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Stories from the NFCCA Newsletter, the “Northwood News”

Northwood News ♦ April 2013

Froggie (and Toad and Newt) Go A Courtin’ in the Vernal Pool

By Carole Ann Barth

For humans, spring symbolizes new beginnings as harsh winter gives way to milder temperatures and longer days.  It’s easy to see why.  For much of human history, people barely eked out a living during the dark, cold portion of the year.  If you and your livestock survived the winter, that was cause for celebration.  Newly sown crops and newly born animals held the promise of future sustenance and income.  So it’s not surprising that lambs, eggs, chicks, and bunnies are all icons of spring.

In the wild, however, amphibians are the true harbingers of spring.  Starting at the end of winter, often with snow and ice still on the ground, these cold-blooded creatures begin to breed.  Species by species, amphibians come out of their winter homes and make their way back to the vernal pool of their birth.  Most 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 in early spring and you can hear the chorus — the quacking of the wood frogs, the cricket-like call and response of the spring peepers, the sweet chiming of the tree frogs, and the loud, clear trill of the toad.

‘Vernal’ is from the Latin ‘ver,’ meaning ‘Spring.’
The vernal pool fills only in the spring, from winter snow melt.

Only the salamanders remain silent in the midst of these nightly symphonic orgies.  So how do they locate potential breeding partners?  According to Mass Audubon:  “To begin with, most individuals in the area arrive at the breeding site on the same night.  The specific trigger for this coordinated migration is determined by a combination of factors, including ground and air temperature, humidity, barometric pressure, and darkness.  In general, the first rainy night over 45 degrees Fahrenheit, after the ground has thawed, is sufficient to trigger the migration.”

These mass migrations are called “big nights” or “grand migration” nights.  Once in the pool, the males gather in groups (called congresses).  They then perform an elaborate courting dance to attract the females.

So what makes vernal pools such a happening place for amphibians?  A vernal pool does not hold water year round.  Without constant water, fish cannot survive.  So, if you’re an amphibian in need of a place to lay your eggs, and you don’t want fish to eat your eggs, a vernal pool is the perfect place.

For more information on vernal pools and the animals that depend upon them, visit:  www.vernalpool.org.  To hear (and see) video of frogs calling, view this YouTube video from Illinois.   ■

More on Our Vernal Pool

   © 2013 NFCCA  [Source: https://nfcca.org/news/nn201304d.html]