An online resource based on the award-winning nature guide

June

Black Bears Communicating

6-21-17 black bear by Alfred 2017-05-24 15.35.19Black Bear males are not shy about making their availability and intentions known to the opposite sex. Their most prevalent means of communicating this information is to leave their scent on trees (as well as other structures, such as telephone poles– see photo) by scratching them with their claws, biting them and rubbing on them with their shoulders, back and neck. Often they will use the same marking tree year after year, with signs accumulating on the tree.

Both males and females mark trees year-round, but at this time of year, at the peak of their mating season, males are especially active markers, in order to convey their social identity, reproductive status and location to female passersby. One might consider such marking trees as ancient “scratch.com” mating sites. If you find one, be sure to look for stray hairs that have been inadvertently left behind. (photo by Alfred Balch)

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Common Green Darners Appearing

6-20-17 common green darner 021The Common Green Darner (Anax junius) is one of our most common dragonflies. often seen near ponds. The family of dragonflies known as “darners” consists of species with large eyes and long abdomens that tend to rest infrequently and when they do rest, usually hang vertically. The Common Green Darner is the only North American darner in which the male and female usually fly in tandem when the female is laying her eggs on emergent vegetation.

Up to 50 of the world’s 5,200 dragonfly species migrate and the Common Green Darner is one of them. In the fall most (but not all) adult Common Green Darners migrate south to Florida, eastern Mexico and the West Indies. Huge clouds of migrating dragonflies have been seen along the East Coast, Gulf Coast and the Great lakes in autumn. Transmitters weighing 1/100th of an ounce that have been attached to migrating dragonflies confirm that they migrate much like birds. Just like avian migrators, they build up their fat reserves prior to migrating; they follow the same flyway as birds, along the Atlantic Coast; and like birds, dragonflies don’t fly every day but stop and rest every three days or so.

Some dragonflies mate and lay eggs along the way, while others do so when they reach their destination. The eggs hatch, larvae develop and the adults head north in the spring. Unlike birds, migration is only one-way for dragonflies. It is the offspring of the fall migrating generation that migrate north in the spring. Here in the Northeast, most arrive before any resident Common Green Darners have emerged. (photo:  female Common Green Darner)

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One-flowered Cancer-root Flowering

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One-flowered Cancer-root (Orobanche uniflora), also known as One-flowered Broomrape, is now flowering  in fens — wetlands similar to bogs, but less acidic and more mineral-rich.  Covered with glandular hairs, its flower looks like it’s made of crystallized sugar. One plant produces up to five flowering stalks, each of which bears a single, fragrant, white-to-lavender flower.

One-flowered Cancer-root has no chlorophyll in the scale-like leaves that grow on its underground stem, and thus is incapable of making its own food. This parasitic plant is classified as a holoparasite – entirely dependent upon other host plants for its nutritional needs. A One-flowered Cancer-root seedling must find a suitable host plant (often sedums, saxifrages and asters) within a few days of germinating or die. The search for a host by One-flowered Cancer-root is guided by chemicals released by the growing roots of the host species. Once a host plant is located, the One-flowered Cancer-root’s root hairs exude an adhesive substance that attaches its roots to those of the host plant. Enzymes break down the cell walls of the host, and a tuber-like connection (haustorium) forms between the vascular tissue of the two plants, allowing the movement of water, minerals and carbohydrates to flow in one direction, from host to parasite. (Thanks to Shiela and Steve Swett for photo op.)

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Snapping Turtles Laying Eggs

6-19-17 snapping turtle laying eggs2 309In June,  mature female Snapping Turtles leave their ponds in search of a sandy spot in which to lay their eggs. (Capable of storing viable sperm for up to three years, female snappers do not necessarily mate every year prior to laying eggs.) Once this prehistoric-looking reptile locates a suitable location she slowly scoops one footful of earth at a time up and to the rear of her, alternating her left and right hind feet. If the soil is dry and tightly packed, she will urinate on it in order to facilitate digging.

Hole made, she proceeds to slowly lift her body and release ping pong ball-sized, -colored and -shaped eggs, usually one at a time, but occasionally two, into the hole beneath her. Down she comes for a minute or two of rest, and then up she rises again to release another egg. She does this anywhere from 20 to 40 times, a process that can take up to several hours, depending on the number of eggs she lays. Then her large, clawed hind feet slowly begin to scrape the two piles of soil she removed back into the hole, one foot at a time, until the eggs are covered, at which point she tamps the soil down with her plastron, or bottom shell. She then returns to the water, leaving the eggs and hatchlings to fend for themselves.

It is hard to accept that after all the effort that has been put into this act, studies have shown that 90 percent or more of turtle nests are raided by the likes of raccoons, skunks and crows. For those nests that are not discovered by predators, the sex of the turtle that emerges from each egg is determined by the temperature it attained during a specific part of its development. Eggs maintained during this period at 68°F produce only females; eggs maintained at 70-72°F produce both male and female turtles, and those incubated at 73-75°F produce only males. The eggs hatch in September, with many of the Snapping Turtles emerging then, but in the northern part of their range, young Snapping Turtles sometimes overwinter in their nest and emerge in the spring. (Thanks to Chiho Kaneko and Jeffrey Hamelman for photo op.)

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Modest Sphinx Common & Scientific Name Correction

6-16-17 moest sphinx IMG_8668Poplar Hawk-moth and Big Poplar Sphinx are both common names used for more than one species of moth. Normally, the scientific name would clarify the identity of a species, but in yesterday’s post, the scientific name given was that of another moth with the same common name.

The confusion over the use of the same common names for different species of moths has led to the current use of the name Modest Sphinx for the moth depicted in yesterday’s post, with a scientific name of Pachysphinx modesta. It derived both common and scientific names from the fact that when it is seen up against a tree or other substrate with its forewings not fully extended, the bottom half of the moth is dark, as though “modestly covered” by a cloak or shawl. Thank you, Andree Sanborn, for your sharp eyes!

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Millipedes Meandering

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How do you distinguish a millipede from a centipede – both multi-segmented arthropods that have a lot of legs? Although there are many less obvious differences, centipede bodies are relatively flexible and they have one pair of legs per body segment. Most of a millipede’s segments have two legs, and their tubular body is quite rigid.

Depending on the species, millipedes have between 80 and 750 legs, with most having fewer than 100, but they didn’t start out their lives with this way. When they hatch, millipedes only have three pairs of legs; every time they molt, they add more body segments and legs. When threatened, millipedes quickly coil their body into a spiral, protecting their legs and fragile underbody with their armor-like body plates (tergites).

If you come across a millipede, know that you’re looking at one of the earliest animals to breathe air and make the move from water to land. Pneumodesmus newmani, a fossil found in Scotland, dates back 428 million years and is the oldest fossil specimen with spiracles for breathing air.

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Poplar Hawk-moths Emerging, Mating & Laying Eggs

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June is well-known for the giant silk moths that emerge this month, but there are other large moths that are encountered as well, one of which is the Poplar Hawk-moth (Laothoe populi). Hawk-moths, also known as Hornworms (their larvae, which feed mainly on species of poplar, usually have a horn), are a type of Sphinx moth, which are known for their fast, enduring flight. One of the more familiar species of this family is the day-flying Hummingbird Hawk-moth, which can be seen hovering at flowers while sipping nectar with its proboscis.

Adult Poplar Hawk-moths, with wingspans as large as four inches, emerge in early summer. Their life is so short that they do not have a functional proboscis and do not eat, but concentrate on mating. Females extend a scent gland from the end of their abdomen to lure in the night flying males whose large claspers are frequently wide open as they fly in to lights around midnight. The moths mate and the females lay their pale green eggs on the leaves of poplars and willows, which the larvae eat once they hatch. Fully-grown caterpillars pupate and overwinter in shallow burrows in the ground.

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