Sunday, August 4, 2013

The Dragons of Summer

The male White-faced Meadowhawk

The Turtle Pond is home to many dragonflies this summer
This summer the number of dragonflies at the turtle pond is way up. Perhaps the season’s record rainfall is responsible for the population growth. Certainly there has been a net increase in wetlands for insects to breed in. Even vernal ponds have retained high water levels long into the summer. Mosquitoes and other small flying insects provide the adult dragonflies with much of their food, and definitely there has been a net increase in those pesky creatures this summer.

An adult male Widow Skimmer has a highly recognizable wing pattern
The male 12-spotted Skimmer - another easily recognizable species
At the turtle pond on a hot afternoon, the diversity of dragonflies is quite incredible. Around a dozen species were represented around one section of the shore. Mostly these were males, patrolling their territories and simultaneously searching for females to mate with.
Clashes between males of the same species were common, and they consisted of the rivals giving chase and then making very audible wing to wing contact. This warfare doesn't seem to result in any damage to the combatants and often the very same individuals will continue to duke it out off and on for hours at a time and even for many consecutive days.
The male Eastern Pondhawk at rest on his highly contested territory
The female Eastern Pondhawk
Egg laying is also taking place on the pond. The females of different dragonfly species have different techniques of laying, but all of them lay directly into the water. The female Common Whitetail hovers low over one spot and repeatedly, rhythmically dips the tip of her abdomen into the water, laying egg after egg. While she lays, a male Common Whitetail hovers just above her and occasionally flies down to make brief contact. I also watched The female Green Darner laying eggs; she did this while perched on a piece of floating vegetation.The male was clasping her neck as she deposited her eggs into the water.
The female Green Darner Lays eggs while the male clasps her by the neck
A female Spatterdock Darner attaches eggs to a submerged cattail stem
On cattails and other emergent vegetation, the empty exoskeletons of dragonfly nymphs remain hanging on to the leaves where they were shed. The nymph lived a relatively long life as a fierce underwater predator - consuming a wide variety of underwater creatures. 

The shed exoskeleton of a dragonfly nymph hangs onto a cattail leaf
My goal of getting pictures of each species at the pond proved too difficult. The fact is that some species rarely ever seemed to land. I watched the male Black Saddlebags Dragonfly chasing away rivals, mating, and clasping his mate while she laid eggs on the wing, but I could never find one perched. Surely, they have to rest at some point! I could only think that they prefer to perch in a secluded place - possibly in the tall reeds.
The male Common Whitetail perches in a prominent place right above the water
White-faced Meadowhawks mating - note the female's lighter color
The Eastern Amberwing is a small but beautiful species 
Some of my favorite dragonflies are the smaller species like the meadowhawks and pondhawks. The Eastern Amberwing is also quite small - only about half the size of a Green Darner. Its wings are amber colored and its abdomen is orange with white segment bands.

The male Calico Pennant is hard to mistake with its red wing markings
Dragonflies are fearsome predators but they are by no means at the top of the foodchain. They are the preferred food of some birds – chiefly flycatchers like the Eastern Kingbird. Occasionally I come upon discarded dragonfly wings on the trail – that’s a sign that the flycatchers have been busy.
The Eastern Kingbird is a well known dragon slayer

Unicorn Clubtail - note the black club at the end of abdomen & aqua eyes
Blue Damselflies (not a dragonfly species) also mate at the Turtle Pond

Sunday, July 28, 2013

The Baltimore Checkerspot Returns

A Baltimore Checkerspot Butterfly nectars on Indian Hemp
We've had our first good Baltimore Checkerspot season in at least 5 years. Lately They've been spotted in various meadows around the nature preserve. Its interesting how some species, like the Baltimore, can become so rare even though their available food supply (larval food plants) varies so little year to year. Turtlehead is the traditional food plant for the species and it has only expanded in the past 12 years - both on its own and due to our restoration efforts. 
Turtlehead is the traditional host plant of the Baltimore Checkerspot
Turtlehead occurs in wet meadows and along stream sides
The Baltimore also utilizes English Plantain as an adopted food plant. This alien weed is ubiquitous in fallow fields, suburban yards and so called "waste places". Though the ability to feed on such a prevalent plant could only be considered as good news, it still has not resulted in making the checkerspot very common.
The Baltimore is one of our most distinctive butterfly speices
Baltimores mating in one of the upland meadows

With the ability to inhabit both low land swamps (the domain of turtlehead) and dry upland fields  (where plantain often dominates), the Baltimore may be encountered in a range of diverse habitat settings. At the preserve, it has been the wetlands where they occur most reliably - and when the population contracts, it's most often the wetlands that hold the last remnant of the population.
A female Checkerspot with its abdomen swollen with eggs
The female lays her eggs on the underside of the Turtlehead leaf
The eggs are yellow or orange and are laid in a large cluster
Essentially, Baltimore Checkerspot Butterflies are tent caterpillars. Oh no! Not dreaded tent caterpillars. Unlike the Eastern Tent Caterpillars and the Forest Tent Caterpillars, the checkerspots do not defoliate forests. They make their tents around their perennial foodplants and have no reason to ascend into the trees.
The silk tent is woven around the Turtlehead plants
The early instar of the Baltimore larvae create the tent
Unlike most butterfly species that deposit their eggs individually on their host plants, Checkerspots lay large clusters of eggs on a single leaf. The young caterpillars feed together and collectively spin a large silk tent around the host plant. The tent offers them some degree of protection from predators - at least during the early period of their development. Ichneumon wasps patrol the outside of the tent and search for outliers that they can reach with their ovipositors and attempt to parasitize. When does a checkerspot  caterpillar appear to metamorphosize into a wasp? That's after its had an ichneumon egg laid inside of it.
These caterpillars are now large enough to live outside of the tent
The Baltimore caterpillar starts to shed its final larval skin
Later instars of the checkerspot caterpillars are more independent and they feed without the protection of the tent. Their larval skins are covered with hairs which make them  unpalatable to most birds and other predators. Baltimore chrysalises are small structures, but they are colorful and well bejeweled. Certainly it's a fitting packaging for one of our gaudiest butterflies.
The ornate chrysalis of the Baltimore Checkerspot
I was watching several Checkerspots as they raced around the meadow. Males were chasing off other males while females were scouting for their host plants. Some females had noticeably swollen abdomens and were presumably full of eggs, but the one that I followed appeared to be empty. She kept landing on turtlehead leaves, but although she went through the motions of laying, nothing was being deposited on the leaves.
Note the orange antenna clubs, eyes and legs
An explosion of orange - the Baltimore nectars on Butterflyweed
Nectaring on Valrian flowers
The males were mostly nectaring on Valerian plants. These tall non-native perennials superficially resemble wild carrots and parsnips, but unlike those common plants, Valarian is not in the parsley family. The plant has been expanding primarily in damp meadow habitat throughout the region. A decade ago we had only a few patches of it, now it is difficult to find a place where they are not represented.    

Sunday, July 21, 2013

The Plight of Bobolinks and Other Grassland Birds

The male Bobolink gives warning calls from a bush overlooking the meadow
In recent decades, in our region and generally in the northeastern US, grassland birds aren't fairing very well. Much of the agricultural land is now being planted with row crops like soy beans and corn and is in effect, no longer viable as breeding habitat.  Maintained hay fields are pretty much ideal for their nesting, but unfortunately, too often these fields are mowed too early in the season for the birds to finish their nesting cycle. In other words, the birds are unable to fledge young before their nests are destroyed. This phenomenon has made grassland birds some of the hardest to find species in the rural areas where they once thrived.
A group of male (Tom) Turkeys feed in a recently cut hay field
Savannah Sparrows are becoming less common due to early mowing
This year there was somewhat of a reprieve for a few grassland species that nested in local fields. The massive amounts of rain that fell during June (at the height of the breeding season) necessarily delayed the first cutting of many hay fields. This meant that the nests begun on time, most likely were able to produce young. That's assuming that parents were able to secure enough insect food for their nestlings, which is not always  easy during periods of persistent rain.
A Savannah Sparrow with a beak full of insects for its nestlings
Decades ago, the Eastern Meadowlark was a common grassland bird in the region
Savannah Sparrows, which seem to be the latest grassland species to suffer serious population declines in our region, did apparently manage to complete their nesting cycle in the hay fields just west of the nature preserve. This is the first time in years that I can say that. Bobolinks too seem to have been beneficiaries of the rains. 
A group a male Bobolinks gather in early July - they may be "refugees"
Hopefully, someday our grassy wildflower meadow will be used by Bobolinks
In recent years one of our preserve's meadows have played host to bobolink refugees. These birds were forced to abandon their nests once the tractors came onto their breeding grounds. The Bobolinks will not try to nest again, but will linger in the habitat for a few weeks before pushing into other areas with better food supplies. In only a month or so they’ll be starting to migrate south.
Gray-headed Coneflower begins to bloom in the wildflower meadow
As the habitat grows in it with bushes and small trees it attracts the Field Sparrow
Bobolinks still nest in the nature preserve's north field. This fallow field, which is only half on our property is just barely acceptable as breeding grounds for the Bobolink. The grass is giving way to goldenrod, asters and other tough stemmed perennials.  Certainly, the meadow as it is wouldn't even be considered viable nesting grounds by other grassland species. Most of them are much more particular than the Bobolink is about the make-up of the meadow's plant community.  
Increasingly, the Blue-winged Warbler is found in and around the Bobolink's field
The Rufous-sided Towhee is another bird that prefers brushy meadows
Now the Bobolink field is also slowly growing in with trees and shrubs. Every year there are more birds moving in that prefer brushier terrain to nest in. One of the Bobolink's new neighbors is the Clay-colored Sparrows, which were first identified as using this habitat only last year. This species along with the Field Sparrow, Blue-winged Warbler, Rufous-sided Towhee, Brown Thrasher and Alder Flycatcher will all benefit from the evolution of this habitat. 
The Clay-colored Sparrow is a very uncommon breeders in the region

Sunday, July 14, 2013

Turtle and Crayfish Refugees & Recent Butterfly Wars

Painted Turtles were common refugees following recent flooding
Following the floods of June and early July, some of our nature trails were transformed into streams and a few were even began to be used as avenues by wetland denizens. Most often I was finding turtles –most of which had presumably been dredged out of their lairs by rushing flood waters.
A painted Turtle swimming in the pond after its release
A Crayfish was a most unexpected traveler on the foot trail
The most interesting refugee was a large Crayfish that I noticed purposefully trotting down the trail. It was heading away from the traditional streambed, so I scooped it up and carried over to one of the ponds. I had previously done this with a half-dozen turtles and so I expected no intrigue.  I thought that it might be nice to video the Crayfish release –just a simple shot of it walking into the pond, but we both got more than we bargained for when a large Green Frog hopped out of the grass, intercepted and engulfed the crustacean in its gaping mouth!
Walking a few short feet to the pond - expecting no trouble
A Green Frog comes out of nowhere at nabs the Crayfish!
After the frog lets it go, the Crayfish, unharmed, settles into its new home
All 3 of us were surprised, including the Frog, who upon seeing me, immediately relinquished his prize and dove back into the water. The Crayfish, looking no worse for the experience, quickly sought refuge beneath a submerged bed of algae. Somebody got their money's worth from their suit of armor today!
 
A Banded Hairstreak - ready for battle
The rival Banded Hairstreak 
I've witnessed several pitched battles between butterflies in the past week. So much for the idea of butterflies as symbols of peace and coexistence. In fact many butterfly species can be quite combative.  
The Acadian Hairstreak has been uncommon at the Preserve in recent years
Most often male butterflies fight over territory and access to females. That was the motivation behind a battle between two male Banded Hairstreak Butterflies. It was a remarkable contest –2 nickel-sized butterflies chasing and colliding with each other for bouts lasting at least several minutes. I wondered how these minute insects could imbibe enough nutrients in order to allow such a sustained energy output, but they managed it. The next day, what I presumed were the same pair were at it again. Noteworthy is the fact that I saw neither contestant feed while I observed them on both days.

 
The Common Woodnymph Butterfly is well camouflaged on my camera bag
The purpose for the fight was to allow the victor exclusive rights to the territory --and the right to proposition any female that happens by. After his rival had vacated the area, the champion hairstreak seemed to briefly turn his attention to me. And yes he did try to drive me out of the territory, but fortunately for me, after a few minutes, I just merged with the terrain and became like an oddly shaped snag.
 
One of 3 Northern Pearlyeye Butterflies - just itching for a fight
A few meters away on the same trail, 3 Northern Pearlyeye Butterflies were fighting it out for possession of another prime piece of real estate. These guys are generally weaker fliers than the hairstreaks, and they did take more frequent rests. But their breaks were short, and soon all 3 were at it again. Since the Pearlyeyes are larger butterflies, it was much easier to follow all of the action in their little war.
Silver-spotted Skipper - the largest skipper in our region
The Little Glassywing is one of the "3 Witches"
We have 3 species of tiny dark skipper butterflies that are difficult to identify without getting a very close look at their wings, and since the 2 that were fighting it the meadow were a constant blur, I had little hope of getting a solid ID. These similar species are sometimes referred to as the “3 Little Witches” and they include the Dun Skipper, Little Glassywing and Northern Broken-Dash.
The Dun Skipper is most often the darkest of the 3
With wing shapes that resemble fighter jets, these diminutive insects can attain relatively impressive speeds; indeed, there is no lackadaisical fluttering around with these guys. As you might imagine, it’s hard to clock the speed of a darting insect that changes direction so frequently, but some estimates have them reaching around 30 MPH.
Eastern tailed Blue Butterflies have been more common lately
The skipper battle that I was watching was much more of a high speed chase, than a fight and I didn’t perceive any physical clashing. They would each alight briefly on meadow plants, but not long enough for me to positively identify them – perhaps tomorrow.
Baltimore Checkerspot Butterflies are starting to fly in the wet meadows