The project
The purpose of this project is to map the migration system of European dragonflies. A migration system describes the movement of a migratory species: where individuals are going, where they came from and the composition of migrants and potential non-migrants in a population.
Very few migration systems are fully understood among dragonflies, but the green darner (Anax junius) is a exception. The range of the green darner reach from southern Canada to northern South America and so far, we know that individuals may migrate as far as 380km within this area. The migration system is best known in North America, where stable isotope analysis has revealed that migrants from the south fly to higher latitudes in the spring to breed. The offspring of these migrants emerge as flying adults in the summer, return southwards and breed and then a third generation is hatched. This third generation, which fly in the winter in areas such as Florida and Mexico, refrain from migrating and breed locally, and the subsequent fourth generation close the migratory circut by migrating north in the spring to breed.
Complicated, multi-generational and long-distance migrations such as that of the green darner is likely occuring worldwide where migratory dragonfly species exist. Currently, the migration system of all European dragonfliles are unkown, and this project aims to remedy this by stable isotope analysis and the creation of migrant dragonfly isoscapes.
What is an isoscape?
Stable isotopes are versions of chemical elements that do not deteriorate. Hydrogen, H, for example, have two stable isotopes. One of these, Deuterium (d2H), is naturally occuring in water, and will become deposited in certain patterns around the globe depending on rainpatterns. Living organisms will pick up deuterium in their tissues, as they consume items from their environment. By analysing certain tissues of, for example a dragonfly, and comparing the amount of deuterium in, for example their wings, their origin can be pinpointed. This is possible since the dragonfly will have developed its wings at the freshwater site where it lived as a nymph. Where an individual is encountered as an adult, and where its wings were developed, can then be compared to approximate its migration. When several such comparisons can be made, and a larger pattern emerges describing the movement of an entire popualtion or species, you will have an isoscape.
Dragonfly migration in Europe
In Europe there are about 143 species of dragonflies (‘Anisopterans’) and damselflies (‘Zygopterans’). Of all the European Anisopternas, approximately 21 species are regarded as migratory. This number is not fixed, as more is constantly being discovered about the movement ecology of dragonflies.
These 21 species are noted as migratory based on several types of data, for some the evidence is weaker, and for some their migratory behaviour is very well documented. Good data on migratory behaviour consist of several well recorded events of large migratory swarms, either observed over land or coming in from the ocean. In areas where human observers are regularly noting these kind of movements, for example bird observatories and research stations, the evidence becomes very strong. Species that are regularly seen migrating in these instances are for example the four-spotted chaser (Libellula quadrimaculata), the migrant hawker (Aeshna mixta), the lesser emperor (Anax parthenope), the common darter (Sympetrum striolatum) and the vagrant emperor (Hemianax ephippiger).
Roosting migrant hakwer (Aeshna mixta) swarm in Ukraine, by Dyatlova and Kalkman 2016
Importantly, not all individuals of all migrant species are migratory. Similar to the green darner described above, individual dragonflies in certain species may not be enticed to migrate. Our knowledge of migratory behaviour in insects and dragonflies is still limited, and we know very little about what elicit migration. In the four-spotted chaser, it appears as though high density and crowding results in mass-movements, where as the migrant hawker likely only migrates at colder latitudes. The vagrant emperor represents yet another system, where migration is obligatory and movement patterns are believed to be adaptations to cope with draught and to utilise rain-bearing seasonal winds.
A roosting swarm of four-spotted chasers (Libellula quadrimaculata), photographed in Kazakhstan by Koshkin et al 2016
Certain migrant species are frequently encountered far from their breeding grounds at certain times of the year, or known to be observed moving in great swarms along Mediterranean or African coasts, only to appear in the form of a diminished number far north a couple of days or weeks later. Species engaging in these vagrant and long-distance migratory movements include the vagrant emperor (Hemianax ephippiger), the red-veined darter (Sympetrum fonscolombii), scarlet darter (Crocothemis erythraea), the black pennant (Selysiothemis nigra) and the lobe-tailed dragonfly (Lindenia tetraphylla).
21 migratory species
A list of species with migratory tendencies that breed in Europe (Scientific name, English name, Swedish name):
Aeshna affinis, Southern migrant hawker, Klarblå mosaikslända
Aeshna cyanea, Blue hakwer, Blågrön mosaikslända
Aeshna isoceles, Green-eyed hawker, Kilfläckslända
Aeshna juncea, Moorland hawker, Starrmosaikslända
Aeshna mixta, Migrant hawker, Höstmosaikslända
Anax imperator, Blue emperor, Blå kejsartrollslända
Anax parthenope, Lesser emperor, Mindre kejsartrollslända
Hemianax ephippiger, Vagrant emperor, Brun kejsartrollslända
Crocothemis erythraea, Broad scarlet/ Scarlet darter, Karmintrollslända
Libellula quadrimaculata, Four-spotted chaser, Fyrfläckad trollslända
Selysiothemis nigra, Black pennant, Svart vimpelslända (inte officiellt namn)
Sympetrum danae, Black darter, Svart ängstrollslända
Sympetrum depressiusculum, Spotted darter, Svartfläckad ängstrollslända
Sympetrum flaveolum, Yellow-winged darter, Gulfläckad ängstrollslända
Sympetrum fonscolombii, Red-veined darter, Vandrande ängstrollslända
Sympetrum meridionale, Southern darter, Ljusröd ängstrollslända
Sympetrum pedemontanum, Banded darter, Bandad ängstrollslända
Sympetrum sanguineum, Ruddy darter, Blodröd ängstrollslända
Sympetrum striolatum, Common darter, Större ängstrollslända
Sympetrum vulgatum, Migrant darter, Tegelröd ängstrollslända
Lindenia tetraphylla, Lobe-Tailed dragonfly / Bladetail, Roderstjärt (inte officiellt namn)
SEND IN Samples and specimens please
If you want to support this project, it would be greatly appreciated. Here is what you can do:
If you have a migrant dragonfly in your posession, please send it in! Anyone who wants to can send in a specimen (a whole dragonfly or just one wing), the important thing is that you dry the specimen (if it is a whole dragonfly) and that you note where and when you collected it.
You can dry the dragonfly by placing it on a radiator or in a sunny window. If it still starts to smell a bit, it can still be used for stable isotope analysis, but it will, well, smell.
Please contact the project coordinator for more information and where to send your specimen:
j.hedlund at exeter.ac.uk or johanna.hedlund at biol.lu.se
THANK YOU!!
Vagrant emperors (Hemianax ephippiger) arriving to Cyprus, by Will Hawkes
References
Boudot and Kalkman 2015. Atlas of the European Dragonflies and Damselflies.
Corbet 2004. Dragonflies. Behaviour and ecology of Odonata. Cornell University Press.
Dumont and Desmet 1990. Transsahara and transmediterraneanmigratory activity of Hemianax ephippiger( Burmeister) in 1988 and 1989 (Anisoptera: Aeshnidae).
Dumont and Hinnekint 1973. Mass migration in dragonflies, especially in Libellula quadrimaculta L.: a review, a new ecological approach and a new hypothesis. Odonatologica 2(1):1-20
Dyatlova and Kalkman 2016. Massive migration of Aeshna mixta and Sympetrum meridionale in the Ukrainian Danube delta (Odonata- Anisoptera: Aeschnidae, Libellulidae). Entomologische berichten 68:5
Halloworth et al 2018. Tracking dragons: stable isotopes reveal the annual cycle of a long-distance migratory insect. Biology Letters 14: 20180741.
Koshkin et al 2016. The ‘Waterfall Spectacle’ Of Libellula Quadrimaculata-Aggregations (Odonata: Libellulidae). Odonatologica 45(3/4):213-224