Posts Tagged ‘Vermont Institute of Natural Science’

Data mining for Autumn Meadowhawk

October 28, 2019

This is a follow-on to my last blog post, Are adult Autumn Meadowhawks arboreal?

Data mining can be used to recognize patterns in official records of field observations by many amateur and professional odonate hunters, confirmed by experienced vetters.

Let’s begin by looking at the adult flight period for Autumn Meadowhawk (Sympetrum vicinum), the target species for a proposed field study during 2020 at the Vermont Institute of Natural Science.

Adult Flight Period

According to records for the Commonwealth of Virginia maintained by Dr. Steve Roble, Staff Zoologist at the Virginia Department of Conservation and Recreation, Division of Natural Heritage, the adult flight period for Autumn Meadowhawk (S. vicinum) is from May 28 to January 03. The species is classified as “common.” Its habitat is “ponds.”

Bear in mind, Dr. Roble’s records are for the entire state, therefore the adult flight period for S. vicinum seems to be longer than it is in reality. The adult flight period for a single site is probably shorter. For example, according to records for Northern Virginia maintained by Kevin Munroe, former manager of Huntley Meadows Park, the adult flight period for Autumn Meadowhawk is June 13 to December 10 (seen most September to October).

DSA Odonata Central Records

What is shown by a deep-dive into the Dragonfly Society of the Americas Odonata Central records database for Autumn Meadowhawk in the Commonwealth of Virginia?

There are currently 38 confirmed records for S. vicinum in Virginia, as shown by the following distribution map.

Source Credit: Abbott, J.C. 2006-2019. OdonataCentral: An online resource for the distribution and identification of Odonata. Available at http://www.odonatacentral.org. (Accessed: October 27, 2019).

Key: blue dots = Dot Map Project; green dots = Accepted records; yellow dots = Pending records.

Analysis

There are 14 records for teneral/immature adult Autumn Meadowhawk, ranging from 30 May to 19 August: May (1); June (5); July (5); August (3). Notice that the greatest cluster of records for teneral/immature adults occurs in June and July. There are a few records for mature adults toward the end of this time period and no records for mating pairs.

There are 24 records for mature adult Autumn Meadowhawk, ranging from 07 August to 03 January: August (2); September (5); October (13); November (1); December (2); January (1). Only a few records for teneral/immature adults occur at the beginning of this time period. The greatest cluster of records for mature adults occurs in October. Seven (7) of the records throughout the time period are for mating pairs, beginning in September; the greatest cluster of records for mating pairs also occurs in October.

What are the take-aways?

38 records is an admittedly small sample size. In the opinion of the author, patterns in the data are muddied by analyzing data for the entire state rather than a single location. There is almost certainly a south-to-north pattern in dates of emergence, mating, and disappearance for any given species, as well as atypical patterns resulting from micro-climates that exist throughout the state.

All of that being said, the data in the DSA Odonata Central records database for Virginia is consistent with my first-hand observations in Northern Virginia showing that Autumn Meadowhawk emerges in mid- to late-June, disappears for two- to three months, and returns to the ground/water when it’s time to mate during fall.

One big question remains to be answered: Where do adult Autumn Meadowhawks go when they disappear soon after emergence — do they live in the forest canopy? One thing we know is certain: There are few if any official records for mature adult Autumn Meadowhawk on the ground during mid- to late-summer. Food for thought.

Related Resource: Are adult Autumn Meadowhawks arboreal?

Copyright © 2019 Walter Sanford. All rights reserved.

Are adult Autumn Meadowhawks arboreal?

October 25, 2019

Autumn Meadowhawk (Sympetrum vicinum) is classified as a fall species of odonate. In the mid-Atlantic United States, meadowhawks seem to disappear for several months after they emerge during early to mid-summer and reappear during fall. Where do they go? No one knows for sure. I speculate Autumn Meadowhawk is an arboreal species of dragonfly that returns to the ground/water when it’s time to mate.

Emergence

The first individual — photographed soon after emergence — is a/an teneral/immature male, as indicated by the tenuous appearance of his wings, coloration, and terminal appendages.

24 JUN 2016 | HMP | Autumn Meadowhawk (teneral/immature male)

The next individual is a/an teneral/immature female, as indicated by the tenuous appearance of her wings, coloration, and terminal appendages.

24 JUN 2016 | HMP | Autumn Meadowhawk (teneral/immature female)

Time to mate

Fall is the time to mate for mature adult Autumn Meadowhawk dragonflies (S. vicinum), as you can see in the following photo.

15 NOV 2013 | HMP | Autumn Meadowhawk (mating pair, “in wheel”)

This mating pair is “in wheel”: the male is on the upper-left; the female is on the lower-right. All dragonflies and damselflies have a 10-segmented abdomen, numbered from front to back: male dragonfly secondary genitalia, called hamules, are located in segments two and three (S2 and S3); female genitalia in segment eight (S8). Dragonflies form the mating wheel in order for their genitalia to connect during copulation.

Forest Canopy Walk at Vermont Institute of Natural Science

Observing dragonflies at the Earth’s surface is fairly easy; observing dragonflies at the treetops, not so much. The new Forest Canopy Walk at the Vermont Institute of Natural Science (VINS) should facilitate the latter.

During 2020, I hope to collaborate with Kelly Stettner, Black River Action Team (BRAT), and Anna Morris, Lead Environmental Educator, VINS, to gather evidence that supports my speculation that adult meadowhawk dragonflies are arboreal. Field observations will be collected on the ground and along the Forest Canopy Walk.

Hosted by Anna Morris, Kelly Stettner and her family scouted the VINS site on 05 October 2019, including the new Forest Canopy Walk and nearby water bodies that provide suitable habitat for Autumn Meadowhawk. Special thanks to Anna for providing a behind the scenes tour a week before the official opening of the Forest Canopy Walk.

Gallery photos used with permission from Kelly Stettner, BRAT.

A week later, Autumn Meadowhawk was observed along the Forest Canopy Walk for the first time. The following photos provide circumstantial evidence that we might be on the right track. I love it when a plan comes together!

Gallery photos used with permission from Anna Morris, VINS.

I’m happy to share that during our public Forest Canopy Walk opening today [12 October 2019], I was stationed at the Eagle platform and got to see two (2) meadowhawks zooming around, then perched on the railing (pictures attached)! This is about 60 feet up, near a Sugar Maple and a Red Oak. [More meadowhawks were seen] the next day at nearly 90 feet up! At this height and as it was so sunny there were at least four individuals zooming around, landing on visitors, etc. Source Credit: Anna Morris, Lead Environmental Educator, VINS.

Related Resources

Copyright © 2019 Walter Sanford. All rights reserved.


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