Sunday, March 9, 2014

Aerial Acrobatics: The Odonates


Dragonflies and damselfies, also known as odonates, are truly remarkable creatures. Apart from their often impressive physical characteristics and vibrancy, these small insects dazzle in the sky with their aerial acrobatics. They have the required finesse to hover over an object while scanning their surroundings in all directions, then alight with their tiny appendages on even the narrowest of vegetation with a gracefulness seen nowhere else in the insect kingdom, and a second later, if the site doesn’t meet their requirements, take to the sky again at lightning speed and be out of eye sight before you can even blink. If that isn’t enough, they also have the innate ability to fly backwards, as each wing is capable of moving independently. In short, odonates have evolved into something special, and unlike many of their contemporaries have been this way for quite some time. These organisms are incredibly ancient and have hardly changed over the 300 million years that have elapsed since their original emergence. This lack of alteration only further demonstrates their exceptional efficiency, as they need not be further refined by the forces of evolution—they’re already at their peak.
In southern New York State alone there are approximately 128 dragonfly and 55 damselfly species. The Hudson Valley is inundated with numerous common varieties, along with harboring several rarer species. The high diversity is bolstered by the large estuary that runs through the heart of the region. The Hudson River provides crucial habitat to some species which require the optimal conditions that are only dished out by water bodies that contain brackish tidal marshes. The hardening of shorelines and the destruction of marshes has led to vast declines in certain species and are now severely restricted in distribution.
All odonates require being situated by water—mating, ovipositing, and the larval stage of the life cycle are all dependent on it. Most can make due in fresh water, and undoubtedly anyone that has passed by a lake or swamp in the warmer months has seen countless dragonflies basking in the sun on reeds or skimming over the water and taping it gently at regular intervals like a stone being skipped across the surface. The latter sight is when an odonate is deposting its eggs; each tap is one being released into the water. When these eggs eventually hatch they enter into the naiad (named after Greek water nymphs) or larval stage of their lifecycle. They hardly resemble their adult counterparts, being green-brown or dark brown, with varying degrees of mottling, so not to stand out in their watery environs where they could easily be devoured by fish. They also have a comparatively frightening appearance, resembling something more akin to an underground grub than an organism that will eventually take to the sky.  At this stage they are entirely aquatic. They also are carnivorous, feeding on other insects and possibly even small fish at times. Some naiads will remain below the surface for up to 6 years.
After numerous molts of the exoskeleton (sometimes up to 15), each time the naiad getting progressively larger in the process, it’s time for the creature to emerge to the surface and begin its life as a dragonfly or damselfly. Upon making it to dry land the odonate’s exoskeleton is still relatively soft and the adult generally must take it easy for a week until it successfully hardens. During this time the individual will normally recuperate in the woods or in an isolated field or glade until it is ready to partake in the rigors of the mating process. Males will frequently compete with one another in duels for the opportunity to claim the right to mate with females of their claimed territories.
Best Spots to View
The Mid-Hudson Valley, and more particularly, the undeveloped Hudson Highlands, contains numerous favorable locations for odonates to thrive in. In these sheltered and protected areas rare varieties which have been pushed out elsewhere live in relative peace and thrive among the lush vegetation and salubrious aquatic environs.
Iona Island Marsh

Common Sneezeweed, Marsh Mallow, and Cardinal Flower 

In Bear Mountain State Park in the southern tier of the Highlands two particularly unique species can be found.  On the eastern flank of the park lies Iona Island. This rocky citadel holds dozens of different odonates which buzz past your head in copious quantities, similarly to a swarm on gnats on a humid summer’s day.  Among the congregation is the bright orange Needham’s skimmer. This species inhabits the brackish marshes surrounding the island, and individuals are often spotted clinging to some of the ubiquitous reeds of the invasive phragmites. These creatures are found in only a handful of counties in lower New York. Orange County is the farthest north they have been documented in the state. Intermixed with the Needham population is the deceptively similar looking golden-winged skimmer. From a distance it’s often difficult to tell the two apart.
Needham's Skimmer

 Golden-winged Skimmer

Just west of Iona Island lies the Doodletown Brook which penetrates the narrow vales between Bear and West Mountains. This moderately sized brook flows through land once occupied by a thriving town, but was completely abandoned upon creation of the park in the 1960’s, a result of eminent domain. It’s now essentially a bona fide ghost town, complete with crumbling foundations, subsiding roads, and forgotten cemeteries two hundred years old that are gradually being engulfed by the looming forest. Along the dark openings next to the Doodletown Brook, the primeval looking gray petaltails dart about in minute quantities. As the name suggests, this species is rather mundane in appearance, not exhibiting some of its kin’s vibrant color schemes. However, gray petailtails are unique among all other dragonflies in the eastern half of the country in that their larvae are not completely aquatic. Instead, they tend to reside in moist mud beds, living amid low lying vegetation that’s only fed by minor trickles of water from an adjacent stream or spring.  Only 11 locations within New York are known to harbor this distinctive species.
Doodletown Brook
                                                        
Farther north, in Orange County, just outside the bounds of the Highlands, the russet-tipped clubtail lives along beaches that line the Hudson near the Moodna Creek area.  Uncommon, but not exceptionally rare, these creatures prefer to spend their time along mudflats usually containing freshwater. They’re frequently documented inhabiting inland lakes and streams, but seem to be situated along tidal rivers more commonly. Their large, vivid green-blue eyes and puffed russet colored abdomens makes this an impressive species to identify. The moderately bulkier black-tipped darners also line the shores here, decked out in varying tones of aquamarine.

Moodna Creek
Russet-tipped Clubtail

Black-tipped Darner

Also lying west of the Hudson, Sterling Forest State Park has a dramatic odonate display. A prime spot for a view is around Sterling Lake. The 3 mile long loop path that circumnavigates the sizeable water body passes through forest along the way that’s some of the wildest in the region. Dense stands of hemlocks border the lake and flow into the depths of the surrounding mountains as if applied by a painter drawing his brush quickly across a matte canvas with broad and hurried strokes. Growing among, and atop, some of the larger glacial erratics that litter the ground in vast boulder fields are gnarled bushes of mountain laurel that provide the forest with a thick and impenetrable understory, moderately mixed with low bush blueberries. Both the eastern and western sides of the lake are flanked by steep, rocky slopes that abruptly rise from the water’s edge; to the north a shallow and weedy inlet contains the traces of lively beaver activity. The more mundane southern outlet has a noisy whitewater stream that always keeps the stones bordering it damp and cool, with its continual mists and relentless sputtering that only abates with the harshest of droughts.
Sterling Lake

In the swampy northern portion of the lake many fluvial shrubs grow along the sandy shoreline. It’s in this location the largest gathering of odonates present themselves. On a sweet pepperbush one may see a slaty or widow skimmer resting itself, basking next to the white flower spikes that appear in the early days of summer, each swaying in the air like a twitching squirrel’s tail. Or, looking into a weed covered cove see the insects zoom just above the waterline, taking the occasional break on a slimy, hole-ridden lily pad.
Slaty Skimmer

 Juvenile Widow Skimmer

Now casting your eyes onto the bright yellow sand dozens of lancet clubtails relax themselves on the beaches, resting as intently as a fatigued and over-worked vactioner. Their orb-like eyes are of an especially rare blue, and look as if chunks of turquoise. With their bodies matching the color of the substrate, these turquoise gems are the only part that stand out among the golden sands. In several of the stony pockets near the banks, individuals defend their gravelly kingdoms from invaders, taking to the sky to duel and once chasing away their would-be usurper, quickly descend again to the beach in a fluid, almost spiral motion as though they’ve been gently blown by the wind. Their ability to return to the exact same spot, however, just demonstrates their graceful and apparently effortless skills. They’re the figure skaters of the air.
Lancet Clubtail

Autumn Meadowhawk

Stewart State Forest in northern Orange County contains another diverse assortment of odonates. About half of the 6,700 acre preserve contains wetlands or moist areas perfect for the establishment of abundant populations. This property was originally purchased to be included as part of the nearby Stewart International Airport. In 1982, the area was converted into parkland when plans to make the airport host supersonic travel fell through and the large buffer zone necessary for noise abatement was no longer needed.
Swamp in Stewart

Most of the property was residential in the past, evinced by the many crumbling roads and foundations still extant throughout. There are around 18 miles of road, although now only passable on foot. The land still serves utilitarian uses, however. A police shooting range exists in the western portion and is used quite frequently. New York State also allows local farmers to cultivate some 400 acres with wheat and corn.
Along some of the shallow ponds and swamps there are broad meadows consisting of tall grasses and numerous weedy and invasive flowers, comprising such plants as golden rod, purple loosestrife, asters, and the ever-ubiquitous dandelion. In most cases, these meadows were purposely created, and continue to be mowed on a regular basis in order to provide an additional type of habitat for the park. Apart from the odonates which prowl through these areas, the land is rich in butterflies, wasps, and even the occasional moth seen during the light of day, such as the odd, but impressive looking hummingbird moth. While walking through the high grass one may even come across a bird’s nest constructed from the same material in which it rests.
Hummingbird Moth Visiting Purple Loosestrife



Unlike their larger cousins, the damselflies exhibit a much daintier and reserved demeanor, as their name aptly suggests. Frequently they are seen placidly bouncing from spot to spot and not moving farther than necessary. Rarely do they show the same level of agitation as the jittery dragonflies that grow restless at the least bit of disturbance. A resting damselfly is likely to move if approached, but probably not more than a few feet at a time, just enough to feel comfortable that harm has been avoided. They don’t like to make a fuss and draw attention to themselves—they’re much more covert and drama-free.
Familiar Bluet

Ebony Jewelwing 
A unique class of damselflies known as spreadwings, inhabit the wet environs of Stewart. While a vast majority of damselfies fold their wings together neatly behind their backs, as a shopper would their hands while examining the contents of some glass case in a ritzy store, these bold creatures have their wings fully extended while at rest, in intimation of the dragonflies. The metallic green-gray swamp spreadwing could well pose as the models of the odonate world. With their tooth-pick thin abdomens and their seemingly weightless bodies they would be a perfect fit for the job. While supporting themselves on some scrap of vegetation with their diminutive appendages, all as slender as an eyelash, it looks wholly effortless, as though they’re buoyed by water, gravity never having latched on to these creatures. Their wings are beautifully wrought, with delicate geometrical lattices stretched throughout to the max, giving a firm support, reminiscent of a tennis racket weave. Each structure looks as though threaded from spider thread, but of a grade and fineness superseding anything an arachnid could produce. The exquisite needle-work is something only Nature herself could tenderly sew.


Swamp Spreadwing
In the tall grass and shub-filled fields the Halloween pennants unshyly come into view and show off their beautifully stained calico wings. The shine and glassy reflections from each brings to mind the ethereal windows of a European cathedral, especially when the light filters through. Each pane is softened and warmed by the light; the cold stiffness melts away and life is breathed into the slumbering scene. Like biblical depictions that embolden religious piety when illuminated seemingly by the grace of God, so too, does each spotted wing restore our faith in the land, showing that the wilderness holds an airy paintbrush and is far more refined than the dim brute we too often imagine. The pennant’s entire body is a work of art, meticulously sculpted and painted. The symmetry of form and outline alone amazes.

Halloween Pennant
***
Most who are acquainted with watching the sky for wildlife are accustomed to the sights and sounds coming solely from the avian variety, paying little notice to the diverse world of the odonates. While lacking the delightful calls that birds superbly deliver, dragonflies and damselflies impress in other ways. Often, their vivid color scheme, usually as rich and fresh as those reflected from a transient summer rainbow, emblazon the sky like parade ribbons twirled in the air in rhythmic fashion. Their subtle and indistinct motions leave interpretation of this mesmerizing show open to the viewer, where one may at anytime simply wander over to a lake or stream to see a tranquilizing encore.