Three northern darners

The mosaic darners, genus Aeshna, are of course the large, conspicuous dragonflies that fly, sometimes in impressive swarms, throughout the Ontario summer. Of the one dozen species found in Ontario, eight are known from the Thunder Bay District. Of these, three - the Sedge, Zigzag and Subarctic - have distinctly northern affinities and are among the less commonly seen species in our region.

All three seem to be flying right now in the Marathon area. During the last half of July I crossed paths with Sedge and Zigzag Darners at sites where I'd found them previously. The Subarctic Darner, a lifer for me a few weeks ago, has been observed only a handful of times in NW Ontario and it wasn't one I expected to find so close to home.

Here's a quick overview of the trio with some habitat and locality notes.

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Sedge Darner (Aeshna juncea)
Date: July 15, 2012.
Habitat: Breeds in rock/splash pools along the rocky Lake Superior shore. It's also commonly found in shore fens and sedge-fringed beach swales along the coast where, I suspect, it breeds as well.

Sedge Darner locality and habitat.

Locality: Rock pools at Ypres Point, Peninsula Harbour, Lake Superior (48.73619, -86.43059). I netted and released males and females at this site and observed mature nymphs foraging in the deeper pools.

Male Sedge Darner, July 15, 2012

Female Sedge Darner, July 15, 2012

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Zigzag Darner (Aeshna sitchensis)
Date: July 27, 2012.
Habitat: Nutrient poor, often open fens and bogs.

Zigzag Darner locality and habitat.

Locality: Open fen at low-lying centre of peatland west of the Prairie River at Hyw 17 (48.80185, -86.78627). Last September at the end of the flight season, I blogged about my first encounter with the species at this site. I returned this month and found many patrolling males, copulating pairs and a few ovipositing females.

Male Zigzag Darner, July 27, 2012.

Mating Zigzags, July 27, 2012.

Female Zigzag Darner, July 27, 2012.

Male Zigzag Darner, September 17, 2011.

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Subarctic Darner (Aeshna subarctica)
Date: July 23, 2012.
Habitat: Nutrient poor, often open fens and bogs.

Subarctic Darner locality and habitat.

Locality: In the Town of Marathon, along the dirt road leading to Shack Lake (48.74482, -86.35753). The female in these photos is my first and only Subarctic Darner to date. I assume that she emerged from the nearby bog-fringed shore of Shack Lake. On July 29th, Sue Bryan netted a male from a bog mat on Harvais Lake, near Dorion.

Female Subarctic Darner, July 23, 2012.

Male Subarctic Darner. July 29, 2012. Courtesy of Michael Bryan.

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A really great source of information about these and other boreal odes is Dragonflies and Damselflies in the hand: An identification guide to boreal forest odonates in Saskatchewan and adjacent regions. This slim, attractive volume is available from Saskatchewan Nature.

Full citation: Hutchings, G. and D. Halstead. 2011. Dragonflies and Damselflies in the hand: An identification guide to boreal forest odonates in Saskatchewan and adjacent Regions. Special Publication #29. Nature Saskatchewan, Regina.