NEWBURY —The tide nuzzles her nest. She shifts on her eggs but does not leave – the tide will not rise much more today.
She peers through the woven fingers of marsh grass, the moon is filling. As it does it will pull with the sun on the rope of the sea against the earth in a Newtonian tug-of-war and bring the spring tides on top of the marsh. When tides flood she will have to abandon the nest and wait for the ebb. Then she will return to incubate any eggs that remain.
At 10 years old, she is an old saltmarsh sparrow (Ammodramus caudacutus) and this is her last brood. She has made her last trek from her overwintering grounds as far away as Florida to her natal breeding grounds of the Great Marsh. She comes here because there are fewer predators than down south and the Great Marsh has acres heaped upon acres of high-marsh habitat of soft grasses, which exist only in thin bands down south.
These grasses seclude her. She is a secretive bird, brown and small, well-suited for hiding in the marsh grasses. She is modest, allowing herself only the slightest blush of orange or yellow on her cheeks, swept across her face as though she flew quickly against an artist’s brush.
In her youth, she has returned to nests emptied of eggs by the tide or filled with limp, drowned chicks. The sun and moon don’t know about the gumball sized, chalky off-white eggs or the raggedly bald and screaming pink fledglings of the saltmarsh sparrow that are nestled in the marsh grass. They only follow their astronomical rhythms.
She has now learned these rhythms. She now lays her eggs 2-3 days just after the highest spring tides. The next marsh-overtopping waters arrive 10 days later.