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Slugs Mating

Monday’s post stated that the nature of the activity the slugs were engaged in was undetermined.  Since then it has come to my attention that had I been truly “naturally curious” and popped the bubble of slime, I would have had the rare opportunity of seeing two entwined slug penises.  Here is a descriptive quote describing slug reproduction.

Like all slugs, those in the genus Arion are hermaphrodites (possessing both male and female sex organs). They can reproduce either by self- or cross-fertilization, depending upon conditions and habitat stability. When two slugs mate with each other, they each simultaneously play the role of both sexes, exchanging sperm with their male genitalia. At times, the male sex organs of two slugs become entangled during mating and the slugs may bite them off in order to free themselves, a not uncommon sacrifice known as ‘apophallation.’ From then onward, the apophallated slugs are only able to reproduce as females. Arion subfuscus mates in the mid-to-late summer. Several days after mating, slugs will lay hundreds of 3-4 mm eggs in the soil, and die shortly thereafter. Although there is no parental care in this species, the eggs are imbued with a caustive agent called miriamin that serves in a large part to protect them from predation. In around a month, the juveniles hatch as small, pale-brown versions of their adult selves. They typically take at least 4-6 months to achieve sexual maturity, mating and dying themselves before the new generation hatches from the eggs.” (https://www.projectnoah.org/spottings/1952620518)


Slug Slime

Most of us who have encountered slugs know that if you handle one, the slime it produces on the lower surface of its body persists on your hands even when you wash them with soap and water. (If you let the slime dry and rub your hands together, it will come off in small beads.)  Slug slime contains water, mucus and salts. It keeps a slug’s skin moist, preventing it from drying out, and aids in locomotion.

Slug slime changes as the slug moves. Initially it has the consistency of a liquid gel.  It is solid at rest and turns to liquid under pressure.  A slug sticks part of its body to the ground with its slime, uses its muscles to move its body forward, and then pulls its body away from where it was stuck. More slime is released and the process is repeated.  It’s interesting to note that slugs are strong enough to move without the aid of slime, but nonetheless are always producing it.

Slug slime has its good and bad points. Scientists are studying slug slime properties in their search for a better surgical adhesive. Most substances are either flexible or sticky, not both, like slime.  On the other hand, there are some aspects of slug slime that are not all that appealing.  In addition to being next to impossible to remove from your hands, slug slime can carry rat lungworm (Angiostrongylus cantonensis), a parasitic roundworm that mainly lives in rodents such as rats and can infect slugs (and snails) that come into contact with infected rodent feces.  This disease can cause a form of meningitis which is prevalent in Southeast Asia and tropical Pacific islands.

(Photo:  Two slugs & bubble of slime. Nature of activity not determined! Thanks to Alice Trageser and Mary Landon for photo opportunity.)

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Owlet Moths Laying Eggs

One morning multiple 1”-2” white blotches appear on the screening of your porch or windows.  They weren’t there the previous day, so they had to have been deposited during the night.  What nocturnal creature is responsible and what exactly are they?

A close look reveals that each white patch consists of hundreds of minuscule white balls – eggs that an insect must have deposited.  Their size, shape and coloring indicate that they were most likely produced by Owlet Moths or noctuids, members of the Noctuidae family.  Owlet Moths make up over 25% of all butterflies and moths — there are 75,000 known species worldwide with thousands yet to be identified. Most adults are a fairly drab shade of brown and are well camouflaged with lines and spots that resemble tree bark or bird droppings. (Moth coloring often resembles the bark of the food plant its larvae prefer.) Owlet Moth larvae are relatively hairless and are referred to as cutworms or armyworms (they can occur in destructive swarms and cut the stems of plants). Several species are serious crop or garden pests.

A majority of the moths in this family are nocturnal and are attracted to light.  After mating, female Owlet Moths produce between 300 and 1,500 eggs, depending on the species.  Newly laid eggs are spherical and often cream color but may turn yellow, orange, pink, red or gray within a day. Those laid this fall will overwinter and larvae will hatch in the spring.

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Caspian Terns Migrating

Caspian Terns are the largest terns in the world, with a wingspan of up to nearly five feet.  It’s hard to miss their large orange bill, but you’re not likely to see one in most of New England except during migration. (One exception is the Lake Champlain Islands in Vermont.)  A few weeks after fledging, juvenile and adult terns gather at feeding sites near breeding areas and migrate south in stages.  They sometimes migrate individually and sometimes in families or larger groups. The last of the migrants are passing overhead in the next few weeks, heading for overwintering sites along the Atlantic and Gulf coastlines.

(Photo: The Caspian Tern flies over the water with its bill pointing down, looking for fish. When it locates its prey, it plunges into the water to capture it, sometimes submersing its entire body.)

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Eastern Gray Squirrels Preparing For Winter

Eastern Gray Squirrels (Sciurus carolinensis) eat about two pounds of food per week.  Nuts and other seeds are at the top of the list, but fungi, berries, bird eggs and nestlings, tree buds and sap are also consumed.  Because they stay active in winter, Eastern Gray Squirrels must store food in the fall in order to survive the colder months, and this food must be viable for the duration of the winter.  They are what are called “scatter-hoarders” – they bury each nut separately, not all in one spot. After digging a hole 1-2 inches deep with its front paws, the squirrel places a nut in the hole and forcibly puts it in place by pounding it into the ground with its front incisors.  It then fills the hole with soil and covers it with leaves.  A combination of memory (experiments found that this works for about 20 minutes) and after that, scent, allows squirrels to relocate a portion of their cached nuts.

Hickory nuts are the food of choice for Eastern Gray Squirrels, in part because they have twice the calories of an average acorn.  They also store well over winter, as they don’t germinate until spring.  As the accompanying photograph shows, Eastern Gray Squirrels, before burying the nuts (in this case, Shagbark Hickory, Carya ovata), methodically remove the fragrant husks, leaving a pile of small pieces of husk on the ground. It’s likely this practice developed in order to prevent competitors from smelling, digging up and consuming the squirrel’s winter food supply.

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Chirping Thermometers

The evenly-spaced chirping notes of the male Snowy Tree Cricket (Oecanthus fultoni) greet our ears nightly at this time of year.  Named for its pale color and tendency to be found in trees, vines and shrubs, this cricket is well known for its ability to convey the temperature to anyone who can count the number of chirps it makes in 14 seconds.  Add “40” to this number and you know how hot or cold the evening is in degrees Fahrenheit.  The relationship between the air temperature and the rate at which crickets chirp is called Dolbear’s Law.

Crickets make chirps (stridulate) by rubbing a structure on the top of one forewing wing (scraper) against wrinkles (file) on the underside of the other forewing.  To find a Snowy Tree Cricket that is stridulating, check the underside of branches and leaves.  A living thermometer awaits you there.

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Highbush Cranberry

The bright red fruits (and reddening leaves) of Highbush Cranberry (Viburnum opulus) are starting to appear.  Contrary to that which its name implies, this shrub is not a cranberry – it is a Viburnum, a member of the Caprifoliaceae, or Honeysuckle, family. The fruit resembles cranberries, matures in the fall like cranberries, is tart tasting, and is rich in Vitamin C like cranberries, all of which most likely contributed to its common name.

The fruit is acidic and persists through the winter.  It is more or less a “last resort” food source for birds, but those birds that do eat it prefer to do so after the fruit has been frozen and thawed, which reduces the acidic content.  People also consume the fruit in the form of jellies, jams, juice and smoothies.  A recipe for juice, from http://www.ediblewildfood.com follows:

Highbush Cranberry Juice

Ingredients

3 cups water

2 cups highbush cranberries (they can remain on the wooden umbels so long as they look healthy)

2 cups orange juice

1 tsp. maple syrup

Instructions

Bring water to boil then turn stove off. Place the berries into the water and slightly mash. Let sit 30 minutes.

After 30 minutes, thoroughly strain. Allow this cranberry liquid to thoroughly cool. Once cool, add the orange juice and maple syrup; stir. Store in fridge up to 5 days.

 

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Mink’s Cubs

One last update, as so many readers have inquired about the welfare of Mink’s three cubs.  They have been sighted several times, traveling apart from one another.  One cub has been spotted more than once, but not captured, at someone’s bird feeder.  Efforts (game cameras and bait food) are being made to lure and capture them after which they will be brought to the Kilham Bear Center in Lyme, NH where they will be fed and cared for and eventually released into the wild.

Mink’s cubs are about 8 months old and weigh between 25 and 35 pounds. Black Bear cubs typically stay with their mother until they are 18 months old, at which time they are weaned and on their own.  Cubs as young as five months old have survived the loss of their mother, so one can only hope that, if not caught and raised by humans, Mink’s cubs will be as fortunate.

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Mink Update

I wanted to update everyone on Mink, the deceased Black Bear in New Hampshire, as more information regarding her death has been released. Biologists now think she may have died of natural causes.  From the condition of her teeth they have determined that she wasn’t in her teens, as previously thought, but  between 20 and 30 years old.  That is the normal life span of a Black Bear.  Her death is still very sad, but perhaps a little easier to accept if humans were not involved.

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A Tribute To A Grande Dame

This week I learned of the death of an old acquaintance.  Mink, a Black Bear whom I’ve photographed numerous times with numerous batches of cubs, was found dead on the banks of a river in New Hampshire, close to where she had lived for many years.  If you’ve read my children’s book, Yodel the Yearling, you’ve met one of her offspring.

Mink was an extraordinary mother — sending her cubs up a giant White Pine tree whenever danger threatened, tolerating with unbelievable patience being climbed on and bitten by her cubs, grooming burs out of the coats of rambunctious offspring with her teeth and much, much more.   She was so acclimated to people (having raised many cubs within sight of houses) she allowed me to witness her nursing her cubs multiple times (see NC post, 4/4/18).

Four years ago I stumbled upon Mink and her three yearling cubs sleeping at the base of a “baby sitter” tree.  Since then they have had a life of turmoil, having been transported to the wilds of northern New Hampshire due to becoming “pests” where they lived because people left their garbage and bird feeders accessible during times of the year when bears are active. Mink managed to find her way back to her home territory and was raising the three young cubs she bore last winter when she met her untimely death, most likely as a result of being hit by a car.  I couldn’t let her passing go by without a nod to her and the richness she added to so many peoples’ lives.  I, for one, shall forever be indebted to her for tolerating my presence and allowing me to observe and photograph ursine behavior in the wild so few are privileged to see.  (Photo:  Mink & one of her three cubs, taken 4/24/20, soon after emerging from winter natal den)


Snake-birthing Video

A Naturally Curious blog follower, author and naturalist Kathie Fiveash, was kind enough to share this video in her comments on yesterday’s post.  In case you missed it, I’m sharing it now!  Thank you, Kathie!

 


Cabbage Whites Mating

Cabbage White butterflies (Pieris rapae) are seemingly common, rather ordinary and unremarkable butterflies.  That is, until you become acquainted more intimately with their reproductive idiosyncracies.  The male’s sperm, along with a nutritious snack, is contained within a package called a spermatophore. It is the size of the spermatophore that defies belief, as it makes up 13 percent of the male’s body weight.  Translated into human terms, a 150 male would possess a 20-pound package of sperm.

The male Cabbage White deposits its spermatophore into a pouch within the female’s reproductive tract and the sperm proceed to swim to a second pouch where they are used to fertilize the female’s eggs.  The female absorbs the nutrients that accompanied the sperm and uses them to make approximately half the eggs she lays.

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Eastern Garter Snakes Giving Birth

Seventy percent of the world’s snakes lay eggs and only about thirty percent give birth to live young.  Eastern Garter Snakes (Thamnophis sirtalis sirtalis) are among the latter, giving birth in August to between two and thirty-one offspring (averaging 23).  Carrying and incubating developing embryos within their body is more common for northern snakes and there is good reason for this.  Whereas eggs are subject to whatever temperature fluctuations occur where they were laid, a snake that carries her young to term within her is able to move to warm areas that are ideal incubation temperatures. This causes less stress for the developing embryos and also results in a greater number of viable young.

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Male Walkingstick Cerci

Congratulations to Sharon Weizenbaum, Beth Herr and David Ascher for correctly identifying the Mystery Photo as the tip of the abdomen of a Common Walkingstick (Diapheromera femorata), also known as Devil’s Darning Needle, Devil’s/Witch’s Riding Horse, and Prairie Alligator due to its unusual shape.  While the Common Walkingstick is a mere 3” long, the largest North American species can grow to 7” and one tropical species may reach 14”.

The Walkingstick lives up to its name – it is easily mistaken for a twig with its slender body and legs.  By remaining motionless during the day (or gently swaying in the wind like a leaf or twig would), and feeding on the leaves of various deciduous trees at night it avoids many predators with its physical and behavioral adaptations. The practice of using both camouflage and mimicry is referred to as crypsis.

Both the male and female Walkingstick possess a pair of appendages at the tip of their abdomen known as cerci.  The cerci on a female are short and straight, while those on the male are longer and curved.  They are sensory organs, but in addition, the male uses his cerci to grasp the female when mating with her (see inset).  According to entomologist Dr. Gilbert Waldbauer, the cerci are very effective, allowing the male Walkingstick to clasp the female for many hours (weeks for some species) in order to prevent another male from mating with the female.

This is the time of year you are most likely to notice Walkingsticks, as this is when they are maturing and reproducing. Females drop their eggs to the ground from the canopy and because a portion of the outside (capitulum) of each egg is edible (like the elaiosomes of many spring ephemerals), ants carry the eggs below-ground to their nests and eat the capitulum, leaving the intact eggs to hatch and develop.

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Mystery Photo

Do you think you might know what this is part of?  The two structures that look like hot dogs are approximately 1/4″ long.  If you would like to hazard a guess, go to the Naturally Curious website, scroll down to “Comments” and submit your entry.  The answered will be in Monday’s Naturally Curious post.


Praying Mantises Preying

Between being able to swivel its head nearly 180 degrees and having two large compound eyes and three simple eyes, the Praying Mantis (Mantis religiosa) misses very few insects within reach. Due to its green or brown coloration, the Praying Mantis is well camouflaged as it lies in ambush or stalks its prey.  Spines, tooth-like tubercles and a claw near the tip of each foreleg enable this predator to have a secure grasp on the moths, crickets, grasshoppers, flies, and other insects it consumes.  (A Praying Mantis in Pennsylvania was photographed successfully capturing a Ruby-throated Hummingbird.)

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Milkweed Leaf Beetle Survival Mechanism

Many insects use splashy colors and color patterns to defend against being eaten.  (This practice is called “aposematism” from the Greek for “away” and “sign.”) If you spend time in a milkweed patch, you’ll notice that several of the insects you see have bright orange and black coloration.  Milkweed contains defensive chemicals known as cardiac glycosides and Monarchs as well as several other insects (many of which are black and orange) that feed on milkweed can tolerate them and store these chemicals as a defense. When avian predators consume a Monarch butterfly containing these chemicals, a bird suffers digestive upset.

Once a bird has gotten sick after eating a poisonous black and orange insect such as a Monarch, it tends to avoid any and all insects with similar coloration, regardless of their toxicity or lack of it.  Milkweed Leaf Beetle larvae and adults do not absorb the cardiac glycosides in milkweed like a Monarch, so they have no toxic compounds in them and will not poison a predator.  Insect-eating birds don’t know this, however, and the beetles successfully deter predation through their coloration.

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Green Herons’ Versatile Necks

Most of the time Green Herons appear to be stout, compact herons.  When perched or stalking, they tuck their neck into the contours of their body and appear quite small (see inset).  Only when threatened or when striking prey is the true length of a Green Heron’s neck revealed.  If startled, a Green Heron will stretch its neck way out, most likely in order to appear large and formidable to a potential predator.  When hunting for prey, it can extend its neck an inordinate distance (see photo). A specialized vertebra in their neck enables them to strike at prey with a tremendous amount of force.  Some scientists compare the Green Heron’s extendible neck to that of certain dinosaurs, from which they are thought to have evolved.

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White-blotched Heterocampa Caterpillars On The Move

It’s hard to believe, but this fuschia-colored caterpillar is going to emerge from its cocoon next spring as a relatively dull black and white moth called the White-blotched Heterocampa (Heterocampa umbrata).  These caterpillars have two shiny knobs behind their head which are the remnants of “antlers” that the caterpillars have during their first instar. White-blotched Heterocampa larvae change color as they mature and develop.  At any given stage, a caterpillar could be purple and fuchsia, or brown and tan or green and white; it is not unusual for them to be mistaken for three different species.  The caterpillars can be found feeding on oak leaves.  Look for the adult woodland moths at night, when they are attracted to lights.  (Thanks to Lily Piper Brown who found two of these amazing caterpillars recently, and her mother, Sadie Brown, who photographed this one.)

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Ruby-throated Hummingbirds Pollinating Cardinal Flower

Cardinal Flowers are to Ruby-throated Hummingbirds what Goldenrod is to Honey Bees in the fall —  an important source of nutrients just when it’s needed most.  Just as hummingbirds are preparing for their migration south and nearly doubling their weight (from about 3.25 grams to 6 grams) before crossing the Gulf of Mexico, Cardinal Flower blossoms. A single migration can mean a nonstop flight of up to 500 miles over a period of 18 to 22 hours and nectar such as they obtain from Cardinal Flower helps sustain them.  This relationship is not one-sided however – it is mutually beneficial for both the bird and the plant.  In acquiring nectar from the blossoms of Cardinal Flower, hummingbirds inadvertently perform a crucial task, that of pollinating many of the flowers they visit.

The blossoms of Cardinal Flower have two phases.  In one the male reproductive part of the flower (the white “moustache” you see above the petals) matures and produces pollen.  After the male structure matures and disappears, the female reproductive part develops and extends out from the same place where the male flower was.  The flower parts mature at different times in different flowers on a given stalk, so both male and female flowers are present on the same plant at the same time.  In order to reach the nectar from Cardinal Flower, a hummingbird must get into a position where the top of its head brushes against the flower’s reproductive parts.  If the flower is in the male phase the hummingbird’s head gets dusted with pollen (see inset).  If the flower it visits is in the female phase, the pollen on its head (from previous visits to male flowers) is deposited on the stigma of a female flower, pollinating the flower.

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Luna Moth Caterpillars

The large, green swallow-tailed moth known as the Luna Moth (Actias luna) is familiar to many.  Its short life of about a week begins in June when it emerges from its cocoon, mates, lays eggs and then dies. The larval stage of this giant silk moth is not as well known, but has just as striking an appearance as the adult moth.  It is an unforgettable lime-green with tiny magenta spots along its length.

When threatened by a predator, Luna Moth caterpillars have several defensive behaviors, including emitting clicks as a warning and regurgitating the contents of their intestine, both of which have proved to be effective deterrents.  Look for these caterpillars on their host trees which include birch, hickory and walnut.  (Thanks to Susan and Dean Greenberg for photo op.)

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Juvenile Common Loons Molting For A Second Time

When Common Loon chicks first hatch, they are covered with down and look like sooty black puffballs.  These feathers are pushed out when the loons are 10 to 14 days old by a second plumage of brownish-gray down feathers.  When the young are about a month old, these feathers start to be replaced by juvenal contour feathers. By the time the young loons are 10 or 11 weeks old, their down feathers are mostly gone and their juvenal plumage is nearly complete. This plumage is very similar to the winter plumage of adult loons. You can tell the difference between the two by the whitish-gray tips of the juveniles’ feathers, which the adults lack.  (Pictured juvenile loon is about seven weeks old, showing remnants of the second down plumage.)

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Mystery Photo: Bald Eagle or Osprey Pellet

 

Congratulations to Jill Osgood (“osgoodjill”), the first reader to correctly identify the pellet of either a Bald Eagle or an Osprey.  Many people are familiar with bird pellets – lumps of material consisting of the indigestible parts of a bird’s diet which are regurgitated by the bird hours after they’ve eaten their prey.  Raptors often consume their prey whole, including parts that are not easily digestible such as fur, feathers, bones, teeth, nails, etc.  These parts get as far as the proventriculus, an organ located between the esophagus and the gizzard, where they are packed into a pellet.

We often associate pellets with owls, but many species of birds, in addition to owls and other birds of prey, form pellets.  They include grebes, herons, cormorants, gulls, terns, kingfishers, crows, jays, dippers, shrikes, swallows, and most shorebirds.  The size of the Mystery Photo pellet (3” long) indicates that the bird that regurgitated it was very large – in general, the larger the bird, the larger the pellet.  It was found near the shore of Lake Champlain, where Ospreys and Bald Eagles are not uncommon.

If I had to, I would guess the pellet was regurgitated by a Bald Eagle. Osprey are piscivores, eating primarily fish, and bald eagles are carnivores, eating a variety of fish, mammals and amphibians. A close look at the pellet reveals, in addition to fur and fish scales, the upper mandible of a very small rodent on the left hand end of the pellet.  An Osprey’s pellets consist of primarily scales and bones, whereas a Bald Eagle’s pellets are composed primarily of hair (its stomach acid breaks down the bones and scales).

Twelve to eighteen hours after consuming prey, a Bald Eagle casts a pellet. Relatively odorless and light-weight, these pelleted remains can reveal the varied diet of this raptor.

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Mystery Photo

If you think you recognize the subject of this Mystery Photo, please go to the Naturally Curious blog, scroll down to “Comments” and enter your thoughts.  Size:  3” x 1 ½”.  Hint:  found near a large body of water. (Discovered and submitted by Jody Crosby)

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