Monday, November 2, 2009

From Two Wings to Four

As this blog is headed ‘birds and wildlife’, it’s about time I mentioned some wildlife other than birds! Migration at Cape May happens largely as a result of prevailing winds; if it wasn’t for the north-west winds that push so many birds to the coast each fall, Cape May would be a mere shadow of its present self. As the winds push birds towards southern New Jersey, so too do other winged creatures get pushed our way and Cape May can be a great place to witness the migration of insects, especially butterflies and dragonflies. On a number of days in late September and early October, we enjoyed some great spectacles, not least of which was the day that Megan and I got home in the evening to find at least 50 Green Darner and 10 Swamp Darner dragonflies hawking smaller insects over our lawn. Both Carolina and Black Saddlebags have moved through in large numbers this year and provided a great spectacle as they streamed along the dunes at Cape May, with at times upwards of 100 a minute passing around the point.

Butterflies always have a special place in people’s hearts and, though there can be a good passage here of Red Admirals and both Painted and American Ladies, it is the iconic Monarch butterfly that really gets people buzzing. Weighing just half a gram, it seems unfathomable that such tiny creatures can migrate over 2,000 miles from Cape May to wintering areas in central Mexico – and some have come a great distance even before they reach Cape May. A long-term tagging program is helping researchers to understand migration routes, stop-over points and journey times as we gradually build up a knowledge of just what these winged waifs have to go through.

If you’re in Cape May next September or October, stop off at the Northwood Center and you may be lucky enough to see a Monarch emerge from its chrysalis. If nothing else you should go to the Monarch Team’s talk at the Cape May Point State Park and hear just how the research is allowing us to better help this amazing creature.

So here’s some pictures of some of the dragons and damsels that graced our yard this autumn and some of the butterflies I encountered around Cape May Point (click on a picture for a better version).

Cloudless Sulphur is common and widespread throughout the New World tropics and subtropics. In warm years, large numbers move north in eastern North America in the late summer and autumn and the species is annual in New Jersey at this time.

This Sleepy Orange was a nice find at Bill & Edie's garden at Cape May Point on October 11th. Rare enough to tempt the veteran Michael O'Brien away from the Hawkwatch platform for a few minutes. Another common tropical/subtropical species that wanders north on occasion. Named after the black crescents on the forewings which reminded the namer of sleepy eyes.

I added this just to show Cape May's potential for vagrancy - though I didn't take the photo this year. This is the first record of Dainty Sulphur for New Jersey, which I found at Cape May Bird Observatory's Goshen Center on September 28th 2007. Though widespread in the mid-west as far north as southern Canada, on the east coast the species is confined to the deep south - though it does seem prone to vagrancy and there are previous records from New York and Pennsylvania.

Red-banded Hairstreak resting on our lawn. This individual has a hole in the back of its hind wings, between the red band and blue spot. This was most likely caused by a bird attack. It is believed that the intricate patterning on hairstreak wings creates the effect of a false head, bigger and more obvious than the real head at the other end of the body. The twin tails stick out like antennae and even have white tips, The butterflies move the wings in a way that mimics the movement of antennae too. In addition, the coloured spots could easily be mistaken for eyes. This all serves to deflect the attack of a predator away from the real head to an area where the butterfly can survive a non-fatal peck.

Eastern Tailed Blue. This female is egg-laying on the introduced Japanese Clover Kummerowia striata that grows commonly on gravel drives and in lawns around Cape May (as here in our garden!).

As with the closely-related European Comma, the Question-mark of North America is named for the appearance of a small white mark on the underwing. This species hibernates as an adult and the ragged wing shape helps it avoid detection by predators by helping it to resemble a dead leaf.

Known as a Mourning Cloak in North America and as a Camberwell Beauty in Britain, this species is found right across the temperate zones of the Northern Hemisphere. Along with the Question-mark above, this individual was attracted to ripening Persimmon fruits at The Meadows.

Common Buck-eyes are plentiful in Cape May in the fall, especially around the coastal marshes, where the adults feed at flowering Seaside Goldenrod (as here) and the caterpillars feed on the leaves of the pink-flowered False Foxgloves that grow in abundance in many places.

A Monarch I hear you cry!! Well, not quite - and not even the same family. This is a Viceroy, a member of the Nymphalid family and a wonderful example of what is known as Batesian mimicry, where a non-toxic species is left alone by predators because it closely resembles a toxic species (in this case the Monarch). Actually, recent research in Florida has shown Viceroys to be toxic too, which would make it an example of Mullerian mimicry, where a number of toxic species look the same so that predators don't have to keep testing them out to see if they're OK to eat! The easiest way to tell a Viceroy from a Monarch is by the thin, dark band running across the hindwing, which can be surprisingly easy to see at times, even in flight.

Silver-spotted Skippers are large, fast-flying creatures that whizz rapidly around the local Buddleia bushes, but do occasionally stop for a rest.

A sure sign of autumn at Cape May comes with the arrival of Ocola Skippers puching north from the deep south. Never common, numbers fluctuate from year to year and this year, perhaps because of non-conducive weather patterns, the species has been scarce in New Jersey.

Common Checkered Skipper at the Rea Farm, taking in some late autumn sun.

Ahh, the orange and brown skippers! While Europe has its abundance of confusing blues, North America has a super abundance of painfully similar 'little brown jobs' when it comes to small butterflies. This one is the yardstick species in New Jersey, by which all others are compared, for it is by far the most common of the confusing skippers. This is a female Sachem, as told from the male by the presence of silvery spots on the forewing.

One of the easiest of the 'little brown jobs' this bright chap is a male Fiery Skipper.

A female Fiery Skipper nectars at Buddleias at the circle gardens at Cape May Point.

Yes, another exciting skipper!! The obvious, dark, square mark on the leading edge of the hindwing shows this to be a Zabulon Skipper, taking the sun in our garden.

Looking flashy in striped pyjamas, Monarch caterpillars become poisonous to predators by having the capability to store in their bodies the toxins that they accumulate from the milkweed plants that they eat.

During pupation, Monarchs are a wonderful milky green colour, bejewelled with gold spots. However, in the final 24 hours or so prior to emerging as an adult butterfly, the green colour turns to black, then the pupal case becomes completely transparent and it is possible to see the butterfly's wings through the side. The Monarch Project team provide us at the Northwood Center with a few caterpillars each year, which allows visitors to see this amazing transition taking place.

Even the most hardened of birders can't fail to be impressed when cold fronts pass through and the Monarchs form temporary roosts until the weather improves and they can continue with their migration. These are just a few of a large gathering of Monarchs on Seaside Goldenrod at Cape May Point State Park.

All tagged and ready to go. Tiny, sticky labels with an identifying number and contact details are attached to the butterfly's wing by removing a few of the colour scales so that the label can be attached to the transparent membrane of the wing itself. Research is being carried out to provide information on actual migration routes and stop-over points so that more can be done to understand and protect these amazing creatures. Not the small black circle on the hindwing of this individual which shows it to be a male.

Rambur's Forktail is a local breeder rather than a migrant, but is nevertheless abundant and a feature of autumn at Cape May.

When conditions aren't right, migrants need to rest. Hundreds of Green Darners can sometimes be found hanging up in the trees and bushes at Higbee's Beach, where they have spent the night and await the morning sun to get them going again.

Once warmed up, Green Darners soon get going again, and are just about big enough for the autofocus of my camera to find!

More of a summer beast than an autumn one, a few Common Whitetails hang on into September - this one showed up in our garden at the same time as the container with all our belongings from the UK.

One of the most stunning of all the world's dragonflies, the male Twelve-spotted Skimmer really is a great sight and is easily seen at favoured localities around Cape May.

The black marks curving round the tips of the forewings, and the milky white face are good identification features on a male Great Blue Skimmer at our garden pond.

Though superficially similar to the Great Blue Skimmer in these photos, in reality this Blue Dasher is tiny in comparison and also has a dark thorax with pale shoulder stripes. This species was common at our pond this autumn with up to 30 present.

The third common blue species around Cape May in autumn is the Eastern Pondhawk - again seen here at our garden pond. Males start off green like the females but soon become blue and this one is still in the process of changing colour. The species can be readily told by the white tip to the abdomen.

Female Eastern Pondhawks are a rich apple green on the thorax and upper abdomen - but still sport the white tip that is also seen in the male.

A male Blue-faced Meadowhawk hunts from a Purple-flowering Raspberry stem in Cape May Point State Park.

Yellow-legged Meadowhawk is a subtle and delicate species which can be easily overlooked.

Black Saddlebags can be abundant at Cape May in autumn and get their English name from the dark, saddlebag-like marks at the base of the hindwings.

The Carolina Saddlebags is also often an abundant migrant at Cape May and was particularly noticeable this year by virtue of its numbers.

Always a delight to see, the golden-winged Halloween Pennant is a truly superb insect to have hanging out in your yard!

And to finish, the true master of all migrants. The Wandering Glider is also known as the Globe Wanderer, for the mass movements and migrations of this species has taken the species full circle around the entire world and it is plentiful throughout the Tropics. It breeds on every continent except Europe and is the only species of dragonfly on many Oceanic islands, even having made it to such remote outposts as Easter Island in the South Pacific. In late summer and autumn, the species generally turns up in Cape May, though numbers do vary and this year it has been very hard to find, with only a handful being reported. Recent studies of this insect have found its presence far out to sea in the Indian Ocean to be the sustaining lifeforce that allows Amur Falcons to migrate direct across the open ocean from Asia to East Africa, feeding on the hapless gliders as they go.