Monday, August 19, 2013

In Praise of Pantala

A challenge to net, members of the genus Pantala are well-known long-distance travellers.  This is a specimen of Pantala flavescens, the Wandering Glider, taken at the small ephemeral pond at Pittsfield Preserve on Aug. 16. Supreme aerialists, these dragonflies seem to be able to hover effortlessly over a body of water, and then zoom off vertically in pursuit of a potential mate or to chase off a rival.  It's sort of like watching one of those fighter jets go from landing speed to vertical with afterburners, but with a LOT less sound and energy expended.  Due to their ability to take advantage of wind currents, their high wing area to body-mass ratio, and their ability to go from egg to adult in 3 months, these dragonflies are found all over the world.  It's a global species, with migratory flights reported from the Indian subcontinent to Africa, and of course, all over North America.  Sometimes we laugh at their miscues - such as an ovipositing female mistaking a shiny car hood for a pond, but the laugh is on us if we try to swing a net and capture one.
Small temporary ponds can often have a lot of small creatures in them, including larval fishes.  The rapid development of Pantala nymphs is dependent on having access to a good food source, and however many miscues the females may make, it's obvious that many of them are successful.
This world-wide distribution map from Discover Life obviously lacks ALL the collection localities, but you can see that is it a cosmopolitan species.  Our UMMZ collections has hundreds of specimens from all over the world.  Alas, except for the MI specimens, the rest are not cataloged.  You can read about the migratory flights of Wandering Gliders in the Indian Ocean here., and in Venezuela here. In Michigan, we have numerous sightings of Pantala flavescens all over the state.  It's the other species - Pantala hymenea - that we see much less often.   August and September are the months when we most often see swarms of Wandering Gliders -- as they complete their summer's life cycle and emerge from the ponds, they will become more numerous (especially this year, with adequate water all summer). Eventually, these amazing fliers will make their way south of the Great Lakes and down the Atlantic coast to new ponds and deposit their eggs and fly off to the next pond.  We will see some of their offspring next May/June as they return to the North. In Michigan, we have specimen vouchers for counties as shown at the left.  Undoubtedly, there are many sight records that are not indicated here.

Thursday, August 01, 2013

Golden-Winged Skimmer Incursion into Michigan.

L. auripennis in Jackson Co., courtesy of Craig Robson.
Earlier this summer, Rick Nirschl collected the first Michigan record of Libellula auripennis in Washtenaw County at the powerline ROW in Nan Weston Preserve.  There is a small fen there, and the specimen was photographed and collected by Rick and Curt Powell.  Obviously, a great find, and then the question becomes -- is it a one-off vagrant or an indication that there may be others? One observation means a new state record, a second site means that the species is perhaps establishing a beach head in SE Michigan.  That second site turned up today as I received an e-mail from Dave Cuthrell, forwarding an email from Craig Robson who photographed a Golden-winged Skimmer at the Grand River fen in Jackson County on July 30. That second sighting is very important, and it's possible that the species will be found elsewhere in S Michigan. Libellula auripennis is typically a SE US and Gulf Coast species, with a few scattered records S of the Great Lakes, in central OH and N Indiana.  It will be interesting to see what happens in Michigan.

On another front, the Xerces Society has a new program out called "Dragonfly Pond Watch Project." It looks to be an interesting endeavor, and should engage a bunch of citizen-scientists to record both migratory and resident odes across the country.  It's part of the Migratory Dragonfly Partnership, and the Xerces Society has a really good PR and web presence.  I encourage you to give the site a look!