The detailed Green darner's migration in France

 As an echo to Noushka's post on Dragonfly migrations, here is an add-on relative to this species. The info comes from Martinia, the French Odonatology Society's (Société Française d'Odonatologie) scientific journal that has dedicated a special issue in May 2013 to this subject.

General presentation of the species, by Philippe Lambret and Jean Pierre Boudot:
" We call remind a number of characteristics in order to better understand the migratory behavior of this species. Its occurrence area extends from the South of Africa to the North of Europe and to India. It is native to the tropical and Mediterranean zones where the larvae quickly develops, preferentially in temporarily or permanent shallow waters. This compulsory migration forces 

 the insect to leave its emergence site early, at the beginning of its post-teneral stage. As massive emergences occur important migrations lead the species high in the North and in the West, to such an extend that it has been observed in Iceland, Central Asia, in Guiana and the Caribbean islands.

These long distance migrations appear to be mainly passive travels with the help of winds blowing steadily in a constant direction. In Africa, migrations take place essentially from September to November with the massive emergences following the summer monsoon rains. They can be observed throughout winter along the African Atlantic Coast giving rise to more egg laying and to a new generation in the most favorable reproductive sites and the species moves on, still in winter and at the beginning of the spring, further north in Western Europe.

More inland, where the atlasic barrier cannot be overcome in winter, great concentrations of adults linger in Sahara during the cold season. They will resume their migration northward in spring. These two migration flows, coastal and continental, go on laying eggs leading to new emergences in Africa, in Mediterranean Europe and sometimes in Central Europe..."

Ecology :

"This species is a compulsory migrant reproducing in permanent or temporary lentic environments, in fresh or brackish water especially in open areas. Egg-laying takes place generally in tandem, on floating or dead vegetation and in humid soil, underlining the opportunist character of the species."

Life cycle and migration:

" The larval development is fast and estimated to last only from 70 to 120 days. Egg laying and emergences are synchronous and massive emergences seem to at the origin of important migratory swarms.
The fact that it is a compulsory migrant can be interpreted as being an adaptation to the general climate in the intertropical zone where puddles filled by monsoon rains dry out quickly and do not allow a sedentary settlement of reproductive species year round.

The groups stuck in the Sahara resume their travels northward and this second migratory wave reaches Europe after having crossed the Mediterranean Sea and reproduces regularly in the Mediterranean zone, Magreb, Iberian Peninsula, Mediterranean coast French, Italy and Greece during the transit..."

Assessment of the 2011 migration in France by Philippe Lambret and Clémence Deschamps:
"This migratory flux to occidental Europe and particularly to France is without known precedent. 177observers (of which I am part of) have collected 560 data in France, spread in 57 departments and corresponding to 18 regions. The majority of the data has been collected between April and June, the second wave was noted from July till November, with at times the observation of over a thousand individuals flying in from the South... In France, they scattered in diverse environments of stagnant water, ponds, vegetated gravel pits and lakes."

These photos bear witness to this massive arrival in the south of France I witnessed in 2011:

Alain Cochet

Translation: Noushka

Dragonfly migrations, the case of the Green darner and the Globetrotter

Most species move only of some kilometers around their emergence spot; however some are "pioneers" and will  travel much greater distances to colonize new reproduction sites. Dragonfly migration has not yet been thoroughly studied and for a reason... Try to follow them on dozens of kilometers!

It is estimated that only 25 to 50 of the 5200 world odonata species listed are migratory. What we know it is that this phenomenon is closely tied to that of bird migrations which follow coastlines, probably because they are a sure source of food for insectivores. Dragonflies get ready for the migration by accumulating reserves of fat, as many of other insects and birds. 

The case of the Green darner - Anax junius
It is one of the 9 migratory species known in the USA.
Part only of its populations is migratory; those living in the North remain there and reproduce locally whereas in the southern ones move northward to reproduce and the following generation returns then southward, travelling so several hundred kilometers each time - see detailed explanations in Charles Anderson's brilliant video [HERE].
They migrate exclusively by day with winds below 25 k/h, whatever these winds' direction and only after 2 successive nights of low temperatures.

Photo Wikipedia

Some years, a few individuals have been seen on Brittany’s coasts in France, carried by high altitude winds but too weak to reproduce.  

Sciencedaily.com

 

In the US, the Green darter is the object of a study with a tiny transmitter placed under the abdomen of a few insects. the results are stunning: Some manage to fly 140km / day!

The Red veined darter (Sympetrum fonscolombii) is also quite a traveller:

Red veined darter, male

  so is the Four spotted chaser (Libellula quadrimaculata)...

 
 

and Hemianax ephippiger, 2011 being an exceptional migration year in France et of which Alain has been a witness:

Finally here is the fascinating case of the Globetrotter (Pantala flavescens), a common species in the tropical regions crossed by the equator, but the species inhabiting the countries around the Indian Ocean have a very particular migratory cycle.
These last years, Charles Anderson (see the video above mentioned), an English marine biologist who has been working in the Maldive Islands for 26 years noted the appearance of million of these dragonflies at a precise moment every year.
He asked his contacts in India if they had been noticed a similar event on the continent at the same dates... The answers confirmed his sightings!  Fresh water lacking totally on the Maldive Islands, he wondered why they were flying there.

As the season turns in, they are seen almost every year precisely on September 24th in Bangalore, in October 12th in the very south of India, on October 17th in the North of the Maldive Islands, the 21octobre in Malé and finally on November 7th in the South of the archipelago. They came thus from the continent but with the northeast monsoon winds, but to go where... To the east of Africa. Anderson's contacts there confirmed the appearance of these dragonflies following the first summer rains coming toward Kenya. The Globetrotters are spot on: the females lay then in puddles and the larvae's life cycle being very short, these emerge only a few weeks later as dragonflies.

In the meantime the rains travel southerly toward the east of austral Africa and this generation will follow them to lay the next and the latter will then travel back to Kenya to lay one more generation which will fly back to India following the south-west monsoon, finalizing the cycle in 4 generations and over 16.000 km around the Indian ocean.

This is the largest insect migration known today.

These dragons are followed by the Amur Falcon the migration of which i as amazing... It extends from the Amur river in China, along the Chinese coastlines and through India, to reach the east of... austral Africa! Well yes, at the same time as the Pantala flavescens... a coincidence?

And they are not the only ones

Photo Wikipedia

 The Jacobin Cuckoo (Clamator jacobinus), 

Photo Wikipedia

 and the Indian Roller (Coracias benghalensis) among many others

 

 Noushka