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Archive for August, 2018

Caddisfly Eggs Hatching

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The Mystery Photo was of a caddisfly’s egg mass which had been deposited on the leaf of a Turtlehead plant that was growing adjacent to the water, so that when the eggs hatch, the larvae will drop straight down into the water. (Congratulations to “bcottam2014,” the first person to correctly identify the Mystery Photo!)

Almost all caddisflies lay their eggs in the water, but in New England there is a family of northern case makers (Limnephilidae) whose members deposit an egg mass above the water on vegetation (see photo). After hatching and dropping into the water, these caddisflies will spend anywhere from two or three months to two years as aquatic larvae and pupae, emerging as adults with about a thirty day lifespan.

While they are larvae, most northern case-making caddisflies have silk glands with which they construct portable cases or attached retreats. Each species of caddisfly builds the same type of case, out of similar material, thus, it is possible to identify the species of caddisfly you’ve encountered from the appearance of its case.  Some species use pebbles, some bits of leaves, some sticks. Vegetative material must be chewed into just the right size and shape pieces. The caddisflies use these cases as a source of camouflage, physical protection and as a means of acquiring food.  When it comes time to pupate, they build cocoons within their cases.

Emergence of adults eventually takes place and for the next month or so they live a terrestrial life.  Like their close relatives, butterflies and moths, adult caddisflies have wings, but they are easily distinguishable from moths and butterflies due to the  tent-like slant the caddisfly holds its wings in when not flying. (Photo:  caddisfly larvae hatching from egg mass; inset – older caddisfly larva inside pebble case it built)

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Mystery Photo

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Do you recognize the spotted jelly-like blob on the lower right leaf of this Turtlehead (Chelone glabra) plant?  If so (or even if you want to make a wild guess), go to the Naturally Curious blog (www.naturallycuriouswithmaryholland.wordpress.com), scroll down and click on “Comments” to submit your entry. Look for the answer in the next Naturally Curious post.  (Hint:  Turtlehead likes its feet damp.)

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Moose & Climate Change

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If predictions for the future of our climate are accurate, and if no significant measures are taken to counter it, one of the hardest hit animals in North America will be the Moose.  While well-adapted to winter conditions, Moose start experiencing heat stress when summer temperatures get above 57°F. Why this intolerance to heat?  A highly insulative coat, thick skin and low surface to volume ratio.  When faced with very warm summers, Moose start spending more time in the shade, in cool water and in locations with cooling winds. They also frequently move to higher elevations.  When it gets really hot, they stop foraging for food during the one season they have to bulk up.

Not only will their chances of survival during the coming winter be compromised as a result of this, but successful reproduction is far less likely. In addition, heat stress can cause lowered immune response which leaves the affected animals more vulnerable to disease and parasites such as winter ticks and brainworm. Adding to these challenges, the make-up of woody plant species in boreal forests will also be affected by warmer temperatures, which in turn will affect both the browsing choices and the availability of shade for Moose.

It is theorized that within the next 100 years temperatures will rise on average 9 – 13°F. in winter and 6 – 14°F. in summer (New Hampshire Fish & Game).  On top of that, Maine, Vermont and New Hampshire are at the southernmost part of the Moose’s range. The future does not look bright for the largest member of the deer family in the Northeast.

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Green Herons Starting To Migrate

8-24-18 green heron2 20160916_0770Green Herons breed throughout the eastern half of North America.  After their nesting season is over they tend to wander, often to more favorable foraging areas. This dispersal merges gradually into a protracted fall migration for birds in the Northeast, beginning around the end of August, with most birds having left by mid-October.

Most Green Herons from eastern United States migrate south to winter along the Gulf of Mexico, Florida, Caribbean islands, Mexico, through Central America to northern South America.   We usually see our first Green Herons returning in mid-April, earlier than other herons.  This may be due to their crepuscular feeding habits, which gives them a longer span of time to feed each day.

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Second Brood of Snowberry Clearwing Moths In Flight

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Clearwing moths are strong and fast fliers with a rapid wingbeat, like the other members of the Sphingidae family. Most species in the group are active at dusk and feed much like hummingbirds, hovering in front of a flower and sipping nectar through their extended proboscis.  In most species, the larval stage is called a “hornworm” because the caterpillar’s posterior end has a horn-like appendage protruding upward.

Like its close relative, the Hummingbird Clearwing (Hemaris thysbe), the Snowberry Clearwing (Hemaris diffinis) is a day-flying moth, has transparent wings and is a mimic.  While they both hover at flowers, the Hummingbird Clearwing is said to mimic a hummingbird, while the Snowberry Clearwing is considered a bumblebee mimic.  To distinguish these two clearwings, if it has black legs and a black band that crosses the eye and travels down the side of the thorax, it’s a Snowberry Clearwing.

In addition to thistle, adult Snowberry Clearwings feed on honeysuckles, snowberry, hawkweed, lilacs and Canada violets. (Thanks to Barbara and Knox Johnson for photo op.)

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Eastern Gray Squirrels Swimming

e-gray squirrel swimming by Erin 2_H6A2563 copy (002)Imagine coming upon a stick floating in a large pond only to discover the “stick” had a head and tail and was making a beeline for the shore.  The fact that an Eastern Gray Squirrel (Sciurus carolinensis) had paddled half a mile to get from one shore to the opposite shore of a pond shouldn’t have come as such a surprise, as this rodent has a long history of migratory swimming behavior, but it’s such an incongruous and unexpected event that it made my companion and me initially question our eyesight and then laugh out loud.

Historical reports suggest there have been many massive Eastern Gray Squirrel migrations in the United States, beginning in 1749 in Pennsylvania.   Records show the state paid three cents for each squirrel killed; over 640,000 squirrels were turned in for bounty.  One migration from Wisconsin in 1842 lasted four weeks and involved a half billion squirrels. Because of the numerous squirrel migrations, John James Audubon was erroneously convinced that the squirrels on the move were a separate species from the Eastern Gray Squirrel and gave them the scientific name Sciurus migratorius. (This proved to be inaccurate.)

During the 1800’s, thousands of squirrels would periodically move en masse across roads, fields and forests, and swim across lakes and rivers (including the Mississippi and Connecticut Rivers) in an effort to disperse. The consensus is that these mass movements were a response to local food conditions. They occurred mostly during the month of September following a year in which there was a large production of food (acorns).

The most recent mass migration of Eastern Gray Squirrels in eastern U.S. occurred in 1968, when a bumper crop of acorns in 1967 was followed with a corresponding bumper crop of young squirrels in 1968. By fall, as the first litter of the year left the nest, there was a severe shortage of food. As a result, massive numbers of acorn-eating squirrels dispersed in search of food.

One Eastern Gray Squirrel swimming across a New Hampshire pond does not a migration make, but it might not be a bad idea to keep an eye out for excessive numbers of paddling squirrels and/or road-killed rodents come September. (Photo by Erin Donahue)

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Viceroy vs. Monarch

8-18-18 MONARCH vs. viceroy1To clarify yesterday’s post on mimicry, here are the Viceroy and Monarch, side by side. Note the horizontal black line across the hindwings of the Viceroy.  The (larger) Monarch lacks this line.

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Viceroys — Master Mimics

8-17-18 viceroy metamorphosis

A plump caterpillar is irresistible to many insect-eating birds, and some of them (notably Viceroys and Giant Swallowtails) have outfoxed their predators by assuming the appearance of bird droppings, which one assumes is a far less appealing meal.  They do this using color, pattern, choice of resting place and even position – contorting their bodies to match the shape of bird droppings. The Viceroy (Limenitis archippus) uses this technique during its later larval and pupal stages.

The adult Viceroy butterfly also uses mimicry to enhance its survival, but it mimics another butterfly — the Monarch — not bird droppings.  Both the Viceroy and the Monarch are unpalatable and contribute to each other’s protection from birds with this strategy, a relationship known as Mullerian mimicry.

In New England there can be up to three broods of Viceroys, with the larvae of some of the second brood and all of the third brood overwintering and pupating in the spring.

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Red and White Baneberry Fruits Maturing

8-16-18 red and white baneberry-1While the flowers of Red (Actaea rubra) and White Baneberry (Actaea pachypoda) are quite similar (the flower head of Red Baneberry is more globular than the elongated head of White Baneberry), their respective fruits, the color of which gave them their common names, quickly distinguish these two species from each other.

White Baneberry produces white fruits commonly called “Doll’s eyes” due to the persistent remains of the flower’s stigma, which leaves a black dot on each fruit.  Red Baneberry’s shiny red berries also have these black dots, though they are not as apparent. All parts of both species are poisonous, with the berries being the most toxic part of the plant.

Seed dispersal is carried out by animals that have enough tolerance to feed on the berries. These animals include various mice, squirrels, chipmunks and voles, as well as a wide variety of birds and White-tailed Deer.

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Young Common Gartersnakes Appearing

8-3-18 garter snake 081Seventy percent of the world’s snakes lay eggs (oviparous). The rest give birth to live young (viviparous). Oviparous snakes tend to live in warmer climates, where the substrate they lay their eggs in is warm enough to incubate the eggs.  (Most egg-laying snakes deposit their eggs and then depart, relying on the substrate to incubate the eggs.)  Viviparous snakes tend to live in cooler regions, where the ground is too cold to provide incubation.

There is a distinction between egg-laying snakes.  The majority of snakes that lay eggs do so outside their body, in a protected area such as a rotting log.  These snakes are known as oviparous. There are also egg-laying snakes that retain their eggs inside their bodies until they’re ready to hatch. These snakes are called ovoviviparous. Ovoviviparous snakes, such as the Common Gartersnake, appear to give birth to live young, but they actually don’t. Unlike viviparous species, there is no placental connection, or transfer of fluids, between mothers and babies, because the developing young snakes feed on the substances contained in their individual eggs. The snakes emerge from the mother when they hatch from their eggs, giving them the appearance of “live” births. The gestation period for oviparous snakes is generally longer than those of ovoviviparous snakes and vary from a few weeks to a few months in length. (Photo: very young Common Gartersnake, Thamnophis sirtalis sirtalis, consuming an earthworm)

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Young Wolf Spiders Dispersing

8-10-18 wolf spider 076Earlier in the summer, you may have glimpsed a spider carrying its white egg sac around with it, clasping it with the spinnerets at the end of its abdomen.  When the spiderlings hatch they crawl up their mother’s legs onto her abdomen, latch onto special knob-shaped hairs, and ride around with her for several weeks (see inset).  Only wolf spiders carry their egg sacs and offspring in this manner.

After molting, which occurs mid-summer, the young spiders disperse.  Eventually the mother is free to hunt for prey without the encumbrance of hitch-hiking offspring.  If you look closely at the pictured wolf spider, you may be able to make out the last lingering spiderling located at the junction of the wolf spider’s cephalothorax and abdomen.

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Hard-boiled Eggs & Lollipops: American Caesar’s Mushrooms Forming Fruiting Bodies

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This is not the first Naturally Curious post on American Caesar’s Mushrooms, nor will it probably be the last.  Every August the forest floor is bursting with the beautiful fruiting bodies of these fungi, and I find the urge to photograph them as well as the desire to celebrate their beauty with you irresistible. Pardon the repetition.

American Caesar’s Mushroom (Amanita jacksonii), a member of the Amanita genus found in New England, differs from most Amanita species in at least two ways. It is one of the few edible Amanitas (most species are poisonous, so consumption is discouraged unless an expert identifies the fungus). Secondly, unlike many other Amanita species, American Caesar’s Mushroom does not usually have any warts or patches on its cap.

The common name of this mushroom traces back to the fact that its close relative, Caesar’s Mushroom, Amanita caesarea, which grows in Italy, was a favorite of the emperors of the Roman Empire, the Caesars. Both of these species of Amanita are mycorrhizal, forming a symbiotic beneficial relationship with the roots of certain trees. Look for American Caesar’s Mushrooms under pine and oak. (Main photo: American Caesar’s Mushroom rupturing through its protective white membrane, or universal veil, as it matures, leaving a remnant white cup, or volva, at its base.)

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American Kestrel Chicks Fledging

 

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The American Kestrel is the smallest, most numerous, and most widespread North American falcon. Roughly two months ago these birds (formerly known as Sparrow Hawks) were mating and laying eggs in nesting cavities (natural tree cavities, woodpecker holes, nest boxes), most of which are located near open fields with low growth (to facilitate finding insects to eat).  The female kestrel does most of the incubating of her four to five eggs (one month), and all of the brooding (one month).  The male rises to the occasion and feeds the newly-hatched chicks for the first 7-10 days, and then the pair shares the feeding.

After 26 – 28 days in the nest, American Kestrel chicks are ready to fledge.  Their first flight, consisting of alternate fluttering and gliding, can be quite short or as long as 200 yards, and typically ends with an awkward landing.  After the chicks have fledged, the parents continue to feed them for up to 12 days. During this period young American Kestrels have been observed returning to their nest cavity to roost.

(Photo:  Male American Kestrel nestling, roughly 22 days old. Note feathered “eye” spots on back of head (serve to ward off predators) are already showing. Thanks to Joan Waltermire, John Douglas, David Merker, and Sebastion and Carter Lousada for photo op.)

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Robber Flies Active

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You may well have seen a robber fly (also known as an assassin fly) and not recognized it as such.  Big eyes, pointed mouthparts, a hairy face and a fondness for insects are robber fly characteristics to look for.

Robber flies are among our largest flies and are predatorial ambushers.  They tend to perch for minutes at a time on the tips of leaves, or other sunny viewpoints, where they keep a lookout for unsuspecting prey.  Once they spot an insect they lose no time in darting after it.  With their beak-like mouthparts they spear the insect and inject a mixture of nerve poisons and enzymes that liquefy the tissues of their victim.  They then drink the innards of their prey.

Note that there is a prominent “beard” or tuft of bristles (mystax) in the front of the pictured robber fly’s face.  All robber flies have this tuft which serves to protect the face and eyes of the predator from the struggling prey as it dines.

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Shorebird Migration Well Underway

7-30-18 greater yellowlegs 286Contrary to what it’s called, the “fall” migration of shorebirds has been underway since early July, and is in full swing, peaking in August. Vermont is home to only a few breeding shorebirds (Killdeer, Spotted Sandpiper, Upland Sandpiper, Wilson’s Snipe, American Woodcock).  Most of the shorebirds we see this time of year are those migrating south after nesting in the Arctic.

Shorebirds move south relatively early compared to many migratory birds, in part, because the breeding season in the Arctic is quite short. In addition, those birds whose first nesting attempt failed tend to migrate soon afterwards rather than attempt a second nesting, due, once again, to the brief Arctic summer. Also, in several species one member of a pair often leaves before the young are full grown, sometimes even before the eggs hatch, leaving the remaining adult to raise the young.

The young of most shorebirds migrate later than the adults.  There can be as much as a month between the peak passage of adults and that of juvenile birds. (Photo:  Greater Yellowlegs)

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