Migrant Hawkers take to the air. But why?
Whilst sitting in the office it became very noticeable that there were many Dragonflies around Halesworth. I saw several fly past the office window and then one very kindly perched on the light outside our office enabling me to get some pictures.
I then went off on our daily lunchtime walk to Millennium green. We were actual on the look out for the Kingfishers (of which we did get the traditional fleeting glimpse) or Brown Argus that frequents the folly.
On arrival at the folly we came face to face with the amazing sight of around 50 Migrant Hawkers. Wherever you looked in the sky, there was a dragonfly. It was like nothing I had seen before.
Whilst staring in wonderment at what I was watching, I started thinking. What happened to make so many Migrant Hawkers appear at once? Up until this point we had only seen dragonflies in small numbers probably 3 or 4 of the same species at any one time. I have done a little reading and it says the Migrant Hawker can appear in ‘massive migrations’. Well this was a massive migration, but what makes this massive migration happen? They’re not like birds, dragonflies spend the majority of their life in water, so basically in one pool. The questions I started to ask myself were things like:
– Is it when it’s over a certain temperature for a certain number of days? Its been in the 20’s for several days running now.
-I was also reading about Birds migrating at the optimum time after a weather front in the US. They take their opportunity when the time is right after a storm, could this be the same for Dragonflies?
– Was there something that made this the optimum place for this gathering to happen?
– Is it a definitive date in the calendar? Unlikely but is the migration influenced by a full moon (clutching at straws)- Is there something else that influences it like when we saw huge numbers of ladybirds on the North Norfolk coast?
I find this occurrence even more fascinating when you look at the life cycle of dragonflies. The larval stage of large dragonflies may last as long as five years, so in real simple terms how did they all know it was the right time to leave the water and take to the wing? Where had they all come from? The questions seemed to go on and on.
What made this occurrence even more fascinating to me was when I returned home, about 30 miles away and took a walk to my local lake there were migrant Hawkers in large numbers there as well. I hadn’t seen one there this year so on the same day 30 miles exactly the same thing was taking place!