The mission: Construct a home for soon-to-be-born offspring.
The rules: Use only scavenged materials. Carry them to the site in your mouth. Employ nothing but your appendages as tools. Ensure shelter from wind, water, and roving bandits.
The seabirds in love introduced in a previous post set to work. As monitors for the Seabird Protection Network on the Northern California coast, we watch and wonder: Where can these parents-to-be, who spend much of the year over open water, find safe haven on our rugged shore?
The first consideration: Location, location, location. Yet often seabirds opt for what look to us like the most precarious places. Homesteading on steep cliffs, Pelagic Cormorants pile strands of seaweed and grass on ledges so narrow that they can barely turn around. But perched above the sea’s spray and far from terrestrial predators, they can keep constant watch for airborne nest robbers. Pigeon Guillemot also prefer vertical cliffs, but they add an extra level of protection. Burrowing into crevices with their beaks, they excavate hidden spaces for a nest with one or two eggs.
The largest rock off Bodega Head (in photo above) offers prime real estate for both Brandt’s Cormorants, who settle close together, and Western Gulls, who scatter their nests on the remaining turf. A male Brandt’s Cormorant selects a patch of rock, often just three feet away from a neighbor, and defends its perimeter with pecks and shoving matches. Together he and his partner fashion a large circular bowl of algae and moss, held together by a natural cement: their guano (excrement). Western Gulls build veritable McMansions for their broods. The expectant mammas and pappas spend weeks piling algae and seagrasses in shallow indentations on a rock to create a cup-shaped cradle.
Black Oystercatchers choose a flat, open area, often atop nearshore boulders. To us their makeshift dwellings look like a random scattering of stones, but the pebbles and shells provide camouflage for their speckled gray eggs.
On rocky outcrops along the Sonoma coast, pairs of Double-crested Cormorants construct simple structures of sticks and twigs along with other available vegetation. Some re-use nests from previous years, refreshing them with new cushioning materials.
On Gull Rock, a guano-bleached mound about a third of a mile offshore, Common Murres, small black-and-white seabirds, cluster by the thousands in dense colonies. Lacking room for a proper nest, a mom lays a single egg directly on bare stone. Its elongated shape, a marvel of evolutionary adaptation, allows it to roll in circles rather than sliding off an edge.
Incubation typically starts from late March through May and lasts 24 to 37 days. Many couples alternate shifts, with one partner keeping the eggs warm while the other ferries food from the sea. Ever vigilant, seabirds shriek and rise up with wildly flapping wings to fend off aerial nest-robbers.
Predators aren’t the only threat. Several years ago a visitor to Bodega Head released a drone — strictly forbidden by State Park regulations. The terrified Pelagic Cormorants nesting nearby rocketed into the sky. Predators pounced, and a colony of some 30 nests was decimated.
Barring such catastrophes, many seabirds exhibit “nest-fidelity” and come back to the same breeding sites every year. I understand this yearning to return to the security of a familiar place. Be it ever so humble—even if nothing more than a swatch of seagrass or a pile of pebbles—there’s no place like home.
Photo Credits: Djuna Bewley, Wikimedia
