A Drought of Amphibians

This year we are experiencing drought conditions in northeast Illinois.  A drought, defined as a period of little or no rain, can have major impacts on the amphibian populations of an area.  At the end of winter, as snow melts and expected spring rainstorms move into the area, many ephemeral wetlands fill with water.  These pools, marshes and ponds contain water for only short periods ranging from several weeks to a few months.  But they are an important link in the chain of amphibian reproduction.

Many frogs and toads live in woodland areas, but depend on wetlands for breeding and habitat for their young.  Male frogs and toads return to local ponds each spring to find a mate by calling.  Most calling is done in the evening, but sometimes individuals call during the day.  Females will find their way to their favorite singer, then lay a gelatinous egg sac, which the male fertilizes.  Eggs may be located on floating vegetation, hanging under rocks or logs, or laid on the bottom.  Eggs have no shell and must remain wet to live.  Eggs hatch into tadpoles in a week or less.  Tadpoles may transform to adult form in as little as two weeks or as long as the following year.

Wetlands of all types are showing changes due to the drought conditions.  Shallow ponds and marsh areas are dry or retaining only enough moisture to have wet soil, and are no longer a usable wetland for many species.  Deeper ponds are down several inches in depth.  A difference of only a few inches in depth can add several feet of shoreline where banks gradually slope into the water.  Exposed rocks and logs used by turtles for basking are high enough over the water’s surface that they may no longer be accessible to these species.  Creeks and rivers are lower and slower.  Turtles and water snakes that depend on depth and fast flow for protection may find these are no longer a means of escape.

Shrinking permanent wetlands put pressure on the species that already live there.  Ponds are habitat for newts, tadpoles, crustaceans, frogs, toads, turtles, birds,  naiads and insects, and microscopic life.  As the amount of water decreases, habitat in the pond is reduced.  Shallows where a bank slowly submerges may have a steeper drop-off.  Logs once laying at surface level may be several inches higher than the surface, eliminating areas underneath, once used for protection.  Less water means less available oxygen and food for the animals already sharing the pool.  Den and nest sites in banks at the water’s edge become more exposed.

Rain during the early part of May has helped alleviate some of these issues, but more rain is needed, continuing into the summer.   Maintaining your own backyard wet areas with shade and consistent watering provides good habitat for many animals that live among us.  You can watch many of these species in area wetlands on trails and in local parks this spring.