Spring in the Sourlands: The great amphibian migration!

Why did the frog cross the road? To find love in vernal pools!

Ever since I began working for the Sourland Conservancy four years ago, I have been waiting for this moment. I think that even though I have a mask on, you can clearly see my utter and complete delight in what is happening. What is happening? The amphibians of the Sourlands are migrating to their vernal pools and I finally got to see a Spotted Salamander, Ambystoma maculatum!!! I don’t think I can truly convey how excited I was to be part of the Sourland Amphibian Crossing Guard program. I would label myself a plant nerd, but I have a real soft spot for my amphibian friends. Catching frogs and red-backed salamanders was a favorite past time of mine growing up. It is still a favorite past time that I regularly share with my lovely wild boys. This blog post will be a little different than the usual because I want to share some stories from my fellow amphibian crossing guards. We are a group of nature lovers that run out the door on rainy “warm” (45 degree F) nights in February, March and sometimes April to witness the Amphibian migration across roads, help usher them to safely and document those who made it to safety and those who unfortunately do not.

Wood frog – photo by Carolyn

During the winter, amphibians of all kinds hibernate and those first “warm” spring rains in late February and March wake them up and stir the deep primal urge to procreate. Amphibians return to their vernal pools every spring to find mates and interestingly enough they almost always return to the vernal pool from which they came. Vernal pools are critically important for amphibians because vernal pools do not support resident fish populations which would devour all of the frog and salamander eggs. Unfortunately, having a vernal pool alone is not enough. The habitat around the vernal pool needs to have high quality forest cover. The poor drainage of diabase rock on the Sourland ridge provides for many vernal pools and the large contiguous forest provides an excellent forest canopy.

Spring peeper – photo by Carolyn

The amphibians that the Sourland Amphibian Crossing Guards typically cross are Wood frogs, Rana sylvatica, Green frogs, Lithobates clamitans, Spring peepers, Pseudacris crucifer, American toads, Anaxyrus americanus, Red backed salamanders, Plethodon cinereus and Yellow spotted salamanders, Ambystoma maculatum. During the rainy spring nights, hundreds to thousands of these amphibians migrate to their vernal pools and unfortunately for some populations, a road lays between their adult habitat and their breeding habitat. The Sourland Conservancy always encourages folks to stay home on these rainy nights. Studies have shown a relatively low traffic rate of 1 car passing through a migration area every 4 minutes can wipe out 70% of the population of breeding amphibians. Each female wood frog holds almost 2,000 eggs and a female Yellow spotted salamander can lay 200 eggs. Frogs and salamanders are food sources for many other animals and birds, so if their population size is greatly reduced due to road mortality, it could have a profound impact on the rest of the forest community. I am continually impressed with the dedication and enthusiasm of the Sourland Amphibian Crossing Guards. They truly are the guardians of the night.

Thoughts from Sourland Amphibian Crossing Guards

Photo by Bruce Michael

“I have participated in the amphibian crossing now for several years. I think I might be known as “the Old Guy”. It’s always amazing to see a creature like the Spotted Salamander that stays hidden underground all year, except for those first warm rainy nights of late winter and early spring when they emerge after dark to somehow travel to and find the vernal pools, along with the Spring Peepers and Wood Frogs.  Truly one of the amazing feats of nature. It never gets old for me” – Bruce Michael

Photo by Yvonne S.

“I had no knowledge of spotted salamander and wood frog migrations until the end of spring 2019. These animals are doing what they have done for centuries but now local populations are in danger of being wiped out by traffic. Volunteers can help save these populations by standing on roadsides in the dark, wet, miserable, cold nights of early spring? Sign me up! Watching a salamander wiggle or a wood frog hop itself across a road so focused on the directions its internal compass is providing is fascinating. Being able to gently lift it out of the way of danger for a brief moment so it can finish it’s journey? Priceless. Doesn’t hurt that these critters are absolutely adorable!” – Yvonne S.

Photo by Ann P.

“It was an amazing night and all that joy and wonder carried through the whole day today. I am very blessed to have been a part of it.” – Carolyn Wolfermann

Photo by Eric Teitelbaum

“It’s hard to put a finger about what feels so special about the Sourlands, but somehow the concept of a ridge with such ecological diversity and in tact hardwood forests existing in the middle of New Jersey adds to its draw. We saw so many salamanders last night that it was almost hard to walk at times and safely keep an eye on the amphibians in our vicinity. These moments were concentrated to a rain event from about 8:30 – 9:00 PM, and thankfully no cars came through at that time. But it really demonstrated ecosystem fragility, since in those moments a car would have wiped out an enormous fraction of the amphibians that crossed the road last night. We had no DOR at our location, but in our walk home up the road, there was a squashed female wood frog presumably from one of the three cars that passed throughout the night. But regardless, there are these critical moments on the order of minutes that without stewardship can really impact a species that has existed for geological time, and it was really inspiring to witness firsthand the culmination of all the planning and coordination efforts that went into last night. It was wonderful to be a part of.” – Eric Teitelbaum

The morning after our big night in the Sourlands, I took my littlest out for a walk in the woods to see how the frogs were doing. He was just as over the moon as I was the night before and wanted to hold “all the frogs”. I see a future Sourland Amphibian Crossing Guard!

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