In the Pacific Northwest tides move huge volumes of water every day. Along the shore, that translates into different water levels, many feet up and down. Combine that ebb and flow with incoming waves, various currents, and local weather events like wind...the seashore is a formidably dynamic place! Any beach hikers along our coast know tides must be taken into account since many headlands are impassable cliffs at high tide; some of us have learned that the hard way. I almost died of hypothermia once in my youth because I foolishly didn't pay attention to this basic fact of nature, and got trapped behind a headland for hours in the rain.
But Backyard Science is about nature and wildlife, who don't have tide tables and grocery stores. For them, survival depends on managing a tidal-dependent lifestyle. I saw a little of that on a recent trip out to the coast.
The Daily Bucket is a regular feature of the Backyard Science group. It is a place to note of any observations you have made of the world around you. Rain, sun, wind...insects, birds, flowers...meteorites, rocks...seasonal changes...all are worthy additions to the bucket. Please let us know what is going on around you in a comment. Include, as close as is comfortable for you, where you are located. Each note is a record that we can refer to in the future as we try to understand the patterns that are quietly unwinding around us.(All photos by me. In Lightbox...click to enlarge)
Olympic Peninsula coastline
In winter, daylight hours are few, and that's when seabirds feed for the most part. There are some situations (such as lighted piers, birds fishing on nocturnal prey like squid), and one particular species noted for nocturnal feeding, the Swallow-Tailed Gull, that are exceptions. But the gulls, oystercatchers, and ducks I see near the shore out on the wilderness Olympic coast stop foraging at nightfall. Since much of their food is in the intertidal and nearshore zone, the daylight hours of low tide are their peak feeding opportunity.
The time of low tide changes daily, and some days it's lower than others. During the last week of December, the cycle of the tide happened to be super-high in the middle of the day and super-low around sunset, a difference of more than 12 vertical feet of water in about 6 hours. The birds spent much of the day waiting for the tide to be low enough to get access to their food. These are some photos I took on my walks in the afternoons.
Gulls stand quietly in a group on Second Beach in the drizzle. That's the Quillayute Needle offshore.
Eventually the ebbing tide reveals rocks covered with mussels, barnacles, crabs and worms. The gulls I saw that week were mostly Glaucous-Winged gulls, with some Western and Mews also. They share the rock with Black Oystercatchers.
More birds (and a special guest) below the clump of seaweed...
The gulls are quite a bit larger than the oystercatchers so there's a lot of jockeying for space on the rock.
When the rock is small and barely out of the water, birds come and go.
These two oystercatchers (Haematopus bachmani) appeared almost bemused by the wealth of food all to themselves at this moment.
Special guest, as we head north from Second Beach to see some other afternoon ebbing tides: California Sea Lions. At the mouth of the Quillayute River, the tide has turned, and as the incoming tide washes up the river, it swirls around the fresh river water flowing out into the sea. I'm standing on the jetty, looking over the mix of river and tide.
In this turbulent water, several California Sea Lions were fishing aggressively, snatching up fish tumbled by the currents and whirlpools. One Sea Lion swam up below me and barked. Loudly! Think German Shepherd x 5. Startling, a few feet away.
North of the Quillayute River, Rialto beach is a 2-mile stretch of rounded black pebbles on a steep shore with constant pounding surf rattling through the pebbles, tossing and rolling driftwood. This plankton-rich water supports dense populations of intertidal life on the few patches of solid rock which emerge at low tide. First come first serve for these gulls, whose perch is splashed and flooded by waves. They are experts in knowing when to lift off and where to land as the wave drains off.
Out at Shi Shi beach, a long sandy beach about 30 miles north, I saw three Harlequin ducks (Histrionicus histrionicus), swimming in the breaking surf when the tide dropped low enough so the rock formations low in the intertidal formed tidepools of a sort. Harlequins dip their heads under the surface after small fish and invertebrates, negotiating the waves breaking there. See how small these colorful ducks are compared to the gull!
All these strangely tipped and layered sedimentary rock formations were invisible an hour earlier. Most of the time this beach is pure fine-grained sand for miles. In the distance is Point of Arches, a headland of seastacks composed of more resistant rock, at the far end of the beach.
Oystercatchers perch on a higher rock, waiting for the tide to get low enough to get to the shellfish below. It's almost sunset though. The feeding window is closing.
(this is Episode 2 in What I Did On My Holiday Trip to The Ocean :))
What's happening in your neighborhood? How's the weather and the wildlife?
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