Nature Watch: Above it All

About the author: Steve Ellis is a naturalist and Land Trust member who enjoys sharing his love of the natural world. His blog series, “Nature Watch,” will appear each month in “Habitchat,” chronicling native plants and wildlife you can expect to see during that particular time of year. We thank Steve for sharing his passion, illustrating the importance of island conservation.

Overview

Few people have been to the bottom of the Salish Sea. Rarer still are the numbers who’ve spent time in the forest crown. Virtually no one has firsthand experience above it all.

The air above the treetops teems with a wide variety of life. Many of these organisms on high are at the whim of the air currents as they lack the ability to change direction on their own.

Aeroplankton is the name given to the organisms caught up in the air. Like marine plankton, they are the building blocks of airborne life.  Fungi spores, bacteria, pollen and tiny insects make up a good portion of aeroplankton. In addition, algae, moss and liverworts spend part of their lives drifting with the aeroplankton biomass.

Many of the small insects in the air were borne aloft by wind gusts. Others fly there with the intention of consuming pollen and other aeroplankton components. They in turn may fall prey to various predatory insects, with dragonflies being at the top of the invertebrate food chain.

We earthbound creatures cannot detect aeroplankton, but we can watch the ultimate sky predators – birds and bats.

Several species of swallows and flycatchers zip back and forth during daylight hours, capturing beetles, leafhoppers and other flying insects.  Next month, they will be joined by the much larger Common Nighthawks.

Bats work the night shift with most species active at dusk and before dawn. The highest-flying bats over our islands are probably big browns.  Their main prey items are beetles on the wing. Big brown bats have the ability to bite through the tough carapaces of beetles.

Some butterfly and dragonfly species use the open air to migrate. Spiderlings shoot out gossamer to hitch a ride in order to disperse; aided partly by the earth’s electric field, they can soar to great heights, contributing to aeroplankton.

Birds are masters at using the air for migrating, hunting and courtship. For Common Ravens, the sky is a playground where they invent tricky flight maneuvers for their enjoyment.

A warm sunny day in mid to late April is perfect for studying the flights of Tree and Violet-green Swallows, our local summertime species who are the apex of life above it all.

Pine pollen in the air by Martha Ellis.

Flora: Pollen

For those of us with allergies, March and April usher in the sneezing season.

Pollen originates from male blooms. For trees and shrubs, pollen is contained in blossoms or catkins. Woody plants generally specialize in either airborne pollen or  they have a reliance on animals to transmit it to female flowers. A few species – bigleaf maple, for example – have it both ways.

A third method of pollen distribution is accomplished by eelgrass and others that depend on water currents to propel their pollen.

Generally those flora species with inconspicuous blooms have airborne pollen. Strong winds can blow pollen for many miles.

Showy blossoms or those with sweet scents attract an array of pollinators, including bees, beetles, hoverflies, butterflies and hummingbirds.  Bumblebees should get the credit for much of the animal-based pollination.

Many insects eat pollen, especially ants, beetles and bees. These in turn are preyed on by larger insects and many bird species.

Willows and red alders are the first trees to bloom with alders beginning pollen release in mid-February. Willow catkins can be seen bravely blooming in January. Conifers tend to bloom in March and April, with the latter having the heaviest pollen release. This coincides with reliable winds, something not always encountered in mid-summer. Often, cars and decks are covered in yellow pollen in April, a result of Douglas-fir releases.

Bigleaf maples hedge their bets by waiting for bees but also take advantage of breezes for the distribution of their pollen.

Most showy-flowered plants wait for warm weather and the advent of bees. Here too, bumblebees are the workhorses because they fly in colder conditions than other pollinators.

Plants on the forest floor are buffered from winds so they must wait for the appearance of hoverflies and bees.

Another big wave of pollen comes from grasses in July and August. Grass pollen is dry and smaller than tree pollen and need very little wind to boost it aloft. It makes for a second pollen allergy season.

Much of life relies on pollen and its distributors. It, along with spores of fungi and ferns, helps make land-based life possible.

Violet-green swallow by Martha Ellis.

Fauna: Violet-green Swallow (Tachycineta thalassina)

The return of Violet-green Swallows to our islands is always a happy event. Their dapper appearance and delightful calls brighten our April days.

Violet-green Swallows are 5 ¼ inches long. Their bills are tiny and they sport long, pointed wings. The back, nape and crown of males are a beautiful green, while the wings, rump and tail are purple. They are white underneath, with that color extending up over the eyes and onto the rump. Females are similar but the colors are more dull.

The calls of these sprightly birds include a “chew-cheet” and a more rapid, chattering “cheet-cheet-cheet-chuweet.” These are an exuberant expression of spring.

Pairs of Violet-green Swallows use cavities in snags, crevices in cliffs or birdhouses for nesting purposes. Both sexes help with nest construction. The female often returns to the same nest site year after year. Competition for nest sites is intense. Violet-green Swallow pairs have been noted helping to feed Western Bluebird chicks in an effort to speed up the fledging process and thus freeing up the nesting space.

The genus Tachycineta translates to “I move fast,” an appropriate description of their foraging habits. Violet-greens chase down ants, leaf hoppers, flies, mosquitoes and other flying insects. This is often done at great heights, with morning flights reaching the highest. No other local swallow species attains those same altitudes.

These charming birds will remain until the end of August, with migrants from Alaska and Canada filtering south throughout September.  Violet-greens winter in Mexico and south to Honduras.

It’s quite easy to entice a pair to a nest box. The Washington Department of Fish & Wildlife has bird house plans available on their website. We’ve found the version with horizontal oval holes to be highly attractive to Violet-greens.

One of my favorite early summer activities is to toss white feathers in the air as the swallow pair is in nest-building mode. This generates great excitement, especially with male swallows. They grasp a feather in mid-flight and take it back to line the nest. I have a friend who invented a blow gun from PVC pipe for the sole purpose of projecting feathers upward. Use molted chicken feathers if you’re interested in this activity.

Violet-green Swallows can be seen almost everywhere over our islands. Their high-flying ways are truly above it all.

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