September 20, 2007

• Frogspawn Update

  This update is updated below.
  We had a hard frost here one night early this week.  In the morning, I pulled sheets of ice about a quarter-inch thick from each of the two pans at the tadpole ranch. (shown at left in an image captured earlier this summer)

  I moved the half dozen or so tadpoles from the south 40 (on left) into the north 40 (upper right), ran a long extension cord out and put a fifteen watt light inside the black bucket that supports the north 40.  Now, except when the sun is shining, I keep the pan covered with the translucent white domed lid, for warmth.

  Lately, each time I remove the cover,  Jumbo is there at the surface to greet me.  If I put my hand into the water, he swims into it.  Jumbo and Blackie, the largest tadpole from the south 40, are the only ones who don’t flee from the hand when it descends.  They are the ones I have handled most, and I suppose my body heat is by now familiar and welcome.

  Blackie and four or five of the larger tadpoles are now showing signs of legs, and are developing froglike body shapes and features, while more than half of the remaining tadpoles have grown very little and have kept their immature shape.

  I didn’t know what to expect when I rescued the eggs from the muskeg as it was drying out.  Walking home with the bucket of eggs, I was thinking that if I could keep just one tadpole alive to mature froghood, it would be worth the effort.  I still do not know whether Jumbo has time to mature before real cold weather sets in, so I don’t know if my effort has been worth it for her or him.  For me, the discovery that these tiny cold blooded animals could grow to accept me as a warm presence and not a threat, has been worth a lot more than what I have invested in their care.

  UPDATE:

  Zvanoizu asked:

  Are frogs supposed to mature before frost? What is the life process?
  I’ve been mildly curious… do they have the natural mechanisms to
  mature despite the weather? I don’t know much about froggies so I’m
  curious. A lot of me is curious mostly because the frogs must have
  survived before without help… or not? Will they mature and then
  hibernate?

  Frog eggs need water in which to hatch and tadpoles must have water to survive.  Those eggs I rescued wouldn’t have hatched if left to dry out in the muskeg.  My Frogspawn album includes a shot I captured of some dried eggs after the muskeg dried this year.  I’m sure there were millions of eggs out there this year that never hatched.  If there had been enough rainfall this spring and summer to keep the marsh wet, the tadpoles that didn’t become prey to water beetles, birds, other predators, disease or accidents would have matured in the muskeg.  I watched that process from beginning to end in wetter years.  As it is, there will be no survivors from this year’s spawning in this little area of marshland, because there was no standing water out there through the summer.

  There are still adults surviving out there, spawned during years when the muskeg stayed wet all summer.  We have heard their voices a few times, and Doug saw one recently.  Researchers at the University of Alaska in Fairbanks found that this species can survive frozen underground for at least five years.  Their research was done on adults, and I don’t know whether an immature tadpole, if frozen in ice, would thaw out and swim the following year, or just thaw out and rot.  I may get a chance to find out next year during breakup.

  Mature frogs are known to burrow into mud to hibernate.  The tadpoles’ activity decreases as their water cools.  This summer, with the sun shining on their pans of water, they were in constant motion.  This week when I removed the film of ice from the pans, they were all motionless until I picked them up and they warmed from the heat of my hand.  The species as a whole doesn’t need my help to survive.  There are
  places at the edge of lakes and streams where this year’s hatch
  proceeded normally.  I don’t imagine that my contribution will ensure
  the survival of the frogs in this muskeg.  What I can do is just a drop
  in the bucket.  If climate change persists in drying out the marsh each
  summer and none of the young survive beyond the lifespans of the
  existing adults, they will be gone.

  The things I don’t know about these frogs vastly outnumber what I do know.  I am learning as I go.  Rescuing those eggs was an impulsive act, partially motivated by a desire not to miss out this year on watching the tadpoles mature.
  

  • 5:54 pm
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