Transcript Citizen Monitoring of Wisconsin’s Frogs

Frog, Toad, and Treefrog
Identification Guide
Citizen Monitoring of Wisconsin’s
Frogs
by
Wisconsin Audubon Chapters
Randy Korb, Project Director
Training Guides by Mary Linton
This guide will help you identify
the Wisconsin frogs, toads and
treefrogs that might be active during
salamander sampling. Two other
guides are also available: a guide
to Wisconsin’s salamanders, and a
guide to the Protocols for the citizen
salamander monitoring project.
The guides are in PowerPoint, a presentation software made by Microsoft.
You move through the guide by clicking your mouse or touchpad until you
see “THE END”.
There are many other good resources available, and we will list some
good sources at the end of this guide.
Purpose of this Project
• Wisconsin has a long-term and successful monitoring program for frogs,
toads and tree frogs, the members of the Class Amphibia that have males
that call during mating . They use the calls of these amphibians to verify
their presence in habitats all over the state.
• Salamanders, the other large group of the Class Amphibia, don’t make
mating calls, so cannot be monitored simply. This project seeks to begin
a systematic monitoring of salamanders that will add to what is already
known about their populations in Wisconsin. In specific, your efforts will
help verify distributions of salamanders and fill the large gaps of
knowledge in areas where salamander surveys have not been conducted.
• The data you collect will help preserve and protect Wisconsin’s
salamanders.
Amphibians come in two types
those without tails
These belong to the Order Anura
which includes Frogs, Toads and Tree Frogs
The juvenile stage is called a Tadpole
those with tails
These belong to the Order Caudata
which includes Salamanders, Newts
and Mudpuppies
The juvenile stage is called a Larva
Clyde Peeling
Missouri State Biology
While you are out looking for salamanders, you will also encounter
the tailless amphibians – the Anurans. That data will also increase
our knowledge of Wisconsin’s amphibians and the protection of the
vital habitat that salamanders use. So, it would be great if all
could learn to identify and record the presence of Wisconsin’s
frogs, toads and treefrogs.
Order Anura
Anurans divide into three families
Hylidae: Treefrogs
Mink Frog
Bullfrog
Pickerel Frog
Northern Leopard Frog
Green Frog
Wood Frog
Ranidae: True Frogs
Western Chorus Frog
Blanchard’s Cricket Frog
Spring Peeper
Eastern Gray Treefrog
Cope’s Gray Treefrog
American Toad
Bufonidae: Toads
Some characteristics useful for identifying Anuran species:
1. Are there swollen toepads (useful for climbing)?
These are the tree frogs.
2. Skin texture and presence of large skin glands
3. Color patterns
Spots
Masks
Background
Stripes
4. Some folds in the skin
Dorsolateral fold
from eye to hind leg
Tympanum
Tympanic fold from eye, around
tympanum, to front leg
5. And, of course, size
Let’s sort out Wisconsin’s frogs first, then talk about when
you might encounter them in your pond. The sorting will
Involve several questions (a dichotomous key to field biologists).
1. Is there a paratoid gland present?
a.YES! Family Bufonidae with our only
representative, the American Toad, or
Bufo americanus
b. No. Go to question 2 on next slide.
American Toad
The American toad is a medium sized anuran (2-3.5 inches) and is identified by its
rough skin and paratoid gland. It will not give you warts to handle the toad, but
you will be able to feel how that rough thick skin helps them retain water so they
can live far away from water – like in your garden.
2. Are there suction cups on the toes?
a. YES! The treefrogs in the family Hylidae. Wisconsin has several species
of treefrogs. Go to question 3 below to begin to sort them out.
b. NO. The true frogs in the family Ranidae. We will get to those when
we come to question 7 in three slides.
3. Are the suction cups wider than the toes?
a. YES. Proceed to question 4 on the next slide.
b. NO. Proceed to question 6 in two slides.
4. Is it a very small tan frog with a darker X marking on the back?
a. YES! The Spring Peeper, Pseudacris crucifer.
The Spring Peeper is one of Wisconsin’s
Smallest frogs (0.7 to 1.1 inches). They live in
Moist woods and their shrill “peep” can be
Heard in wetlands in and near those woods.
b. Not colored as in 4.a., go to question 5 below.
5. a. A small (1.5 – 2 in. )green-brown frog with white spots below the eyes – the
Eastern Gray Treefrog, Hyla versicolor.
b. A small (1.25 – 2 in.) green-brown treefrog with no white
Spots under the eyes – Cope’s Gray Treefrog, Hyla chrysoscelis.
Don’t let the above pictures deceive you! These 2 very closely related frogs can both change
their colors from brown to green and back to match their backgrounds. The eastern gray
treefrog does tend to have a bit more mottling than the Cope’s. They live anywhere with places
to climb and wetlands for breeding. Perhaps you’ve seen them on your house, boat, etc.
[You got here from 3.b. Suction cups are not wider than the toes.]
6. a. A very small frog (0.7 to 1.2 in.) with a striped
pattern on the back – Western Chorus Frog,
Pseudacris triseriata.
The Western Chorus Frog is as small as the Spring
Peeper and breeds at the same time, but the chorus
frog’s stripes make it easy to distinguish. The call
sounds like that produced when running your
fingernail over the teeth of a plastic comb.
b. A very small frog (0.7-1.2 in.) with a small brown
triangle on its head (between the eyes) –
Blanchard’s Cricket Frog, Acris crepitans
blanchardi.
The Blanchard’s Cricket Frog is Wisconsin’s only
endangered amphibian It was abundant in southern
Wisconsin until the 1970’s, then experienced a rapid
decline. The call sounds like metal balls clicking
together. They like to breed in permanent water with
lots of vegetation.
[You got here from 2. b. No suction cups on the toes.]
7. Does it have a dorsolateral fold on the back?
a. NO! Go to 8 below.
b. YES. Go to 9 on the next slide.
8. Is there a prominent tympanic fold between the eye and forelegs?
a. YES! The Bullfrog, Rana catesbiana.
The bullfrog is Wisconsin’s largest anuran. It is green to olive
colored with a large tympanum and tympanic fold. Their
tadpoles take 2 seasons to mature, so bullfrogs are always
found in permanent waters. Their “jug-o-rum” call is classic.
Twingroves.district96.k12
b. NO. The Mink Frog, Rana septentrionalis.
The mink frog has dark mottling on an olive-brown background.
The skin has a distinctly musky smell, so if uncertain, give it a sniff.
Mink frogs live only in northern Wisconsin in association with lakes
and rivers.
Museum.gov.ns.ca
[You got here from 7.b. Has a dorsolateral fold on the back.]
9. What are the spots like on the frog?
a. Large spots on body and legs. Go to 10 below.
b. Small or no spots on body. Go to 11 on next slide.
10. a. Medium-sized frog (1.75-3.25 in.) with squarish spots,
yellow on the thighs – Pickerel Frog, Rana palustris.
The pickerel frog has dark large rectangular spots on a green-brown
background But notice the yellow peeking through at the bend
of the hind leg. The call of the pickerel frog is a low short snoring
sound. You must listen carefully to hear it.
b. Medium-sized frog (2 – 3.5 in.) with roundish spots with no
yellow on the thigh – Northern Leopard Frog, Rana pipiens.
The N. Leopard Frog has large dark dark spots on a green-brown
Background. The call is a loud snore broken by clucks and croaks.
A species that is still common but declining significantly.
[You got here from 9. b. Small or no spots on the body.]
11. a. Small frog (1.5 – 2.5 in.) with a dark mask behind
the eye – Wood Frog, Rana sylvatica.
A tan-brown frog with a dark mask that includes the
tympanum. The call sounds like quaking. Wood Frogs
live in moist woods and breed in ephemeral ponds formed
by snow melt and spring rains.
b. Medium-large frog (2.4-3.5 in.) with no mask – Green
Frog, Rana clamitans.
The green frog has small dark spots on a green-brown
background. Some people confuse the green frog with
bullfrogs. The green frog has a strong dorsolateral fold. Like
the Bullfrog, the tadpoles live for 2 seasons, so the green frog
must breed in permanent waters. The call sounds like a
plucked banjo string.
Cortland Herpetology Collection
OK, maybe a summary would be helpful here:
1.Bufonidae – has paratoid gland behind the eye.
American Toad
2. Hylidae – does not have a paratoid gland, has suction cups on their toes.
Spring Peeper: suction cups wider than toes, a very small tan frog with a
dark X on its back.
Eastern Gray Treefrog: suction cups wider than toes, a small green-brown frog
with some darker skin mottling, with a white spot under the eye.
Cope’s Gray Treefrog: suction cups wider than toes, a small green-brown frog
with much less mottling on skin than the Eastern Gray treefrog
and no white spot under the eye.
Western Chorus Frog: Suction cups NOT wider than toes, a very small frog
with a strong stripe pattern on its back.
Blanchard’s Cricket Frog: Suction cups NOT wider than toes, a very small
frog with a small brown triangle between the eyes.
3. Ranidae – No paratoid gland, no suction cups on toes. May have
a dorsolateral skin fold.
Bullfrog: NO dorsolateral fold, a very large frog with a prominent
tympanic fold.
Mink Frog: NO dorsolateral fold, a medium frog with strong
skin mottling and a musky smell.
Pickerel Frog: Has dorsolateral fold, a medium frog with large
squarish spots and yellow on the thighs.
Northern Leopard Frogs: Has dorsolateral fold, a medium frog with
large roundish spots and no yellow on thighs.
Wood Frog: Small frog with dorsolateral fold and a dark mask
behind the eyes.
Green Frog: Largish frog with dorsolateral fold and a green-brown
body with small dark spots.
There are three confusing pairs. Here are hints about how to tell them
apart:
Bullfrogs and Green Frogs – Green Frogs have a dorsolateral fold and
coarser skin.
Twingroves.district96.k12
Cortland Herpetology Collection
Bullfrog
Green Frog
Northern Leopard Frogs and Pickerel Frogs – Look at the spot shape
and yellow on the thigh.
Pickerel Frog
Northern Leopard Frog
The Gray Tree Frogs are highly variable, so can be confused easily. The
call is the only sure-fire way to tell them apart. But – check for the white
spot.
Eastern Gray Treefrog
Cope’s Gray Treefrog
When will I see these frogs at my pond?
Early Breeders: March and April
Wood Frog, Western Chorus Frog, Spring Peeper, and Northern
Leopard Frog
Late Spring-Early Summer Breeders: May to mid-July
Northern Leopard Frog (May and a little June), Pickerel Frog,
American Toad, Eastern Gray Treefrog, and Cope’s Gray Treefrog
Summer Breeders: June, July, and August
Blanchard’s Cricket Frog, Mink Frog, Green Frog and Bullfrog
And, of course, any frog that lives in the water through the summer,
such as the bullfrog and mink frog, will be seen at the pond all summer.
TADPOLES
Frog tadpoles can be VERY difficult to tell apart. For this study, you should
able to distinguish toad tadpoles from Rana tadpoles, and then each of the
treefrog tadpoles. Here’s a way to sort tadpoles:
1. Where are the eyes?
a. On top of the head (dorsal), Go to 2 below.
b. NOT on the top of the head, go to 3 on the next slide.
American Toad
2. a. Very dark body, clear tail fin – American Toad.
b. Not as in 2.a. – Rana.
Pickeral Frog
Northern Leopard Frog
Green Frog
Pwrc.usgs.gov/tadpoles
[You got here from 1.b. Eyes not on top of head]
3. How much of tail fin is mottled?
a. Most of the tail, go to 4.
b. Only a small part or none, go to 5
4. a. Tail has a red-orange tint, mottled all the way to the tail muscles –
Gray Tree Frogs (not possible to tell Cope’s from Eastern)
pwrc.usgs.gov/tadpoles
fin
tail muscles
b. Tail fin not red-orange, tail fin clear next to tail muscles – Spring Peeper.
pwrc.usgs.gov/tadpoles
Clear, unmottled area
[You got here from 3.b., only part or none of tailfin mottled.]
5. a. Large dark tail tip – Blanchard’s Cricket Frog
umesc.usgs.gov/terrestrial/amphibians
b. Usually clear tail fin, tail musculature bi-toned: dark on top,
light below – Western Chorus Frog.
pwrc.usgs.gov/tadpoles
Two toned
tail muscles
Tadpoles can be difficult to identify, especially when young.
The groups that should be fairly easy to ID are:
1. American Toads
2. The Genus Rana: you will not ID the species of true frogs.
3. The Gray Treefrogs
4. The Western Chorus Frogs
5. Blanchard’s Cricket Frogs
Spring Peepers are pretty variable, so may not be easy to identify.
And, depending on where you are, you may not catch some of these.
Wisconsin’s amphibians are not evenly distributed across the state.
You can discover what has previously been seen in your area
by checking the Wisconsin Herp Atlas. It can be found on-line at:
www.uwm.edu/dept/fieldstation/herpetology/atlas/atlas.html
Why not take some time to check the atlas out now?
----- first click on the hotlink above.
------when the Herp Atlas home page appears, click on “Species
Accounts”, then on a species from the list on the left margin.
Make special note of the species not strongly represented in your area.
Feel free to review this presentation as often as you wish.
Here are some other great resources:
Books
Amphibians of Wisconsin by Rebecca Christoffel, Robert Hay and Michelle Wolfgram.
can be viewed or purchased on-line at:
http://dnr.wi.gov/org/land/er/herps/amphibians
A Field Guide to Amphibian Larvae and Eggs of Minnesota, Wisconsin, and Iowa by
Jeffrey R. Parmalee, Melinda G. Knutson, and James E. Lyon
can be ordered from the US Geological Survey (1-800-553-6847 or 703-487-4650
or contact the author at [email protected]).
Amphibians and Reptiles of the Great Lakes Region by James H. Harding.
-available from Amazon, or ordered from your favorite local bookstore.
Websites:
EEK (Environmental Education for Kids) by the Wisconsin DNR [http://dnr.wi.gov/eek]
Wisconsin Frog and Toad Survey [http://inventory.wiatri.net/FrogToadSurvey]
Frog Calls [http://www.midwestfrogs.com]
The End
Gallery.cce.cornell.edu