21 February 2009

Can't Wait for the Chorus

More snow! We woke up this morning in northern Indiana with a fresh coating of the white stuff; we're up to about 5 inches right now. This weather certainly doesn't make it seem like we'll be enjoying the euphonious verses of frogs and toads anytime soon. But as sure as the Red-winged Blackbirds have returned, the ice will melt and our amphibian acquaintances will soon be singing. To get in the mood, here is a preview of what is to come.

The three frogs to begin calling as early as late February in Indiana are the Spring Peeper (Pseudacris crucifer), Western Chorus Frog (Pseudacris triseriata), and Wood Frog (Rana sylvatica). It is usually March before we begin to hear them in the northern part of the state, however.
The Latin name for Spring Peeper gives a good hint for how to identify this approximately 1 inch long frog. Crucifer means "cross-bearing," a reference to the characteristic dark "X" on the back of the tan body. If you live in eastern North America, there is a good chance that you've heard these guys, even if you didn't know it; males try to attract females with a repeated, high pitched "peep... peep" call that in full chorus sounds like jingling sleigh bells. When in large groups, their collective calls can be deafening. The best places to find Spring Peepers are swamps and vernal pools in moist forests. Like many other amphibians, while they require wet areas to breed, they spend most of their time in upland forests. This is one reason why it is important to preserve and restore not just wetlands, but complexes of wetland and upland.
Western Chorus Frogs are about the same size as the previous species, but can easily be distinguished by the gray-brown base body color with three dark stripes on the back (hence the specific epithet triseriata, meaning "three stripes"). They are common from Ontario to Tennessee and from lllinois to New York, but are less common in Pennsylvania and West Virginia. Western Chorus Frogs prefer open wetlands, especially marshes, damp fields, and temporary ponds, but can also be found in more wooded habitats including swamps and bottomland forests. Their characteristic breeding call is similar to the sound made if you ran your finger across the teeth of a comb... pprrreeeep... with the pitch rising at the end. Western Chorus Frogs start calling at about the same time as Spring Peepers, sometimes just a bit earlier.
One of my favorite northern Indiana frogs has to be the Wood Frog... just look at that cute little thing! Wood Frogs can reach a size of about twice that of the previous two species. They are easily recognizable by sight, with the key identification character being the chocolate-brown mask through the eye. The furthest north ranging of North American amphibians, Wood Frogs are found in a general band stretching from Alaska to Georgia. In northern Indiana, they aren't nearly as common as the other early calling frog species. They can be found in swamps, forested bottomlands, on edges of lakes, and in moist woods. However, they are typically found in the water only during breeding season. Wood Frogs sometimes begin breeding earlier than Spring Peepers and Western Chorus Frogs, an activity made evident the male's call that is a series of two to six duck-like quacks or clucks.

The next species to begin calling in northern Indiana is the Northern Leopard Frog (Rana pipiens), which is about 2-3 inches long. The spotted pattern on a green or brownish body narrows the identification down to four potential species in Indiana (Northern Leopard Frog, Southern Leopard Frog, Plains Leopard Frog, and Pickerel Frog), but of these, only Northern Leopard Frog and Pickerel Frog are known from the northern part of the state (although Plains Leopard Frog may also have been found in the northwestern part of the state historically). Northern Leopard Frogs have round to oval spots with distinct light borders on their backs, and the two ridges that run down the frog's back usually are uninterupted all the way to the groin. Northern Leopard Frogs also often have a spot on their snout. They are found in bogs, marshes, and wet meadows, around ponds, and along streams throughout southern Canada and most of the United States, but are absent from the southeast. The wonderful breeding call of Northern Leopard Frogs has been described as sounding like a heavy, creeking door; Lindsay says they sound like a drumming woodpecker. They also make a grunting sound that is similar to the sound made by rubbing your fingers on a balloon.

In mid- to late-March, we begin to hear the long, flute-like, tranquill trill of the American Toad (Bufo americanus). This species can be up to three-and-a-half inches long and is easily recognizable by having small dark spots enclosing one or two warts each on their backs. The underside of the American Toad is also usually heavily dark splotchy. American Toads are common throughout most of eastern North America, most commonly found in grasslands and open woods. They are also commonly found in suburban and agricultural areas. Be careful if you handle an American Toad, because if they pee on you, you will get warts. JUST KIDDING!! That's just a myth. But they do have a large gland behind each eye, called the parotoid gland, that contains a bitter chemical that is toxic to predators, so you probably shouldn't eat one.

Photo from www.in.gov/dnr/fishwild/3333.htm

As stated earlier, the Pickerel Frog (Rana palustris) can look a bit like a Northern Leopard Frog, but you will notice that the spots on the back are large and rectangular. Also, the area on the underside near the groin of Pickerel Frogs is bright yellow to orange. Pickerel Frogs begin calling in mid- to late-March. Their unique call sounds like a low-pitched, steady, mechanical, gutteral snore... yyyyeeeeeeooww. Distributed throughout most of eastern North America, they are most often found near spring-fed streams and lakes, but are also found in wet meadows and in swamps.

The Eastern Gray Treefrog (Hyla versicolor) is very similar to the Cope's Gray Treefrog (Hyla chrysoscelis), and can really only be distinguished by call and genetic analysis. However, Cope's Gray Treefrogs are not known from the northern part of Indiana. Eastern Gray Treefrogs are up to about 2 inches long as adults. Their appearance changes from the time they are young until they are adults, and as adults, their color can also change depending on temperature and the color of their surroundings (hence the specific epithet versicolor, meaning "of various colors"). As young frogs, Eastern Gray Treefrogs are green and very smooth. They begin to develop a warty texture as they mature.

By the time they are adults, their color can range from putty white to pale green to almost black, with a somewhat warty skin and black and dark gray patterns.

Eastern Gray Treefrogs are found in the eastern United States, with the exception of the southeast, and range north into southern Canada. Most commonly, they are found in moist forests surrounding swamps or ponds, but you can hear them calling from almost any forested habitat from late April or early March into the middle of summer. Eastern Gray Treefrogs produce a musical, bubbly trill that ususally lasts just a few seconds; their calls are often confused for Red-bellied Woodpeckers.

Northern Cricket Frogs (Acris crepitans) begin calling at about the same time as Eastern Gray Treefrogs. They are small (approximately an inch long) and have dark, somewhat warty skin, and are often easily identifiable by the wide green or reddish stripe down their back. Northern Cricket Frogs can be found throughout most of the eastern United States (absent from New England) west to Colorado and New Mexico. They are fairly uncommon in the northern part of Indiana. Habitat preferences include ponds, marshes, ditches, and along edges of lakes and streams. These small frogs are often easier to locate by breeding call than by actually seeing them. Their rattling calls sound like steel balls clicking together, getting quicker and quicker as the call progresses. This is where the specific epithet originates; crepitans means "hand rattle".
Fowler's Toads (Bufo fowleri) also begin calling at about the same time as Eastern Gray Treefrogs and Northern Cricket Frogs. They appear similar to American Toads, but the dark spots on their backs are larger and usually contain three or more warts. Also, their undersides are white with a dark spot only on the chest. Fowler's Toads are found throughout most of eastern North America, usually in open or sparsely forested areas that have sandy or loose soil. They are more common in southern Indiana, where they are often found in gardens, than in the northern part of the state. Males give a loud, low-pitched, nasal bleat (similar to a bleating sheep) that lasts four to seven seconds.
In May, we begin to hear the banjo-like twangy calls of Green Frogs (Rana clamitans). Clamitans means "noisy" - a reference to the breeding calls and the distress call, a high pitched squeak, given by this species as individuals jump into water to escape predators or a botanist trampling through their habitat. One of our largest and most common species, Green Frogs can reach a size of three-and-a-half inches long. They are generally brown in color with green on the head, and they have a pair of ridges on their backs which distinguish them from the following species. Green Frogs are found throughout eastern North America, barely reaching into southern Canada; they have also been introduced in several states and provinces in western North America. They are found in permanent water, typically in swamps, ponds, streams, and on edges of lakes. They sometimes overwinter as tadpoles. Like the following species, Green Frogs are hunted and eaten by humans.
At about the same time that we begin hearing Green Frogs, we also start to hear the monster of our frog and toad world, the Bullfrog (Rana catesbeiana). Bullfrogs have been measured at up to 8 inches long, weighing up to 2 pounds! Almost no small animal is safe in the presence of Bullfrogs... they've been known to eat fish, snakes, turtles, small mammals, other frogs, and even birds! They can look similar to Green Frogs, but do not have the ridges on the back seen in Green Frogs. Bullfrogs overwinter in the tadpole stage, sometimes for 2 years. The native range of the Bullfrog includes the eastern United States north barely into Canada and west to Wyoming and Texas; however, they have been introduced in the western United States, southwestern British Columbia, the West Indies, Hawaii, Italy, Taiwan, and other places. Bullfrogs are common in Indiana, where they are found in ponds, lakes, and streams; they require permanent water. The breeding call of the Bullfrog is a deep bass "rrrummm... rrrummm... rrrummm" that can be heard for up to a quarter of a mile. Bullfrogs also let out a yelp when disturbed. While hunted and eaten by humans, the introduction of Bullfrogs into the western United States has been detrimental to populations of other frog species.
I have heard that Spring Peepers are already calling in Missouri, so it won't be long before we begin to hear this night music here in snowy northern Indiana as well.

4 comments:

Justin said...

Great stuff! The quick refresher on calls and identification was much appreciated by a frog novice such as myself.

Scott said...

Thanks. You and Dana should do Frogwatch (http://www.nwf.org/frogwatchUSA/) at your place to record the species that you have and find out if populations there change over time.

beetlesinthebush said...

What a great post. I first learned of Frogwatch through Allison's blog - what a nice resource to have recordings of all the species.
regards--ted

Scott said...

Thanks Ted. Ownership of the Frogwatch program is in the process of being changed from National Wildlife Federation to the Association of Zoos and Aquariums. I hope they still have all the resources. If not, there are some great frog and toad call CDs available.