Wednesday, June 29, 2011

Day 30: The skimmer "S"

Week two of platform recon is complete. Here are the species by number of visits: starling 9, red-winged blackbird 7, mockingbird 6, osprey 2 and sparrow 1. The osprey arrived around 7:00 AM on two days, remaining each day for a half hour. On the second day, two showed up.

During takeoff one managed to dislodge the Styrafoam wedges holding my camera trap in place. A more stable mounting system is now being employed.

Skimmers sliced across the marsh throughout the day, sometimes three at a time. I'd seen many feeding on the bay side of Breezy Point, usually at dusk. Years ago, while fishing there, I unintentionally clotheslined one (it quickly returned to its activities unscathed). Today was the second time I'd seen them use the marsh, where plenty of killifish are to be had at low water.

The main channel is narrow, about twenty feet across. That's not much of a runway for a bird that flies with half its face in the water. But today I observed an incredibly acrobatic strategy for getting the most out of the little marsh. Instead of making one long pass lengthwise, the skimmers made multiple dips on an S-shaped sweep, dipping in for just a few seconds before banking hard to come around for another dip. They caught fish on nearly every attempt this way. Because I watched this from the opposite side of the marsh, without a camera, this crude recreation will have to do...

Least terns were present as well, but the green herons were especially bold today. Perhaps that's because of the willets. They've been less aggressive toward me and everything else. I'd seen them chase away the green herons so many times that I was astounded to see this chummery.

On to cleanup. As the main stems of the marsh are gradually cleared of debris (indicated yellow) we turn our attention to the smaller channels (indicated red), which sit on mounds of debris above the high-water mark. This means water rarely penetrates a significant portion of the marsh.

One way to promote tidal flooding is to gradually deepen these channels by shovel. Researchers Juan Gallego Fernandez and Francisco Garcia Novo found that after opening channels to create a ditch network on a marsh restoration in Spain, fish immediately colonized the new water paths 1. This technique is employed widely, and notably in the case of the Hackensack Meadowlands, where the creation of more channels improved water quality by creating greater water surface for oxygen exchange and increasing tidal flushing 2. Sarah and I have begun prepping the smaller channels by clearing them of wood and debris in hopes that we can deepen them in the future.

High of 83, max humidity 91%, average wind ( ) @ 2 MPH, 5.6 high tide @ 06:30 PM. Moon 12% visible.
Water level recorded at 4 inch mark.
Birds seen in marsh: red winged blackbird, willet, common tern, least tern, skimmer, osprey, cedar waxwing
Birds seen in bay: laughing gull, herring gull, willet, mallard

1. Weis, Judish S. and Carol A. Butler. Salt Marshes: A Natural and Unnatural History. Rutgers University Press, New Brunswick, 2009. P. 178
2. Ibid, p. 208

Wednesday, June 22, 2011

Day 29: Sharp terns

The marsh fish fell under heavy fire today, as various seabirds took advantage of the low water to snap up easy meals. A lone skimmer swept the pond twice before snatching a killifish and gliding off to the ocean. But the major assault came from the least terns. At first, I was a little slow on the draw.

But the robin-sized seabirds gave me hundreds of opportunities to study their strategy. It begins with a jittery yet controlled hover around 30 feet off the water, where it can find a target without being detected. Its countershaded white underside makes it invisible against the sky, especially on an overcast day like this.

Once locked into position, it releases the air from its wings and begins its descent.

Dropping quickly now, the legs press against the chest to reduce drag, and the wings make minute adjustments as the target nears.

A split second before impact, the wings fold inward and backward, and tern becomes torpedo.

Immediately upon entry the tern rights itself. Wings always emerge first.

Hit and miss. The majority of the attempts I witnessed failed, which speaks to the killifishes' successful evasive strategy. But catch or no catch, the terns lift off to try again. Their dramatic emergence doesn't look like much, until it's stopped at 1/3200th of a second.

One more and I'll move on.

Sarah and I began our day with a stranded horseshoe roundup. Rammed headlong into the sand this way, they almost look like crash-landed extra terrestrials. Or cruel experiments involving cannons and schoolboys. But this is a normal predicament. When they can't escape the marsh on the outgoing tide, they dig in to stay moist until the water returns.

Since the water won't reach them for a week, we assure safe passage to the bay.

The massive tides of late pushed a lot of debris against the bank, where it made for easy removal.

While raking, a flapping commotion was heard in the heart of the marsh. This is one of the few patches of spartina that isn't regularly flooded, and it is heavily guarded by the willets. I clambered up the wood pile to investigate, and witnessed this, taken from the Cornell Lab of Ornithology:

Male approaches female from behind; when <1.5 m from female, male calls “click-click,” depresses tail, increases rate of calling, raises wings over back and waves wings with increasing frequency; display lasts 20–30 s (Hansen 1979). Receptive female lowers head, squats, and raises tail and utters “click”; male flutters to mount and grabs head or neck of female (Hansen 1979). Female regulates duration of copulation, often interrupting coitus (Vogt 1938, Douglas 1996). 

Although it's late in the season, this bodes well for one or two Rocky Point willet chicks. Meanwhile, hundreds of crab holes pockmark the sand and mud surfaces of the marsh. Despite this, one rarely sees an actual fiddler crab. The instant a threat is detected they vanish into their burrows. They eventually emerge, but only after a good long wait.  So today I put the timelapse to fiddler surveillance. This was a test... I hope to shoot a full fiddler bonanza next time the conditions are right. [One shot taken every three seconds for 40 minutes, animated at 30 fps.]

High of 80, max humidity 78%, average wind ( ) @ 9 MPH, 4.9 high tide @ 12:59 PM. Moon 74% visible.
Water level recorded at 8 inch mark.
Birds seen in marsh: red winged blackbird, willet, common tern, least tern, skimmer
Birds seen in bay: laughing gull

Thursday, June 16, 2011

Day 28: Platform recon and supertide

I'd been curious about the osprey sighting. Had it been a fluke visit that I just happened to witness, or were they actually considering moving in? Or, were lusty ospreys simply using the platform as a by-the-hour motel room, never intending to stay? To find out, I mounted a camera trap to the perch post and kept it up there for five days. I programmed the camera to shoot a burst of two photos every time it detected motion, and to wait two minutes before detecting motion again.

Listed in order of how frequently they visited, the camera recorded: starlings (big surprise), willets, mourning doves, red-winged blackbirds, and a grackle.

And this.

The osprey leisurely spent three hours dining on a large menhaden, here compressed to 12 seconds:

But it only made this one appearance. I doubt the platform will be occupied this season, but it's nice to know the ospreys are still making use of it.

Another raptor made a cryptic appearance about an hour before I arrived. Leave a comment if you can ID. My guess is that it's a peregrine falcon, based on the wing and tail pattern. They nest on the Marine Parkway Bridge, less than a mile and a half away. But it's hard to imagine the willets would let it stay for long, especially with photos like this circulating the internet. The mystery bird vanished after two shots.

Sarah V. spent her second day at the marsh and her first day of "real toiling." She's already made a lot of progress and hopes to come regularly until classes start.

The two of us cleared a respectable swath of debris.

After Sarah left, photographer Francois Portmann showed up to shoot timelapses of the supertide with me.

The tide was predicted to reach 6.6 feet, and it won't be that high again until April 2012. After setting the cameras to roll we went exploring. This was my first evening in the marsh. By 7:00, the channels had become torrents, ripping the horseshoe crabs from the bottom and tumbling them into the marsh. Once there they droned about in slow circles like so many pool cleaners. Well over 50 were counted.

The females burrowed in to lay eggs and were piled upon by the males, who released their sperm in fizzy trickles. (Excuse the shaky photo, it was dark).

Among the flotsam that floated into the marsh was this egg. It slightly resembles an osprey egg, but it doesn't seem blotchy enough. Then again I'm no egg detective. Leave a comment if you can ID. [update: it's a herring gull egg, thanks Chris and Don]

In with the horseshoes and flotsam poured hundreds of killifish. Meanwhile, the channel banks lined up with anxious beaks. A great egret, a snowy egret, a green heron and three black-crowned night herons took turns spearing the water and coming up with fish. The killifish weren't the only life forms under attack. As the night wore on, a squadron of mosquitoes laid siege to Francois and yours truly. They plunged their syringes into hair and clothes, between the fingers and behind the ears, leaving me just enough blood to make it home. But it was a small price to pay to experience the marsh at its most dynamic hour.

Here's the three hours of peak tide in 17 seconds:

High of 84, average wind NNW @ 8 MPH, 6.6 high tide @ 08:20 PM. Moon 98% visible.
Water level recorded at 26 inch mark (record high).
Birds seen in marsh: cardinal, red winged blackbird, willet, green heron, great egret, snowy egret, black-corwned nigh heron, common tern, least tern, oystercatcher, crow, skimmer
Birds seen in bay: red-breasted merganser

Saturday, June 11, 2011

Day 27: Whatchu talkin bout, Willet?

NPS intern Sarah spent her first day in the marsh today. Upon arrival we found the willets chasing a heron around. Having driven off the heron, the willets turned their attention on us.

When they weren't dive bombing they were guarding my equipment.

Or house sitting for the ospreys, which haven't been seen since last week's encounter.

The water was low, and bottom of the main pool twitched conspicuously. I'd seen a crab in there before, and was afraid it might be the invasive green crab. But I was wrong. They were Callinectes sapidus, better known as the blue crab of jumbo lump fame. This photo shows how deftly it blends into the sediment of the marsh bottom.

As the tide rose they began their seaward migration through the sandy channels, where they were more easily photographed.

On the eastern edge of the mouth I found several horseshoe orgies. One male attaches to a much larger female, and is joined by other "satellite" males. The larger the female, the larger her following. She slips a few thousand eggs just under the sand near the high tide line. At that point the waiting males blast their sperm.

After conducting a series of paternity tests, University of Florida Biology Professor Jane Brockmann discovered that although satellite males aren't as close to the 'action' as an attached male, they often succeed in fertilizing eggs through strategic positioning.

Inside the marsh were dozens of ribbed mussels, Geukensia demissa, filter-feeding during the tidal shift.  The mussels of Rocky Point might present an interesting opportunity for research, since they appear to thrive despite week-long dry spells.

High of 87, average wind ESE @ 5 MPH, 5.8 high tide @ 03:42 PM. Moon 59% visible.
Water level recorded at 4 inch mark.
Birds seen in marsh: red winged blackbird, willet, green heron, great egret, common tern, least tern, oystercatcher, crow, skimmer
Birds seen in bay: black-bellied plover, ruddy turnstone, red-breasted merganser

Sunday, June 5, 2011

Day 26: Osprey tease and willet kamikazes

We have ospreys on the platform, that's the good news. The bad news is that they took off as soon as they saw me.  I might have disturbed a he'n-she'n session, but to my credit, there was at least an acre of heavy shrubbery between us. That's plenty of privacy for most lovers. I immediately called Tony who came down and watched them circle the platform for a few minutes. We decided to give them a break and sneak around the bay side to see if they'd returned. After a half hour they hadn't. But it's a good omen, I think. [UPDATE: Broc checked Sunday and they still weren't there]

The willets were very vocal today.

In flight they are said to make a "pill-will-willet" sound. But those field guide song descriptions never sound like the real thing to me. Birds create matrices of consonants and vowels beyond the purview of the English alphabet. Describing bird call through written word is like describing thrash metal through interpretive dance.

I didn't manage to record the "pill-will-willet" flight call, but I did capture their unceasing ground sound:

Two pairs occupy the marsh now. They nest in the spartina grass. Anytime I would approach their little area, one of them (I can't distinguish between sexes) would make a low beeline for my face and veer off about four feet away. Always to the right.

I didn't see any eggs or chicks, but I did find a small mound of downy feathers which might have been the remains of an unlucky hatchling. If that's the case they'll probably try again.

On to cleanup. During low tide periods I focus on raking the infinite mats of plastic debris woven into the dead grass. I wonder what conclusions the alien archaeologists will draw when millennia from now they discover the obscene variety of expendables we manufactured from such an in-expendable resource. Below is my homage to the material that makes the world go round.

I invite any 'found materials' artist to drop by sometime. We can also offer you an endless supply of water bottles, shopping bags, and household detergent/ cleaner/ drano-type bottles. Consider where these things might end up next time you toss one in the trash. The stuff is so small and widely dispersed that it spoils not only the environment but my before-and-after shots.

High of 78, average wind NW @ 9 MPH, 4.8 high tide @ 10:21 AM. Moon 4% visible.
Water level recorded at 3 inch mark.
Birds seen in marsh: mallard, dove, starling, red winged blackbird, cardinal, willet, osprey, common tern, least tern, oystercatcher, crow, skimmer