Thursday, July 15, 2010

Ebony Jewelwing Study

Several months ago, Dr. Chris Hassall of Canada's Carleton University biology department asked if we would assist with his Ebony Jewelwing (Calopteryx maculata) damselfly study by collecting male specimens from the old-growth, cypress-tupelo swamp at Audubon's Francis Beidler Forest.  Dr. Hassall is looking at variation in morphology of the Ebony Jewelwing damselfly across its range, which includes the eastern two thirds of the United States and eastern Canada.

Yesterday, we had the opportunity to head out into the swamp and collect Ebony Jewelwings along the boardwalk (Site A) and downstream along the canoe trail (Site B).  In the Google Earth image below, Site A is shown in red and Site B is shown in yellow.  The collection sites were not as large as the shaded area as we were never more than 10 meters from the boardwalk or the canoe trail.  However, the graphics were expanded slightly so that they would show on the map.

Although damselflies are in the same order (Odonata) as dragonflies, there are differences.  The wings of a dragonfly are horizontal to the body when the insect is perched, while a damselfly's wings are held vertically when perched.  A dragonfly's wings remain nearly horizontal as it flies, while a damselfly flits about like a butterfly with its wings ranging from horizontal or vertical as it flies.  They can remain still for long periods, which makes them difficult to locate when perched.  Damselflies eat insects, mostly gnats, but they are a prey item for some species of dragonflies.  Therefore, the Ebony Jewelwing's ability to remain motionless protects it from predators and net-swinging, for-the-day researchers.

Male and female Ebony Jewelwings can be identified by their wings. Males, our target, have all-black wings, while the females accessorize with a white dot (stigma) at the end of each wing.

Once a male Ebony Jewelwing was spotted, we approached the damselfly with the insect net at the ready.  As noted earlier, the damselflies would remain motionless as we approached.  However, if we missed on our first attempt, the jig was up!  The damselfly in question would know that we were a threat and flit away just as we reached the appropriated distance for another strike attempt.  How foolish can a small insect in a swamp make a mammal look in pursuit?  Ah...let us count the ways.  There are more than a few male Ebony Jewelwings that will be passing along their escape and evade DNA!

For those male Ebony Jewelwing less adept at evasion, the insect net was likely (but not always) the last stop before being quickly euthanized in a jar of nail polish remover (acetone) fumes.  We collected and packaged 11 male Ebony Jewelwings from each site.  That number will not have a detrimental effect on the population at the Francis Beidler Forest, but it will hopefully contribute to a better understanding of the species across its range.

"...and you call that work?"  We did!

Images by Mark Musselman

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