I decided today was a good time to brush up on the minutae of blue damselfly identification. With a sunny day forecast I headed off to a local site with at least 4 species on the wing. They are all little blue jobs, but with some effort and a good field guide, I did manage to get the hang of separating them in the end.
I learnt at least three things today:
1. I need a new pair of binoculars. My trusty Bushnell natureview 8x40 are now more than 10 years old and although I prefer to use the eco-friendly 'make do' attitude to most of my kit, I have come to the conclusion that I really do need something that will focus down to my feet, rather than 4 meters away.
2.Variable damselflies are a bugger to photograph.
3. I need a new pair of binoculars.
Luckily I already had the other essential piece of kit: "field guide to the dragonflies of britain and europe" by Dijkstra/Lewington, so at least I could identify anything I could get a good view of.
My main technique was to photograph each damsel on the FZ7 on full macro zoom, then use the review screen to look for the key id features:
- size and shape of the antihumeral stripe (top of the thorax)
- black shape on segment 2 (behind the wings)
not an ideal method, but as it happened, it did have the attraction of forcing me to get to know the jizz of each damsel just based on its size/shape and flight. The variable damselflies in particular seemed to have a very 'jerky' low flight and would not settle which made photography a tad difficult.
Common blue damselfly
- antihumeral strips thick, unbroken
- mushroom shape on S2
male
male
male
immature female (dull-form)
azure damselfly:
-antihumeral stripe thin, unbroken
-U mark on S2
male
mating pair
variable damselfly:
- antihumeral stripe is exclaimation mark
- Y mark on S2
male
male
male
male
female
female
mating pair
No comments:
Post a Comment