Tuesday, March 15, 2011

Spring Unofficially Begins

The first wood frog (Rana sylvatica) activity of the season was observed this past Saturday at a small wooded pool in Mead Township as temperatures climbed into the low 60's.  The arrival of wood frogs is usually a good indication of winter's demise along with bluebirds, coltsfoot and red-winged blackbirds.  The next 60 degree day could bring out the first chorus frogs (peepers).  Wood frogs can be tricky to locate due to their weak vocalizations which are barely audible 100 ft from pools in quietest conditions.  Breezy conditions like those of this past Saturday can easily drown out a chorus at short distances.  Wood frogs are notorious for being the first frogs to breed in late winter in eastern Ohio often arriving poolside by the dozens then disappearing into the surrounding woods before most other species begin chorusing.  A large pool with a good population can yield 20-30 clutches of eggs per season with 300-500 eggs per clutch.

A globular mass of wood frog eggs deposited
in the shallow end of a wooded pool.  The mass
is approximately fist-sized and appears to be a
few days old due to its swollen appearance. 

Another mass from the same pool that was deposited more
recently.  As the eggs enter the water they begin to swell
from about the size of a quarter to fist size in a couple of days.
Larvae will hatch in 1-2 weeks depending on water temperature.
Amplexed pairs will choose the warmest areas of the pool to
deposit eggs which is usually in a shallow area exposed to the
A photo from a previous post of an adult wood frog for reference.
Wood frogs appear in a variety of earth tone colors from
dark brown to tan to grayish but all have a dark band passing
through each eye (robber's mask), parallel dorsal folds and
distinct banding on each leg.  Adults range from 2-2.5 inches
from snout to vent in length.

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