By Allen Crabtree

Senior Rambles Columnist

The honking of geese overhead on their flight north and the calls of the male wild turkeys down back who are seeking a mate are all familiar sounds of spring returning to Maine.

For me, however, the most significant sign that spring has come is the nearly deafening frog chorus of Spring Peepers (Pseudacris crucifer) from the Vernal Pool across the road from our farmhouse. They have a loud and piercing peep that rises slightly in pitch from the beginning to end, and distant choruses sound like the jingling of sleigh bells.  

Other than enjoying the Spring Peeper chorus, I’ve never paid much attention to these very vocal signs of spring until I listened to Loon Environmental Association’s Alana Doughty and her great talk on Vernal Pools at Senior College at Bridgton last term.  She talked about what a Vernal Pool is, how to recognize one, why they are important, and the animals that depend on them for their very life cycle.  

Vernal Pools are naturally occurring, shallow depressions that hold water from snow melt and spring water run-off for part of the year, and often dry up in summer.  They provide the primary breeding habitat for Wood Frogs, Spring Peepers, Blue- Spotted and Spotted Salamanders and Fairy Shrimp and provide habitat for other wildlife including several endangered and threatened species. Many amphibian species are pool specific and must return to the pond in which they were born in order to breed. Juvenile and adult amphibians associated with Vernal Pools provide an important food source for small carnivores as well as large game species. 

A Ramble in the Woods

During the “stay at home” orders imposed as we all cope with the Corona virus, I have kept myself busy doing the annual pruning of our blueberry bushes. We do this every spring, while the bushes are still dormant from the winter, and were able to start in mid-March this year. I’m making good progress on the 40 rows and 1,500 blueberry bushes that need attention. The pruning gets me out of doors and busy, and I am also by myself so there are no problems with social distancing – it is just the blueberry bushes, me, my nippers and my MP3 often playing Leonard Cohen.

It was a sunny day on Tuesday, March 31 with temperatures in the low 40s, so after pruning several rows of blueberries I played hooky. It was too fine a day not to stretch my legs a little and take a stroll down through the woods behind the house. I swapped my nippers for my camera and headed out on a mission to get some exercise and possibly also find a Vernal Pool. 

When we first moved to the farm 22 years ago, I cut a cross-country ski trail through our woodlot below the blueberry fields and then following old skid trails to make a two-mile loop. Later, my neighbor Alan Greene kept the trails brushhogged out and groomed them for the snowmobile club.  

It has been a few years since I have skied the trail, and Alan no longer brushhogs and grooms it, so it has grown up into pioneer species – blackberries and sweet fern. I found that following the deer trails was much easier hiking because of the now waist-high growth in the ski trail. When I got to the junction where the private Greene-Crabtree trail joins the snowmobile club trail, I was pleased to see that the club had mowed their trail and the way was much easier hiking.  

Vernal Pools

As I rambled along, I checked out several small ponds of snow melt to see if they might be Vernal Pools. I know from hiking here before that many of these dried up in the summer. No frog sounds and no frog eggs – too early I thought.

I was enjoying the sunny day and being out by myself when I heard a lone Wood Frog (Rana sylvatica) croaking off the trail. They make a duck-like cackling: ca-ha-ha-ac, ca-ha-ha-ac, ca-ha-ha-ac, and from a distance, a chorus sounds like a gathering of miniature ducks quacking. This was just one frog, by himself, but he was persistent in his calls.

Following the sound of the lone frog croaking, I discovered a delightful pool about the right size to fit the definition of a Vernal Pool, about one to two feet deep, tucked away off the trail and surrounded by hardwood trees.  As soon as I got to the edge of the pool, the frog stopped croaking and was silent. This small pool looks just like the Vernal Pools that Alana had described, and I walked around it but I could find no egg masses. Still too early in the spring I would guess. 

I was in the back yard last night, April 5, 2020, when I was overwhelmed by the very loud chorus of Spring Peepers from the Vernal Pool across the road from our house. That was my wake-up call that spring had been coming along while I’ve been pruning blueberries, and it was time to check for frog eggs. So, a week after my first trip to the woods, Denmark Mountain Hiker Mary Lou Moulton and I came back to see how things were progressing.  

The first pool I’d stumbled upon last week was quiet – no frog sounds and no frog eggs. However, we were delighted to hear a loud chorus of Wood Frogs at a second Vernal Pool, not far from the first one I had discovered on my earlier hike. This pool was a little larger and was surrounded by hardwoods and some white pine and had a number of wetland shrubs growing on the margins. The pool was large enough so that the frog chorus kept up as we got closer, and I saw a frog or two jumping into the water.  I walked completely around the pool and didn’t find any egg masses, but again the weather has been cool. Perhaps in another week when spring continues to come to Maine it will be time.

I hiked back home and plan on revisiting the pools as spring and warmer weather come on. Perhaps I’ll wander out there at night to see if the Spring Peepers are there and in chorus.  

I would recommend, on your walks in the woods to get some needed exercise and fresh air from Corona virus confinement, that you keep your eyes and ears open to the sounds of spring that frogs bring. If you would like more information on Vernal Pools, the Loon Environmental Association (LEA) can be contacted at their website mainelakes.org