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Frogs a key species in making sure wetlands are healthy

American bullfrogs are the largest frogs in North America, measuring up to 8 inches from nose to tail and weighing up to 1.5 pounds. In the Grand Valley, bullfrogs are an invasive species because, in addition to eating insects, which is good, this green frog will eat anything it can fit in its mouth — including other frogs.

The canyon tree frog is hard to spot and tends to match the color of the rocks in its canyon habitat. This tiny frog looks more like a toad and is more likely to be heard than seen.

Northern leopard frogs are green or greenish-brown with dark spots and light colored ridges down either side of their body. This frog has been declining since the 1970s and is listed as a species of special concern.

A Woodhouse’s toad has rough, warty brown skin and a whitish line down the center of its back. It is the most common toad in the Grand Valley.

Do you know the difference between frogs and toads?

No, kissing a frog doesn’t turn it into a prince, and kissing a toad won’t give you warts.

The truth is: There is no difference.

Biologically, toads are simply a kind of frog. The term “toad” is simply a common name for a frog that is brown and bumpy and spends more of its time out of the water. But plenty of frogs are brown, and some species of toads are more closely related to frogs than they are to other toads.

Frogs are full of surprises. When hibernating, some species breathe underwater by absorbing oxygen through their skin. Most frogs lack ribs, which is part of the reason they slipped so easily through your fingers when you tried to catch them as a kid.

Frogs are fascinating creatures, and they can tell us a lot about the health of our environment if we spend a little time getting to know them.

The Children’s Nature Center in Fruita has partnered with FrogWatch, a nationwide citizen-science program created by the Association of Zoos and Aquariums, to get the public involved in collecting data on frog populations in local wetlands.

Janet Gardner, executive director of the center and local FrogWatch coordinator, says the Grand Valley is the only area on the Western Slope participating in the project.

Because frogs spend at least part of their lives in wetlands and their permeable skin makes them sensitive to water pollution, they are considered “indicator species.” The health of our frog populations can tell us a great deal about the health of our wetlands.

Despite being semi-arid, the Grand Valley is home to plenty of frogs and toads. The American bullfrog is the most familiar frog in our area, but surprisingly this big green frog is not native to Colorado. The bullfrog belongs in the eastern U.S. and is considered an invasive species in our state.

Though bullfrogs feed primarily on insects, these large frogs are happy to eat virtually anything that will fit in their mouths — reportedly even rodents, birds and bats. Unfortunately they will also eat other frogs, and it is believed the invasive bullfrog may be contributing to the decline of the native northern leopard frog. 

As its name suggests, the leopard frog is known for its spots. This attractive frog used to be quite common but has been declining since the 1970s and is now listed as a species of special concern by Colorado Parks and Wildlife.

The reason for the leopard frog’s population decline isn’t simple, but it’s probably a combination of factors, including water pollution, habitat loss, disease and introduction of nonnative predators.

If you see one in our area, consider yourself lucky.

You are much more likely to come across a Woodhouse’s toad. They can be found all over the valley, from suburban gardens to the dry desert scrub of Colorado National Monument. These classic brown, bumpy toads are most active at night.

They make lovely tenants in your garden because they eat insects and slugs, but be prepared to wash your hands if you pick one up as the toad will likely “pee” on you. This tactic is used to startle the predator (you) into dropping it.

Toads can also secrete a white, toxic substance from glands on their skin that irritates the mouths of predators. So, as with most animals, it is better to look and not touch.

The tiny canyon tree frog is a great example of a frog that looks like a toad. Its brown and blotchy appearance provides camouflage in the rocky canyon habitat where the tree frog lives.

These tiny frogs, which are about two inches long, are relatively rare and more likely to be heard than seen. Their loud calls are described as a rapid stutter, similar to a woodpecker drumming or a bleating sheep.

Gardner says FrogWatch volunteers have documented six species in the Grand Valley: American bullfrog; northern leopard frog; Woodhouse’s toad; canyon tree frog; red-spotted toad; and the Great Basin spadefoot.

Because frogs are generally masters of camouflage, the best way to find them is by listening. Most species only call during the breeding season, which can begin as early as February for some.

Frog surveys have concluded for this year, and Gardner hopes to expand the program next year. If you are interested in participating, please email her at .(JavaScript must be enabled to view this email address).

In the meantime, you can do some informal frog watching at your local pond, or check out some more exotic species, like the tiny colorful poison dart frogs, at the Children’s Nature Center.


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