Chasing the climate: Broad-bodied chaser and the dragonflies of East Yorkshire

There are 45 dragonfly and damselfly species in the UK, of which 23 breed in East Yorkshire. I was amazed to find that 15 of these have established themselves in the county only after WWII. The recent colonists include now common and widespread species like the Common Darter, the Blue-tailed Damselfly and the Emperor Dragonfly.

Cumulative number of East Yorkshire dragonfly and damselfly species and the first record of each colonist species (data compiled from Paul Ashton's Dragonflies of South East Yorkshire, 2013).

 Recent studies taking advantage of the wealth of records held by the British Dragonfly Society indicate that warming climate largely explains northward range shifts, range expansions and earlier emergence observed in most British dragonflies and damselflies. In contrast, the few northerly species have also shifted their range north, and their ranges remained stable or slightly contracted in size. Some extreme examples of range expansions are the Common Darter, with a northern distribution range that moved north 346 km in 40 years, the Keeled Skimmer shifted 190 km.

  One of the recent East Yorkshire colonists is the Broad-bodied Chaser, with a first record in 1995. It is now quite widespread but still establishing and expanding its range.

Today I visited a pond in a site in the outskirts of the city, which has maintained water until now this year probably due to the higher than usual rainfall this winter and spring. I took advantage of a short sunny spell this afternoon in an altogether warm muggy day to try and see the Broad-bodied Chaser I had seen there before in mid May. This is a large, striking dragonfly, which readily colonises new ponds, including garden ponds. They have a flattened abdomen and dark spots on the base of the wings. Males have a powdery blue abdomen and yellow spots on the sides (top shot), the females a yellow/brown abdomen (below). Males maintain territories in ponds, where females may only approach the pond to mate and oviposit. As an adaptation to the shallow, small ponds where they develop, their larvae are able to move over damp, but otherwise dry terrain if the pools where they are developing are dry.

A female Broad-bodied Chaser (22nd May 2017, Leven Canal)

  Not long after I arrived, a male passed flying by hunting and patrolling over the pond, about half a meter above the water. I briefly saw a female too, which didn't settle. This species flies in a zigzagging way which makes it hard to follow, but it is a large animal, and has a habit of perching in favourite spots regularly, which more than compensates for it. The male settled on the most inaccessible part of the pond a few times, but finally it alighted on a large clump of Yellow Flag irises near me, where I could watch and photograph it easily.

More information

Ashton, P. (2013) Dragonflies of South-east Yorkshire. 105 pp.

Hassall, C., Thompson, D. J., French, G. C. & Harvey, I. F. Historical changes in the phenology of British Odonata are related to climate. Glob. Chang. Biol. 13, 933–941 (2007).

Hickling, R., Roy, D. B., Hill, J. K. & Thomas, C. D. A northward shift of range margins in British Odonata. Glob. Chang. Biol. 11, 502–506 (2005).

Piersanti, S., Rebora, M., Salerno, G. & Gaino, E. Behaviour of the larval dragonfly Libellula depressa (Odonata Libellulidae) in drying pools. Ethol. Ecol. Evol. 19, 127–136 (2007).

Azure Damselflies ovipositing

On Monday, I went to my local wildlife garden to check on dragonflies and damselflies. There were only Azure damselflies, Coenagrion puella. The Azure Damselfly is a common species, frequent in small ponds. Males are blue and black and females greenish and black. It can be distinguished from the Common Blue Damselfly by a forward pointing sput on the sides of the thorax. I walked around the pond and counted three mating pairs in tandem, and many individuals, including two teneral ones - just emerged and still not showing their full colour. The females were egg laying, with the males clinging to their thorax, guarding them as they lay from the attentions of other males. The females insert their eggs into stems of submerged aquatic plants. Females can lay over 4,000 eggs in their lifetime. I noticed that the pairs were not randomly assorted around the pond, but tended to gather in the same spot (top shot). Indeed, ingenious field experiments by A Martens showed that this species form aggregations to oviposit, the pairs particularly attracted to the vertical posture of the male in a tandem. Pinned models of a male in vertical position attracted tandems, but pinned models of females did not. Two model tandems were more attractive to pairs than single tandems, which will start an aggregation.

An adult male resting.

A teneral male, recently emerged.

Two pairs egg laying. 

The exuviae of three damselflies still stuck to the stem of a plant. 

More information

Martens, A. Field experiments on aggregation behaviour and oviposition in Coenagrion puella (L.)(Zygoptera: Coenagrionidae). Advances in odonatology 6, 49–58 (1994).