Tides Happen, plus, By the Length of Their Legs They Will Rise

 

[Juvenile American Golden-Plover, left, with Red Knots at the Wetlands Institute, Stone Harbor Causeway, Cape May, NJ today at about 11:00 a.m. The reddish plants are Salicornia, or glasswort. The grasses are the hugely important Salt Marsh Cordgrass (Spartina alterniflora) - salt marshes have autumn colors just like forests. The plover is told from Black-bellied in this view by its thin bill, small head, and dark cap highlighting the white eyebrow. Click to enlarge all photos.]

Tides happen, and birders, fishermen, boaters, crabbers, waterfowl hunters and coastal homeowners had better pay attention.

[At this point, you may just want to scroll past the brief but technical tide fact sheet that follows to go straight to this weekend's birds, but then again, maybe not. Our natural lives are driven by natural forces, and tides, winds, storms, and birds are all interconnected. Your call.]

A first thing to know is that tides vary on macro- and micro-geographical scales. Simplifying with a couple examples: what happens in the mid-Atlantic is not the same as what happens in Florida, and what happens on the Delaware Bay, NJ is very different temporally and in scale from what happens on nearby Barnegat Bay, NJ.

In the mid-Atlantic, we have two high tides and two low tides every day, separated by about 6 hours. The time of each tide gets later with each passing day. You can Google why, but trust me, it does. So get a good tide app or tide chart from a local fishing tackle shop.

Looking at the micro-geographical scale, today on Delaware Bay near my house the tide was low at 8:16 a.m. and high about 6 hours later at 2:43 p.m., with a theoretical range from high to low of 5.5 feet. (This is based on the North Highlands Beach tidal station.) If you think about it, 5.5 feet is a hell of a lot - stand on the tidal flats of the bay at low tide and realize that in 6 hours the water will be spilling into your mouth. And, as everybody knows, there are plenty of places where the tides are way more extreme, e.g. the Bay of Fundy.

I use the word theoretical because with the long-lasting northeaster we're enduring, the tide hasn't gone fully out for a few days, so the tidal range hasn't been so widespread between high and low. This morning on the bay, at "low tide" it was basically close to a normal high tide, and I eyeballed "high tide" as about a foot higher than the forecast high.

Looking at nearby places, one notices that some places have greater tidal ranges, some less, and every place has different tidal timing. So. . .  consider for example the Beach Haven Coast Guard Station, on Barnegat Bay on the bay side of Long Beach Island, 40 miles northeast as the crow flies from Delaware Bay. There, today, the tide theoretically varied about 2 feet from low to high, and low tide was 8:47 a.m., high at 3:03 p.m. - running a half hour or so behind the tide on Delaware Bay. Pretty limp tidal variation compared to the big Delbay tides, due to variation in what I've come to think of as the "plumbing" of the system. This plumbing is complex, and I'm still trying to work out the mechanics of it on the finest of scales, as in, the particular places I bird or launch a kayak from.

So, you've got to know what's predicted at your particular spot, and then you have to know how the weather and the moon will affect that.

On the moon, the reader's digest version is that at full and new moons, the tidal variation between low and high tide will be substantially greater than during the rest of the month. Full and new moon tides are referred to as "spring tides," and they are big, and can wreak consequences on bird and beast, including man.

On the weather, the reader's digest version is that on west (from the west) winds, the tide will tend to be pushed out, staying lower than predicted. East (from the east) winds keep the tide higher on the Atlantic coast, because wind-driven wave action holds the water close to shore. That's what's happening right now, big time.

This has already become way more theoretical than a simple bird blog should be, so let me give a couple examples of when I got screwed by the tide because I wasn't paying attention.

One summer, I was a leader on a birding by boat trip in Great Egg Harbor, NJ, on a fine large pontoon boat captained by an experienced man. The tide was low and theoretically rising, but a west wind was keeping the water offshore. We nestled up to a wonderful heron rookery, enjoyed the comings and goings of 100's of 5-6 species of herons and egrets and ibis for a while, and got soundly stuck. No problem, the tide would come in and lift us off.

Not. Sea Tow pulled us off 2 hours later.

Another "fun" episode: last summer I went kayaking one day on a falling tide. The theory was, ride the tide out, hang out for a while, then ride the tide back in. This usually works out remarkably well, making for a lazy man's kayak trip (as long as you have a good map and sense of direction).

Unless it's a full moon and west wind.  Then, you ride the falling tide out, hang out, try to come back in, realize there's not enough water to float even a kayak that only draws 3" of water, hang out more and eventually drag your kayak while forcing yourself through knee-deep muck (which you know at any moment could turn into neck-deep muck). At least you got some good Clapper Rail pictures on this trip. . .

One more example, and then back to today's birds. When Hurricane Sandy came through in late October, 2012, east winds had already been keeping the Atlantic coast tides very high for several days. I live, on purpose, about a mile from Delaware Bay and 7.5 miles from the Atlantic Ocean. I want to be near all the great Cape May birding, fishing and kayaking areas, but want nothing to do with coastal flooding or hurricanes, other than chasing the rare birds or birding spectacles that such events might bring. Sandy was a monster, and thank goodness she just grazed Cape May (and instead came ashore directly over Edwin B. Forsythe National Wildlife Refuge, where I work. . .). But those damn east winds meant at high tide the night Sandy passed, I had 3 feet of water in my street. Luckily, my house sits a few feet above the street, my dog swims well, and I have a canoe and two kayaks in case it got higher. . .

Right, birds.

[As the tide rose at the Wetlands Institute today, the short-legged shorebirds became increasingly nervous. The American Golden-plover flew around and landed briefly, before eventually pulling out for good. Where it went to spend high tide, no one knows. Click to enlarge.]

I have recently been tweeting about this unusual persistent and pernicious pattern of easterly winds that has pretty much crushed the normally brilliant late-September neotropical bird migration in Cape May, NJ. It's been pretty depressing, especially for the many people who timed their birding vacations to hit the neotrops.

But the birding hasn't been "bad." It's just been different.

[Speaking of tides, today the normal high tide was going to come early because of the east winds, and the pool east of the Wetlands Institute near Stone Harbor NJ is a known hotspot for shorebirds at normal high tide - which luckily I figured out that today meant 3 hours before the actual forecast high tide. This juvenile Hudsonian Godwit (back bird, with yellowlegs) was exactly the species I was looking for. Perfect time, place and weather. Most HUGO's migrate offshore over the Atlantic to South America, but east winds bring them to the Atlantic Coast. Sam Wilson made a nice pick on this bird, and together we worked out which godwit it was. In this photo, the bill looks slightly foreshortened because the bird is angled towards the camera. Note the eyebrow, patterned back (indicating a juv.), and long, thin, bi-colored bill. At one point it raised its wings, showing black wing linings to rule out a fancier godwit. It was far, so this photo is heavily cropped; click to enlarge.] 

[As the tide rose, the short-legged birds - the Red Knots (there were 210+) and dowitchers (at least 2 Long-billed and 4 Short-billed) became increasingly anxious, and shuffled about trying to find bottom.]

[Soon, the American Golden-Plover, Red Knots and Dowitchers cashed it in, and headed for higher ground as the tide flooded the pool. Their legs weren't long enough to stay.]

[The big, strong, long-legged Western Willets and a few Greater Yellowlegs were the last shorebirds standing in the rapidly flooding pool, seeming determined to stay right up to the point of swimming for it. Somehow, the Hudsonian Godwit snuck out of there with only a couple members of the accumulated crowd of birders spotting it go, and no photos taken. So it goes sometimes.]

[Eventually, by about 12:15 p.m., still 2 hours to go before official high tide, even the long-legged Western Willets and Greater Yellowlegs had to throw in the towel and search for higher ground.]

[A few days ago, this was somebody's house on Grassy Sound, near North Wildlwood NJ. Northeasters are a serious business. . .]

[Take tides, northeasters, and sea-level rise seriously. This is the high-tide view of the salt marsh west of Stone Harbor, NJ today, after days of a northeaster, at about 2:15 p.m., taken from the top of the Route 147 bridge into North Wildlwood, NJ. Those houses are along the Stone Harbor Causeway.]

Here's a list of birds seen at the Wetland's Institute today. No, it hasn't been good for warblers lately, but there's always something to thrill to during fall migration.

Stone Harbor Causeway--Wetlands Institute, Cape May, New Jersey, US
Oct 4, 2015 10:30 AM - 12:15 PM
Protocol: Traveling 0.3 mile(s)
Comments: Northeaster, half tide and rising, already quite high.

Submitted from eBird for iOS, version 1.1.2 Build 27

27 species

American Black Duck 10
Double-crested Cormorant 75
Great Egret 8
Snowy Egret 15
Little Blue Heron 2
Black-crowned Night-Heron 3
Yellow-crowned Night-Heron 1 Juv
Osprey 1
Clapper Rail 1
American Golden-Plover 1 Juv
Semipalmated Plover 2
Greater Yellowlegs 50
Willet (Western) 71 Actual count, there have been a bunch here lately.
Lesser Yellowlegs 15
Hudsonian Godwit 1 Juv
Red Knot 210 Actual count.
Stilt Sandpiper 2
Short-billed Dowitcher 4
Long-billed Dowitcher 2
Laughing Gull 10
Herring Gull 10
Forster's Tern 2
Tree Swallow 300
Northern Mockingbird 1
Song Sparrow 1
Red-winged Blackbird 5
Boat-tailed Grackle 10
View this checklist online at http://ebird.org/ebird/view/checklist?subID=S25289409