Winged dragons and damsels.
Walking opened up a whole other world. Instead of running through the area, I now stopped to take a closer look at the local inhabitants, often photographing them. I quickly gained a greater appreciation for the complex web of life at the pond.
The area attracts great numbers of migrating waterfowl and songbirds, as well as a wide variety of pollinators. But another less obvious group of fliers increasingly caught my eye: dragonflies and damselflies. What were just "blurs" while I was running came into focus as colorful combatants in constant competition for food, mates and space.
Dragonflies and damselflies comprise one of the most distinctive and intriguing groups in the animal kingdom. Classified under the Order Odonata (meaning "toothed ones," referring to their serrated jaws), odes (as they're affectionately known) are carnivorous insects commonly seen flying near water during warmer months. There are more than 7,000 species worldwide, including 194 species known to occur in New York. I've personally observed and photographed 35 ode species at Cedar Pond.
Having sleek, aerodynamic bodies, huge eyes, and two pairs of independently controlled wings, odes are fascinating to watch as they zoom around in search of food. The larger of the two groups of odes are dragonflies, measuring 1.5"-3" in length. These robust-bodied insects are strong fliers, with asymmetric wings held perpendicular to their bodies. In contrast, damselflies are thin-bodied, measure 0.75"-1.5" long, and are weak fliers. At rest, they hold their symmetric wings along their abdomens.
As a group, dragonflies and damselflies have been around for more than 300 million years. The fossil record indicates that they survived two major extinction events during which up to 90% of Earth's species perished.
The early and largest odes had 272-foot wingspans and date back to the Carboniferous Period when evolving trees flourished in vast forested wetlands. As plants diversified and created new habitats, estimated oxygen levels reached 35% (vs. 20% in the air today). Since insect size is largely limited by oxygen transfer within their primitive breathing systems (tracheal pores and tubes), higher oxygen levels allowed larger insects to evolve. Over time, changes in atmospheric oxygen and pressure from predators may have assisted in the "downsizing" of odes through natural selection.
Odes are incredible fliers, performing amazing mid-air acrobatics. They can rapidly reach speeds of 30+ mph, and can literally turn on a dime. Separate muscles within the thorax (portion of body between the head and abdomen) can variably control each of four wings at 20 to 40 flaps per second. This enables them to perform complex maneuvers and to hover.
Ode wings are independently controlled, allowing nimble powerful flight and swift aerobatic maneuvers in any direction, including reverse--a feat shared only with hummingbirds. A structural network of supportive veins, transparent "panes" of chitin (a major constituent of the exoskeleton), and corrugations (alternating ridges and grooves) on ode wings provide high strength, low weight, and variable flexibility for peak performance and efficiency. These amazing fliers can skillfully maneuver to precisely alight on tiny twigs, plant tips, and leaves, and to efficiently snatch prey out of the air, virtually at will.
Seasons of Odes at Cedar Pond
I love visiting Cedar Pond, no matter the season. My regular visits, usually with camera in hand, allow me to observe and document the various species and life stages of these fascinating critters.
When I first started photographing odes, I used a simple 3Xzoom pocket digital camera. This taught me patience and stealth, and I was able to capture plenty of damselflies and perchers, who would remain in place and "pose" nicely for the camera. It wasn't long before I upgraded to a super-zoom camera (eventually getting a digital SLR) and was able to photograph the more elusive fliers and rarely-seen odes. Through trial and error (and many missed shots), I discovered that some odes tolerate a slow approach (stalk and shoot often), while for others it's best to settle into a popular spot and wait.
Come April, warm days with southern breezes herald the appearance of dragonflies and damselflies. After over-wintering beneath the ice--where some nymphs actively fed and grew, while others, and some eggs, were in diapause (dormancy) --the first species to typically emerge from the aquatic realm is the hardy but dainty damselfly, known as the eastern forktail. Common here, it keeps a low profile, inhabiting dense vegetation near water, gleaning small insects and avoiding predators.
One year, a few weeks after the first forktail sighting, I saw dozens of large dragonflies patrolling and sparring over the water. Two species--the common green darner and black saddlebags--had not been there the day before. The sudden and early appearance of large numbers of mature dragonflies of these two species indicated a migration wave from the south.
The early emergence of forktails and early arrival of migrant species are competitive strategies for survival. Less competition and predation on the nearly empty pond promotes greater success for individuals and populations. Some migrants move on after replenishing their energy reserves, but others remain to mate and lay eggs. Where migrating and resident populations co-exist, genetic vigor, dispersal and success of the species are enhanced.
By May, the pond is hopping with an assortment of baskettails, clubtails, dot-tailed whitefaces and bluets. Perhaps to blend in with still-developing plants, many of these early odes lack the flashy color of the summer species.
Early summer brings the greatest diversity of ode species as new emergents (eastern pondhawks, blue dashers and prince baskettails) mix with the spring fauna. By the end of June, numerous widow skimmers, Halloween pennants, eastern pondhawks and eastern amberwings dominate the shoreline. With this peak in diversity and abundance, intra- and inter-species competition for space and mates is constant. For example, male widow skimmers are very territorial and drive off any species, especially their own, from their patch of shoreline. In contrast, Halloween pennants are non-territorial and can be found far from water. Since both of these species are perchers, I've been able to take a number of nice photos of them. It's the fliers that are difficult to photograph.
By late August, if you look closely, you may spot empty nymph skins (called exuviae) of black saddlebags attached to cattails. And if you're lucky, you might even spot a newly-emerged (teneral) dragonfly. I've been fortunate enough to see a number of them: just emerged, not fully capable of flight, drying their magnificent wings. These are likely the progeny of spring migrants, just emerged for a probable return trip down south. It's amazing to watch the rapid transformation from a stubby, one-inch-long aquatic nymph into one of the largest dragonflies, with a four-inch wingspan primed for long distance flight.
With many of the summer species in decline or gone (having completed their life cycle by mating and depositing eggs in the pond), brilliant-red meadowhawks become the dominant odes, along with spreadwings and familiar bluets. Dainty and approachable, these colorful autumn meadowhawks blend well with fall vegetation. Their distinctive tan legs distinguish them from the other meadowhawks (band-winged, white-faced and ruby/cherry-faced).
Autumn meadowhawks are the last dragonflies seen flying here. In a flurry of breeding activity, they mate well into October to propagate the species before the onset of winter. Resident odes over-winter underwater as aquatic nymphs for one or more seasons (most of their life cycle) before emerging in spring when they will start the cycle again.
During the course of my daily walks, I've taken thousands of pictures of dragonflies and damselflies. I never grow tired of watching the aerial antics of these beneficial and beautiful creatures. I have also grown to appreciate the importance of, and need to conserve, the wetland habitats that are home to the seemingly endless variety of odes and many other critters.
Next time you are near a waterbody (or even in your own backyard), be sure to stop and watch the various dragonfly and damselfly species as they zoom and dive around the area. You'll surely be entertained. And if you have a camera handy, snap a few pictures.
Ode enthusiast James Craft is an engineering geologist in DEC's Avon office.
Remarkable Dragonfly Traits
Prehistoric Lineage--Ancient dragonflies had wingspans of up to 2 1/2 feet and ruled the skies for approximately 100 million years. Exceptionally preserved fossils from the Jurassic age are remarkably similar in appearance to modern dragonflies.
Acute 360[degrees] Sight--Two bulbous compound eyes, each with up to 30,000 lenses, cover most of the head and provide a near-full spherical field of view. Along with three small simple eyes (ocelli) sensitive to movement, little goes unnoticed.
Agile 360[degrees] Flight--Four, independently controlled wings enable dragonflies to quickly move in any direction, and also to hover.
Peerless Predators--Constantly on the hunt, dragonflies intercept and consume large numbers of flying insects (up to 20% of their body weight per day) including many pests such as mosquitoes. They have a 95% prey-capture rate, far greater than most predators. Below water, ode nymphs use their barbed lower lip to snag various larvae, tadpoles and even minnows.
Long-distance Migrants--A few ode species migrate south, with flight distances likely exceeding 1,000 miles. Wandering gliders are known to cross oceans and fly more than 4,500 miles!
Mating "Hearts"--After transferring sperm from his lower to upper abdomen, the male grasps the female behind her head with his terminal appendages (claspers). The female then curls her abdomen to join the male, forming a heart-shaped wheel. Following mating, females deposit fertilized eggs on or in aquatic vegetation, or directly into the water.
Tiny Eggs to Winged Dragons--Eggs may develop quickly into nymphs or overwinter in the pond. Nymphs feed voraciously for months to years. Growth occurs in stages (molts/ instars) until they finally undergo metamorphosis to emerge as adults. During this emergence, the wings unfurl from tiny wing pads and are pumped with fluid into final form, perhaps 20X the initial size. Until wings dry and harden, the teneral ode is very vulnerable.
Colorful Critters--Odes come in a variety of colors and patterns. Color, as well as wing pattern, size and shape, can be very useful in identifying species.
Scientists from the U.S., Canada and Mexico are working together to better understand the migratory patterns of dragonflies. This relatively new study provides a variety of opportunities for citizen scientists to contribute to the research. Since raptor migrations often include dragonflies, bird watchers can help record observations of them. Citizen scientists can also participate in Pond Watch (http://www.xerces.org/dragonfly-migration/pondwatch/), whereby they visit a pond and record the number of dragonflies they see.
Become part of this continent-wide effort to learn about how, where and when dragonflies migrate. Visit the Migratory Dragonfly Partnership website for more information. www. migratorydragonflypartnership.org
Please note: Some tables or figures were omitted from this article.
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|Title Annotation:||species found at Cedar Pond, Avon, New York|
|Publication:||New York State Conservationist|
|Date:||Aug 1, 2016|
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