Beavers Consuming Herbaceous Plants
One associates Beavers with a fairly strict diet of bark and twigs. While their winter diet consists primarily of woody plants, they consume a variety of herbaceous and aquatic plants (as well as woody) during the spring, summer and fall months. Shrubs and trees make up roughly half the spring and autumn requirements, but as little as 10% of the summer diet when herbaceous plants such as sedges and aquatic plants become available.
Recent observation of a local active Beaver pond revealed that Interrupted Fern (Osmunda claytoniana), Jewelweed/Touch-Me-Not (Impatiens capensis) and grasses are high on the list of preferred foods of one Beaver family during the summer, although woody plants such as poplars (Populus spp.) and Paper Birch (Betula papyrifera) have also been consumed in fairly large quantities. All too soon Beavers in the Northeast will be limited to the bark of branches they’ve stored under the ice. Until this time, they take advantage of the accessibility of more easily digested herbaceous plants. (Thanks to the Shepards and Demonts for photo op.)
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Gallium Moth Larvae Burrowing
Some of the largest moths in the world belong to the hawk, or sphinx moth family. They typically have long narrow wings and thick bodies. Hawk moths are fast flyers and often highly aerobatic. Many species, including the hummingbird moths, can hover in place, and some can even fly backwards. Mostly nocturnal fliers, hawk moths are exceptionally good at finding sweet-smelling flowers after dark.
As larvae, most hawk moths have a “horn” at the end of their body. One of the most familiar hawk moth caterpillars is the Tobacco Hornworm, found on tomato plants. Most species produce several generations a summer, pupating underground and emerging after two or three weeks. One exception is the Gallium Sphinx Moth, pictured, which usually has only one generation a year. In this photograph it is working its way underground, where it will overwinter as a pupa inside a loose cocoon in a shallow burrow, emerging as an adult moth next spring.
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Naturally Curious 2017 Calendar
It’s time for 2017 Naturally Curious calendar orders! Please specify the number you would like as well as the mailing address to which they should be sent, and mail them to me at 134 Densmore Hill Road, Windsor, VT 05089 along with a check made out to Mary Holland. Orders can be placed up until October 31st. The calendars are printed on heavy card stock and are $35.00 each (includes postage). They will be delivered by mid-December. Thank you!
Solitary Sandpipers Migrating
Solitary Sandpipers nest in the boreal forests of Canada and Alaska (in the abandoned tree nests of several different song birds!), and winter in the tropics, from northern Mexico south through much of South America. Individuals started their nocturnal inland and offshore migration south in June. In the fall, some birds appear to fly southeast over New England towards the Atlantic Ocean, as if on direct course to South America, while others follow the eastern coastline. Although their migration over New England peaked in July, you can find them through mid-October on the shores of ponds, resting and feeding during their long flight. One benefit of the dry weather we’ve had this summer is the large number of exposed mud flats and pond banks on which migrating shorebirds can forage. As their name indicates, Solitary Sandpipers migrate singly, not in flocks like most migrant sandpipers.
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Boletes Fruiting
Boletes are fleshy terrestrial mushrooms that have sponge-like tubes, not gills, as most mushrooms have, under their caps. (Polypores also have tubes, but are tough and leathery and usually grow on wood.) Spores develop on basidia (club-shaped, spore-bearing structures) which line the inner surfaces of the tubes. Because the basidia are vertically arranged, the spores, when mature, drop down and disperse into the air.
The majority of bolete species are edible, but there are two reasons not to harvest them unless you are with an expert. One reason being that there are some poisonous bolete species. The second reason is that because they are large and fleshy, larvae can often be found inhabiting them, as well as parasites.
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Dog-day Cicadas Emerging, Courting, Mating and Laying Eggs
Adult annual cicadas, including the pictured Dog-day Cicadas, have emerged from their subterranean dwellings. High up in trees most males are vibrating their abdominal tymbals (drum-like organs) in order to woo female cicadas with their “song.” Thanks to an abdomen that is relatively hollow, the sound is intensified, and very audible to human ears as a high-pitched whining drone, somewhat resembling a buzz saw. We associate it with the hot, humid “dog days” of July and August.
Annual cicadas emerge from the ground (where they have been feeding off of the sap of trees through the trees’ roots for two to four years) every year as nymphs. They climb a tree, split and emerge from their exoskeleton, or outer skin, and pump their wings full of fluid. After their exoskeleton dries, the adult cicadas (also called imagoes) head for the canopy, and males commence “singing” to attract a mate. Within two weeks mating takes place, eggs are laid in slits of live branches and the adults die. After hatching, the nymphs will drop to the ground and burrow into it with their shovel-like front legs. (Thanks to Wallie Hammer for taking and providing today’s photograph. Mating usually takes place in the canopy, and therefore rarely seen.)
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Moose Affected By Global Warming
It is fairly well known that the Moose population in the Northeast (and elsewhere) has plummeted — New Hampshire has lost more than 40% of their Moose in the last decade, and this trend is occurring throughout northern New England. Global warming is at the heart of this decline. Warm winters have allowed the tick population to soar, and blood loss due to ticks has weakened Moose, making them susceptible to anemia and unable to fight off disease. The negative effect of warmer temperatures doesn’t stop there. Summer heat stress promotes weight loss, a fall in pregnancy rates and increased vulnerability to disease. Excessive warm weather drives Moose to seek shelter, rather than forage for much-needed food. This phenomenon has been described by Moose biologists as “one of the most precipitous non-hunting declines of a major species in the modern era.”
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Eggs Of Migrating Generation Of Monarchs Hatching
The Monarch eggs that are hatching now contain the larvae that will metamorphose into the butterflies that will migrate this fall to central Mexico. Unlike earlier-hatching generations that only live six to eight weeks, the Monarchs that result from late summer and early fall hatchings live six to nine months. Part of the reason for this difference in life span is that, unlike the earlier generations that mate soon after emerging from their chrysalides, late-hatching Monarchs postpone mating (reproductive diapause) until the end of winter, thereby conserving energy for their two to three thousand-mile, two-month migration. (Photo: monarch larva’s first meal – its eggshell.)
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Great Egrets Dispersing
Although Great Egrets breed sporadically as far north as Vermont, seeing one in northern New England is always noteworthy. The likelihood of a sighting increases as summer progresses, due in large part to the phenomenon of post-breeding dispersal. After young Great Egrets have fledged, individuals wander well outside their typical breeding range, as far north as southern Canada. The northward dispersal of juvenile birds peaks in August and September. Most Great Egrets migrate in the fall, from September through December.The extent of their migration is influenced by annual fluctuations in temperature. When winters are mild, individuals may remain as far north along the Atlantic Coast as Massachusetts.
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Female Black and Yellow Mud Dauber Wasps Making Cells & Laying Eggs
If you look closely at the ground directly in front of this female Black and Yellow Mud Dauber wasp you will see the clump of mud that she has collected and rolled into a ball with her mandibles. This lump of mud will be carried back to the nest site in the wasp’s mandibles, and then used as building material to mold a cell. After making the mud cell, the wasp then goes and locates spiders, stings them (paralyzing but not killing them) and brings them back to the cell, into which she packs them. When the cell is sufficiently stuffed with spiders, she lays an egg and seals the cell with more mud. She makes and fills several of these cells and typically covers all of them together with a final layer of mud. When the wasp egg in each cell hatches, the larva has living spiders to eat that haven’t decomposed, due to the fact that they are not dead. Eventually the larval wasp pupates and the adult wasp chews its way out of the cell.
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Green Frogs’ Coloring
Despite their name, Green Frogs are not always green. They can be brown or tan, as well as many shades of green. Usually Green Frogs in the Northeast are a combination of these colors, but occasionally one sees greenish-blue coloring on a Green Frog. An understanding of what causes a frog’s green color sheds light on why sometimes all or part of a Green Frog may be close to turquoise than green.
Basically there are three types of pigment cells (chromatophores) which stack up on top of each other in a frog’s skin. The bottom layer (melanophores) of pigment cells contain melanin, a pigment that appears dark brown or black. On top of these cells are iridopores, which reflect light off the surface of crystals inside the cells. When light hits these cells, they produce a silvery iridescent reflection in frogs, as well as other amphibians, fish and invertebrates. In most green frogs, sunlight penetrates through the skin to the little mirrors in the iridophores. The light that reflects back is blue. The blue light travels up to the top layer of cells called xanthophores, which often contain yellowish pigments. The light that filters through the top cells appears green to the human eye.
The pictured turquoise-headed Green Frog most likely lacks some xanthophores in the skin on its head, and thus we see reflected blue light there.
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Great Spangled Fritillaries Flying, Feeding & Mating
There are five species of fritillaries in New England: the Great Spangled, Aphrodite, Atlantis, Silver-bordered and Meadow. The largest and most common is the Great Spangled Fritillary.
The adults are in flight now, feeding on the nectar of a variety of flowers, including Joe-Pye Weed (pictured), mints and milkweed. In general they prefer long, tubular flowers. Males patrol open areas for females. After mating, female Great Spangled Fritillaries enter a resting state called diapause, which they emerge from in late summer. At this time they lay their eggs near patches of violets (larval host plant) and die. The caterpillars hatch in the fall and overwinter as larvae, becoming active in the spring at the same time as violet plants begin to grow. Feeding takes place at night, and is limited to violet leaves. Hopefully global warming will not upset the synchronization of these two events.
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Broad-leaved Helleborine Dispersing Pollen
Having known since childhood that most insects have only one pair of antennae, imagine my surprise when I came upon a hornet on Queen Anne’s Lace that appeared to have two: a pair of slender, black antennae, and between them, a shorter pair of white ones. A bit of research revealed to me that in fact, these white “antennae” were actually the pollen sacs (pollinia) of an introduced and somewhat invasive orchid, Broad-leaved Helleborine (Epipactis helleborine).
Broad-leaved Helleborine is entirely dependent on insects to spread its pollen, especially wasps. It attracts them with nectar, which is said to have an alcoholic and narcotic effect which may help with the spreading of pollen, as an inebriated wasp is less likely to clean pollen off its body before leaving. Helleborine also produces a chemical which other plants produce and use to signal that they are being attacked by insects. It is used purely as a ruse by Helleborine, in order to attract wasps, Helleborine’s primary pollinators, who arrive to fend off other insects, and end up inadvertently collecting Helleborine’s pollinia.
Unlike the pollen of most plants, Helleborine’s pollen grains are so sticky that they cannot separate – thus, the entire package of pollen remains intact and is removed at one time. Wasps are capable of reaching the plant’s nectar without disturbing the pollinia, but cannot crawl out of the flower without striking against and detaching them and in so doing, getting them stuck to their heads. Can you find the pollinia in the insert photograph of a Broad-leaved Helleborine flower (which has not been visited by a wasp yet)?
Due to computer issues, Naturally Curious will resume posts next Tuesday, August 16.
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Ghosts of August
Flowering plants have a variety of ways to obtain food. Most have chlorophyll and thus are capable of photosynthesizing their own nutrients. A majority of these plants (90%) are also associated with mycorrhizal fungi – fungi which attach to the roots of other plants, often trees, with which most have a symbiotic relationship (both benefit). The plant receives minerals and water from the fungi, and the fungi feed on carbohydrates and other nutrients the plant produces.
Flowering plants with no chlorophyll cannot make their own food and must rely completely on other organisms for their nutrients. Some of these parasitic plants get their nutrients directly from the roots of another plant (Beechdrops) and others (Indian Pipe and Pinesap) receive food indirectly from fungi which get their nutrients from a photosynthetic plant. In these situations, the mycorrhizal relationship between the non-photosynthetic plant and the fungi is not mutualistic, as only the chlorophyll-lacking plant benefits. (Photo: Indian Pipe, Monotropa uniflora (one flower per stalk) and (insert) Pinesap, Monotropa hypopitys (many flowers per stalk).
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Beavers Engaging In Mutual Grooming
In these days of political strife and global conflict, it is immensely reaffirming to see that not all species are engaged in this craziness. Yes, predators do, of necessity, kill prey, and there are disputes over territory and mates, and countless other acts of aggression in the natural world which I often write about, but today I choose to celebrate the cooperation between members of the same species that my camera occasionally captures. These two beavers are participating in “mutual grooming” – a practice that involves using their incisors to remove debris as well as increase the insulating capacity of each other’s coat .
Beavers are fastidious about keeping their coats clean, well-aligned and waterproofed. (Their life actually depends on it, as they would suffer from the cold water in winter without the latter.) They spend an immense amount of time grooming themselves, applying waterproofing oil from their anal glands to their coats with front and back feet and combing sticks, parasites, etc. out of their fur (a split toe on each of their hind feet enhances this endeavor) Research shows that a primary function of grooming is maintaining an insulating layer of air between their hair and skin. Upon occasion they perform this act for each other, probably in an effort to reach spots that self-grooming can’t. Lucky are those who have observed this seemingly tender moment between two beavers.
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Robber Flies Capturing Prey
The robber fly family, Asilidae, is one of the largest families of flies. All robber flies are predaceous and are recognized by their long bodies, forward-facing beaks and a tuft of hairs above the beak. You find them on the ground or on leaf tips and other sunny spots where they survey the area for flying insects. Once a robber fly has spotted a suitably-sized prey, it darts out and impales it with its stout beak. It then inserts its needlelike “tongue” into the prey’s neck, eye or other weak spot, immobilizing the insect and liquefying its innards with an injection of saliva that contains nerve poisons and enzymes that break down proteins. Finally, it drinks its meal. Pictured is a species of robber fly in the genus Diogmites, whose members are known for dangling by a foreleg while dining.
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Red-eared Sliders
If you’re of a certain age, you may remember having a small pet turtle (complete with a plastic container and palm tree) when you were young. Those turtles were Red-eared Sliders, and so many of them were released or escaped into the wild that they are now considered an invasive species and many countries ban their importation. Even though it is illegal for hatchlings with a top shell length of less than 4 inches (they can reach 16 inches) to be sold for anything other than educational purposes, many pet stores in the U.S. still sell them. Wild populations can be found in most of the New England states, though they are very localized in some.
Red-eared Sliders are named for the red ear stripe on both sides of their head, and the fact that when basking they typically slide into the water at the slightest hint of danger. They are semi-aquatic and strong swimmers; when not basking, they can usually be found in the water. Like many other species of turtles, the sex of Red-eared Sliders is determined by the incubation temperature during critical phases of the embryos’ development. Males are produced when the incubation temperature is between 72° and 81°F. and females develop at warmer temperatures. (Thanks to Sadie Brown for photo op.)
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Dead Man’s Fingers
When it first appears above ground in the spring, the club or finger-shaped fruit of Dead Man’s Fingers (Xylaria polymorpha) appears powdery white from the asexual spores that cover its surface. As it matures, it acquires a crusty, black surface. This is the sexual stage. The interior of the fruiting body of this fungus is white; just inside the outer surface is a blackened, dotted layer containing structures called perithecia which hold sacs of spores.
Dead Man’s Fingers, unlike most fungi, which release their spores in a few hours or days, releases its spores over months, or even years. It can have many separate fingers, sometimes fused together to resemble a hand. Look for this fungus growing on hardwood stumps and logs, particularly American beech and maples.
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Belted Kingfishers’ Distinctive Traits
You often hear a Belted Kingfisher before you see it. Their territorial, mechanical “rattle” is quite distinctive and issued frequently. This call is just one of their more distinctive traits. They are one of the few species of birds where the female’s plumage (two “belts” on breast) is more colorful than the male’s (one breast “belt”). Kingfishers have a distinctive pattern of wingbeats: whereas most birds beat their wings several times and then glide, kingfishers’ wingbeats are irregular and intermittent, lacking the flap and glide pattern. Kingfishers have the unusual ability to hover in one spot while surveying the water 20 to 40 feet below for fish or other prey. When they capture a fish, they often return to a branch and whack it multiple times against the branch to assure its compliance in being swallowed head first without a struggle. Even the nesting site of a Belted Kingfisher is fairly unusual — a chamber located at the end of a 3 to 6-foot-long bank burrow they dig with their bill and feet.
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Case-bearing Leaf Beetles Eating & Growing
It’s not every day that I discover a species I’ve never seen before, but when it comes to insects, it happens regularly. Rarely, however, are they as interesting as the Case-bearing Leaf Beetle I observed on a blackberry leaf recently. An oval, brown, stationary case about ¼” long was at a 45° angle to the leaf it appeared to be attached to it. Upon closer inspection and with a bit of probing, a head and six legs appeared at the leaf end of the case, and the case began to move.
How its case was created is as, or more, interesting than the beetle itself. The adult female Case-bearing Leaf Beetle lays an egg and wraps it with her fecal material as she turns the egg, until it is completely enclosed. Once hardened, the feces create a protective case for both the egg and eventually the larva. When the egg hatches, the larva opens one end of the case, extends its head and legs, flips the case over its back and crawls away. As the larva eats and grows, it adds its own fecal material to the case in order to enlarge it. Eventually the larva reseals the case, pupates and then emerges as an adult Case-bearing Leaf Beetle. If it’s a female it then prepares to mate, lay eggs, and recycle its waste.
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