Re: RE : [Odonata-l] Texas Dragonfly to identify...

[Glenn Corbiere]

Dennis, Josh, George et al,

I'm wondering it if was indeed Fort Bend that I was at? I'm going to have to go back to the maps and have a look. I was really stunned. It was as Josh described - E. simplicicollis occupied every square foot of every open bit of ground. There were almost no damselflies whatsoever. I think you are right in that, at least superficially they looked to be healthy waterways, but I couldn't help thinking that something went terribly awry, almost certainly due to anthropogenic changes. Whatever the changes are, apparantly E. simplicicicollis tolerates them magnificently, and P. longipennis only admirably. It is quite disturbing.

Glenn


Glenn Corbiere 
100 Prospect St. 
Chester, MA. 01011-9657 

www.dragonhunter.net 




________________________________
From: "dennispaulson at comcast.net" <dennispaulson at comcast.net>
To: Glenn Corbiere <gcorbiere at dragonhunter.net>
Cc: Odonata List Server <odonata-l at listhost.ups.edu>
Sent: Tuesday, July 14, 2009 10:09:40 PM
Subject: Re: RE : [Odonata-l] Texas Dragonfly to identify...


Glenn, 

You spoke volumes when you tallied up those dragonflies. I've had the same experience, once at Fort Bend State Park in the same part of Texas and often in Florida. I couldn't believe that such a nice series of wetlands as those at Fort Bend supported virtually nothing but those two common species. Often Slaty Skimmer, Libellula incesta, is #3 behind the first two in these situations, but far less common.

It may be noteworthy that that rapacious predator Erythemis simplicicollis is one of the most common dragonflies now in the Southeast. It's conceivable that its abundance is the cause of the disappearance of damselflies from many parts of the Southeast in midsummer. I'm still working on that hypothesis. However, Erythemis eats a lot of Pachydiplax too, and that species is still superabundant. The other alternative is that these two species are favored by anthropogenic changes in wetlands, but a lot of the wetlands where they are common seem on superficial examination to be nice habitats. However, perhaps they have undergone more eutrophication than one might think. Why would the larvae of these two libellulids become so common?

Dennis

----- Original Message -----
From: "Glenn Corbiere" <gcorbiere at dragonhunter.net>
To: "Michel Pilon" <Michel.Pilon at rncan-nrcan.gc.ca>, "Odonata List Server" <odonata-l at listhost.ups.edu>
Sent: Tuesday, July 14, 2009 6:46:43 AM GMT -08:00 US/Canada Pacific
Subject: Re: RE : [Odonata-l] Texas Dragonfly to identify...


Michel,

I was visiting Texas a few years back on a business trip, I was near the coast Southeast of Houston. I spent an entire day on three beautiful wetland areas. I saw 6,010 (in round numbers) different individual dragonflies and or damselflies.

5,000 were Erythemis simplicicollis / Eastern Pondhawk
1,000 were Pachydiplax longipennis / Blue Dasher
The remaining 10 were a total of about 6 or 8 other species.

I was not amused.

Be that as it may, you have one very common dragonfly there, and probably the most common dragonfly around any of these parts, but you have one of the nicest photos I've ever seen of that species!

So ultra common or not, Congratulations on a great photo!

Glenn



Glenn Corbiere 
100 Prospect St. 
Chester, MA. 01011-9657 

www.dragonhunter.net 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailweb.ups.edu/pipermail/odonata-l/attachments/20090714/0da69d02/attachment-0001.html