John Muir famously pointed out that any time you pull on a thread in nature, you find that it is connected to the whole universe. The truth of this is nowhere more evident than in the dry sand of a public beach. There is a secret world of complex and interwoven animal life at any beach access point, and it takes only the slightest effort to begin seeing it. Next time you go for a walk at Limantour Beach, for instance, slow down for a moment and look at the sand as you cross through the dunes and head for the beach. Let your eyes begin to focus on the details in the sand surface.
The short walk from the car to the shore goes through several distinct habitats merging from one to another, each with its own characteristic life systems. You will pass through estuary, mudflat, chaparral, back dunes, foredunes, inner beach, foreshore and tidal wash. A complete ecological system is laid out here and a complex world of plants, insects, worms, crustaceans, birds and mammals is deeply woven into this underlying fabric.
Right there in front of you, slightly hidden amongst the thousands of human tracks, are hundreds of animal tracks and dozens of interlocking stories. During the night, when the humans have gone home, a rich world comes to life.
Though the sand is loose and dry at this time of year, observation will reveal a slight surface crust, created each morning when the sun and wind dries out the night-dampened sand. This crust is the key to tracking here: anything that steps on the dried crust, early in the evening or late in the morning, leaves a track with a thin broken crust-edge and loose sand in the middle. But a track made in the middle of the night when the sand is damp will harden in the morning, leaving a crust across the floor of the track. Getting a sense of when different trails were made brings the whole scene to life. It’s a little like looking at the starry sky with an understanding of the three dimensionality of the universe.
With this in mind, walking through this cross section, within 50 feet of almost any trailhead, you can begin to decipher a little of what has taken place over the last few days. You are likely to see the tracks of many birds—crows, jays, buzzards, gulls, ducks, plovers, sandpipers, herons and sparrows; of several mammals—deer, skunks, foxes, bobcats and coyotes, families of raccoons, solitary opossums, brush rabbits by the dozens, mice by the hundreds; of insects—black beetles, burrowing beetles, many fly species, spiders; of crabs and even, if you are lucky, the tracks of living sand dollars at extreme low tide…
There is logic in this richness and diversity. If we step back and look at the structure of the beach, we can see that the foreshore is created by the parameters of tidal action. The high point of the beach is at the highest level of wave wash, and the beach flattens out as it extends into the ocean at low tide. Extreme high tides and storm waves breach the high berm and wash great amounts of various seaweeds, grasses, kelps and algaes, along with the carcasses of dead sea birds and mammals, over the top where they are deposited across the inner beach.
In the tidal zone, uncountable numbers of shrimps, crabs and other crustaceans, along with untold species of other invertebrates, live on the constant wash of nutrients brought in by the ocean currents. Up on the inner beach, hundreds of insect species live on the decaying plant and animal matter. Back in the dunes, where the lightest and finest sand particles are blown and deposited by the constant winds, the dune grasses, coyote brush and lupines create the basis for mouse and rabbit survival.
Here is the story then: the beach is a smorgasboard, an extravagant feast. All of the opportunists are out—the ravens, with their long toenail drags; the gulls and the buzzards, searching out and inspecting any possible food source, from mole crabs to dead birds; and the plovers and sandpipers probing the water edges and dashing across the sands picking flies and other insects and larvae, their probe holes riddling the edges of any clump of kelp where flies have laid their eggs. During the night, raccoons leave their hideouts and trot straight to the water’s edge to pick up crabs and carry them back to their hidden middens in the dunes, while the skunks forage the sand in their erratic little lopes.
Up in the dunes, mice have been busy all night, speckling the sand with their little bounding tracks, which will spread 10 or 15 feet into the open sands where they are harvesting windblown seeds and nighttime bugs. Driftwood and other objects far out on the open sand are attractive shelters and will be surrounded by speckles of tracks. Mice find safety here from night-hunting owls who will often walk long distances across the sand in search of prey. Meanwhile, the larger predators, the coyote, bobcat and fox, have been hunting along the foredunes for brush rabbits and mice, leaving long walking and trotting trails, which speak eloquently of how the landscape plays the animal like a musical instrument.
So put down the frisbee and the cooler for a moment and look around. One track and a little observation will begin to unravel the universe. A mouse track in the dunes, then, is related to the grasses and the flies, to the winds and the tides, to the moon and the stars, and to yourself. Take a moment to absorb and appreciate this world and your place in it.
Richard Vacha lives in Point Reyes Station, where he makes a living as a craftsman and has studied tracking for 30 years. For information about the Marin Tracking Club and the Point Reyes Tracking School programs, email [email protected].
This article originally appeared in the Marin Coast Guide.