Sunday, April 10, 2011

Wood Frogs in a Breeding Frenzy

Wood Frog Air Sacs 

After the big thunderstorms last night, I hoped the rain would hold off today so I could check out the vernal ponds on the Chippewa River State Trail - where I spotted Wood Frogs in amplexus last March.   When I left the house around 11am, the sky was overcast and threatening, and the temperature had climbed up into the 60s.

Would the Wood Frogs be a quackin' today?

I parked the Prius on County M and walked up-river to the trail marker at Mile 26.

I've read that you can hear some frog calls from a mile away, but not today.  I was about 100 yards from the ponds before I heard the springtime noise made by boys:  a chorus of loud raspy quacks (Wood Frogs) interspersed with a few peep-peep-peeps (Spring Peepers) and an occasional trill (Western Chorus Frogs).

The pool was full of hundreds of Wood Frogs.  I scanned the water but I couldn't see them - at first.   The light was harsh and every time a cyclist rode by, the pond went silent.  I waited and waited.  Then they started up again.  Floating on the surface of the pools, Wood Frogs are relatively easy to spot.  So I focused on them.

Wood Frog in Duckweed

Wood Frog Inflating Air Sacs

It was mesmerizing.  Frogs chasing each other in a shallow vernal pond.  Splashing, sinking, swimming and quacking.

After sitting for an hour or so, I walked further down the trail, hoping to spot a Chorus Frog or a Spring Peeper.  I could hear them, loud and clear... but I still couldn't see them.

Then a frothing ball of Wood Frogs caught my attention.   It looked like they were all hanging on to one frog, who seemed to be drowning or dead.  I tossed a pebble at them, but they did not disburse.  What is going on here?

Five Wood Frogs in a Ball

When I got home, I "googled" Wood Frogs.  "Breeding can be stressful for females; plagued with the weight of multiple competing males, some females drown."  That's seriously stressful.

Another interesting fact:  Females lay only one egg mass.  Count the number of egg masses in a vernal pool and you get a good estimate of female numbers.

On the way back to my Prius... I spotted three "first-of-the-year" birds and one wildflower: Rusty Blackbird, Ruby-crowned Kinglet, Field Sparrow and Bloodroot.

Rusty Blackbird
Ruby-crowned Kinglet

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