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Tag Archive | "frogs"

Late season frogs


Ranger Steve Mueller

By Ranger Steve Mueller

Northern leopard frogs were common when I was young and exploring neighborhood wetlands. They have become uncommon and even rare in many locations for reasons unknown. It is not just because I have grown and developed other pursuits that they seem less abundant. Herpetologists studying the frogs confirm decreased numbers. If you have them in abundance, celebrate and protect healthy habitat. We do not understand all the critical features in their nature niche needed for survival.

The pickerel frog is a small North American frog, characterized by the appearance of seemingly “hand-drawn” squares on its dorsal surface. Photo by Brian Gratwicke, CC BY 2.0 <https://creativecommons.org/licenses/by/2.0>, via Wikimedia Commons

They begin breeding later in spring than the Wood Frogs, Western Chorus Frogs, and Spring Peepers described in last week’s article. The late season frogs do best in permanent water. Shallow water near lake shores with lots of grassy vegetation, marshes, and moderately slow stream borders and inlets provide good breeding habitat. I think that clearing lake shores of vegetation for better beaches and eliminating vegetation for better swimming areas contributed to frog decline. I have not seen that confirmed by amphibian studies so that hypothesis remains unanswered. 

Removing vegetation chemically or with manual equipment does not bode well for aquatic organisms. People want fish to thrive, but fish are challenged with more sterile habitat as are amphibians, insects, and wetland feeding birds and mammals. 

Pickerel frogs look similar to leopard frogs but can be distinguished by two features. Pickerel frogs have large rectangular dark spots with narrower light areas between them. The leopard frogs’ dark spots are smaller and rounded with greater light color separating spots. More significant is the Pickerel frog’s hidden bright yellow at the base of the hind legs. Leopard frogs might have a faint yellow there. Both frogs normally develop into an adult in one season but some require two summers. That is a reason they do best in permanent waters. Those breeding in late April or early May are more likely to reach adulthood in one warm season. 

Two similar frogs are green and bull frogs. Bull frogs get much larger but that takes time and may require a few years growth. Both usually take more than one year to transform from the tadpole stage to a tailless adult frog. Green frogs line up around the edge of the vernal pond to the west of the Red Pine interpretive building at the Howard Christensen Nature Center. That pond sometimes retains water throughout the winter but not always. Many developing frogs that breed there must die. The permanent tadpole pond southwest of the building offers better survival chances. 

One habitat management policy I implemented when I was director at HCNC was for interpretive teachers to only take students around the west shore of vernal pond to allow the east shoreline to remain undisturbed by school groups. The purpose was twofold. Number one was to teach a respect and reverence for life and secondarily to hopefully improve survival opportunity for frogs in that half of the pond.

Green frogs have what is called a dorsolateral ridge or fold that runs from head toward the rear. This ridge is absent on bull frogs so even smaller bull frogs can be distinguished by the lack of the long ridge. Bull frogs have a ridge that runs from behind the eye and wraps around the flat circular eardrum called a tympanum that is behind and below the eye. Green and bull frogs sing when the temperature warms to above 70ºF making them the latest to join the seasonal orchestra. A green frog sounds like someone plucking a banjo or guitar string. Bull frogs resemble a cow mooing. 

The last late season frog common in our region is the gray tree frog that is medium sized between the wood frog and green frog. It is somewhat toad like in appearance and has suction cup toes and can climb windows. Like other frogs it breeds in water. It moves away from ponds when grown, like chorus frogs, spring peepers, wood frogs, and leopard frogs. These frogs all feed in moist forests but the gray tree frogs seems to tolerate drier areas better. They can be found hiding on the siding of our homes and feed on insects by lights at night. Their call is a sharp short trill unlike the exceedingly long trill of American toads that reside in insecticide free gardens.

Natural history questions or topic suggestions can be directed to Ranger Steve (Mueller) at odybrook@chartermi.net – Ody Brook Nature Sanctuary, 13010 Northland Dr. Cedar Springs, MI 49319 or call 616-696-1753.

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Vernal Cacophony


By Ranger Steve Mueller

 

Sit by a vernal pond that will dry by late summer to experience joyous ear pain during April. Listen to the massive cacophony of thousands of frogs vying for the chance to mate. Each species has a unique mating call.

Spring peepers make enough noise in the spring to cause ear pain.

Spring peepers have a single peep but when in mass with other peepers, the sound will generate enough volume to cause ear pain. When you are somewhat distant from a pond, the noise is a pleasant sign of spring. Western chorus frogs make a sound compared with running your thumb across the teeth of a comb. For some reason chorus frogs and their calls have become less abundant. Wood frogs are the third early spring species. They generate a duck-like quack. It seems wood frogs have the shortest period for making mating calls. 

The three early callers actively seek mates as soon as ice melt begins on ponds. They often do not wait for ice to clear the entire pond. If a warm rain arrives, the activity and volume maximize. 

The greatest activity is at night, but daytime choruses abound. Walk to a pond and, as you approach, all will become quiet. Sit quietly and remain still for a few minutes. Soon a brave peeper will venture its call. Another will follow with many soon joining. Continue to be quiet and move your hands slowly so you do not alarm the frogs. Cup your hands in front of your ears with palms facing back. Notice how greatly the sound is diminished when your hands block the sound. Rotate your cupped hands behind your ears. You will not be able to tolerate the volume for long. Cupped hands behind your ears catch the sound and direct too much volume to your ears. It will be necessary to remove your artificially enlarged ear pinnae because of physical pain.

Frogs instinctively grab a nearby frog and begin squeezing to force egg laying. As eggs come out, the males milt filled with sperm fertilizes an egg cluster. A jelly mass containing eggs soaks up water and will become larger than the frog that laid it. Anxious males often grab a nearby male by mistake. The grabbed male will protest with a unique trill that means let go. Listen and you should be able to recognize this sound. 

The egg masses are attached to twigs, vegetation, or debris in temporary spring ponds. Survival is extremely difficult for amphibian eggs. Best survival is in the temporary vernal ponds that dry by midsummer because fish are absent. This allows for eggs to develop without being eaten. Many insects will eat the eggs as well as some birds. Small vernal ponds are often filled or drained by people, but they are essential for frogs.

Counter shading helps hide the eggs. Find a cluster of eggs and lift it from the water. Notice the eggs are surrounded by jelly that protects the eggs. The top of each egg is dark. When a predator is peering into the pond, the dark blends with the bottom and helps camouflage the developing embryo. From beneath they are hidden from underwater predators by having a light or white coloration that blends with the sky above. Algae and cyanobacteria grow in the jelly making it green and they gradually digest it. By the time the polliwogs are ready to escape their protective gel, it is adequately decomposed to allow the young frogs to break loose and swim freely into the water. 

As water warms, larger frogs begin calling and mating activity. Gray tree frogs have a short loud trill that stops abruptly. They continue their calling well into summer even after they leave ponds. Leopard and pickerel frogs have a ratchet-like call that is compared with snoring. When the air temperature reaches 70ºF, American toads and bull frogs begin their calling. The American toad has a trill somewhat like the gray tree frog, but it continues for an excessively long time. 

Make a trilling sound yourself by vibrating your tongue behind your teeth and try to continue until you are out of breath. That will be about how long the toad sings. Frogs pass air back and forth between their lungs and mouth when calling and do not expel air like we do when making sounds. Each frog species call is unique for its mating nature niche. Most depend on temporary ponds. Green frog and bull frog tadpoles require more than one year to develop so they require permanent ponds. Spend time enjoying the vernal cacophony.

Natural history questions or topic suggestions can be directed to Ranger Steve (Mueller) at odybrook@chartermi.net – Ody Brook Nature Sanctuary, 13010 Northland Dr. Cedar Springs, MI 49319 or call 616-696-1753.

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Report reptile and amphibian sightings


 

From the Michigan DNR

A Blanding’s turtle, a species of special concern in Michigan. Photo courtesy of Michigan DNR.

As you are out enjoying Michigan’s natural resources this summer, please take a moment to help collect valuable information on Michigan’s reptiles and amphibians.

Anyone can help by reporting sightings of turtles, frogs, toads, snakes, salamanders and lizards online at www.miherpatlas.org.

There is also a mobile app available for download to make field reporting quick and easy. The Mobile Mapper is available for Android and iOS (Apple) devices.

The Michigan Herp Atlas Project is the first statewide inventory of reptiles and amphibians ever conducted in Michigan. The project’s purpose is to document the distribution of Michigan’s reptiles and amphibians, collectively known as herpetofauna or “herps.”

In addition, citizen scientists around North America are being asked to report any possible disease cases in reptiles or amphibians to the new Herpetofauna Disease Alert System. More information about this new reporting tool and how to submit an observation can be found at http://wildlife.org/new-herp-disease-alert-system-relies-on-info-from-public.

Learn more about Michigan’s herpetofauna by visiting mi.gov/wildlife – click on Wildlife Species and look for Amphibians and Reptiles.

You also can find out more about Michigan’s snake species by watching our 60-Second Snakes videos.

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