An insect’s view of the world

Motionless, a dragonfly perches on a twig seemingly watching every movement I make without a twist of its head. No pupils follow my movement, no movement at all. 

Dragonflies can see objects up to 30 feet away and detect movement nearly 60 feet away

While I can see the fine details on the dragonfly, the dragonfly’s view of me is completely different. Unlike cartoon depictions of an insect’s view of the world as looking through a kaleidoscope, most insects see a very grainy view of the world--like an extremely pixelated photo. 

Most insects have two compound eyes allowing them a greater field of vision than vertebrates. Dragonflies can see in every direction except for the blind spot created by their body.

Compound eyes are composed of multiple facets, or ommatidia. Each ommatidia has a narrow field of view, approximately 20 degrees. Compound eyes differ from vertebrate eyes in that they have one lens for each photoreceptor while vertebrate eyes have one lens for all the photoreceptors.

The lens opening on each ommatidia focuses light onto the photoreceptive nerve cell at its base, which then sends a signal to the brain to process. Nearly 80 percent of a dragonfly’s brain is reserved for analyzing what it sees. 

Grasshoppers have five eyes-- two large compound eyes and three smaller eyes 

Dragonflies possess one of the largest concentrations of ommatidia in the insect world--over 25,000 in each eye. Most insects possess between 3,000 to 9,000 ommatidia. Butterflies have 12,000 to 17,000 ommatidia but worker ants have as few as six ommatidia. 

Within the hemisphere of the compound eye, the ommatidia are packed in a hexagonal pattern, similar to honeycomb. The more ommatidia an insect possesses, the higher the resolution of the image produced. 

Day-time moths and butterflies have excellent vision and can detect movement, a wide range of colors and can see in the ultraviolet range of the spectrum. They have poor vision on the red end of the spectrum though. 

The simple eyes on the back of butterflies' heads are often hidden

Bees use the ultraviolet spectrum to find flowers with lots of pollen and butterflies use the ultraviolet spectrum to find a mate.

Some insects cannot focus an image like vertebrates but can detect movement in ways superior to other animals. A dragonfly can detect movement up to 60 feet away. 

While people view a movie as constant motion, dragonflies and bees can process the movement quick enough to see the still images creating the movie. 

The large eyes of a praying mantis are very sensitive to movement and their forward facing eyes allow for binocular vision, enabling them to accurately judge distance to capture prey.

The forward facing eyes of the praying mantis enable it to judge distances

Insects relying on hunting typically have larger, more efficient eyes, such as praying mantis and dragonflies, than plant-eating insects. Insects that rely on vision to find mates also have larger eyes, such as fireflies. Male mayflies have specially adapted dorsal regions on their eyes that face upwards, allowing them to have a higher sensitivity to movement above them--where the females are flying. 

Not only do some insects have compound eyes, they also have their own type of simple eyes. Both grasshoppers and honeybees have five eyes-- two large compound eyes and three simple eyes. The simple eyes, called ocelli, are smaller and usually between the antennas or on the back of the head. Researchers believe they are used to detect light levels. 

Whether two, three or five eyes, an insect’s view of the world is completely different than ours in terms of clarity, but they can detect movement more efficiently without the slightest movement of their head. 

Note: Published in the Bonners Ferry Herald on Sept. 26, 2013.

Alpine larch usher in autumn in the high country

As autumn begins, a golden color will highlight timberline as alpine larch turn from a light green to a golden yellow. Turning color and losing its needles a month earlier than lower elevation western larch, the alpine larch ushers in autumn in the high country.

Alpine larch eke out a living in sites too cold, too rocky, too boggy or too snow-covered for other trees, such as subalpine fir, whitebark pine and Engelmann spruce. Other high-elevation trees have a broader distribution than alpine larch, which only exists above 5,000 feet elevation in portions of the Rocky Mountains and Cascade Range. 

Alpine larch in late autumn

Within the Cascades, alpine larch grow in a 120-mile north-south stretch and in the Rockies, its distribution is limited to a 430-mile stretch between central Idaho and just north of Lake Louise, British Columbia.

The rugged terrain the alpine larch exists in makes the often park-like groves of golden-yellow trees a sight to remember. Being a deciduous conifer helps the tree withstand the extreme conditions that prevail at high elevations. Without any needles in the winter, hurricane-force winds have less surface area to pummel and for snow to collect on. 

A deep root system anchors alpine larch in rock crevices to help them withstand the winds and snow. Young saplings concentrate growth on roots before extending upwards significantly. An eight- to sixteen-inch tree, which may be 16-25 years old, can have a taproot 16 to 24 inches deep. Growth during the first 20-25 years is focused on the root system because a short trunk is protected by the snowpack.

Rarely does one find an uprooted alpine larch blown over by gale-force winds, but will instead find trunks snapped off and exposing the hollow, rotten inside of old trees. 

Dense wood helps alpine larch endure the strong winds and avalanches that batter the high country. Before a tree reaches five inches in diameter and twenty feet tall, it can withstand being flattened in annual snowslides before straightening again in the summer. Once larger, the strong trunk and lack of foliage makes the tree resistant to breakage in snowslides.

Growth in avalanche chutes is common and helps stabilize snow loads and reduces the severity of avalanches. 

The lower reaches of avalanche chutes can be one place where alpine larch extend down to the uppermost reaches of western larch. Several features distinguish the two larches.

Alpine larch exhibit long, spreading limbs that form a broad crown, whereas western larch have a narrow crown. 

The first hint of autumn in the high country

Upon close inspection, the new twigs and buds of alpine larch are covered in woolly hairs, whereas new twigs of western larch appear smooth. The needles of alpine larch grow in clusters of 30-40 whereas those of western larch grown in clusters of 15-30. Needles of both larch grow singularly on the first year’s growth.

The needles of alpine larch are square in cross-section while those of western larch are triangular in cross-section. 

While western larch attain greater heights, alpine larch can attain sizable proportions for the rough terrain in which it survives. In sheltered basins, mature alpine larch can attain heights of 95 feet when 500-700 years old. The tallest alpine larch exists in the Cabinet Range of Montana at an impressive 152 feet.

Whether short or tall, alpine larch survive in the cold, snowy high country and host a golden finale in autumn that is not to be missed.

Note: Published in the Bonners Ferry Herald on Sept. 19, 2013.

Don’t be surprised by songbird swimming in mountain streams

Standing on an almost-submerged rock in the mountain stream, the chunky gray bird waded into the fast-flowing water and stuck its head underwater. Snorkeling, the bird made its way to another rock downstream. 

As North America’s only aquatic songbird, the American Dipper has filled a niche left open by other songbirds. While most songbirds stop at the water’s edge, the dipper capitalizes on the aquatic insects within mountain streams. 

The dipper can skim the water for insects or search underwater, even turning over small stones, to find food. They also easily catch insects in mid-air. Dippers forage for aquatic larvae of mayflies, mosquitoes and caddisflies, along with dragonflies, worms, small fish, fish eggs and tadpoles. During insect hatches, they often fly just above the water’s surface to catch the swarming insects.

American dippers look like a cross between a thrush and a wren

Many adaptations allow the dipper to thrive in cold, swift streams. Nostril flaps prevent water from entering the nasal passages when snorkeling or swimming. A third eyelid acts as a windshield wiper when underwater--they can remain submerged for 15 to 30 seconds. With a high amount of hemoglobin in their blood, dippers possess the greatest oxygen capacity of any songbird.

Dippers counteract their natural buoyancy by “flying” underwater with powerful strokes from their short wings and paddling with their feet. They also use their strong toes to grasp rocks below and above water.

A dense coat of feathers insulates the dipper from the cold water year round. On average, a dipper has 4,200 feathers compared to a robin’s 3,000 feathers. A thick layer of down feathers is protected by a dense layer of waterproofed contour feathers. 

Dippers maintain the waterproofing by preening extensively to spread the waterproofing oils over all their feathers. Compared to other songbirds, the preen gland containing the waterproofing oils is 10 times larger for dippers. 

The waterproof oil and thick down coat are essential to a bird that doesn’t migrate south for the winter. Instead, the dipper seeks patches of open water to forage, whether a hole in the ice near rapids or where two streams meet. With an efficient internal system of thermoregulation, the dipper survives winter as far north as the Brooks Range in Alaska.

Even above the babbling sound of mountain streams, the dipper can be heard singing its sweet, bell-tone. Both males and females can sing for 10 minutes straight. 

American dippers are North America's only aquatic songbird

As the name implies, the dipper is also known for its habit of dipping or bobbing while perched on a rock or ledge. The reason for this behavior is unknown but scientists think the behavior may help in visual communication, predator concealment or in spotting prey. 

The gray dipper blends in well with the earthen-tone rocks of the streams and it creates a nest even more camouflaged. The volleyball-sized nest is covered in an outer shell of moss. Unlike other songbirds who build an open-cup nest, the dipper builds an enclosed ball with a side opening to prevent stream-side water spray from entering the nest. 

The nests are built on cliff ledges, caves in boulder piles, dams and bridges. The life-long pair returns to the same nest every year. After nesting is completed, the pair removes the dried grass lining of the nest in preparation for the next brood. 

When leaving the nest, the fledgings readily swim to begin their lives among the rocky boulders of mountain streams where competition is scarce.

Note: Published in the Bonners Ferry Herald on Sept. 12, 2013.

Benchmarks lay the foundation for maps

“Where am I?” “How high am I?” These questions are easy to answer today with a GPS. People have always wondered where in the world they were located. Where is Bonners Ferry in relation to New York City? 

The National Geodetic Survey (NGS) was established in 1807 to provide the framework for all positioning activities in the nation, including latitude, longitude and elevation. Without knowing the latitude and longitude of a location, no relationship could be established between faraway places except for a general direction. 

The benchmark on Parker Peak was placed in 1924 with no trails to the peak

Beginning in 1833, the NGS placed the first survey disc north of New York City. Today, these discs are found on mountaintops, bridges, post offices and prominent landmarks across the nation. Numerous peaks around the county bear a small metal disc with an identifier and other information. 

Benchmark is the generic term for all geodetic control points. There are two main types of benchmarks: vertical control points and horizontal control points.

Vertical control points, as the name suggests, marks a precise elevation above sea level. Vertical control points are true bench marks with the word “BENCH MARK” printed on the rim of the disc. 

Horizontal control points mark a precise latitude and longitude. Professionals refer to horizontal control points as stations or marks. 

Besides metal discs, benchmarks can be a bolt, rivet, chiseled square or cross, or prominent landmark, such as a church spire or water tower. Each benchmark is linked to an identifier and a datasheet describing the location. 

Not all metal discs represent a precise elevation, longitude or latitude. Some discs contain arrows, RM or AZ and these discs help surveyors locate the bench marks, stations or land boundaries.

This benchmark references the Goat Mountain Lookout which no longer exists.

Benchmarks were primarily placed by two sources: the NGS and the U.S. Geological Survey (USGS). Between 1878 and 1970, the NGS was called the U.S. Coast and Geodetic Survey. 

Over 730,000 benchmarks exist in the United States (including Alaska and Hawaii) with precise elevations or coordinates. However, many more exist because of the USGS. The USGS placed thousands of benchmarks to assist them in creating topographic maps. However, they are not in the NGS database because they were not “bluebooked”, meaning they did not undergo a process that ensures the disc meet minimum geodetic quality requirements.

Those with GPS units may find disparities between the elevation on the GPS and the elevation printed on the map. This difference may lead to the question, “How high is the summit?”

NGS suggests that traditional leveling techniques are more accurate than GPS databases. However, differences in elevation occur over time due to inaccuracies, new surveys and tectonic movements.

Surveying across an entire mountain range and beginning with an inch discrepancy can lead to slight inaccuracies in the end.

Many benchmarks offer the finder a commanding view of the surrounding country

One of the reasons for the difference between the true elevation and the elevation stated on a map is the original reference point. Originally, all elevations were based on NGVD 29, a reference based on mean sea level (an average from several locations). Later, elevations were based on NAVD 88, one sea level measurement at the St. Lawrence Seaway. Many maps have not been updated to reflect the switch to NAVD 88, which resulted in a several foot difference in some locations. 

Lastly, the Earth is in constant flux with mountain ranges lifting up or eroding down as tectonic plates move. Mt. Borah, Idaho’s highest peak, gained seven feet of elevation in 1983 when a 7.3 magnitude earthquake shook the land. 

The question of “how high am I?” can change in an instant but for the most part the early surveyors used techniques that provided accurate positions. Surveyors ranged across the countryside without the help of today’s trails or helicopters to satisfy their curiosity of “Where am I?”

Published in the Bonners Ferry Herald on Sept. 5, 2013.