The Power of Citizen Science: Tracking Invasive Species

The Small red-eyed damselfly (Erythromma viridulum) male Image credit: Pam Taylor
Small red-eyed damselfly (Erythromma viridulum) male Image credit: Pam Taylor

A damselfly species that came to the UK from Europe poses a minimal risk to native damselflies and dragonflies, new research shows.

Recently in The Orkney News we published an article about Invasive Species:

It’s a tricky one because many invasive species have been introduced by people, either deliberately or by accident, something which has been going on since the earliest of times in the Human era. Today many species are also moving into areas they are not native to due to more human action – climate change.

In research conducted by the University of Exeter and the UK Centre for Ecology & Hydrology – using data from the British Dragonfly Society- a study of the small red-eyed damselfly has looked at if its appearance had caused native damselflies and dragonflies to decline.

Dr Regan Early, of the Centre for Ecology and Conservation on Exeter’s Penryn Campus in Cornwall explained:

“With range-shifting increasing globally, we need to understand what impact newly arrived species have on ecosystems. In this case, it seems the small red-eyed damselfly has established itself in the UK without harming similar species. It may be establishing itself most strongly in areas with good habitats, and these biodiverse sites could be important for increasing numbers of range-shifters in the future.”

Range-shifters have typically evolved in similar ecosystems to those they arrive in, and the existing native species have usually encountered similar species before.

Using British Dragonfly Society records from almost 50,000 site visits from 2000-2015, the new study focussed on sites where each of 17 native UK dragonflies and damselflies were found in each year.

Researchers then estimated whether the arrival of small red-eyed damselflies had affected these native species.

 Dr Jamie Cranston, the University of Exeter said:

“Our approach allows rapid assessment of how range-shifters are affecting native wildlife. It shows how citizen science can be really powerful, in this case by providing an ‘early warning system’ about possible threats to UK wildlife.”

Of the two damselfly species that have declined where small red-eyed damselflies have established, one is closely related to the new arrival. Dr Early suggests that similarities between their habitat preferences and flight season could cause the small red-eyed damselfly to outcompete its sister species.  

However, damselflies eat a wide variety of foods, so competition should be low unless conditions caused severe food shortages.

Additionally, the UK has a relatively small variety of these species compared to the rest of Europe, so there may be “vacant niches” for new arrivals to exploit.

The study was funded by the Natural Environment Research Council (NERC).

Click on this link to access, Associations between a range-shifting damselfly (Erythromma viridulum) and the UK’s resident Odonata suggests habitat sharing is more important than antagonism, published in the journal Insect Conservation and Diversity

See also: Orkney’s Dragonflies

Male Black Darter dragonfly by Graeme Walker

1 reply »

  1. Small Red-eyed Damselfly is one of several species which has colonised eastern and southern England in recent decades. Range shifting is a perfectly natural and evolutionary phenomenon, and in this instance is most probably due to climate change. Orkney’s most recent odonate arrival is Emerald Damselfly, which appeared in Hoy in 2010 and has subsequently been recorded in Flotta, Graemsay, South Ronaldsay and East Mainland. Who’s next? Common Darter dragonflies are resident in Caithness and Sutherland, but have yet to be confirmed on this side of the Pentland Firth. Or perhaps Southern Hawker dragonfly (an increasingly glaring misnomer as they have been recorded as far north as Brora in recent years).

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