Friday Fact: The Wondrous Whirring of Many Small Wings

 dragonfly-blog.jpg

(All pictures from www.princeton.edu)

Blue Ridge Blue Collar Man and I were talking at supper last night when he mentioned something he’d heard on NPR, on Fresh Air (with Terry Gross).  “Did you know that dragonflies migrate like birds?” he said.  “And that they fatten up before migrating, just like birds?”

I stopped in mid-chew.  “No…that’s amazing!”  And just like that, as we ate our flounder, my Friday Fact was born.  When Tom mentioned this, I remembered a conversation we’d had at supper about two months earlier. Then, Tom had told me about a friend of his at work, a very masculine tough guy, who had related his experience to Tom with the awe and wonder of a child .  He told Tom that he was driving down his driveway in Linville Falls when, suddenly, he encountered thousands of dragonflies flying in front of his truck in a cloud so thick he had to stop.

Scientists have only recently developed the technology to study the migration patterns of dragonflies.  (The problem was making a transmitter tiny enough not to weigh down the flying insect).   Only about a dozen of the approximately 400 known dragonfly species in the United States and Canada are known to migrate.  The most prevalent of these is the Green Darner dragonfly (Anax junius), which is the one they have primarily been studying.

Martin Wikelski, a professor of ecology and evolutionary biology at Princeton University is leading the study. He follows the dragonfly migration with the help of tiny transmitters, weighing .01 ounces, glued (with eyelash adhesive!) to the dragonfly’s underside.  He carries a receiver that picks up the transmissions, but because they move around so much, he has to follow and track the dragonflies in his airplane.

dragonfly.jpg    (Dragonfly with transmitter)

What they have found so far is that the migration of dragonflies is very similar to that of birds.  Like birds, they migrate in the fall.  “The dragonflies’ routes have showed distinct stopover and migration days, just as the birds’ did,” said Professor Wikelski.  “Additionally, groups of both birds and butterflies did not migrate on very windy days and only moved after two successive nights of falling temperatures.” [This means a cold front is moving in with a tailwind that will aid their flying]  “We saw other similarities as well, which makes us think that dragonflies find their way south using natural landscape features, such as seacoasts and large rivers.”

And, like migrating monarch butterflies, the dragonflies migrating south will not be the ones making the return trip.  It will be their offspring flying back north in the spring.

Another interesting pattern was discovered by a birdwatcher named Frank Nicoletti who was studying hawk migration when he noticed that the migration of the dragonflies coincided with the migration of juvenile American kestrels.  The thick clouds of migrating dragonflies made it easier for the inexperienced young falcons to catch their dragonfly meals, so the insects are an important food source for the migrating kestrels. 

And, of course, I just had to know where the Green Darner dragonfly got its name.  Just as I suspected, the name came from its resemblance to a darning needle (the big one used to mend holes in sweaters and socks).   In fact, one of its nicknames is “darning needle.”  Apparently, some parents used to tell their children to be careful not to let the dragonfly get near their mouth because it might stitch it closed with its darning needle! 

Hmmm.  So that’s what parents mean when they say, “Darn that kid!” :-)

About these ads

8 Responses to “Friday Fact: The Wondrous Whirring of Many Small Wings”

  1. June Says:

    First the butterflies, now the dragonflies! It still baffles me how birds do it, let alone these little ones. I wonder if they “know” when they leave that they’re never coming back. Interesting how the migration patterns coincide – leave it to nature! When I was a kid, I remember how excited we’d get at seeing a clear-winged dragonfly (vs the leopard patterned winged ones that were the most common.

  2. lucky pennies Says:

    That is amazing indeed! I hope I get the chance to see that someday. I wouldn’t mind seeing the great migration of the monarchs either.

  3. bluemountainmama Says:

    i can imagine that dragonfly swarm was a sight to see! i’ve always been fascinated by dragonflies…… both they and hummingbirds have always reminded me of faeries, just the way they flutter and dart everywhere, and the speed of their wings.

    very interesting FF! another thing that fascinates me, both with this migration and the monarchs, is how the offspring know to fly somewhere they have never been before, when they fly back north. since all the adults have their offspring while they are down south(in canada, for monarchs), and then die…. the offspring are on their own to make it to their *summer homes*…. it’s all quite fascinating that they just KNOW. … instinct. scientists have been baffled about the monarchs migration…. sometimes nature stumps even the best minds! :)

  4. CountryDew Says:

    That is a most amazing fact! I never thought about dragonflies living to move on … if I thought of it at all I just assumed they had a short lifespan. I am educated today! Thanks.

  5. colleen Says:

    Growing up, we called them sewing needles and thought if they landed on us they would sew us up! Now I just see fairies or as though they evolved from them.

    I love the photos your husband took below!

  6. Shannon Says:

    Where oh where is Beth? It’s been 5 days since your last post! Shannon

  7. lucky pennies Says:

    Yeah! We want more posts! We want more posts! We want more posts!

    Really, I have no room to talk…it’s been veritable ages since my last post. And you have good reasons not to have posted, though it makes me very very sad indeed. :(

  8. Friday Fact: When the Sky Smiles « Blue Ridge Blue Collar Girl Says:

    [...] co-workers had seen.  (There are many advantages to working outside!)  A few weeks ago, it was a huge cloud of dragonflies.  This time, it was an upside down [...]

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s


Follow

Get every new post delivered to your Inbox.

Join 39 other followers