Pools, Frogs, and Salamanders: A Spring Night at the Outdoor Lab

Text and photos by Laura Gilmore (except as noted)

On a cool evening in early March that had begun to feel more like spring than winter, 25 Arlington Regional Master Naturalists (ARMN) gathered at the Arlington Outdoor Lab. This was the third year ARMN members were invited to witness one of the most exciting seasonal events in our local ecosystems: the emergence of amphibians beginning their annual breeding cycle. First reported on two years ago by Mary McLean, this iteration of the activity had less of a lecture component and a longer hike through the woods to provide many ARMN members a first-hand experience like no other.

Early spring is prime time for amphibian activity in Northern Virginia. As temperatures rise and late winter rains arrive, frogs and salamanders migrate from their upland forest habitats toward wetlands, vernal pools, and ponds to reproduce. Our goal for the evening was simple: walk the property and see which amphibian activity we could find, led by Neil Heinekamp and Jessica Leslie of the Arlington Outdoor Lab.

A Streamside Start

Our first stop was a small stream flowing through the Lab’s forested landscape. Even before reaching the water, the distinctive chorus of spring peeper (Pseudacris crucifer) calls filled the evening air. These tiny chorus frogs are often heard long before they are seen, their high-pitched peeping signaling that spring breeding has begun.

From the stream itself, we were excited to be shown the larva of a Northern two-lined salamander (Eurycea bislineata) that had been found earlier in the day. Salamander larvae resemble small aquatic lizards, complete with external feathery gills used for breathing underwater. Their presence in the stream hinted that amphibian reproduction was already underway across the property.

Life in a Vernal Pool

From the stream we continued to the meadow where we stopped by a nearby man-made vernal pool. Vernal pools are shallow, seasonal wetlands that fill with water during late winter and spring but typically dry out later in the year. Because they lack fish predators, they provide critical breeding habitat for many amphibians.

Here we found several gelatinous masses of eggs belonging to wood frogs (Lithobates sylvaticus). Wood frog egg masses are often attached to submerged vegetation and can contain hundreds to thousands of developing embryos. Nearby, we also spotted an adult wood frog partially submerged under some leaves (bottom center of the photo).

Among the other discoveries was a larval spotted salamander (Ambystoma maculatum), likely from the previous year’s breeding season. Because salamander larvae can sometimes overwinter in pools that remain wet, finding larger larvae alongside fresh egg masses offered a fascinating glimpse into overlapping generations within the same habitat.

Activity at Hunsucker Spring

Next, we visited a historic area on the property known as Hunsucker Spring, where water had collected to form a small seasonal pool. This stop proved to be one of the liveliest amphibian sites of the evening.

Several wood frogs were actively attempting to mate. During the breeding season, male frogs grasp females in a behavior known as amplexus while the female releases eggs in a mass into the water. The male releases sperm to fertilize the egg mass as the female lays it. Unlike the wood frogs, male salamanders drop packets of sperm called spermatophores on the vernal pool floor for females to take into their bodies to fertilize their eggs.

We found both wood frog egg masses and clusters of spotted salamander eggs attached to submerged sticks and vegetation. Spotted salamander egg masses often appear as clear or milky globes suspended in the water..

Occasionally, a spotted salamander would briefly emerge from the water before quickly burrowing down into leaf litter or soft sediment to escape the beams of our flashlights. Their secretive nature and nocturnal habits make sightings particularly exciting, even when they are only fleeting glimpses.

Champ’s Pond Discoveries

With excitement running high by this point, we continued on to Champ’s Pond, located behind Stryker Cottage on the Outdoor Lab property. Larger and more permanent than the vernal pools, this pond supports a wider variety of aquatic life.

Here the chorus of spring peepers was near deafening. Our guide showed us some exciting finds collected from Champ’s Pond earlier in the day. We observed another larval Northern two-lined salamander and an adult Eastern newt (Notophthalmus viridescens). Eastern newts have one of the most complex life cycles among local amphibians, transitioning through aquatic larval stages, terrestrial juvenile “eft” stages, and finally returning to the water as adults. All newts are a specialized subfamily of salamanders that have rough, warty skin and live primarily in water as adults, whereas other salamanders have smooth, moist skin and are largely terrestrial or burrowing.   

The pond also revealed various tadpoles and a variety of aquatic macroinvertebrates moving through the water column. These insects and other invertebrates play an important role in pond ecosystems, serving as both predators and prey within the aquatic food web.

Spotlight on our Spotted Friend

To conclude the evening, we returned to the Lab building where we were able to observe a spotted salamander up close.

With its glossy black body and distinctive yellow spots, this forest-dwelling amphibian is a signature species of vernal pool habitats throughout the Eastern United States. Spotted salamanders spend most of the year hidden underground in forest soils, emerging only briefly during early spring rains to breed.

Seeing one clearly at the end of the evening felt like the perfect finale to a night spent exploring the hidden amphibian life of the Arlington Outdoor Lab.

Signs of Spring

Excursions like this highlight the importance of intact forest and wetland habitats for amphibians. Vernal pools, streams, and ponds, as well as the surrounding woodland, form an interconnected system supporting these species. Many amphibians, such as the spotted salamander and wood frog live underground in moist forest soils or beneath logs and leaf litter for much of the year. These cool, shaded environments help them avoid drying out and provide abundant insects and other prey. Each spring, they migrate from the forest to nearby vernal pools and ponds to breed, making healthy forests just as important as wetlands for their survival.

For naturalists willing to venture out on cool, damp evenings in early spring, these habitats reveal a remarkable seasonal phenomenon. Beneath the forest canopy, a quiet but essential cycle of migration, breeding, and renewal is unfolding, one chorus of spring peepers and cluster of eggs at a time.

ARMN Support of the Arlington Outdoor Lab

ARMN appreciates its ongoing relationship with the Arlington Outdoor Lab. The Lab is a 311-acre outdoor education center in Fauquier County, Virginia that partners with Arlington Public Schools. The property includes forests, streams, ponds, and wetlands that provide hands-on environmental education opportunities for thousands of students each year. Its diverse habitats also make the site an excellent location for observing wildlife and seasonal ecological events like amphibian breeding.

ARMN members and interested members of the public have the opportunity to support the Lab during volunteer work days (shared via the Lab’s volunteer email list). The Lab welcomes ARMN and members of the public to visit the site on April 18 for their Spring Open House from 10:00 am to 2:00 pm.