Beaches and tideflats

sightings and discoveries in a sudden spring

Several sunny (!!) days in a row in mid April. I’ve now hacked most of the ice off my driveway and trimmed back the piles of snow on my terraces from two feet deep to a few inches. Mallards are thronging to my pond, which has ice only in the middle, with wide open channels around the edge. I hear juncos, ruby-crowned kinglets, varied thrushes, and nuthatches in my yard. Maybe it’s really spring!

All that sunny weather drew me out to soak up the sunshine. On Boy Scout beach, while a group of friends perched to have lunch, a beautiful, huge queen bumblebee checked us out—she particularly liked a certain blue/purple jacket, to the consternation of the human inside. Those bees just love that hue and come buzzing around, as if it were one huge flower. They usually figure things out fairly quickly and go away.

On another day, I visited Eagle Beach and found a partial skeleton near the high tide line—one forelimb and a body sans skull. The bones were quite well picked-over by scavengers. I was puzzled—they clearly didn’t’ come from a deer or a seal; otter and bear were quickly ruled out; so who was it? A little bony detective work on the internet later found a likely prospect—a small Steller sea lion. The clues were the short, stout bones of the forelimb, a curve at the back edge of the shoulder-blade, and the lack of well-developed flanges (neural spines) on the outer part of the vertebrae. That tentative ID was later confirmed by a photographer-friend who had seen the carcass. The forelimb was especially interesting—the upper arm bone (humerus) was very short (maybe five inches long); the two lower arm bones (ulna and radius) were not quite so short but quite thick. That morphology might be related to how they use their forelimbs on land, hoisting the heavy body over the ground.

A couple of days later, I walked the dike trail with a friend, and the place had really come alive. Ruby-crowned kinglets serenaded us all along the trail, helped by a song sparrow or two. Golden-crowned sparrows scratched around in the thickets for fallen seeds and occasional bugs. Four pipits explored a channel left dry by the low tide. Robins were scattered widely over the grassy tideflats, foraging, and scolding when disturbed. A male yellow-rumped warbler hawked for flying insects over a pond and a female flitted about in a semi-dry channel after bugs that apparently jumped around. Two shorebirds got away from me but a greater yellowlegs was poking around in some shallows. All that warm sun had made green shoots of several species begin to rise from the soil, and on the trees a few leaf and flower buds were ready to open.

The next day I walked Eagle Beach again. Things were very quiet until a northern harrier coursed over the flats, scattering a few small birds and provoking the geese into vociferous protests. Harriers often cruise the beaches at this time of year, no doubt hoping to nab migrating shorebirds. Although I’d missed (sadly) the migrating mountain bluebirds reported from several beach areas, I did score a minor coup—a Townsend’s solitaire was hanging out in the brush at the edge of the big meadow at Eagle Beach, making occasional forays into the open in pursuit of small flying insects. This species typically nests in the Interior, often in open forest habitats, placing its nests in cutbanks and steep rocky slopes; the nests are on the ground but usually have some overhanging rocks or stumps.

Townsend’s solitaire. Photo by Scott Ranger

A few more fine, sunny days, and there were blueberries in flower, skunk cabbages up and open for their female-phase flowers, a flock of snow geese on the wetlands, and reports of wood frogs chorusing in a pond over on Douglas. It’s happening!

Eagle Beach at equinox time

swans and lugworms on a lovely day

Just before the vernal equinox, I strolled in the Eagle Beach area with a couple of friends. The lower reaches of the river bore a few cakes of ice drifting to the sea. We stood on the bank, looking toward the Chilkats, enjoying the view. Then, down around a bend, one of those ice cakes surprised us as it suddenly sprouted a long neck and a head. Oh. Not an ice cake. Presently, the swan spread its big wings and set sail over the estuary. It was too far away to be sure of the species, but it was probably a trumpeter swan, which appear to be more common here than the smaller tundra swan.

Trumpeters migrate through here in spring and fall, and occasionally overwinter in estuaries and ice-free freshwater ponds. We see them in various places, including Amalga and the Dredge Lakes area. They are probably from the population that nests in coastal areas farther north; those that nest in the Interior are more likely to migrate inland. They have a huge wingspan, similar to that of eagles, but they are much heavier; they are said to be the heaviest flying bird in the world.

Trumpeter swans once nested in marshes and ponds across much of North America, but hunting (for meat, feathers, skin), habitat destruction, and lead-poisoning (from ingesting shotgun pellets that sank to the pond bottoms, where swans often feed) decimated their numbers. Thanks to conservation efforts, the species is not endangered now, and many breeding populations are thriving.

They can live to be more than twenty years old, but they mature slowly; they usually mature when four to seven years old, occasionally sooner. They are monogamous, the pair bond usually lasting as long as both birds are alive and well, and the pair often staying together year-round.

On the nesting grounds, they choose freshwater marshes, ponds, and small rivers, building nests on beaver dams and lodges, hummocks, and platforms of floating vegetation. The nests are typically surrounded by water, giving them room for a running take-off when departing. Both male and female work on nest-building, both birds collecting material but the female doing most of the construction. The big eggs are laid at intervals of one and a half to two days (not daily, as in most birds). Both members of the pair incubate the clutch of (usually) four to six eggs, but neither develops an incubation patch on the body…they incubate the eggs with their huge, well-vascularized feet!  

They are territorial, fiercely defending their chosen area at least until the eggs hatch and often, with declining intensity, until the chick fledge. That takes three or four months. Both adults tend the chicks, but become flightless for a few weeks during the summer molt. The young birds stay with their parents throughout their first winter. They forage on submerged and emergent aquatic vegetation, sometimes grubbing up tubers. Birds that winter farther south often forage in agricultural fields, and even digging up potatoes and carrots.

A bit later that day, we wandered out onto the sand flats exposed at low tide. And there was the swan again, walking slowly toward a group of grazing Canada geese. We imagined that it had thoughts of joining the group; swans sometimes migrate and forage in flocks of geese, ducks, and cranes. But these geese would not have it! They went on full alert and eventually took off. The swan then ran across the flats and took off toward the estuary.

Photo by Aaron Baldwin

Along the bank of the lower river, we found a lugworm, lying on the sediments. I don’t know why it was there…They normally they live in J-shaped or U-shaped tubes within the sediment, although they can move out and build a new tube at times. At one end of the tube, they deposit coiled fecal castings on the surface, which we often see when the tides have not washed them away. Fecal deposition may sometimes be a slightly dangerous activity, because a foraging bird or crab may snap up the tail end; however, the worm can regenerate a new one. At the other end of the body is an eversible pharynx with a mouth that engulfs the sediment. The worm then digests some of the tiny organisms and perhaps organic detritus, passing out the partially cleaned-up sediment grains in the castings. Some lugworms can also feed on suspended particles. These worms breathe water, using their external gills alongside the body, when inundated by the tide, but reportedly can breathe air through the skin, when the tube is exposed at low tide.

The sexes are separate, raising the question of how these burrow-dwellers manage to make offspring. The available online reports are contradictory and confusing. The males simply eject sperm out into the water, hoping they can find eggs to fertilize. By some reports, the eggs are held in a female’s burrow and released sperm have to find and enter the burrow; that’s a system that probably works best when the worms live at high densities and spawn at about the same time, as indeed they often do. Then what? The fertilized eggs and larvae may be brooded in a female’s burrow; when still small, they leave and make a burrow of their own. However, we often see gelatinous sacs lying on the surface at low tide; they are tethered somehow to a female’s burrow. The sacs contain eggs or embryos; but why are they lying on the sediments?