18 July 2012

Rare and uncommon saddlebags, wandering meadowhawks, and gliders galore

This is an excellent year for several uncommon or rare species in the upper Great Lakes and northeastern states, and an opportunity for getting plenty of new county records. Three of the species -- Red and Striped Saddlebags and Variegated Meadowhawk -- are pretty much considered vagrants from the south or west in Michigan. Often their extra-limital movements are triggered by environmental conditions, especially drought. Specimens are extremely valuable in tracking range expansions, as well as for molecular research that can determine source populations, colonization histories, and other important characteristics of their population ecology. For more background on the value of voucher specimens, see this post on our record of Striped Saddlebags for Michigan.

Carolina Saddlebags and Spot-winged Glider are much more common, although more so in some years than others. However, all the Trameas and Pantalas can be pretty tough to net due to their habit of flying continuously over water and/or up high. Thus, they are under-represented in the MOS collection.

Here's what we're looking for:

Red Saddlebags, Wayne County. Photo by Julie Craves. Map of MOS voucher specimens through 2011.

Red Saddlebags (Tramea onusta). As of the end of 2011, this species has only been collected in four Michigan counties. They are making a strong movement north this year, with sightings well into Canada. Red Saddlebags are smaller than the abundant Black Saddlebags (T. lacerata) and Carolina Saddlebags. They differ from Carolinas in lacking a purple frons; having less black on s8 and s9, usually restricted to the top of the sections and not extending down the sides; and having a larger clear "window" in the base of the wings.  Males also have larger hamules. Here is a side-by-side from the Iowa odes website.

Carolina Saddlebags, Wayne County. Photo by Julie Craves. Map of MOS voucher specimens through 2011.
Carolina Saddlebags (Tramea carolina). If you have some trouble distinguishing red-colored saddlebags, don't despair. If you can catch them, we can use them. Carolina Saddlebags is present in the southern counties pretty much annually, but every few years can be very numerous. This is one of those years. With fewer than a dozen counties being represented by vouchers, we can surely fill in much of the southern part of the state, at least, in 2012.

Striped Saddlebags, Wayne County. Photo by Julie Craves.

Striped Saddlebags (Tramea calverti). The only record in Michigan of this species is from Wayne County in 2010. That year saw an unprecedented northern invasion of this southern species. This year is shaping up to be another great year. In June, there were photographic records of Striped Saddlebags for Minnesota and Wisconsin, and in early July they were photographed in northern Ohio (none of these records indicated vouchers were taken -- remarkably, of the dozens reported the last few years in northern states, the two specimens we took in 2010 are the only vouchers that I know of).

Spot-winged Glider, Wayne County. Photo by Julie Craves. Map of MOS voucher specimens through 2011.

Spot-winged Glider (Pantala hymenaea). While not as common as Wandering Glider (P. flavescens), this species is not rare in Michigan. As is evident by the map, it is clearly widespread, but really under-represented by specimens. Vouchers are needed to accurately show the distribution in the state. Here are some ID tips from the Migratory Dragonfly Partnership.

Speaking of Wandering Glider, although it is one of the more common species, voucher specimens are also missing from many counties. Fill in the blanks!

Variegated Meadowhawk, Alger County. Photo by Mark O'Brien. Map of MOS voucher specimens through 2011.

Variegated Meadowhawk (Sympetrum corruptum). This is another hit-or-miss species in Michigan. They aren't anywhere near as hard to catch as the Trameas or Pantalas, since they tend to stay near and perch in waist-high vegetation. They are more common in the western U.S. and Great Plains, but tend to wander and are strongly migratory. When we found them in Wayne County in 2006 (after last being collected in 1931), they were emerging from tire ruts in a wet field in June, so presumably they can also breed and overwinter here. The map indicates they can show up anywhere, so be on the lookout. Here are some ID tips from the Migratory Dragonfly Partnership.

1 comment:

  1. Interesting post. It's an exceptional year for most of the species you mention here on the north shore of Superior. So far our only saddlebags are T. onusta (many, some ovipositing at several sites) and T. lacerata (one so far, third district record). 'Will keep an eye out for the others. Michael