Stories from the NFCCA Newsletter, the “Northwood News”

Northwood News ♦ February 2009

Froggie Goes A Courtin’ ... in Our Vernal Pool!

By Carole Barth

In February, we celebrate romance with our valentines.  While we head out to buy cards and chocolates, frogs heed a different call.  Species by species, frogs come out of their winter homes and make their way back to the pool of their birth.  They don’t need an online service to find a mate; they simply call out and listen for a reply.  Walk down by the Northwest Branch and you can hear the chorus — from the quacking of the wood frogs, to the cricket-like call and response of the spring peepers, to the sweet chiming of the tree frogs.

Frogs use sound to identify which species is which, so they don’t waste their time pursuing an incompatible partner.  Just like birdsongs, these calls are distinctive enough that even humans can learn to identify who’s singing.  Of course, it helps to know what to expect before you head out frogwatching.  The National Wildlife Federation has a website [URL redacted; no longer active] where you can hear the songs of all 19 frogs found in Maryland.  [Editor’s Note:  Try The Frog Lady instead.]  To start, look at the chart of calling dates for common Maryland frogs and see which frogs are likely to be out and about now.  That way, you can concentrate on one or two songs at a time.

Calling Dates for Maryland’s Frog Species

Wood FrogXX
Southern Leopard FrogXXX
Pickerel FrogXX
American ToadXX
Spring PeeperXXXX
Western Chorus FrogXXXXX
Eastern Spadefoot ToadXXXXXX
Green Tree FrogXXXX
Fowler’s ToadXXX
Northern Cricket FrogXXX
Gray Tree FrogXXX
Green FrogXXX

Why take the time to listen to the frogs?  First off, it’s fun.  Anytime I come outside and plug in to the rhythms of the natural world, it always makes me feel better.  But there are also serious reasons for frogwatching.

Amphibians are considered good indicators of general ecosystem health.  Many amphibians lay their eggs in water and their offspring spend the first part of their lives in water.  Both amphibian eggs and skin are highly permeable, allowing them to absorb water and oxygen.  Unfortunately, this makes them especially vulnerable to pollutants which can also readily enter the body.  Amphibians also need upland areas where they can live as adults or burrow into leaf litter to overwinter.  Therefore, monitoring amphibian populations gives us an indicator for multiple habitats.

Amphibians play essential roles, both as predators and prey, in the ecosystems of the world.  Adult amphibians regulate populations of pest insects — those which damage crops or spread disease.  In the absence of fish, amphibians are usually the top predators in freshwater systems.  However, amphibians are also prey to numerous predators, including snakes, fish, birds, mammals, spiders, and even each other.  Consequently, amphibians influence the population dynamics of other organisms, as well as the cycling of nutrients and the flow of energy.

Researchers are also finding new product ideas from studying frogs.  Amphibians can provide vital biomedicines.  These include compounds that are being refined for analgesics and antibiotics, stimulants for heart attack victims, and treatments for diverse diseases including high blood pressure, potentially life-threatening fungal infections, stroke, seizures, and Alzheimer’s.  A manmade version of a molecule discovered in the egg cells of the Northern Leopard frog could provide the world with the first drug treatment for brain tumors.  The Australian red-eyed treefrog and its relatives give us a compound potentially capable of preventing HIV infection.

So this year, get hopping down to the vernal pool and open your ears.   ■

Editor’s Note:  To locate the vernal pool, enter the Northwest Branch Trail from the northern end of Lockridge Drive (between Belton Road and Glenwild).  Continue straight past the first bridge (don’t turn onto the bridge).  When the trail turns sharply to the right, don’t turn; instead, continue going straight, down the hill, to the shore of the Northwest Branch.  Turn right and travel about 10 yards.  The vernal pool (a large but shallow depression in the ground which fills up only during the spring) will be on your right.

More on Our Vernal Pool

   © 2009 NFCCA  [Source:]