Nocturnal animals specially adapted to life in the dark

Walking in the dark heightens our senses and imagination. The rustle of leaves at the edge of the clearing sounds like a bear or moose but really a mouse is scampering across the dry leaves. 

Accustomed to daylight, we heavily depend on our vision to determine what is happening in our surroundings. Once darkness falls, our vision is limited to that of a headlamp or the outlines created by the light of the moon. 

Snow reflecting moonlight and tracks left in the snow help us see what animals are active at night

Animals active at night depend on more than their vision to know what is happening in their surroundings. Nocturnal animals have at least one highly-developed sense. Special adaptations include big ears, large eyes, sensitive whiskers and keen noses.

Bats use echolocation (sound waves) to determine where prey is located and to navigate in the darkness. Raccoons have extremely sensitive fingers that help them locate crayfish and other invertebrates beneath stones in shallow water at night. Great gray owls can hear a vole tunneling through snow up to 60 feet away with their offset ears. Snakes can sense minute changes in temperature. 

More animals than we think are active at night--we just aren’t outside to see or hear them. Nearly half of all living vertebrates are nocturnal, including coyotes, mink, beaver, deer, river otters and wolves. In late winter, owls can be heard calling at dusk and in the spring and fall, some waterfowl call to each other as they migrate through the moonlit sky. 

People need artificial light, like a campfire, to distinguish objects in the dark on a moonless night

Being active at night is no safer than being active during the day. While prey can hide under the cover of darkness, their predators have developed keen senses to seek them out.

A mouse may hunker down during the day to remain out of sight of a hawk, which can still see the ultraviolet glow of the mouse’s urine in its trails. But at night the hawk’s domain becomes the owl’s domain and the mouse is no safer than during the day.

Nocturnal hunters have the advantage of not competing with diurnal (day-time) predators over the same resources. Swallows perform aerobatic maneuvers to catch flying insects during the day while bats rely on echolocation to capture night-time flyers. 

Many nocturnal animals still rely on sight to function at night but their vision isn’t the same as diurnal animals. The eyes of nocturnal animals contain higher concentrations of rod cells in the retinas to allow the creation of images in low light. However, the image is not as clear as those created by a higher concentration of cone cells in the eyes of diurnal animals. 

Nocturnal animals, such as owls and flying squirrels, tend to have larger eyes to capture more light. An owl’s eyes are so large they cannot move in the socket and take up half of the owl’s skull. 

To aid in creating images at night, some animals have a layer of reflective cells (called the tapetum lucidum) behind their retina that reflects back photons of light not captured by the rod or cone cells the first time through the eye. The reflective tapetum lucidum creates the eye shine we see when our headlights or headlamps shine in a nocturnal animal’s eyes. 

The body behind the eye shine can be difficult to identify unless a light illuminates it. In this case, car headlights eventually illuminated a black bear.

The glowing pair of eyes staring back from the darkness of night could be as benign as a flying squirrel or porcupine, dangerous as an armed skunk, or as spine-tingling as the determined eyes of a cougar hunting for its next meal. 

Note: Published in the Bonners Ferry Herald on Oct. 31, 2013.

Can woolly bear caterpillars predict winter weather?

What will winter be like? Many look to the woolly (wooly) bear caterpillar for a prediction. The black and orangish-brown banded caterpillars may be the most widely recognized creature for predicting winter. 

According to folklore, if the woolly bear caterpillar has more black area than orangish-brown then the winter is going to be long, snowy and cold. If the caterpillar possesses more orangish-brown area then the winter is going to be mild. 

Woolly bear caterpillars curl up in a ball to protect their soft underparts. Striped skunks are the only animal patient enough to pluck each bristle off in order to eat the caterpillar.

Many factors determine the coloring of the woolly bear caterpillar and one of the most influential is how last winter ended. To better understand the woolly bear caterpillar’s coloring, we have to look at its life cycle.

Woolly bear caterpillars, like most insects, progress through four stages in their life: egg, larva, pupa and adult. In autumn when woolly bear caterpillars are seen the most frequently on roads and sidewalks, they are nearing the end of their larval stage as a caterpillar. 

The caterpillars seek out shelter in winter hibernacula under leaves, in rock crevices and under bark. When temperatures increase in the spring to a certain point, the woolly bear caterpillars emerge from their hibernacula and briefly eat before spinning a cocoon to pupate. 

The cocoon is fashioned from the bristles (called setae) of the woolly bear caterpillar--which aren’t woolly feeling at all-- and are held together by silk. After one to two weeks a dull, orange-yellow Isabella tiger moth emerges. The two-inch wingspan is speckled with small black spots.

Caterpillars are the only stage at which the insect has chewing mouthparts. So the main purpose of the moth is to mate and lay eggs (if female). Once the eggs hatch (five to twelve days), the larval (caterpillar) stage begins again. 

As the woolly bear caterpillar eats vegetation, such as dandelions, birch, clover and maples, its skin becomes tight. The caterpillar’s growth is limited by its exoskeleton which can’t increase in size. Therefore, the woolly bear caterpillar molts up to six times before maturity. 

Before each molt, a new, larger skin grows underneath the current exoskeleton. When ready, the woolly bear sheds the older, outer skin. With each new molt, an additional orangish-brown segment is added to the exoskeleton. Therefore, younger woolly bear caterpillars have a shorter orangish-brown band than older caterpillars. 

If the spring was mild and the caterpillars had a chance to emerge early, the new caterpillars of the year have more time to grow. With a long growing season, the woolly bear caterpillar would have a longer orangish-brown segment than if it was an late spring or early fall.

In reality, the orangish-brown segment on the woolly bear caterpillar indicates whether the last winter was long or short. 

Another factor influencing the segments on the woolly bear is rain. If the caterpillar endures wetter weather, more black setae are produced.

Whether last year’s winter corresponds to the upcoming winter is anybody’s guess. But informal research since the 1940’s has determined that the folklore of the woolly bear caterpillar’s coloring has been right 70 percent of the time.

Note: Published in the Bonners Ferry Herald on Oct. 24, 2013.

Juniper species grow in tree and shrub form

Nestled on a rocky site north of the Arctic Circle in Alaska, a juniper bush seems out of place. Could it be the same species I’ve seen in North Idaho and the deserts of the Southwest? Despite the dramatic difference in latitude, the common juniper thrives across most of North America. The common juniper ranges from Alaska south to California and east to Newfoundland and the east coast.

The common juniper is one of over a dozen species of juniper native to North America and one of two found in North Idaho. The other juniper species found in North Idaho is the Rocky Mountain juniper. 

Common juniper typically don't grow more than a few feet high

As the name implies, the Rocky Mountain juniper ranges from British Columbia south to Arizona and New Mexico, east into western Nebraska and the Dakotas, and west into Nevada and east central Washington. 

The two juniper are easy to tell apart, one is a tree and the other a low-growing shrub. Rocky Mountain juniper grow upwards of 30-45 feet, often with a round shape to the tree. Common juniper rarely grow more than five feet high in a mat-like shrub. 

Rocky Mountain juniper (far left) grow in a tree form

Upon close inspection, differences can be found in the needles. Rocky Mountain juniper have tiny, scale-like needles on the mature plants and prickly, half-inch long, awl-like needles on juvenile plants.

The needle-like leaves of common juniper are arranged in whorls of three on twigs while those of Rocky Mountain juniper grow opposite in pairs on twigs.

One similarity between the junipers is the cones, which are often referred to as berries. As a conifer, junipers grow cones but they resemble a berry. The berry-like cones are fleshy with remnants of cone scales etched on their surface.

The blue fleshy covering aids in the dispersal of seeds with over 30 birds consuming the juniper berries. Birds are critical to the germination of seeds because juniper seeds don’t germinate unless the fleshy covering is dissolved, which happens when the berries pass through the digestive tract of birds or animals.

Juniper berries are an important food source for many birds because they persist on the plant through the winter, offering food in early spring. Bohemian waxwings can consume over 900 juniper berries in an hour. Other birds that consume juniper berries include juncos, yellow-rumped warblers, cedar waxwings, purple finches,  black-capped chickadees, evening grosbeaks, flickers, bluebirds, wild turkeys, swallows, eastern kingbirds and jays. 

Juniper berries persist on the plant after ripening, offering a food source in winter

Male and female cones grow on separate plants so some plants never produce berries. The female berry-like cones mature the second season and require another year after ripening to be prime for germination. 

Not only do junipers provide an excellent food source but they also provide shelter among their pointed needles. Chipping sparrows, robins, song sparrows and mockingbirds build nests in juniper. 

The wide-ranging distribution of juniper can be attributed to their ability to grow on dry, rocky sites. Rocky Mountain juniper only require ten inches of precipitation a year to survive. 

Juniper adapted to inhospitably dry environments because they couldn’t compete with other forest trees. While shade tolerant when young, juniper become shade intolerant as they mature. 

The ability to grow where other trees cannot has enabled juniper, especially the common juniper, to range far and wide across North America for a long time. The oldest Rocky Mountain juniper, near Logan, Utah, is estimated to be 3,000 years old. 

Note: Published in the Bonners Ferry Herald on Oct. 17, 2013.

A train ride on the other side of the Selkirk Mountains

Chug-a-chug-a-choo-choo. The train began to roll out of the Ione, Washington station on a beautiful October day on a short trip to Metaline Falls. Through the rolling countryside and next to the Pend Oreille River, the Pend Oreille Valley Railroad train chugged. 

The North Pend Oreille Valley Lions Club train prepares to leave the Ione, Washington station

Glimpses of the river could be seen through the trees beginning to show their brilliant shades of autumn. A brief stop on the Box Canyon trestle bridge showed the full width of the Pend Oreille River. On the upstream side, nature’s forces had carved the steep walls of Box Canyon. On the downstream side, Box Canyon dam captures the water’s power to create electricity.

Box Canyon dam was built between rocky islands in the Pend Oreille River and completed in 1956

Seen from the Box Canyon trestle bridge, the Pend Oreille River flows north into Canada to join the Columbia River (the Kootenai River in Idaho does the same)

The Box Canyon trestle bridge and the railroad were completed in 1910

As the train chugged onward, the forest closed in around the railroad until closer to Metaline Falls where the forest gave way to pastures and homesteads. Two tunnels shortened the route for workers building the railroad in 1910. 

The train consists of three classic railroad coaches, three open-air coaches, one caboose and an engine

At Metaline Falls, the engine reconnected to the rear end of the train and pulled it back to Ione. The 90-minute, 20-mile round trip was a novelty for the riders awed by the beauty of the Pend Oreille Valley but for the original riders and railroad engineers, the railroad was a necessity--a means of transportation of people and goods. Apple trees along the route are a reminder of the apple cores railroad workers and passengers discarded along the tracks.

During the winter, train cars are kept under the silos of the Inland Portland Cement Plant in Metaline Falls

The engine reconnects to the rear of the train in Metaline Falls to make the return trip to Ione

The Port of Pend Oreille was created to operate the Pend Oreille Valley Railroad in 1979 after the railroad was deemed no longer economically feasible by private businesses

For more information on the train ride hosted by the North Pend Oreille Valley Lions Club through October, visit www.lionstrainrides.com.

Note: Published in the Bonners Ferry Herald on October 10, 2013.

Blue jays expanding their range into the northwest

A piercing “jay jay jay” call came from the yard. Could it be? Not hearing the familiar bird call since growing up in Minnesota, I wouldn’t believe I heard a blue jay until I saw it.

I stepped outside and looked into the yard, noticing movement in the nut tree near the porch. An unripe nut fell onto the ground and a blue jay quickly flew down to retrieve it. After the blue jay picked up the nut, it flew across the yard. The familiar blue and white bird from my childhood was in my yard even though the bird book showed the western edge of their range ending on the east side of the Rocky Mountains from Texas into Canada. 

A blue jay stashing nuts for winter 

For the last 20 years, birders have reported blue jay sightings in Idaho, Oregon, Washington and Utah. Some years only a few blue jays are reported in Idaho, other years dozens are reported. In Boundary County, records dating back to 2007 record sightings except for 2008. 

The blue jay’s striking coloring is familiar to anyone living or visiting the east and Midwest. Unlike resident Steller’s Jays which are blue and black, the blue jay’s belly and face are whitish and the back, crest and tail are blue. The blue wings and tail are barred with black and a black bridle crosses the face, nape and throat. White also speckles the wings and corners of the tail.

Steller's Jay

As in my experience, blue jays are often heard before they are seen. They make noisy calls outside of nesting season and make quite a racket if they see a bird of prey (such as a hawk or owl).

Back east, they are common in urban and suburban areas because of habitat and food. Blue jays prefer forest edges instead of pure conifer stands and deep forests. 

Blue jays feed on nuts, grains, seeds, fruits and berries, such as elderberries, cherries and dogwood. They will also eat caterpillars (even tent caterpillars), grasshoppers, frogs, beetles and other insects. Despite their omnivorous diet, blue jays tend to eat three times more vegetable matter than animal matter. To eat nuts, blue jays will hold the nut with their feet while perched on a branch and then crack the nut open with its bill.

As I witnessed, blue jays harvest and store nuts for later use, which helps spread trees when they forget where they stashed the nuts--they may only retrieve a quarter of the nuts they stash. Particularly fond of acorns, blue jays have helped spread oak trees across the east. Compared to squirrels, which typically carry nuts a few hundred feet, blue jays will stash nuts over a mile away from the source. 

Blue jays frequent bird feeders and the scattered remains on the snow in the winter

Blue jays also love peanuts and readily snatch them from bird feeders. Blue jays aren’t bashful about eating sunflower seeds and suet from feeders either as long as there is a perch. 

Nuts and seeds provide enough food for blue jays to survive the winter, though some populations migrate south. One bird identification book recognizes a wintering population in southern Idaho.

Researchers suggest bird feeders, urbanization and an increasing population have attributed to the blue jay expanding its range to the northwest. The exact number of blue jays in Idaho is uncertain, but at least two live in Boundary County because both noisy blue jays were calling as they were harvesting the nuts in my yard.

Note: Published in the Bonners Ferry Herald on Oct. 3, 2013.