Spring Peeper (Pseudacris crucifer)
For many, the first calls of the spring peeper mark the return of spring. These tiny frogs are rarely seen but, during the spring mating season, they are often heard. At only three centimetres long, about the length of a paper clip, they are Ontario鈥檚 smallest frog. They are light brown or grey in colour and distinguished from other chorus frogs by a distinctive dark X-shape on their back. The Latin name crucifer, meaning 鈥渃ross-bearing鈥�, refers to this pattern. The females are slightly larger than the males and are paler in colour.
Photo by Scott Gillingwater
Patience and a good eye are needed to spot one. Their small size and colour allow them to easily camouflage in leaf litter where they are normally found. Spring peepers also have some ability to make themselves paler or darker to better match their surroundings.
Like other tree frogs, spring peepers have enlarged toe pads, allowing them to grip onto plants. Although they are good climbers, they spend most of their time close to the forest floor.
Spring peepers spend part of their lifecycle in water and part on land. For successful breeding, temporary ponds or vernal pools, associated with forest habitats, are preferred to avoid predation from fish. In summer, the adults live in moist, wooded areas and grassy lowlands close to water, spending most of their time in the brushy undergrowth. They do not thrive in urban areas.
Spring peepers are among the first frogs to start breeding and begin calling on warm spring nights, right after the ice melts. Although tiny, they have a big voice and are one of our loudest frogs. Their repeated high-pitched peeping sounds produce a beautiful sleigh bell-like chorus and can be heard up to a kilometre away.
Photo by Scott Gillingwater
The call is made by the male while attempting to woo the female. To make its call, the male fills the vocal sac in his throat with air, causing it to inflate like a balloon. When the air is released, it creates a distinctive peeping sound. The call is repeated about 20 times a minute. However, the faster and louder they sing, the more attractive they appear to the females and the greater their chances of attracting a mate. Older, large males tend to have faster and louder calls, which females prefer.
After mating, the female lays around 1000 eggs in small clusters, usually attached to twigs or aquatic plants. Depending on the water temperature, the tadpoles hatch in four to 12 days. They have gills to breathe underwater and tails to help them swim. They complete their metamorphosis to adults within three months and live about three years.
Spring peepers hibernate in tree holes, under loose bark, and beneath logs. Due to a natural 鈥渁ntifreeze鈥� in their blood, they have a remarkable ability to withstand freezing winter temperatures. This substance prevents their cells from freezing and allows their organs to enter a state of protected dormancy. Warmer temperatures in early spring signal the adults to return to water and breed.
Spring peepers are an integral part of the food web, both in the water and on land. Being nocturnal predators, they are most active at night and feed primarily on small invertebrates, such as beetles, ants, flies, and spiders. The adult frogs absorb water through their skin, so they do not need to drink water. The tadpoles feed on algae, zooplankton, and other microorganisms in the water until they transform into young frogs. In turn, spring peppers are hunted by aquatic invertebrates, snakes, salamanders, birds, and mammals.
Loss of habitat through the destruction of wetland and urbanization poses the greatest threat, and peeper populations are declining. They are sensitive to chemicals and pollutants. Because they have permeable skin, this makes them important indicators of environmental health.
In March, be sure to get out and enjoy the sounds of spring.
Contact: Brenda Gallagher, Forestry and Vegetation Specialist