What does the Oregon spotted frog look like?

Oregon spotted frog

Oregon spotted frogs look a lot like the Columbia spotted frog and the red legged Frog. In fact it takes an expert to tell Columbia spotted frogs and Oregon spotted frogs apart. Until recently they were thought to be the same species, but now researchers know that the Oregon spotted frog has a much more aquatic lifestyle than the Columbia spotted frog and spends almost all of its time in the water. The Columbia spotted frog is more common and is found in the interior of BC. Another key difference is in the angle of the eyes and you have to get pretty close to see the difference.

Adult Oregon spotted frogs can grow to a length of 5-10 cm.

They have black spots with light spots on their head and back - these spots give the frog their name.

Juvenile frogs are brown or olive green and adult frogs are reddish brown, brown or green.

The frogs have two folds along their backs that may be lighter in colour and look like stripes.

Where is the Oregon spotted frog found?

In B.C. there are only three scattered wetlands known to contain breeding populations of the frog.

The Oregon spotted frog prefers floodplains and wetlands associated with permanent water bodies and particularly ponds exposed to sunlight to warm the water.

When disturbed they will swim to the bottom of the pond and may stay there for a long time, making them very difficult to find.

They leave the water only for very short periods of time when foraging for food.

They will only move from pond to pond through waterways - this makes them very vulnerable to habitat fragmentation.

They prefer areas with thick algae and vegetation for cover, but may also hide under decaying vegetation.

Why is the Oregon spotted frog so important?

While it is not known exactly how Oregon spotted frogs fit into the local ecology, they do play an important role and that's why it’s so important to save them. Every species is part of an intricate web, and taking a species away from that web creates an imbalance that may have negative effects on other species.

Are Oregon spotted frogs endangered?

Early last century, there were hundreds of thousands of them, ranging from northern California up into British Columbia’s Fraser Valley. Due to habitat destruction and the introduction of non-native species, their numbers have dropped as much as 90 percent from past populations; Oregon spotted frogs are now one of the most endangered amphibian species in Canada. The Oregon spotted frog is locally extinct (extirpated) in California, endangered in BC and Washington and at risk in Oregon. This means that their populations are at critically low levels.
Current populations are declining and are thought to be present in only three ponds in the Lower Mainland. There may be only 300 frogs left in B.C. So far, researchers have been unable to breed the frogs in captivity, however, they are participating in programs to grow eggs into froglets in the lab and re-releasing them in the wild.

Why is the Oregon spotted frog endangered?

Bullfrogs, introduced green frogs and predatory fish introduction compete with the Oregon spotted frogs for food and habitat and eat the tadpoles and young frogs. Oregon spotted frogs spend most of their lives in the water and require connected wetlands and floodplains for habitat. These areas are also desirable to humans for farming and development. Invasive plants such as reed canary grass can also change the habitats to the extent that they are no longer suitable for the frogs.

What is being done to save the Oregon spotted frog?

These frogs are now the target of a recovery program called the Oregon spotted frog Recovery Program involving all levels of government, the Vancouver Aquarium, the Greater Vancouver Zoo and the Mountain View Conservation & Breeding Centre. The Oregon spotted frog program first came to life in 1999 with the idea to collect recently laid frog eggs in the spring and nurture the eggs in protected facilities until they had developed into baby frogs. The frogs would then be released back into the wild in late summer giving them an ecological head start in life. The recovery program is 1 of only 2 such programs in North America. In order to monitor the progress of the wild frog populations, each released frog has been marked with a tiny spot of dye on one leg. The markings will enable researchers to track the frogs and determine how many survive to reproduce.

Did you know?

The call of the Oregon spotted frog is a weak series of 6-9 clucking noises, and is usually only heard during breeding season. Females are typically larger than males. The lifespan is unknown but thought to be 4-5 years.

References:

Amphibian Ark. 2008.

Hammerson, G. & Pearl, C. 2004. Rana pretiosa. In: IUCN 2007. 2007

IUCN Red List of Threatened Species.

Canadian Amphibian and Reptile Conservation Network. Oregon Spotted Frog.

Electronic Atlas of the Fauna of British Columbia. 2007.

Amphibiaweb. Oregon Spotted Frog. 2008.

Matsuda, Green & Gregory (2005) Amphibians & Reptiles of B.C. pp. 142 -144

BC Frogwatch. Oregon Spotted Frog. 2008.

Funding for this Oregon spotted frog Aquafact was provided in part by the Government of Canada's Environmental Damages Fund.

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