®
Spring 2016
Northbound
A Forum for Natural Resource Issues and Education
Volume 33, Issue 2
Let’s Get Hopping With the Frogs of Wisconsin!
blanchard), Boreal Chorus Frog (Pseudacris maculata),
Spring Peeper (Pseudacris crucifer), Copes Gray Treefrog
(Hyla chrysoscelis), and the Gray Treefrog (Hyla versicolor).
Introduction
The last group is the Toads, with only one member, the
It’s that time of year again! The trees are starting to bud
American Toad (Anaxyrus americanus). (1) Most frogs and
out. Birds are coming back. The north woods are waking
toads are found statewide, while some are found in as few as
up from its cold sleep. You may be hearing sounds that
three southern counties. This phenomenon can be explained
have been absent for a while. Maybe the sounds that you are
by the preferred habitat of the particular species.
hearing belong to a frog or toad.
What are the differences between frogs and toads? The
There are many animals that are not hard to recognize on
following chart can help distinguish.
sight. The frog or toad is one such animal. The difficult
The life cycle of frogs and toads are as varied as the
part may be properly identifying a species of frog or toad.
species. The shortest breeding period belongs to the wood
What color is it? Does the specimen have wart like bumps?
frog (Lithobates sylvatica), starting just after frost-out and
How large is the tympanum, (the large oval
only lasting about two weeks.
on the side of the head used to hear sounds)
The other species’ breeding
compared to the eye? Does it have a specific
period may last several months,
pattern on its skin? How large or small is the
with the metamorphosis taking
specimen? These are all characteristics that
up to two years, as is the case of
give clues to the identity to what is seen.
the American toad (Anaxyrus
Frogs belong to the Class Amphibia, which
americanus).
also includes salamanders. Amphibians spend
When frogs or toads mate, the
part of their life in water and the other part
male will climb on the back of
on land. This dual habitat existence may make
the female in an embrace called
them susceptible to a wide variety of pollutants.
amplexus. This may last several
This may also account for their population
days and usually takes place in
decline over the past several years. Frogs also
water. While in this position
belong to the Order Anura, meaning tailless.
the male will fertilize the eggs as
They are sometimes referred to as anurans.
they are laid. Frogs and toads
lay several hundreds of eggs
Wisconsin Species
at a time because of the many
There are twelve species of frogs found
dangers between fertilization
in Wisconsin. They are divided into three
and adulthood. The eggs will
categories as follows: True Frogs including the Photo Credit: Trees For Tomorrow
then hatch somewhere between
American Bullfrog (Lithobates catesbeianus),
6 and 21 days. The next stage in
Green Frog (Lithobates clamitans), Pickerel Frog (Lithobates
development is the tadpole. On average, 7 to 10 days after
palustris), Northern Leopard Frog (Lithobates pipiens),
hatching, the tadpole will begin to swim around and feed on
Mink Frog (Lithobates septentrionalis), and the Wood
algae. By the ninth week the tadpole will see the sprouting
Frog (Lithobates sylvatica). The second group is the Tree
of little legs. As the legs develop the tail will disappear.
Frogs, which include the Blanchard’s Cricket Frog (Acris
Twelve weeks have passed after hatching and the tadpole has
only a short stub tail left. It looks more like an adult. By 12
to 16 weeks the frog has completed the full life cycle ready to
Frogs
Toads
start the process all over again. (3)
By Vern Gentele
TFT Education Outreach Teacher
Two bulging eyes
Have a paratoid (or poison) gland
behind the eyes
Strong, long, legs with webbed feet Short legs and stubby bodies
for leaping and swimming
making them walkers
Smooth or slimy skin because
of their preference for moist
environments
Warty and dry skin
Lay their eggs in clusters
Lay their eggs in a long chain
Have a more massive chest
cartilage
Declining Numbers
Herpetologists, people that study amphibians and
reptiles, first started to notice a decline in the number of
amphibians in the early 1980s. At this point it was not taken
seriously. There was no cause for concern they agreed. By
the 1990s, not simply a local decline, but a global decline
was being noticed. This decline over-stepped any argument
of normal population fluctuation. (4) What is the reason
for this decline? Finding the answer is not that simple. It
Northbound
Spring 2016
is a combination of many factors such as alien or nonnative species competition, over exploitation (specimens
collected and sold as pets), habitat alteration and destruction,
global changes (climate, UV-B etc.), infectious diseases,
and pesticides and toxins. Frogs and toads are considered
to be indicator species to the health of the environment
because of their dual citizenship on land and water. The
last two mentioned
possibilities for
decline are most
significant because
frogs and toads
have delicate skin
that readily absorbs
toxins from their
environment.
Citizen Science
How can you get
involved? There is
a way that does not
take a lot of time or
energy and is actually
fun.
Beginning in 1984,
the Wisconsin Frog
Photo Credit: Trees For Tomorrow
and Toad Survey
(WFTS) was begun
by the Department of Natural Resources to monitor the
declining numbers of frogs in the state. It is now one of
the longest running amphibian monitoring projects in North
America.
The WFTS uses the calls of the different frog and toad
species to develop a relative number count. The males of
each species, as a sign that they are ready to mate, make the
calls. There are typically three time periods when the calls
are made. Early season breeders begin to call when the water
temperature reaches about 50 degrees Fahrenheit. They will
breed in temporary bodies of water that dry up by mid-July.
Their offspring develop quickly in these bodies of water.
The time frame of the early breeders is March through early
June. The second group of breeders become active as the
water temperature reaches 60 degrees Fahrenheit, late April
through mid-July. The final group of breeders begin in late
May and are usually completed by mid-August. By this time
of the summer the water temps have reached 70 degrees
Fahrenheit.
Volume 33, Issue 2
In order to complete the survey the observer must be
able to identify each species of frog or toad by its call.
Like songbirds, the call of each species of frog or toad is
unique. The observer must be able to distinguish between
an individual call and multiple calls that might overlap. He
then gives the calls an index value of 1-3 based on the ability
to distinguish individual calls or a full chorus call. There
are phone Apps or
various recordings
to help with this
identification. A
couple of examples
include Reptiles
and Amphibians of
Wisconsin Field Guide
by Stan Tekiela, and a
phone app called Frog
Calls found on Google
Play Store.
The observer/
volunteer is given
an established
route. Each route is
completed three times
during the season
April 8 – 30, May 20
– June 5, and July 115. When the routes are
completed all of the information is to be sent in by August
15. Certain limitations are placed on when observations can
be taken. The survey should be taken after dark with wind
speeds less than 12 miles per hour. These limits allow for a
better control on the data recorded. For more information
check out the Wisconsin Frog and Toad Survey Website:
http://wiatri.net/inventory/frogtoadsurvey.
Conclusion
Like so many other animals in the world, frogs and toads
are unique and special. Their colors, markings, and sounds
bring out the curious child in all of us. Over the years many
hours of research and money has been donated to their
cause. While they may appear to be insignificant, the niche
they fill in an ecosystem could not be filled in the same
manner by any other creature. Do all that is possible to keep
them healthy and their population abundant. a
Sources
http://www.wiatri.net/inventory/Frogtoadsurvey/WIfrogs/
Vern Gentele joined the Trees for Tomorrow
education staff in July of 2015. Raised in
Washington State, Vern has always had a love
for the out of doors. His education took him in
a different direction however. He received a
Bachelor of Science in Education from Dr. Martin
Luther College, New Ulm, MN, taught for thirteen
years then left the teaching field. He worked in a
factory and found it unfulfilling and returned back to
school to pursue his long time dream. Graduating
from Fox Valley Technical College in 2015, he
earned an Associate Degree in Natural Resources.
With a love of teaching and a desire to learn more,
Vern is excited to be part of the Trees for Tomorrow
staff. Vern can be reached at (715) 479-6456, ext.
235, or [email protected].
http://allaboutfrogs.org/weird/general/frogtoad.html
http://allaboutfrogs.org/weird/general/cycle.html
http://animals.about.com/od/amphibians/qt/amphibiandecline.htm
Northbound, a forum for natural resource issues and education, is published
four times during the year by Trees For Tomorrow, Inc., Eagle River, Wisconsin
as a subsidiary of the quarterly newsletter, Tree Tips. Please send comments
or suggestions to the editor at [email protected] or call (715)
479-6456. Printed April 2016.