An online resource based on the award-winning nature guide

Archive for September, 2013

Common Loons Molting

9-30-13 molting loon MH_20091004_214955_3Loons begin a full body molt (minus their wings) in the late summer and early fall, prior to migration. The black and white breeding plumage of adult loons in summer is replaced by the gray-brown of winter. This process typically begins at the base of the bill and spreads across the head and over the upper back. The process of molting can extend through migration on into December.

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Spider Spinnerets

9-30-13 black and yellow sp. spinnerets2 IMG_4897Responses to yesterday’s Mystery Photo ranged from immediate deletion by a reader (due to the unappealing nature of the photo), to guesses including “bee butt,” “caterpillar mouthparts” and “deer tick.” Most responders, however, guessed correctly – the photograph was of the spinnerets of a Black-and-Yellow Garden Spider, Argiope aurantia.

Most spiders have six spinnerets — organs located on their abdomens from which silk is extruded. The individual spinnerets move independently yet in a highly coordinated manner. Each spinneret is dotted with many tiny spigots, through which various types and thicknesses of silk are extruded. The strong muscles that move the spinnerets also force liquid silk through the narrow spigots. This pressure, as well as external pulling by the spider, rearranges the liquid silk molecules into a solid but flexible thread. Although spider web silk is only about one millionth of an inch thick, weight for weight, it is stronger than steel (but not as strong as Kevlar). Unlike in the Mystery Photo, the spinnerets in this photograph are extruded and in use.

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Mystery Photo

9-26-13  mystery photo2 244You’ve probably seen this many times, just not this close and not from this angle. Most are smaller than the head of a pin. All guesses welcome. Identity will be revealed in tomorrow’s post.

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Canada Geese Migrating

9-25-13  migrating C. geese2 224This is the time of year when the honking of migrating Canada Geese can be heard as the familiar V-shape formation passes overhead. Many of these birds have a long, arduous migration and they need to conserve as much energy as possible. The V-formation that they fly in enables them to do so, in that it greatly boosts the efficiency and range of flying birds. Geese flying in a V-formation have slower heart beats than geese flying solo, and they can achieve a distance of 71% greater than single birds. The birds in front make this possible by enduring the most air resistance and, at the same time, improving the aerodynamics of the birds behind them by reducing the drag by up to 65 percent. The geese are constantly rotating positions in order to share “flight fatigue.”

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Wild Cucumber Fruiting

9-24-13 wild cucumber2  IMG_4085Looking more like a miniature spiny watermelon than a cucumber, the fruit of Wild Cucumber (Echinocystis lobata) grows on an annual vine that can reach a length of 15 to 25 feet. The genus name Echinocystis comes from the Greek echinos for “hedgehog” and cystis for “bladder”, appropriately describing the prickly fruit. The puffy, spherical-to-oblong, green fruits with long, soft spines grow up to two inches long. Despite its common name, Wild Cucumber fruits are not edible, and can cause burning reactions in some people. When ripe, the fruit turns brown and dries up, bursting open at the bottom, ejecting four large, flat, black seeds.

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Grasshoppers Mating and Laying Eggs

9-23-13 mating grasshoppers 137Grasshoppers typically mate in late summer and fall. If it’s a short-horned grasshopper (pictured), the smaller male mounts the female (female long-horned grasshoppers mount the males). The male short-horned grasshopper often remains riding the female for long periods in order to ensure paternity. When the eggs are fully formed, the female pushes the ovipositor at the end of her abdomen ½” to 2” into the ground and produces a glue-like secretion that cements the soil around the egg mass, forming a protective “pod.” Each pod may contain 25 to 150 eggs, depending on the species of grasshopper. Grasshoppers which deposit masses containing few eggs usually lay more pods to compensate. A female may lay as many as 300 eggs which overwinter and hatch in the spring.

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Did you know…

9-20-13  milkweed-did you know2 022Only two percent of Common Milkweed, Asclepias syriaca, flowers develop into pods, and all the seeds in a pod come from a single flower.


Green Lacewing Larvae Use Corpses as Camouflage

9-19-13 lacewing larva  232Green lacewings are aptly named for the prominent venation of the adults’ wings. Some species in this insect family even have “ears” in the larger veins that allow them to detect the ultrasonic sounds made by hunting bats. Lacewing larvae and adults are both predators of soft-bodied insects such as aphids. Larval lacewings have long, hollow mandibles with which they puncture prey and suck out the liquefied contents, leaving the woolly husks. Some species of lacewing larvae have hairy backs, and camouflage themselves when in the presence of woolly aphids by sticking aphid husks on these hairs. These “trash packets” camouflage the lacewing larvae from predators, including ants that would otherwise attack the larvae if they recognized that they were lacewings and not woolly aphids.

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How Slugs Eat

9-18-13 slug radula 262No-one needs a description of the damage that slugs can do in a garden, but the exact way in which they do the damage is quite unique. They actually do not have mouthparts as such, nor do they possess teeth as we know them. They, like most molluscs, have a radula, or rasping tongue-like organ with which they procure food. A bit of cartilage, the odontophore, forms the core of the radula. The rest of the radula consists of a band, similar to a conveyor-belt, covered with thousands of tiny tooth-like protrusions called denticles. The band moves over the odontophore, rasping away particles of food and moving them back into the slug’s gullet. The pictured slug was making short work of a mushroom.

ADDENDUM TO YESTERDAY’S POST: After several reader comments and self-reflection, I’ve come to the conclusion that yesterday’s post could well be black bear, not raccoon, vomit. While all I found in the cornfield were signs of raccoons, it was a huge field, and I may have just missed bear sign or the bear may well have visited another field prior to getting sick. The amount of vomit was so large that it would have taken a giant raccoon to have left it. Both of these animals feed voraciously in the fall in preparation for winter — black bears can double their weight prior to denning.

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Raccoons Gorging

9-17-13  raccoon vomit, corn 203In New England, Raccoons prepare for winter by eating extra food during the fall. Being omnivores, they eat everything from crayfish and mice to nuts and corn. The latter two items are particularly important, as these high carbohydrate foods allow the Raccoons to put on considerable fat reserves for the cold winter months. According to the Farmer’s Almanac, Raccoons are wasteful when it comes to harvesting corn, because they don’t really like sweet corn all that much. You could fool the Raccoon that deposited this pile on the forest floor adjacent to a Vermont corn field. It gorged on so many ears of corn that it got sick, and there wasn’t a hint of anything but corn kernels that came out of its stomach. (The pile was well over a foot in length.)

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Common Green Darners Migrating

9-16-13 common green darner 249The Common Green Darner, Anax junius, is one of our largest dragonflies, measuring three inches long, with a four-inch wingspread. It is strikingly colored, with a green thorax and a bright blue (male) or reddish (female) abdomen. As if that weren’t enough to set this dragonfly apart, it is also migratory. Common Green Darners migrate south from August to November, stopping over (like migrating birds) occasionally along the way, resuming flight after resting and refueling. Thanks to radio telemetry, we now know that over a two-month migration, Common Green Darners, each weighing about one gram, can migrate over 400 miles. (Photograph is of a Common Green Darner perched on Bottle Gentian.)

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Do Yellow-bellied Sapsuckers Really Suck Sap?

9-12-13  yellow-bellied sapsucker tongue IMG_9715My apologies for not posting yesterday — two days without electricity or telephone!

A tell-tale sign of Yellow-bellied Sapsucker activity is the presence of rows of 1/4–inch holes, often drilled in Sugar Maples and birch trees in order to gain access to their nutritious phloem sap. Once the sap begins to flow, sapsuckers insert their tongues into these holes. Here is where their name is misleading, as sapsuckers don’t actually suck the sap, they lap it up with the aid of tiny hair-like projections on the edge of their tongue, which hold the sap by capillary action (see insert). Each flick of the tongue brings more sap into the woodpecker’s mouth.
Because sap is so essential to a tree, wounds are quickly healed over to prevent loss of sap. Scientists still have not figured out how sapsuckers overcome a tree’s defenses and maintain a continuous flow of sap. One theory is that sapsucker saliva may contain a substance that acts as an anticoagulant, preventing sap from clogging up and sealing over the holes the bird creates.

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Pelecinid Wasps Laying Eggs

9-11-13 pelecinid wasp 211The two-inch, skinny, black, shiny wasps with extremely long abdomens (five times the length of their bodies) that have been appearing on lawns lately are not the villains you may think. These female Pelecinid Wasps (males are much smaller and rarely seen) are actually beneficial, in that they greatly decrease the June Bug population. That long abdomen, or ovipositor, cannot sting you – it is strictly a mechanism for laying eggs. Its length is due to the fact that the wasp inserts its ovipositor deep into the ground in order to locate beetle larvae — specifically, June Bug beetle larvae. The wasp then lays one egg on each host beetle larva, and when the egg hatches, the wasp larva burrows into the host as it feeds on it, thereby killing the June Bug beetle larva. Eventually the wasp larva pupates and emerges above ground as an adult wasp the following summer – the phenomenon we are currently witnessing.

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Bottle Gentian Flowering

9-10-13 bottle gentian IMG_8093Bottle Gentian, Gentiana andrewsii, is one of our latest blooming wildflowers, and one of our most beautiful. Because its petals are closed so tightly, only bumblebees (pictured) and a few other insects have the strength to push their way inside the flower to reach Bottle Gentian’s sugar-laden nectar.

Like many other flowers, Bottle Gentian times the maturation of its reproductive parts to discourage self-pollination. Male pollen-bearing stamens mature first, and by the time the female pistil is mature, the stamens have gone by so the flower’s pistil can’t receive its own pollen (see central pistil surrounded by withered stamens in insert).

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American Elderberry & the Elderberry Borer

9-9-13 American elderberry 183Interestingly, while the ripe fruit of American Elderberry (Sambucus canadensis) is used in the production of wine, pies and jelly, the leaves, stems, roots and unripe fruits of this plant are poisonous, due to the presence of calcium oxalate crystals. Elderberry Borers (Desmocerus palliates) seem immune to these crystals, however. They lay their eggs at the base of the plant, and the hatching larvae then burrow their way into the stems and eat tunnels into the roots of the plant. Adult beetles that emerge and are present through the summer are hard to miss, with their shimmering blue and yellow/orange outer wings, or elytra.

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Young Pickerel Frogs Underfoot

9-6-13 young pickerel frog 049If you remember visiting a pond last April or May and hearing a low, snoring sound (the mating call of the male Pickerel Frog) you might see the end results of those snores if you re-visit the pond now. Young Pickerel Frogs the size of quarters are currently abundant on the banks of the ponds in which they grew up, as well as in nearby vegetation. After emerging from the water sometime between July and September, many of these first year frogs move into nearby fields, meadows and damp woods. They are only a few weeks away from burying themselves in mud at the bottom of the pond, where they will hibernate all winter.

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Goldenrod Pollen

9-4-13 goldenrod pollen 305Goldenrod is an extremely important foraging plant for honeybees in the late summer, when its flowers produce prolific amounts of nectar and protein-rich pollen. Goldenrod pollen, the orange lump that you see packed into the pollen basket (after being mixed with saliva) on the hind leg of this honeybee, is often blamed for the allergies that many people experience in the late summer and early fall. It is falsely accused, however, as ragweed pollen is the real culprit. Being wind pollinated, ragweed has light, fluffy pollen, which is easily dispersed (and easily enters nostrils). Goldenrod pollen is large and sticky, allowing visiting insects to gather it (intentionally as well as unintentionally) all over their bodies and transfer it to other goldenrod flowers, therein cross-pollinating them.

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Herons, Egrets and Bitterns & Their S-shaped Necks

9-4-13  great blue heron 1486If you’ve watched a heron, egret or bittern for any amount of time, you know they strike suddenly and rapidly at their prey . They can do this because of the structure of their neck bones. According to David Sibley, modification of the sixth cervical vertebra lets them draw their neck into an “S” shape and then shoot their head and bill forward with lightning speed. This adaptation also allows these birds to fold their neck while flying, which improves the aerodynamics of their flight. (Photograph is of a Great Blue Heron.)

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Slug Mating Behavior

9-2-13 slugs 035Slugs are hermaphroditic, possessing both male and female organs; most species mate, however, with one slug pursuing the slimy trail of another. If a slug is in mating mode, there is a chemical that is present in its slime that conveys this information to other slugs. When two receptive slugs first encounter each other, there can be extensive interaction prior to mating. The pursuer often mouths the tip of the tail of the slug it’s pursuing (see photograph) to confirm that it’s receptive. The pursued slug may shake its tail vigorously to signal that it’s not interested, in which case they go their separate ways. If the leading slug is receptive, however, mating eventually takes place, with sperm being transferred from each slug to the other through penises that extend half the length of their bodies. During this process, the sexual organs are entwined; occasionally, in some species, the organs get stuck. If this happens, one slug gnaws off the other’s penis in a process called apophallation. The penis is not replaced and the slug lives the rest of its life as a female. (The opening you see on the side of the slug is its respiratory opening, or pneumostome.)

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Beaver Tail Boosts Balance

beaver tail 062A beaver’s tail is a wondrous thing. Beavers steer and propel themselves with it, store fat for the winter in it, regulate their body temperature with it, use it as a prop when sitting or standing and signal alarm with it by slapping it against the water. While these functions are fairly well known, there is another use that is not observed as often. When floating on top of the water, beavers use their tail as a stabilizer, to keep their body upright. As this photograph illustrates, beavers often raise their tail out of the water in order to stabilize themselves.

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