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Populations to Watch

Yellow-spotted salamander, Ambystoma maculatum.
Yellow-spotted salamander,
Ambystoma maculatum.

Amphibians of the Rideau River have fascinated Francis Cook and Mike Rankin for more than 50 years. Over the course of their work (they are both research associates with the Canadian Museum of Nature) and particularly during the Rideau River Biodiversity Project, they have observed some 15 species.

If you have heard the call of the bullfrog along the Rideau River, it might come as no surprise to learn that this is among the River's most abundant amphibian species, along with the green frog, leopard frog and the American toad.

Also found along the River are salamanders such as the blue-spotted salamander, the yellow-spotted salamander and the mudpuppy. In very early spring, it is sometimes possible to see mudpuppies just under the ice near the shoreline.

A Good Indication
The size of frog populations can be an indicator of the health of the Rideau River because frogs are sensitive to changes in their habitat and to decreases in the quality of the water. [22]

Shoreline development decreases egg-laying sites and nursery habitat for tadpoles. Drastic seasonal fluctuation of water levels affects shallow shoreline feeding for tadpoles and may affect potential hibernation sites.

Comparison of information collected during the Project with reports from local residents and studies conducted during the preceding 50 years indicates that overall population levels for bullfrogs and green frogs have dropped.

Northern leopard frog, Lithobates pipiens.
Northern leopard frog,
Lithobates pipiens.

Northern leopard frogs are now not often seen in the urban areas of Ottawa because their open pasture summer feeding habitat is reduced. Happily, they are still frequently sighted in rural areas where meadows and pastures are adjacent to the River.

Pickerel frogs were present in Dows Great Swamp off the Rideau Canal in the early 1900s. They have since disappeared because the forest was cut and the swamp was drained, and so their habitat was lost.

The use of frogs as fish bait and the collection of bullfrogs for human food (frogs' legs) has further reduced population numbers. [22] Bullfrogs are protected in eastern Ontario and cannot be taken. The number of northern leopard frogs allowed for use as bait is also restricted.

For Good Quality Water, Follow the Frogs!
Green frog, Lithobates clamitans.
Green frog,
Lithobates clamitans.
Frogs can be indicators of the quality of the water. A high incidence of deformities, such as missing eyes or toes, usually occurs in areas with chemical pollutants or parasite infestations.

Happily, in the Rideau River, the few deformed frogs that have been noticed through the years are not in any greater number than what is normally expected in natural populations. The relative absence of deformities among frogs in the Rideau River is a positive environmental indicator, showing that the water of the Rideau River is in good health.

Help Frogs and Toads
Each spring, participate in frog and toad counts. Frogwatch Ontario and the North American Amphibian Monitoring Program offer opportunities for families and schools to get involved and monitor neighbourhood frog populations.

For more information:

Frogwatch Ontario

North American Amphibian Monitoring Program


 Don't Overlook...  

 Meet the Relatives!  

Bullfrog, Lithobates catesbeiana.
Lithobates catesbeiana.
A Project of the Canadian Museum of Nature
 Images: Canadian Museum of Nature, Thomas Cook