I noticed that my thumb was larger than the Semipalmated Sandpiper’s head when I was holding him. He was sitting quietly before we measured, weighed, and banded him. His bill length, the combined length of his head and bill, his wing length, the length of his lower leg (tarsus), and his weight in grams would all be recorded. We attached small plastic rings to his legs so we would know him next time we saw him, maybe in a day, or maybe we would not see him again for an entire year. Then, much to his personal relief, we let him go. He leapt into the air right out of my hand and immediately flew above us, about 100 feet off of the ground and began a display-flight which included a purring call that sounded like a small idling engine, rrrrrrrrrrrrrRRRRRRRrrrrrrrrRRRRR that lasted for several minutes. His wings whirred in rhythmic bursts with gliding in between that kept him in place, even with a 25 mile per hour headwind. The air was about 35 degrees, with the wind-chill making it seem subfreezing. This was his turf, his patch of high Alaskan tundra, and he knew it well. The display was a declaration to all interested, including his mate, pronouncing that he was on the job of defending this piece of the Arctic National Wildlife Refuge to secure feeding habitat for his soon-to-hatch brood.
I thought about what must be in that little brain of this hardy bird. He had a detailed map of the tundra, all of the large features, including small ponds, the curve of the river bluff, marshy wetland edges, frost sculpted patterns of elevated ground. He knew his neighbors, especially the other males of his species. He had competed with them for his piece of spongy wet ground. He knew the right feeding sites on the water margins, working the down-wind side of the water to pick larvae of the flying insects out of the shoreline froth where they were suspended. He knew how to get out of formidable Arctic winds by tucking in behind a hummock where he could rest, and let his cryptic grey and brown feathers conceal him among the dry grasses and flower stems from the previous summer.
And with amazing accuracy, he could pick his way across the ground back into his nest cup and dappled brown eggs. The nest was the diameter of a teacup, a little depression in the sod lined with dried leaves for insulation from the frozen ground beneath. He would find his nest by walking through the maze of grass clumps, around moss mounds, over patches of plants called saxifrage, clumps of flowering dryas, through wetland patches of rush stems, and finally to the nest. He had a fine scale micro-map that could be used regardless of the direction he was coming from. He could approach, moving like a small rodent, run….stop…tuck under, turn, run again, pause and look, then on with a hasty walk. All of this to avoid giving directions for any onlookers, like a jaeger or fox interested in his eggs. He could do this from a vantage point of about two inches off of the ground, much lower than most of the clumps and patches of vegetation he was weaving though. When he reached his nest, with a light vale of grass overhead as a thin canopy, he would slide in, tail and head sticking above the rim. He would shift back and fourth so all four eggs were aligned under him to absorb his body heat for incubation.
A year before, he had nested less than 40 feet away from where he was now. His territory was about the size of two basketball courts in a landscape of coastal plain tundra of the Arctic National Wildlife Refuge that stretched for about a million acres around him. The mountains of the Brooks Range were thirty miles to the south, and the Arctic Ocean, still frozen to the shore in early June, was 3 miles to the north. He was on the western edge of the Canning River Delta, the western border of the refuge.
Based on plumage, this sandpiper was more than two years old, and might have been five or six. He had migrated round-trip through Canada, the U.S., and Central America, and across the north coast of South America to spend the winter just south of the mouth of the Amazon River, an unimaginably huge landscape stretching well beyond his little postage-stamp size territory. He knew the mountains, the rivers, and ocean coasts. He had been through the White Mountains of the Brooks Range, over the Yukon River, around Mount McKinley in the Alaska Range, over the Rocky Mountains. He knew the Canning River headwaters, the Yukon, the St. Lawrence, the Bay of Fundy, Cape Cod, the Hudson, the Mississippi, the Orinoco, and the Amazon. This small bird was a representative of a hemispheric life force, dependent on specific wetland sites for refueling that were scattered over an impressively large section of the globe.
Everything about him, the condition of flight muscles, the density of his feathers for warmth, the fat he used for energy, the complex proteins in his blood, were all products of his time on migration, most of it many miles away on specific wetland stopover sites to the south. The condition and health of the habitats he had encountered over the past year contributed to his ability to defend a territory by hovering above us now, to avoid predators, and to reproduce. The availability of resting sites on the Bay of Fundy, the power of the tropical storms he had endured flying over open ocean, the stress from the gunfire on Guadeloupe, the availability of undisturbed beach on his Brazilian wintering site, the abundance of marine worms on the Georgia Coast, the water quality on the shores of Delaware Bay, and the availability of freshwater marshes in the central US and Canadian provinces, all played a role for this Semipalmated Sandpiper and other shorebirds as cumulative influences, affecting their ability to get to the Arctic nesting grounds to reproduce.
While his time on the tundra was brief, just about seven weeks, it was a critical period, the apex of his year during his entire annual migration odyssey. He had timed his arrival as the first patches of tundra were exposed. And now I watched in awe as this this little male sandpiper held his spot in the air and the world. I tried to imagine all of the miles those little wings had flown, and the complexity of the geographic landscape he had endured to get here.