6. Monitoring Protocol
1. Be quiet for at least 2 minutes before initiating the
monitoring session so frogs and toads acclimate to your
presence.
2. Cup hands around your ears and listen quietly for
precisely 3 minutes. Use a watch to time this duration
accurately.
3. Listen to, identify, and remember all breeding calls
occurring in the session.
If the monitoring session is interrupted by noise,
restart it, including the 2 minute acclimation period.
7. Monitoring Protocol:
Data Submission
• Volunteers share first four datasheets with
chapter coordinators for review
• Submit all datasheets as soon as possible after each
monitoring visit to:
frogwatch@aza.org
or
FrogWatch USA
Association of Zoos and Aquariums
8403 Colesville Road, Suite 710
Silver Spring, MD 20910
9. Types of Vocalizations
• Advertisement (breeding) call – dominant sound heard
during breeding season.
• Aggressive (agonistic) call – a grunt, growl, or trill
sounded by a male when defending a calling site.
• Release call – a chirp-like sound accompanied by body
vibrations.
• Rain call – Weak version of the advertisement call,
typically following rain events outside the breeding
season.
• Alarm call - a loud squeak emitted as a frog attempts to
escape a predator.
10. Factors Influencing Call Frequency
• Time of year – have a surge in activity
that will decrease as the season
progresses.
• Time of day – peaks after sunset and
tapers off around midnight
• Precipitation – activity tends to increase
following rain events.
11. Factors Influencing Call Quality
• Temperature – the lower (colder) the
temperature, the slower the call.
• Size of individual calling – the larger the
individual, the lower the call.
• Acoustic interference – evidence
suggests that frogs may call higher and
less frequently.
12. • There are 14 species of frogs and toads in
Minnesota
• 3 toads species
• 5 tree frog species
• 6 true frog species
Minnesota Frog Species
13. • Green bars indicate calling and breeding activity in Minnesota.
• Yellow bars indicates species that are very rare in Minnesota.
• Gray area represents FrogWatch seasons
Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec.
Spring Peeper
Wood Frog
Western Chorus Frog
Boreal Chorus Frog
Bullfrog
Northern Cricket Frog
American Toad
Green Frog
Great Plains Toad
Cope's Gray Treefrog
Northern Leopard Frog
Pickerel Frog
Canadian Toad
Gray Treefrog
Mink Frog
Blanchard's Cricket
23. Size: 1 ¼ - 2 inches
Gray to creamy white. This frog
can change colors, so it can be
anything from a mottled grayish
green or solid green to a gray or
creamy white color. The inner
thighs on the hind legs of all gray
tree frogs are yellow.
Habitat: Shallow wetlands near
forests during breeding season.
Forests and wooded areas during
the summer.
Gray Treefrog
(Hyla versicolor)
25. Gray Treefrog
Voice: A musical, birdlike
trill. The call is similar to
the Cope's gray treefrog,
but slower. They may call
while perched in tree
branches.
May
32. Size: ¾ - 1 ½ inches
Minnesota’s smallest frog.
Three dark stripes running from
the head down the back. Color
ranges from tan, to grays and
reds.
Habitat: Wetlands and fields near
trees, cities, Breed in shallow
temporary wetlands and ditches
Western Chorus Frog
(Pseudacris triseriata)
33. Western Chorus Frog
Voice: The call of the western
chorus frog is a rising creeee that
sounds like a fingernail being
dragged across a comb.
The western chorus frog sounds
very similar to the boreal chorus
frog but the pulse rate is longer
and slower for the western chorus
frog.
March - April
34. Size: 1 - 1 ½ inches
Very similar in appearance to the
western chorus frogs but legs are
shorter. Brown, olive, tan, or
green with a prominent black
stripe on each side from the
nostril through the eye and down
the sides. Dark stripes down the
back
Habitat: Shallow and temporary
pools, moist meadows and forests
near wetlands
Boreal Chorus Frog
(Pseudacris maculata)
35. Boreal Chorus Frog
Voice: The call of the
boreal chorus frog sounds
like a fingernail being
dragged across a comb.
March - April
37. Size: 2-3 inches
The mink frog is blotchy green
and brown with a pale underside
and a conspicuous tympanum
(eardrum). Males may have a
bright yellow throat.
Habitat: Mink frogs prefer lakes
and rivers with water lilies. Which
they use to hide from predators
and will hope along the top.
Mink Frog
(Rana septentrionalis)
39. Mink Frog
Voice: A rapid cut, cut, cut
resembling a hammer
striking wood. When mink
frogs call in chorus it sounds
like horses' hooves on a
cobblestone road.
May- July
43. FREQUENTLY USED
REFERENCES
• Consult local resources (e.g., State Dept. of Natural Resources, State Wildlife Agency, State Atlas, etc.)
• FrogWatch USA Species by State Lists: http://www.aza.org/states-and-territories
• National Amphibian Atlas: http://www.pwrc.usgs.gov/naa
• USGS Frog Call Look Up and Quiz: http://www.pwrc.usgs.gov/frogquiz
• Cornell Lab of Ornithology, Macaulay Library (of Natural Sound): http://macaulaylibrary.org/
• Western Soundscape Archive: http://westernsoundscape.org
• eNature: http://www.enature.com
• AmphibiaWeb: http://amphibiaweb.org
• International Union for the Conservation of Nature Red List - Amphibians: http://www.iucnredlist.org/initiatives/amphibians
• NatureServe Explorer: http://www.natureserve.org/explorer
• USGS Checklist of Amphibian Species and Identification Guide: http://www.nwrc.usgs.gov/sc_armi/frogs_and_toads/index.html
• The Frogs and Toads of North America. Lang Elliott, Carl Gernhardt, and Carlos Davidson. Houghton Mifflin Company, 2009.
45. Size: 2- 3 ½ inches
Skin coloration is gray, brown, or
greenish. It has large blotches
which have a strongly contrasting
white border. The blotches
contain several small warts. The
chest is white with no speckles.
Habitat: Damp areas in
grasslands and open fields.
Great Plains Toad
(Bufo cognatus)
47. Great Plains Toad
Voice: Great plains toads
produce a loud, metallic
trill that can last more than
20 seconds.
Spring- Summer
Breeding activity is
triggered by warm, heavy
rains
48. Size: 2- 3 ½ inches
The Canadian toad is brown to
green with darker brown, reddish,
or black spots. Its underside is
light with dark flecks, especially
on the throat.
Habitat: Shallow wetlands,
streams, and roadside ditches. In
summer months found near
prairie wetlands.
Canadian Toad
(Bufo hemiophrys)
50. Canadian Toad
Voice: A clear trill very
similar to the American
Toad, but lower in pitch
and shorter, lasting
approximately five
seconds.
May- June
60. Size: .6- 1 ½ inches
They have warty skin that is tan, brown,
gray or olive. With a broad light stripe
down the back. A dark triangular mark is
usually visible between the eyes on top
of the head.
Habitat: Open edges of permanent
ponds, lakes, bogs, seeps and slow-
moving streams and rivers. They prefer
open or partially vegetated mud flats,
muddy or sandy shorelines, and mats of
emergent aquatic vegetation in shallow
water. Cannot tolerate any pollutants.
Blanchard’s Cricket Frog
(Acris crepitans blanchardi)
61. Blanchard’s Cricket Frog
Range: Eastern
United States. Small
populations in
Hennepin and
Winona Counties.
Documented in
Chisago County in
1967.
62. Blanchard’s Cricket Frog
Voice: Metallic clicking
call, similar to the sound
made when two pebbles
are tapped together.
May- July
Very Rare!
Classified as Endangered in
Minnesota