The Fall Warblers Begin to Arrive

The first Canada Warbler came through last week

Though it seems too early, but by this point in the summer fall bird migration is well underway. Many warblers, swallows, bobolinks, orioles and shorebirds are on the move - and some have been for several weeks. These birds aren't flying directly to their wintering grounds. Instead many will linger in places along the way - in habitats with good food reserves. There they will fatten up as best they can before proceeding on the next leg of their long journeys south.

The Blue-winged Warbler is most often gone by September

In fall the adult Chestnut-sided Warbler molts into less ornate plumage

About a half dozen species of warbler came through today. Most breed locally, but a few are migrants from the north country - from the Adirondacks and Canada.

The Northern Waterthrush (a warbler) looks much the same in fall as it does in spring

An immature Black & White Warbler needs to fatten up before its flight to the tropics

It's interesting that family groups often break up and make separate journeys south. The immature Chestnut-sided Warbler and Black and White Warbler have never embarked on this journey before, but still they know right where to go. With no guidance from their parents, they will fly thousands of miles to the tropics and to a wintering ground that they've never seen before.

 

The Warbling Vireo (not a warbler) sometimes shows yellow on its flanks

The immature Yellow-rumped Warbler (Myrtle Warbler) perches briefly over a stream

At this time of year warblers and other migrant songbirds can be difficult to find. After the breeding season, most songbirds cease singing territorial songs, and quiet birds are generally harder to find than noisy ones. Interestingly, when some of them do attempt to sing, often what comes out is a jumbled song that is barely recognizable. I heard one such "song" today. Rhythm wise, I thought that it resembled the song of a Warbling Vireo, but I couldn't be sure. In a case like this, in order to properly verify the species, all you can do is hope catch a glimpse of the singer or hear one of its more distinctive call notes.

The adult male American Redstart looks much the same in fall as it does in spring

This immature American Redstart is completely independent from its parents

Plumage wise, many of the warblers look much different in fall than in spring, but this is not universal. Some, like the adult male American Redstart, retain the same bold pattern and colors throughout the year. Also, often enough, when the Redstart sings in late summer, the song remains recognizable.

 

The adult male Black-throated Blue Warbler also looks the same in the fall

The female Black-throated Blue Warbler looks like she belongs to a different species than the male

Immature warblers can be hard to identify. It's not unusual for birders to mistake an immature Mourning Warbler for a Connecticut Warbler. The later species is a rarely seen migrant in our area, so legitimate sightings are of particular interest. Both species are shy and often skulk in heavy brush. With both the Mourning and Connecticut, a short glimpse is usually all you can hope to get. Both species are yellow and have a complete dark hood, but in immature Mourning Warblers the hood does not extend over the throat. An obvious white eye ring (absent in the adult) is the feature that causes the most confusion. A close examination, if possible, reveals that the young Mourning Warbler’s eye ring is incomplete and shows a gap by the bill.    

The immature Mourning Warbler shows an incomplete eye-ring and shorter undertail coverts

The adult male Mourning Warbler has no eye-ring

The Nashville Warbler always shows a distinct white eye-ring and a yellow throat

An immature Magnolia Warbler lacks the adult's heavily barred breast

Warblers and their neotropical allies will continue passing through upstate New York until November, but by the end of that period there are only one or 2 species likely to be observed. Warblers only infrequently overwinter in the area; in early winter the most likely species to be encountered  is the Yellow-rumped Warbler – also known as the Myrtle Warbler. Locally I have seen a few in winter – usually in areas that are rich in poison ivy. The small waxy berries that grow on those infamous vines can be a staple food for these warblers in wintertime. So indeed yes, Poison ivy is good for something!

The adult male Wilson's Warbler has a black cap

News from the Pond: Jumping Mice, Beavers, Ducks and Muskrats

Great Blue Heron and a White-tailed Deer fawn at the beaver pond

Last evening I went down to the main beaver pond to see what was happening with our beaver colony. While I waited in the blind, I heard some movement behind me in the meadow. It sounded like several grasshoppers were descending down the hillside. Finally, I saw one of them, and they weren't grasshoppers, they were instead a family of Meadow Jumping Mice.

The seldom seen Meadow Jumping Mouse most often lives close to water

These remarkable creatures were hurdling back and forth through the undergrowth at a good clip. In fact it was impossible to put my camera on them while they were moving. At one point one of them bounded up a Multiflora Rose bush - perhaps to gnaw on a berry or to glean a beetle from a leaf.

These tiny Jumping Mice are mainly nocturnal

I had put a few handfuls of sunflower seeds up on one of the blind's support posts - I do this primarily for birds, but the seeds also  attract Chipmunks, mice, voles and shrews. This time however, it was the jumping mice that were interested in the seed - or at least 2 of them were.

The Jumping Mouse's long tail helps it to keep its balance when jumping

As their name implies, jumping mice get around by hopping - using locomotion more similar to a kangaroo than other mice. Many of us that spend any time in the outdoors and are fond of examining animal tracks are familiar with the footprints of the jumping mouse. A set of their small, narrow prints look like no other mouse tracks in the region. Impressions from their disproportionately large back feet and consistently dragged tail are diagnostic. Despite the fact that this mouse's tracks are sometimes found in the snow, the jumping mouse is supposed to hibernate for the entire winter - well that's what the literature says. Since they do not make a winter food cache and instead rely on their fat reserves to survive the winter, it's conceivable that when these reserves are insufficient  they may break hibernation in order to resume foraging. 

Note the Jumping Mouse's long back leg and toes

The farthest they can travel in a single bound is 10 feet, which is astounding considering the mouse is only 3 1/2 inches long minus its tail. The tail of the Meadow Jumping Mouse is extremely long - fully 1 1/2 times longer that its head and body. The mouse's back legs, and feet are also noticeably longer than those of other mouse species.

A Great Blue Heron perches right near the blind at the beaver pond

"Tippy" the yearling beaver takes an apple

Before I became distracted by the mice, I was watching one of our yearling beavers interact with a family of Mallards. Usually the beavers don't have much to do with the waterfowl that frequent their ponds,  but this particular beaver was intrigued by the Mallards as they repeatedly swam back and forth at the east end of the pond. The ducks wanted to access the overland trail in order to walk to our turtle pond, but they didn't want to walk past me, so they just kept swimming back and forth - and this is what peaked the beaver's interest.

Tippy the Beaver checks out one of the young Mallards

The Mallard family swims back and forth in front of the blind

At one point the young beaver joined the ducks and even swam several laps with them. This culminated with the ducks and the beaver, together climbing onto shore and attempting an alternate route through the field. They hadn't gotten very far when evidently something spooked them - and all came crashing back into the pond - the beaver first, followed by the ducks.

Mother Muskrat waits for a treat

While all of this was going on a resident muskrat discovered a bag of apples that I brought down for the beavers. She bit into the bag and pulled it off of the bench - causing it to dump some of its contents into the pond. The perfect heist! This particular muskrat is quite a character; sometimes she will sit behind me and whimper until I start doling out apples or carrots. She's a mother and has at least 2 young kits that have now begun swimming after her on her foraging adventures around the pond.

One of 2 Muskrat kits

Muskrat kit (left) and mother (right) swim around the pond together

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

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.