Saturday, August 7, 2010

Here Be Dragons!!

Bird activity tails off at Cape May Point as the heady days of summer settle upon the place. Breeding birds get on with raising young and the regular migration hotspots become tourist venues for a while. As temperatures soared into the 90s fahrenheit, some of us spent much of our time further north in the county, where the cool waters of sphagnum bogs await, green and inviting, and far enough off the beaten track to be peaceful and full of wildlife. One of the highlights of these halcyon days for the naturalist at Cape May is the wealth of dragonflies and damselflies to be found with just over 100 species recorded in the county - I don't know the exact figure as new species are still being added; for example, both Tony Leukering and I have independently found Mocha Emerald in the county this year - a species not listed for Cape May in the current New Jersey dragonfly book. So far this year, I've seen 40 species of damsel and dragon in Cape May with another three just outside the county borders (Russet-tipped Clubtail in Atlantic County and both Treetop and Clamp-tipped Emeralds in Cumberland County), with the vast majority being found in the upper third of the county. But Cape May Point is still often where the action is; when the weather is right, thousands of dragonflies move up from the south on a southwesterly high pressure system and so far this summer we have experienced two such events. The first involved Swamp Darners - one of the largest species found here (and hard to photograph as they spend so much time on the wing) - the second influx involved large numbers of Spot-winged Gliders which mostly moved north along the bayshore side of the peninsula. So here's a photo essay of some of the winged dragons that can be enjoyed around here.

Dragonflies appear on the scene in summer as if from nowhere, but look along the edge of waterbodies, on marginal vegetation or sandbanks and you will find mysterious 'dead' creatures that appear to be nothing but a dry husk. These are the exuviae, the dragonfly equivalent of a butterfly's chrysalis. Dragonflies spend one or more years as a nymph - their version of the butterfly's caterpillar stage - and the nymph lives a subaquatic life, breathing through external gills. Once ready to emerge as an adult, the nymph climbs out of the water and moults for the final time. This time, when its outer skin splits, a winged adult emerges - one of the most amazing of natural events. Here, a Swamp Darner is just emerging from its nymphal case. Note the legs tucked up around the body, the tiny yellow wing buds (not yet inflated) and the dark grey-brown case that it's emerging from.

In this picture, the dragonfly's legs are extended and now being used, the wings are starting to expand and turn pale green and only the end of the abdomen remains in the old skin.

Now the adult Swamp Darner is completely free of its old skin.

The wings now extend the full length of the abdomen and are almost completely pumped up. They will eventually lose the green and be completely colourless. Now it's really starting to look like a dragonfly.

The jewelwings are dainty creatures of moving water and are more common in hilly areas than they are in the coastal plain, but this Sparkling Jewelwing was happy enough along the Tuckahoe River. The jewelwings are what we in the UK would call demoiselles.

Spreadwings get their name from the habit of resting with the wings half open - most small damselflies fold the wings back along the body at rest. This Sweetflag Spreadwing is one of several very similar species in Cape May which are best identified by external processes at the tip of the abdomen.

The dancers are fairly large as far as damselflies go and are a very varied lot, with no two species really looking alike. Indeed, this one is known as a Variable Dancer as there are a number of races which differ in general appearance. The local form found in Cape May is also known as Violet Dancer and it really is a great colour for a damsel.

We are still learning a lot about damselflies in Cape May; Double-striped Bluet is not officially recorded from Cape May, but has been found at several sites over the last two years or so. This one near Cape May Court House is about the fifth record for the county. The bluets are all rather similar and hard to tell apart, though this is one of the easier ones, due to the extra blue band on the thorax.

The forktails are all very small, often mostly rather dark in colour and hence easily overlooked. This species is only one inch long and appropriately called Fragile Forktail.

Some of the forktails are more colourful, such as the female Liliypad Forktail which comes in either a blue or a red form. I had to wade out into a lake to photograph this species as they like to hunt from lilypads away from the shoreline. Note the down-turned tip to the abdomen which is a good identification feature.

The sprites are tiny - around one inch long - and so thin that you wouldn't think that any food could pass through! This is a tandem pair of Sphagnum Sprites - don't ask, dragonfly mating strategies are just far too weird!!

Like many insects, dragonflies have compound eyes, made up of a multitude of hexagonal lenses. The Purple Martins at Cape May Point State Park feed on large numbers of dragonflies and often drop unwanted scraps near the nest colony. The abandoned head of a Swamp Darner gave me an opportunity to take this close-up picture of one of its eyes.

The darners include some of the largest of Cape May's dragonflies, many of which are hard to photograph as they spend the bulk of their time on the wing. However, this Harlequin Darner (actually one of the smallest darners) obligingly landed on a house wall and let me take a nice series of photographs.

Another large species - and thus difficult to squeeze into a picture! - the Common Sanddragon usually hunts from or near the ground in the manner of a skimmer. It has a distinctive black abdomen with creamy yellow spots.

The emeralds are perhaps the hardest group of all to get to grips with as they NEVER seem to land!! We had to resort to netting a few to get some photos, after which they were set free again. This close up shot of the front end from above of a male Treetop Emerald shows the fabulous emerald green eyes of this group.

Seaside Dragonlet - a great name for a great little dragonfly. One of the smallest dragonflies in Cape May, this is a very common and widespread species throughout the summer and is often the only species seen around saltmarsh habitats. Males are black or dark blue, but females are very variable; some are similar to the males, some have orange-yellow bodies and others (such as here) have dark blotches on the wings.

Talking of small - this one holds the record in Cape May! Elfin Skimmers are a mere 0.8inches long - smaller than most of the damselfies! This makes them very hard to find, but they are out there to be found if you spend enough time looking. This male is sat on a bladderwort flower in typical sphagnum bog habitat. Despite their size, Elfin Skimmers hunt in exactly the same manner as other skimmers, sallying out from a vantage point to take prey in flight.

Another small species, Eastern Amberwings are very common and especially so down around Cape May Point. They hunt close to water from a handy perch - this one was hunting along a stand of flowering White Melilot, having worked out that the flowers were attracting many insects.

Dragonflies are essentially mean, killing machines and will take on anything that passes if they think they'll get away with it. Here, a green-bodied female Eastern Pondhawk is eating a Calico Pennant - a species that is roughly the same size as it!

I've featured the spotty-winged pennants found around the point in an earlier post but this is a scarce one in Cape May county, the Double-ringed Pennant. Unlike other pennants, this species has unmarked wings.

Spot-winged Gliders periodically occur in their thousands around Cape May and are another species that doesn't perch much. This one was on drift wood at Sunset Beach and had probably just arrived after crossing the Delaware Bay, so was taking a well-earned rest. This is a rather odd-shaped dragonfly, which makes it easy to identify in flight. It always looks too thick and heavy at the front end, stubby at the back and has a bright red face and eyes which stand out when one is flying towards you.

Needham's Skimmer is a fabulous golden beast with the colour extending out along the front edge of the wings. There are several skimmers, all of which perch conspicuously and hunt from open vantage points. Most are quite easily approached too, making them good photographic subjects.

The males of many of the skimmers are blue-bodied and several species are quite similar. The Bar-winged Skimmer can be identified by the obvious, short black band along the leading edge of each wing.