by Edin Sisson and Alaine Zhang
are three main groups that Amphibians are categorized into; urodeles, anurans,
and gymnophiones. Urodeles are composed of newts and salamanders, anurans
include frogs and toads all of which are vertebrates. Gymnophiones are also vertebrates but have no
limbs, and are otherwise known as caecilians. Amphibians are one of the oldest
types of vertebrates and are distinctive because they live on both water
and land at some point during their lives. Frogs and toads spend their early
stages of development with gills, and then develop lungs and limbs to be able
to survive on land as well. This unique development is what makes vernal pools,
swamps, and shallow areas of ponds such great habitats for them to live. In
addition to lacking hair and laying eggs, frogs and toads are exothermic,
meaning their internal temperature is externally regulated by factors such as
the sun. Frogs and toads are active during the spring and summer and hibernate
during the rest of the year, usually in the mud of ponds. What we hear most
frequently in the spring are the male mating calls, sung to attract females.
The males fertilize the eggs after they are laid, during a process called
external fertilization. In order to gain the upper hand over other males during
mating season, they practice amplexus, in which they climb onto the female and
wait for her eggs to be laid so that they can be the ones to fertilize them.
Depending on the frog species, mating happens at different times during spring,
the duration fluctuates as well depending on factors such as temperature and
climate. There are some key differences between true frogs and true toads. True
frogs are skinny with smooth, slimy skin and long legs. They leap and jump
fairly long distances, and they have an upper jaw with small teeth. Frogs also
lay eggs in large, often round, clusters. Toads, on the other hand, are
generally warty and dry, live mostly on land, have fat bodies with short legs,
and don’t hop that far. They also do not have teeth and lay their eggs in long
strands rather than clumps.
Vernal pond at White
While exploring both Avalonia’s Pequotsepos Brook Preserve and White Cedar Swamp, we heard three main species of frogs: The Spring Peeper (Pseudacris crucifer), the Green Frog, (Rana Clamitans), and the Pickerel Frog (Lithobates palustris). Spring Peepers are small frogs active from the end of the winter until the late fall and the most abundant frog species that we heard at our Avalonia sites. The Green Frog is a green or brown colored frog that feeds on insects as well as small amphibians. Green Frogs usually mate in April and early May but can continue into the summer months. Their call sound similar to the buckling of a banjo, which we heard during our final visits to White Cedar Swamp. Finally, we heard the Pickerel Frog at Pequotsepos Brook Preserve, which is a medium-sized frog with a lower-pitched call. It is also dark-colored somewhat rectangular dark spots and yellow or orange on the underside of its legs.
We performed research on the intensity of frog calls this spring under the protocols of the national Frog Watch USA organization. This organization calls upon trained volunteers all over the US to collect data on local populations of frog species and use it to monitor population decline, environmental changes, and potentially make positive steps to protect species countrywide. With the mission statement of Avalonia being to “[preserve] natural habitats in southeastern Connecticut by acquiring and protecting lands and by communicating the value of these irreplaceable resources,” these goals align extremely well, especially when applied to the conservation of the wetland habitats that Avalonia protects. By monitoring frogs on Avalonia’s lands, we can observe and analyze behavioral and population changes that could correlate with environmental concerns that negatively impact the ecosystems we cherish.
“Frogwatch Training Manual.” FrogWatch USA, www.aza.org/frogwatch?locale=en.
Marshall, John. “Indicator Species: Using Frogs and Salamanders to Gauge Ecosystem Health.” GRIT: Rural American Know-How, 2021, www.grit.com/departments/indicator-species-zm0z13jazgou/.
Mosseso, John J. “Green Frog.” Connecticut Frogs and Toads, NBII, wildlifeofct.com/green%20frog.html.
“Pickerel Frog.” Virginia Herpetological Society, Virginia Herpetological Society, 2021, www.virginiaherpetologicalsociety.com/amphibians/frogsandtoads/pickerel-frog/pickerel_frog.php.
Signs of the Seasons: A New England Phenology Program, The University of Maine Cooperative Extension, extension.umaine.edu/signs-of-the-seasons/.