By August, our small, decorative garden pond is looking lush. I purchased a single water hyacinth and one lone water lettuce plant in the spring, and by now these prolific multipliers have covered the surface of the pond. They provide good cover for the frogs that take up residence in the pond for the summer months.
The pond attracts young Bullfrogs (Rana catesbeiana) and Green frogs (Rana clamitans melanota). With a casual glance, it is easy to miss the well-disguised pond residents, but a more lingering examination of the water surface will usually reveal a few amphibians warily watching the watcher.
Green frogs and Bullfrogs are similar, but the green on the Bullfrog’s face is broader and shades into his body colour, while the bright green on the Green Frog’s face more closely resembles a moustache. Also, you can easily see the distinctive line formed by the dorsolateral fold running along the upper side of the Green Frog.
The frogs can be spotted sitting on the log that is partly submerged in the pond, or seated on the rocks encircling the edge of the pond. Smaller frogs rest on the water lettuce leaves.
Others are camouflaged floating amongst the leaves.
Hey! That’s not a frog, that’s a toad! An American Toad, Bufo americanus, to be more precise.
Though I often come across toads in the garden, it is unusual to see one by the pond. This fellow has obviously been swimming. Perhaps the drought we have been experiencing has made him seek out moisture.
Here’s another visitor doing some frogspotting. He has frog legs in mind for dinner.
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It’s been interesting to observe the changes to the frog community in our little pond. Just a few weeks old, the pond already looks quite settled, with water plants and duckweek created interesting patterns on the water surface. Within a few days of set up, frogs were already moving in, little Green Frogs (Rana clamitans melanota). Then I noticed that some of the Green Frogs were, in fact, Bullfrogs (Rana catesbeiana). The two species are rather similar, but Bullfrogs are bigger, the largest frog species in North America. Knowing this isn’t too helpful, though, when you are looking at two juveniles of similar size, and a big Green Frog can attain impressive proportions too.
When I looked carefully at this pair, sitting together on a log, I could see that the individual on the right is a Bullfrog, while the leaper on the left is a Green Frog. The green on the Bullfrog’s face is more broad and shades into his body colour, while the bright green on the Green Frog’s face more closely resembles a moustache. Also, you can easily see the distinctive line formed by the dorsolateral fold running along the upper side of the Green Frog.
For a while, the little frogs all shared the pond. On one day, I counted 15 of them. Then, a very large, mature Bullfrog moved in. That’s him in the opening photo. That cleared the pond! It’s a big frog eat little frog world, and the juveniles decided it was time to seek out new living quarters. I heard the Bullfrog singing last night, but this morning when I looked in the pond, I couldn’t see any frogs. Not one. It will be interesting to see how the population changes over the remainder of the season. Below is a photograph of one of the smaller frogs resting in duckweed. I like the way his pattern camophlages him so well in the vegetation.
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The little frogs that have moved into the new pond are Green Frogs (Rana clamitans melanota), a species that is common around the Great Lakes region and south across the eastern part of the continent. Green frogs aren’t necessarily green. My guide, Amphibians and Reptiles of the Great Lakes Region by James H. Harding, says: “A Green Frog may be green, yellowish-green, olive, or brown, or any combination of these colors; occasional aberrant individuals are blue.”
Blue! Yes please! I want a blue frog in my pond! No luck so far. My visitors are mostly a brownish or olive colour. Green Frogs also have a fold of skin, called the dorsolateral fold, that extends from the eye to about two-thirds down their back, and the upper lip area is bright green or yellow.
Green Frogs get quite large, up to 4.2 inches long, but the little guys in my pond are about an inch and a half. They are likely juvenile frogs stopping by on their search for new habitats. They’ll need much deeper water with mud to bury themselves in for the winter.
Green Frogs are predators of a wide variety of insects and other tasty food items including beetles, flies, caterpillars, snails and crayfish and even, for large individuals, smaller frogs or snakes. They have a ‘sit and wait’ approach to food shopping, capturing any prey that happens to wander into their reach. Green Frogs are in turn considered a good snack by a host of bigger creatures including raccoons, snakes and wading birds.
Males begin calling in May and have a prolonged breeding season. Judging by the evening songs, it is just wrapping up now. Their call is a short, twangy note often compared to a banjo string being plucked. You can listen to their song at the Adopt-a-Pond site here.
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Posted in Animal life, Environmental, tagged American Toad, Amphibian Ark, amphibian conservation, amphibians, Bufo americanus, Green Frog, herpetology, House of Herps, Rana clamitans melanota, reptiles on December 19, 2009 |
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Green Frog (Rana clamitans melanota)
Herpetology is the study of amphibians and reptiles. What an amazing group these critters are. Amphibians undergo an astounding transformation, growing from waterbabies into air-breathing creatures over the course of their life cycle. Reptiles include some of the most ancient of animal species. Some fascinate us, others repel us. All play an important role in their respective ecosystems.
Now there is a new blog carnival to celebrate herps and bring together interesting posts from the blogosphere in one handy location. Please visit the first carnival ever at House of Herps for encounters with some cool animals and great writers. There’s even an irreverent, but not irrelevant, clip from South Park.
American Toad (Bufo americanus)
View Ted’s (Beetles in the Bush) candidate for North America’s most beautiful lizard, the Eastern Collared Lizard that he photographed in Oklahoma. Admire Kenton and Rebeccas’ (Wild About Nature) ambassador corn snakes. Read Hugh’s (Rock Paper Lizard) book review of Snakebit: Confessions of a Herpetologist by Leslie Anthony. This is just a tiny sampling of the great posts “packaged” on the carnival ready for you to open.
There is also information from Amphibian Ark, a conservation effort whose introduction begins: The world’s amphibians are disappearing. More than one hundred species may have already gone extinct and thousands more are threatened with extinction. Many of the threatened species cannot be safeguarded in the wild and require management away from their natural habitat if they are to persist. Aside from their obvious appeal to nearly all humans, amphibians play a critical role in the global ecosystem, provide us with important pharmaceuticals, and may act as our environmental barometers. There is simply too much at stake in losing them.
Willow House is represented by a post about snapping turtles. The frogs shown on this post were photographed here in September.
Northern Leopard Frog (Rana pipiens)
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Okay, bad pun, but it is nice to find a little Gray Treefrog (Hyla versicolor) nestled onto the sill of the screen door. This little guy (or girl? Females are larger than males and this one was quite big.) spent the day there and moved on some time in the night. Gray Treefrogs are noted for the large adhesive pads on the tips of their toes, which are just visible on this individual. They also have notable colour-changing abilitiy, and the same frog may vary from light gray to brown to pale green. Changing colour takes a bit of time, an hour or more, depending on factors such as the temperature. It is not uncommon to come across an occasional representative of the species through the summer, when they are found in deciduous or mixed forests, woodlots, swamps, old fields and even suburban yards with appropriate plant cover and breeding territory nearby. However, the time when Gray Treefrogs really make their presence known is the spring. If you are near a wetland on a spring evening, especially one ringed with willows and dogwood, you are likely to hear the short trills of Gray Treefrogs ringing out into the night.
Just beyond the doorway, American Toads ((Bufo americanus) are common in and around the garden. This was a mid-sized specimen, perhaps a young toad of this year. Toads are regarded as garden helpers as they eat a variety of insects, spiders and slugs. A few days ago, I spied a garter snake making off with a small toad in its mouth. I resisted the urge to try to save the little toad, which we tend to identify with. Snakes need to eat too.
This fine big Green Frog (Rama clamitans) was just outside the front door last Saturday. It didn’t seem bothered by having a photographer leaning over it and had to be encouraged to move into the garden where it was safer. You can clearly see the dorsolateral fold, the ridge of skin that extends from each eye to about one-half to two-thirds of the way down the back, and around the rear of the tympanum. In mature males, the throat is bright yellow, while females have light yellow or cream-coloured throats. This seems to be a female.
One evening when I turned the porch light on, I noticed the individual below sitting on the step. It’s colour doesn’t identify its species as readily as is the case with the amphibians above. Another Green Frog maybe? It does seem to have a green lip.
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Posted in Animal life, Environmental, Plant, tagged Garter snake, Green Frog, Limenitis arthemis, Linnaea borealis, Pitcher plant, Purdon Conservation Area, Purdon Fen, Rana Clamitans, Sarracenia purpurea, Thamnophis sirtalis sirtalis, Twinflower, White Admirals on June 28, 2009 |
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While the Showy Lady’s Slipper Orchids are the star of the show at this time of the year, they are by no means the only feature of interest at Purdon Conservation Area. Twinflowers (Linnaea borealis) were also blooming in the fen. These delicate, moisture-loving flowers are the smallest members of the honeysuckle family. Their upright stalks terminate in a fork, with each side bearing a single pale, pinky-white trumpet-shaped flower.
The Pitcher plant (Sarracenia purpurea) is carnivorous and uses insects for food. Rainwater collects in the hollow leaves of the plant, where an insect-digesting enzyme is mixed with the water. Insects are attracted into the leaves and are unable to escape because of smooth hairs at the opening. In this way, pitcher plants are able to survive in nutrient-poor environments where other plants could not. In early summer, wine and green-coloured flowers are produced on stems separate from the tubular leaves.
Flowers aren’t the only attraction. I also saw a sampling of wildlife. Here is a Green Frog (Rana Clamitans). Check out the green upper lip on this dude!
Several White Admirals (Limenitis arthemis) floated by. These woodland butterflies are common and widespread. Interestingly, White Admirals and Red-spotted Purple butterflies are different morphs of the same species. Their larval food plants include willows, cottonwoods and poplars.
I disturbed this Garter snake (Thamnophis sirtalis sirtalis), who had been contentedly sunning itself on the boardwalk until I arrived on the scene, prompting his hasty departure.
The fen lies at the bottom of a hill, where it is fed by water runoff. Climbing the trail to the lookout on top of the ridge offers a view over the pond that borders the fen. The pond was created in the 1960s by introduced beavers, who dammed the small creek that was draining the area. The conservation area thus features 3 kinds of wetland, with marsh and swamp around the edge of the pond complimenting the fen. A fen differs from a bog in that it has a groundwater source. The moving water brings nutrients and reduces the build-up of acidity. A bog has no water source except rainwater and snowmelt. It is therefore nutrient-poor and highly acidic.
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