Dragonfly Behaviour

 

We’re now roughly halfway through this year’s dragonfly season, and there is no better time to watch the behaviours of these fascinating creatures. While the first half generally has a slightly greater variety of species, the second half carries its own advantages.

From now until late October, even into November if the weather is mild, Old Moor is host to high numbers of Common Darters and Migrant Hawkers. The great thing about both species is that they are both tolerant of people, and you can get some close views of them as you wander the reserve.

Here are some of the things to look for. Please be advised that what follows may invite unwanted questions from younger children.

 

Emergence

This usually takes place in the early hours of the morning, but you may spot the sparkly wings of a newly emerged dragonfly or the skin of a nymph left behind when the adult hatches out and flies away.

Common Darter with exuvia, found in the raised sensory garden pond at Old Moor    D Pritchard

Roosting

The markings on the tails of Migrant Hawkers can make them almost impossible to see until you’re right on top of them, even the blue spotted males. If you take a walk towards the new tower on the island in the mornings, it’s not unusual to be startled by a Brown Hawker taking off near your feet. If you’re lucky enough to catch them early, you’ll see and hear them vibrating their flight muscles to warm up, like a tiny V8 engine.

 

Temperature control

This is something that you’ll see on hotter days. Common Darters (and their darker cousins the Ruddy Darter) will raise their tails right so that the sun strikes less of their bodies, preventing them from overheating. They will usually be flushed with colour on those days. On cooler days they lie flat to absorb heat and will often look duller.

Common Darter in the obelisk position     D Pritchard

Tandem flight

Pairs of Darters will fly connected in straight lines. Male Darters hold on to females while they dip their tails in and out of water, releasing eggs directly into ponds. They do this to make sure that the females aren’t swooped on by other males, because male dragonfly “apparatus” can scoop out the evidence of any males that got there first.

You’ll easily see this around the stepping stones and other shallow ponds around the Discovery Trail.

 

Swarming and interaction

Migrant Hawkers don’t seem to mind each other as much as other dragonflies, and you can see clouds of them hunting over the paths, or grouped together on gorse bushes on Green Lane.

When dragonflies meet in mid-air, there are brief moments when they will fly around each other in very tight circles. It’s quite balletic, and the best place to watch for it is over open water on a warm, still day. Males will fight each other and go their own ways.

When males and females meet, sometimes it results in the pair flying off together.

Sometimes the females drop out of the sky and fake their own deaths to avoid unwanted suitors. Admit it ladies; you wish you’d thought of this first.

 

Anatomy 101  Below Emerald damselflies in mating formation. D Pritchard

 Dragonflies perform some impressive acts of contortion to get all of their bits lined up. If you see two perched or even flying in a sort of distorted wheel or love-heart shape, that’s what’s going on. In Common Darters and Migrant Hawkers, this can go on for some time. In Four Spotted Chasers, it’s more of a blink-and-you’ll-miss-it affair.

Male dragonflies have two sets of bits. One (near the tail) produces the goods, and one (near the underside of the thorax) passes them to the females. The males must bend their tails up under their body before mating, in order to move the package from the manufacturer to the distribution centre. Apologies to any delivery drivers for that comparison.

The female bits are all near the tail. She must curl her abdomen to reach the male’s second set of bits and keep them there until mating is complete. So the male uses claspers at the end of his tail to grab hold of the back of the females head (or the neck plate in damselfies). This produces the unique shape.

Hawkers laying eggs    Below Migrant Hawker laying eggs in a water plant D Pritchard               

After mating, the next step is for the females to find somewhere to lay their eggs. Most Hawkers do this on their own, and it’s one of the best times to see them up close, as they focus solely on the task at hand. Emperors and Brown Hawkers usually lay eggs in plant matter under the water, but Southern Hawkers and Migrant Hawkers often lay eggs over water. You’ll be able to see the sharp hook being used to pierce plants and inject them with eggs. They will stay there until the following spring, when the whole cycle starts again.

Hunting

Without question, hunting is what dragonflies do best. It’s quite something to see a dragonfly take down a butterfly mid-flight. They aren’t above cannibalism either, and it’s horrifying but mesmerising at the same time.

Brown Hawker feasting on a Common Darter with a cluster of eggs on the tip of her abdomen        D Pritchard

Darter-charming.

If you move slowly, you can coax a Common Darter to climb on to your hand. One thing that I’ve noticed over the years is that dragonflies get more laid back and less flighty as the season goes on, so there’s still plenty of time to get out there and enjoy learning about these wonderful insects. Keep an eye on RSPB Old Moor social media for one of my guided dragonfly walks to put that to the test.

Key Species

Check Jane Wilkinson's blogs out to learn about our key wildlife species inc: the Bittern and Marsh Harriers

                              "In 1997, there were only 11 booming males (Bittern) in the whole of the UK. A key cause of this decline was the drying out and loss of their ideal habitat – the reedbed. So, after extensive research to understand the habitat, diet and breeding conditions required by this illusive bird, undertaken by the RSPB and partners, new management practices were implemented on some RSPB sites, and now the species has made a fantastic come-back". 

To understand more, follow these links:

RSPB Dearne Valley Eye Opening #1

RSPB Dearne Valley Eye Opening #2

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