RAINSHADOW WORLD - A Naturalist's Year in the San Juan Islands
PREFACE
On a warm day in May not long ago, I took a walk along an upland trail at the University of Washington Friday Harbor Marine Laboratories. I was eager to see what wildflowers were blooming on a rocky knoll overlooking the harbor, and delighted to find camas still in flower; shiny western buttercups gleaming in the grass; blue-eyed Mary nestled in crevices alongside stonecrop; pink clusters of sea blush clinging to the bluff; and the pods of white fawn lilies that reminded me that a full year would pass before I gazed again upon their soft petals.
I stopped to look at a broad-leaved starflower that cast a tiny shadow under a towering fir, then watched a spring azure flutter by and land in the camas, promptly folding its wings and disappearing into the rich hues of the plant’s blue flowers. A bald eagle made slow measured turns high above madrones, western red cedars, and Douglas firs anchored in the bedrock; chestnut-backed chickadees and dark-eyed juncos foraged in the early creamy inflorescence of ocean spray; and, at Beaverton Cove, a sleek river otter came ashore and lumbered off through the understory of salal, western sword fern, and Oregon grape.
On a grassy bald, I found a little plant I did not know. It was reminiscent of candyflower, its succulent stems with delicate white flowers veined in pink trailing inconspicuously along the lichen-encrusted rocks. I sketched the tiny wildflower and made notes of the landscape. Later, consulting a botanical guide, I identified the plant as moisture-loving montia, Montia parvifolia, named for the eighteenth century Italian botanist Giuseppe Monti.
It was the type of walk I liked the best: investigating unfamiliar niches along a trail; finding new plants to identify; and pondering birds, butterflies, and other wildlings. And, thanks to an islanders’ community that still values wild places, there is plenty of room to roam. The San Juan Archipelago embraces hundreds of rocky resting places scattered from the mainland of northwest Washington to the Strait of Juan de Fuca. There are 375 miles of shoreline on more than 400 islands, rocks, and reefs visible at high time. The San Juan group is generally regarded as including Cypress, Guemes, Sinclair, and Lummi Islands to the east although those islands are not part of San Juan County.
For years, I 
have conducted surveys, kept journals, compiled checklists, taken classes, and joined colleagues and friends in the field delighting in the process of discovery. As a resident of San Juan Island, I have primarily observed the prairies, forests, wetlands, and rocky shorelines I call home, but my visits to Shaw, Orcas, Lopez and the outer islands of Cypress, Stuart, Waldron, and Yellow have produced engaging encounters, too.
The mild climate allows me to explore the archipelago virtually every day of the year. This realm lies beneath the rainshadow of the Olympic Mountains. The passage to the outer coast—the Strait of Juan de Fuca—splits a mountain range between Vancouver Island and the Olympic Peninsula. Rain clouds surging in from the Pacific Ocean surrender moisture to the western slopes of the nearly 7,000–foot peaks, leaving the San Juans, to the north, with less than thirty inches of precipitation each year. The summers are temperate and the winters, while wet and wind-blown, seem moderated by my curiosity.
The islands have stirred to life my senses of wonder and of joy. Years of wandering, watching, and listening have been my way of keeping in touch with this rainshadow world—and with myself. The island year depicted actually spans a decade of experiences and investigations from the late 1990s through 2009. Changes in the landscape and wildlife communities, both subtle and stark, have occurred during this period illuminating the inevitable adaptations of a natural world increasingly impacted by human development. The book is a snapshot in time and, I hope, an accessible reference point for understanding what has come before and what may lie ahead for this extraordinary place. I have asked more questions than I have answered, and the journey has just begun.
Susan Vernon
Friday Harbor, Washington
HERE'S A SHORT EXCERPT
SEPTEMBER – journey south
By September, the late summer sun has bleached the vibrant colors from the prairie, and soft Pacific breezes wash over the plains in a soothing meditation. The birds have given up their songs, and some have already left on their journeys south. As the days progress, the morning fog drifts in and out, gently nudging summer away. A hush falls over the land as if it is waiting for something to happen. The crickets start to chirp. Then a flock of small, buffy-brown birds with shining dark eyes touches down in the tall grass and begins gorging on the insects. There is urgency in their gait, and efficiency in every move, as they work a small stretch of prairie before disappearing into the rosy glow of twilight. It is unlikely people notice the little golden birds that bob their tails with exuberance, but for the pipits the brief encounter with the islands is an important refueling stop on their way south. In the days and weeks ahead, more pipits, larks, sparrows, and kestrels will pause here, and the insects of the fields will oblige their appetites. And through the forests, along the shore, and down the straits, sojourners from the mountains to the sea will stop over in the islands and, when rested and replenished, cast their migrant souls upon the wind doing whatever it takes to reach tomorrow along the vast network of migration routes called the Pacific Flyway.
On to Argentina
In the San Juans, September is a time of transition for the birds. The change seems subtle at first – recognition that the woods have grown quiet, and the meadows have lost their luster. Then I stop and look and listen, my heart sinking as I begrudgingly accept the fact that the summer birds are gone.
In reality, migration begins in July when temperatures creep into the 80s and our summer finally arrives. For many of the birds, their genetically programmed southern imperative is already urging them to move on.
The male rufous hummingbirds, among the first to arrive in March, are one of the first to depart. Having flown north via the Pacific coast route, many return to the southwest and Mexico following the ridges of interior mountain ranges where late-blooming wildflowers fuel their leisurely trip. Female rufous and their offspring remain another month before heading out.
In August, many woodland birds including Pacific-slope flycatchers, olive-sided flycatchers, Cassin’s vireos, cliff swallows, Swainson’s thrush, and western tanagers begin departing for lands as far south as Argentina and the Amazon Basin.
By September, the warblers, waxwings, and goldfinches join the stream. Hundreds of barn swallows flock near False Bay and other staging areas, before flying to southern California, or possibly as far as Costa Rica and Argentina. That bright yellow sprit of our wetlands, the common yellowthroat, leaves to winter along the Pacific coast, the Gulf States, or possibly even Panama. Not all our summer residents travel far. Some winter close by on the mainland. Occasionally, yellow-rumped warblers and Townsend’s warblers, among others, overwinter in the islands.
Muddy waters
With the summer birds departing, it is time to concentrate on migration. The variety of birds moving through the islands keeps me busy. The shorebirds are among the most visible migrants. Nearly forty species regularly reside in, or pass through, the archipelago. These lithe beings sweep down from the Far North stopping here just long enough to rest and refuel before heading out on another leg of a journey that may take some of them to the plains of Patagonia, the islands of the Pacific, Australia, or New Guinea.
False Bay bears witness to the wind birds passing, and so do I. The bay is a primary stopover in the islands, its curvaceous shoreline wrapping around a little more than one square kilometer of intertidal habitats including a sand bar, mudflats, tide pools, and cobbled and sandy beaches. At the outlet to Haro Strait, beds of eelgrass and kelp are nurseries for baitfish, and at the north end San Juan Creek and tiny streams feed in freshwater from the upland watershed. Wave action is minimal on the bay, yet it is still subject to a 12-foot tidal exchange.
The muddy, monotone substrate belies its fecundity. I have watched people stop along the shore, take a quick look, shake their heads and say: “There’s nothing here!” and move on. In 1859, Captain G.H. Richards of the British survey ship HMS Plumper wrote of False Bay: “…It is a fine appearing bay at high water, but low tide reveals the deception, and leaves it entirely bare…” Looks can be deceiving!
Here, highly specialized groups of marine animals live either on the surface or within the mixed substrate of mud, sand, and gravel. Microscopic diatoms and other algae, polychaete annelids (worms), bivalve mollusks (clams and mussels), and crustaceans (including tiny crabs and shrimp), thrive in the muck.
Walking along the flats at low tide it is easy to find clues to this rich subterranean fauna: burrowing and crawling animals leave holes, mounds, depressions, piles of sand, slime trails, and often heaps of shells. The mud-dwellers are part of a protein-packed food chain that feeds tens of thousands of shorebirds, as well as seabirds and marine mammals that live on or near the bay.
The University of Washington Friday Harbor Marine Laboratories owns two hundred acres of tideflat and uplands – a mecca for marine research. The flats have been closely monitored for decades; subtle distinctions in habitat types have been defined, and correlations drawn between these substrates and the species of marine invertebrates that inhabit them. Throughout the realm, ghost shrimp, mud shrimp, hermit crabs, lugworms, ribbon worms, and other invertebrates provide sustenance for the birds.
Shorebirds
The signature bird of the bay is the western sandpiper, the most abundant shorebird in Washington State and one of the most abundant shorebirds in North America. Over three million western sandpipers migrate along the Pacific Coast, and stopovers are critical to their survival. Just north of us in British Columbia, the Fraser River Delta is a crucial site. Over 500,000 westerns have been reported on the delta in a single day, having flown in from the Copper River Delta in Alaska. From the Fraser, many birds go straight through to Grays Harbor and Willapa Bay in southern Washington, then down the coast to the Columbia River Delta and San Francisco Bay. Seal Beach and Tijuana Slough complete the chain of shorebird way stations leading into Mexico and Central and South America including Panama and Peru.
The sandpipers sometimes arrive here as early as the last week of June. This year on July 9, several dozen western sandpipers and least sandpipers appear, scurrying along the shoreline at high tide picking insects out of the wrack. The first westerns to arrive are usually the adults leaving the northern breeding ground ahead of their offspring who are on their own to find the way south.
These diminutive sandpipers, about the size of small sparrows, weight less than an ounce. In breeding garb, the black-and-white birds have crowns, cheeks, and scapulas washed with a rich, rusty hue. Their black legs and a long, slightly drooping bills are distinctive field marks. Approaching fall, after a molt, their subtler grayish plumage is nondescript. Semipalmated sandpipers, also dressed in shades of gray, sometimes mingle with westerns making identification even more of a challenge.
The westerns travel and forage in flocks for protection from predators. They seem to move with a group consciousness and take flight at the slightest hint of disturbance. The first sandpipers I encounter this year are so absorbed in feeding that they peck in the sand and wrack not ten feet away from where I sit. It is a memorable moment watching these tiny birds, literally at my feet, and knowing that their journey will take them thousands of miles away and, hopefully, back again next spring.