The Cephalozygoptera is a newly discovered extinct suborder of Odonata with a rich fossil record. They are rather similar to damselflies in many ways, but are clearly distinguished by their heads, which are more rounded, with eyes set closer together, not protruding. For over a century and a half, paleontologists have described many species in this group, but always classified them as damselflies, thinking that their odd head shapes were only distortions produced by pressures during fossilization. Now, this odd head shape is understood to be their actual shape in life. With this new understanding, we see the suborder stretching back into the early Cretaceous alongside the dinosaurs and thriving across the Northern Hemisphere after the dinosaurs were gone until they were last seen only about ten million years ago in Spain. Understanding the Cephalozygoptera makes the history of Odonata richer and more interesting, particularly in the time since the extinction of the dinosaurs, as the world became modern.
Species of the Month
Wandering Glider or “Global Skimmer” Pantala flavescens from Madagascar. Photograph by Dennis Paulson
Hyacinth Gliders (Miathyria marcella) line up. Photograph by Netta Smith.
Hyacinth Gliders (Miathyria marcella) roosting on a tree. Photograph by Dennis Paulson.
Hyacinth Gliders (Miathyria marcella) swarms. Photograph by Netta Smith.
Dwarf Glider (Miathyria simplex). Photograph by Dennis Paulson
JULY’S FEATURED SPECIES:
Wandering Glider
This month’s DSA species focus is the Wandering Glider (Pantala flavescens), our most widespread odonate species. The Wandering Glider, or “Globe Skimmer” as it is sometimes known, is found on every continent except Antarctica (although surprisingly rare in Europe). It is slightly under two inches long (or just under 5 cm). The Wandering Glider breeds in shallow ponds and travels thousands of miles in migration. Read on to see how this species figures in an amazing migration event, seen by our July guest blogger Dr. Dennis Paulson in Mexico.
Migration Marvels
Living in the Puget Sound area of Washington in the United States, I see only two migratory dragonfly species, Common Green Darner (Anax junius) and Variegated Meadowhawk (Sympetrum corruptum). I don’t see them migrating very often. They appear in the spring, and their offspring disappear in the fall. When asked to write about a particular species for this blog, I immediately thought of migratory dragonfly species, including the Wandering Glider (Pantala flavescens), and a spectacular flight I observed.
On September 13, 2001, Netta Smith and I were on a beach in Matanchen, Nayarit, Mexico for two hours in the afternoon. It was very hot and sunny. A big storm had come through the previous day, with very strong winds and torrential rain. Thousands of dragonflies were flying along the west side of the bay, heading north into a light northerly breeze. All seemed to be heading in the same direction, with no deviation and a slow but steady forward movement. They flew from ground level to about 10 meters up, many of them out over the water to about 50 meters from shore.
The most common species by far was the Spot-winged Glider (Pantala hymenaea), but Great Pondhawks (Erythemis vesiculosa), Wandering Gliders, and Red Saddlebags (Tramea onusta) were all common. Finally, a few Tawny Pennants (Brachymesia herbida), Black-winged Dragonlets (Erythrodiplax funerea), Hyacinth Gliders (Miathyria marcella) and Dwarf Gliders (Miathyria simplex) made up the rest of the species that we saw.
About five individuals per second passed us at the maximum rate, down to one individual per second at slower times, for the 15 minutes we closely watched the flight. At the same time, there were swarms of hundreds of dragonflies flying around in nearby tree groves but not in any directional movement. They included very dense swarms of Hyacinth Gliders, with a few Wandering Gliders mixed in. These two species figured prominently in the hundreds of dragonflies hanging in rows from the bare branches of a fallen tree in a clearing near the beach. All the roosting dragonflies seemed to be in this tree. Dragonflies were also abundant at all fresh and brackish ponds along the road that afternoon.
Two days later, there was no beach flight. No stationary swarms. No roost! The ponds were almost free of dragonflies.
I interpreted this flight as a response to the storm the previous afternoon. The strong winds and heavy rain may have concentrated the dragonflies. When we observed them, I concluded they were moving back inland. Such unidirectional flights are usually classified as migrations. That’s what it looked like to me!
Our guest blogger for July is Dr. Dennis Paulson. He received a Ph.D. in Zoology from the University of Miami, and taught college and adult-education courses about natural history for more than three decades. Dr. Paulson recently retired after 15 years as the Director of the Slater Museum of Natural History at the University of Puget Sound. He is the author of Dragonflies and Damselflies: A Natural History; Dragonflies and Damselflies of the East; Dragonflies and Damselflies of the West, and many other natural history books and field guides.
ESPÈCE du mois
Pantale flavescente, Pantala flavescens, Madagascar. Photo Dennis Paulson.
Miathyria marcella alignés le long d’une branche. Photo Netta Smith.
Miathyria marcella au repos dans un arbre. Photo Dennis Paulson.
Essaim de Miathyria marcella. Photo Netta Smith.
Miathyria simplex. Photo Dennis Paulson.
Sélection du mois de juillet : La Pantale flavescente
L’espèce choisie ce mois-ci par la DSA est la Pantale flavescente (Pantala flavescens), notre espèce d’odonate la plus répandue. La Pantale flavescente est présente dans tous les continents sauf l’Antarctique mais, étonnamment, est rare en Europe. Sa longueur atteint presque deux pouces (un peu moins de 5 cm). Elle se reproduit dans des étangs peu profonds et parcourt des milliers de miles pendant sa migration. Lisez la suite de cet article pour en apprendre plus sur un événement migratoire surprenant qui a eu lieu au Mexique et est décrit par notre hôte de juillet, le Dr. Dennis Paulson.
Les merveilles de la migration
Vivant dans la région du Puget Sound, situé dans l’état de Washington aux États-Unis, j’observe normalement seulement deux espèces de libellules migratrices : Anax junius et Sympetrum corruptum. Je n’observe pas souvent ces espèces pendant leur migration. Elles apparaissent au printemps et leur progéniture disparaît en automne. Quand je fus invité à écrire un article relatif a une espèce particulière, je pensai immédiatement à une espèce migratrice telle que la Pantale flavescente (Pantala flavescens), et à un vol migratoire spectaculaire dont je fus témoin.
L’après-midi du 13 septembre 2001, Netta Smith et moi étions sur une plage à Matanchen, Nayarit, Mexique. Il faisait très chaud et ensoleillé. Un gros orage accompagné de vents forts et d’averses torrentielles avait eu lieu la veille. Des milliers de libellules volaient le long du côté ouest de la baie et se dirigeaient vers le nord, portées par une légère brise venant du sud. Toutes semblaient se diriger dans la même direction, sans s’en écarter et en un vol lent mais continu. Elles volaient entre le ras du sol et une hauteur d’environ 10 mètres et beaucoup volaient au-dessus de la mer, jusqu’à une distance d’environ 50 mètres du rivage.
L’espèce de loin la plus abondante était la Pantale bimaculée (Pantala hymenaea), mais il y avait également beaucoup de Pantales flavescentes et de Tramea onusta. Les autres espèces présentes étaient quelques Brachymesia herbida, Erythrodiplax funerea, Miathyria marcella et Miathyria simplex.
Jusqu’à environ cinq individus par seconde, ce nombre se réduisant par moment à un individu par seconde, ont défilé devant nous durant les 15 minutes pendant lesquelles nous avons observé attentivement le vol migratoire. Nous avons aussi vu des essaims composés de centaines de libellules volant sans suivre une direction particulière dans les bosquets proches de nous. Ces essaims incluaient des groupes compacts de Miathyria marcella avec, parmi eux, quelques Pantales flavescentes. Ces deux espèces représentaient la majorité des centaines de libellules posées verticalement sur les branches nues d’un arbre mort dans une clairière proche de la plage. Toutes les libellules au repos semblaient être dans cet arbre. Cet après-midi-là, de nombreuses libellules se trouvaient aussi aux étangs d’eau fraîche et saumâtre le long de la route.
Deux jours plus tard, il n’y avait plus aucun vol de libellules le long de la plage. Aucun essaim stationnaire ! Aucun groupe de libellules au repos ! Les étangs étaient presque dépourvus de libellules.
J’interprète le vol comme étant une réponse à la tempête de la veille. Les vents forts et les pluies torrentielles avaient peut-être causé une concentration de libellules. Nos observations de leur vol m’ont conduit à conclure qu’elles retournaient à l’intérieur des terres. De tels vols sont habituellement considérés comme étant migrateurs. C’est en tout cas mon impression !
Notre hôte du mois de juillet est le Dr. Dennis Paulson. Il a reçu un doctorat en zoologie de l’Université de Miami et a enseigné des cours d’histoire naturelle collégiaux et d’éducation d’adultes pendant plus de 30 ans. Dr. Paulson est retraité depuis peu du poste de Directeur du Slater Museum of Natural History de l’Université de Puget Sound, qu’il a occupé pendant 15 ans. Il est l’auteur des livres intitulés Dragonflies and Damselflies: A Natural History; Dragonflies and Damselflies of the East; Dragonflies and Damselflies of the West, ainsi que de nombreux autres livres d’histoire naturelle et de guides de terrain.
Traduction: Pierre Deviche
Save the Date! Our next DSA Virtual Lecture will be next July 16th!
The 2021 field season marks the 6th year of odonate surveys done at three sites in the Johnson Creek watershed in Portland, OR. Volunteers are trained by a professional entomologist and supported by staff of a local watershed council; data are reported on an iNaturalist project page. Most records are of common cosmopolitan species, but regular monitoring has allowed community changes following restoration to be tracked as well as effects of natural disasters (wildfires), and new species were added to the county list. This talk will discuss project design, lessons learned for volunteer training and retention, data usage by local natural resource agencies, and exciting dragonfly encounters.
Our next DSA Virtual Lecture will be June 18th!
Want to contribute to the science of dragonflies & damselflies? Consider using Odonata Central (OdonataCentral.org), one of the longest running entomological citizen science web platforms. Odonata Central was launched in 2004 and has become a popular and robust tool for serious odonate enthusiasts and professionals alike to contribute their records and observations. This talk will cover a history of the site, how it differs from other citizen scientist platforms, an overview of how to use it and introduce the first ever Odolympics (odonatacentral.org/odolympics) sponsored by the Dragonfly Society of the Americas.
ODONATE RESEARCH GRANT PROGRAM 2021 AWARDEES
Congratulations to this years recipients DSA Odonaate Research Grant!
Biddy, A.R. Can species distribution models identify genetic isolation? A case study examining genomic structure of a high-altitude, stream specialist damselfly (Canyon Rubyspot, Hetaerina vulnerata) across “sky islands” in Arizona, New Mexico, and Utah.
Husband, D. Odonates Assemblages Across Four Wetland Types in the Texas Panhandle.
Peters, D. Using Dragonfly Exuviae as a No-Kill Approach to Monitor Persistent Organic Pollutants in the Potomac River.
DSA Virtual Lecture Series starts May 14th!
Check out our first lecture by Dennis Paulson! Please register in the Buy Tickets button below the flyer.
Odolympics starts June 2021!
The Dragonfly Society of the Americas is partnering with Odonata Central to conduct the Odolympics 2021.
Visit the Odonata Central website to learn more!
DSA ELECTIONS - APRIL 6 2021
Two candidates are on our slate to fill vacancies on the SA Executive Council, Steve Collins is nominated to fill one of our regular member seats for a term of six years, and Chris Beatty is nominated for the two-year president-elect position. DSA members can vote online until midnight on 23 April 2024 on the DSA Website.
