Oregon Spotted Frog Details

Did you know that Seabird Island’s own Maria Slough is home to the rarest frog in Canada?
The name Rana pretiosa comes from the Latin language. Rana meaning true frog and pretiosa meaning precious. Therefore, precious true frog!

Description:
The Oregon Spotted Frog is a medium size frog, no longer than 4 inches. The adult frogs can vary in color from reddish-brown, brown to tan on top. The inside of the back legs can be reddish or golden. The juvenile’s are olive green or light brown. Tadpoles are a brownish-green. Adults have a narrow, pointed snout, upturned eyes, and a light colored stripe on the upper lip. They also have black spots with light centers. The female frog is bigger then the male frog. The male has larger thumbs, which are used to grab on and hold the female.

The Oregon Spotted frog looks a lot like the more common Red-legged frog which you will often see in Maria Slough and surrounding ponds. They both have red or golden color on the inside of the back legs and their coloration on top is similar. They are quite difficult to tell apart. The differences in their appearances are subtle. For example, when holding the Oregon Spotted frog in your hand and looking directly down at it, the eyes seem to look right up at you; whereas, the eyes of the Red-legged frog tend to look to the side. The webbing extends to the end of the longest toe of the Oregon Spotted frog while it stops about half way down the toe of a Red-legged frog.

Reproduction:
Breeding time is late February to March. The male will be 2 years old before he is ready to breed, a female will be 3 years old. The male will congregate in one area and call to the female. When a female is ready to breed, she will move towards the calling male. These frogs will go to the same spot every year to breed. The male will grab the female around the waist in a mating hug called the amplexus. He will release sperm into the water to fertilize the eggs as the female lays them directly into the water. The egg masses are laid communally in tight groups. Egg masses contain approximately 500-700 eggs. A female will lay one egg mass per year. Hatching takes 14-28 days depending on water temperatures. In three-four months, the tadpoles will metamorphose into little froglets.

Food:
Adults will eat small insects, beetles, ants, spiders, flies, and water striders. Tadpoles eat algae and decaying vegetation.
Did you know that frogs eyes help push food down their throats?

Population declines:
The Oregon Spotted Frog populations have declined all over the world. There are only three places left in Canada where these frogs occur. These three sites are Aldergrove, Agassiz and Seabird Island.
Causes of declines:
· Habitat destruction
· Introduced species that compete or eat them (e.g. Bullfrog)
· Chemical pollution
· Climate changes
· Epidemic diseases
· Invasive vegetation

What do frogs do for us?
Frogs eat untold millions of insects each year making them economically valuable to agriculture. They also provide a critical food source for birds, fish, snakes, and other wildlife. But the most important contribution frogs make may be their role as environmental indicators. When pollution or other environmental changes affect a habitat, frogs are often the first casualties. These delicate creatures provide an early warning for endangered ecosystems.

Habitat:
This species requires large warm-water marshes, with lots of vegetation. Shallow pools and small floodplain wetlands associated with permanent water bodies are important habitat features. It is unknown as to where these frogs over winter.