce large numbers of single eggs randomly throughout the pond. Each individual egg is encased in its own jelly mass and is laid in the shallower areas of the pond. Wood frog and peeper eggs generally develop at the same rate. Within a few months their tadpoles will be seen swimming about.

Standing in the middle of the pond literally surrounded by hundreds of frogs, I observe a new group of amphibians arriving on the scene to reproduce - the spotted salamanders. These fairly large salamanders are strikingly colored, black with bright yellow spots extending from the tops of their heads down to the tips of their tails. These animals also arrive in great numbers. On this cool, rainy evening, hundreds of individuals can be seen lumbering from their wooded retreat toward the pond. It is an unbelievable sight! These amphibian burrowers live under rotting logs and tunnel into the earth most of the year, but tonight they are quite conspicuous.

Salamanders do not vocalize and their breeding activities are quite different from the frog's. Male spotted salamanders arrive a few days before the females to deposit on the bottom of the pond a sperm capsule called spermatophore. The sperm capsule is attached to an anchoring structure, laid firmly onto a submerged leaf or twig. Later the females arrive, and after a brief courtship "dance" with the male, the female actually picks up the sperm with her cloaca and fertilizes her eggs. The eggs are then attached to a submerged twig or branch.

Many species of amphibians will utilize this same pond for reproduction throughout the year. If it weren't for the fact that different species breed at different times of the year, this pond would soon become choked with tadpoles and salamander larvae. Fortunately, amphibian breeding cycles are staggered to obtain maximum use of the limited space and food sources. While some species of tadpoles are transforming into frogs, others are just laying their eggs or the eggs are just beginning to hatch. The large number of eggs laid by each individual frog or salamander, coupled with the many species utilizing this same pond, make it easy to comprehend what could happen if they all bred at the same time. It is a delicate cycle, timed perfectly to benefit all of the amphibians utilizing this same niche.

While photographing a male spring peeper calling from a floating leaf, I notice a few red-spotted newts crawling on the bottom of the pond close to my feet. I realize this is a pair of newts. The male is a handsome creature, green in color with bright red dots along his sides extending from the neck to the tail. Males have broader tails and larger hind legs than females.

Seeing this pair together tonight is a real coincidence, for newts will not reproduce until later in April. When newts become reproductively active, the male shows a unique courtship display. Approaching the female, he clasps her around the neck with his hind legs (equipped with nuptial pads) and begins to fan odorous substances towards her snout with waving tail movements. He then dismounts and the female follows him and butts her snout against his tail. This will signal the male to deposit, on the floor of the pond, the spermatophore. He will then raise his tail, deposit the sperm packet, and lead the female directly over the sperm where she will "pick up" the packet and fertilize her eggs. She will then attach her eggs, singularly, to surrounding aquatic vegetation. Larvae will hatch from the eggs, and by late summer, will lose their gills and transform into young newts, known as efts. They will leave the water and spend one to three years on land. Efts are red and have thick, rough skins. They are often encountered in the woods, especially after rains. When mature, efts will change from red to a greenish brown, return to the water to breed, and will remain there for the rest of their lives. Seeing the pair of adult newts tonight is an unexpected pleasure.

Along with the newts, another April breeder in this pond is the American toad. While the wood frog, peeper and the spotted salamander larvae are on their way to becoming adults, the toad is just beginning to breed. Like the wood frog and peepers, male toads arrive first and begin calling to attract females. The mating calls of the male chorus may be audible for up to a mile. Their vocal sacs serve as resonators for their characteristic melodious calls. Males use their front limbs to clasp attracted females and may cling to a female for days, until she lays her eggs -- typically -- in a pair of long and twining gelatinous strings. American toads may lay as many as 25,000 eggs in a single clutch, probably more than any four-legged creature in the world.

After the various courtships are completed, the pond remains fairly quiet during the summer months. An occasional gray tree frog can be heard in June or July, but their breeding activity is less obvious as the peeper's "spring frenzy." It is during the summer that the pond begins to shrink in size and lose much of its substance to the water table below. Only the deeper pools remain, and it is in these pools that the green frogs stake their claim.

Male green frogs have a pair of vocal pouches, which protrude simultaneously as they are croaking. Their voice is similar to the sound made on the lowest banjo string. A single note is used and repeated three or four times; the last two notes fading in intensity. Eggs are laid on top of the water in a flat, round floating mass, spaced randomly throughout the deeper pools. Tadpoles hatch later in the summer, and spend the winter in the pond, transforming into frogs by the following summer. Green frogs obtain a body length of three inches and are quite common in Maryland.