Sunday, May 8, 2016

Night & Day: Plumb Beach

     On Friday I joined NYC Audubon as a volunteer with a coworker of mine to help monitor horseshoe crabs. These ancient creatures each year, using climate cues and the lunar cycle, time an annual trek to the sandy beaches within protected waterways to lay eggs and continue the line.
     Why would Audubon study horseshoe crabs? Well, they are not birds, but they are tied closely to shorebirds and their survival, especially the red knot, recently listed a s threatened. Both red knots and horseshoe crabs are declining in number. Audubon counts and keeps data each year on horseshoe crabs at 4 locations in NYC, and we today helped count at Plumb Beach East. And bonus, you get to wear head lamps!
We gathered at 8pm on the overcast, windy, and cold beach, looking out toward Sheepshead Bay, where on a clear day, we'd be graced with a gorgeous sunset. The monitoring happens at the peak of high tide (8:36pm), but we had to do some prep (measuring our strides), taking water temperature, wind speed, etc.
It was a cold, rainy, generally gross week in terms of weather, and this resulted in some seriously higher than normal tides.
A carapace remains from a female horseshoe crab-- an animal that is not a crab or crustacean at all. They are in their very own family, Limulidae- putting them more closer to spider, scorpions and ticks in the great tree of life. A woman's size 7.5 foot for comparison, the females are more than double the size of some males!
You gotta be when you can lay up to 60,000 eggs.
Our first live encounter. The way the survey works is we measure out paces to sample the beach in quadrats. For our specified number of paces, we place the quadrat down and count what's within. This guy did not count as he was not in our sample area. 
Unfortunately more common than horseshoe crab that night was the marine debris, littering the shoreline.
These animals have 2 compound eyes (visible), like insects, but they also have many other sets of eyes around their carapace, under neath, and have light receptors on their telson (tail).
Our first AND ONLY, horseshoe crab for the night that was countable. Countable crabs are sexed and tallied. This one was a male. The quadrat is placed just in front of the counters toes and the number is reported to the recorder (that was my role).
A not countable pair of crabs (attempting) spawning. The male takes the rear and spawns over eggs that are laid. It is not an easy dance to be had, as they are tossed in the rough surf we had that night. In coming nights, numbers should increase. We wondered also if that nights weather had any affect on the crabs.
the first two legs of the male are shaped like boxing gloves with a hook, which he uses to hold onto the female with. He has a pretty good grip too.
With our count of one, I decided that I should come back durung the day at low tide the next day, after I finished at work, to compare the scene. Other things that we spotted that night were 5-7 fishermen, at least 100 peeps (sandpipers), we heard oystercatchers, and had a low flyover of 100-200 brant, in the dark, backlit by the Belt Parkway. It was very much a once-in-a-lifetime experience!
     I got to Plumb after work on Saturday at low tide, as opposite as you could get from the night before...
Low tide exposes both life and death. Here periwinkles eat a deceased spider crab. You could tell where something dead was (or pieces of dead things were)  by looking for piles of periwinkles.
Horseshoe crabs who couldn't escape low tide take cover by burying themselves in the silty sands of the flats. 
It is a great time for gull behavior, this herring gull is trying to figure out the best way to pick, eat, and carry his prize.

It may not look like much, but a lot is happening here... these are barnacles, on slipper shells, on the back of a horseshoe crab. Maybe a closer look will help... watch the video below:
The barnacles, a crustacean-- in the crab family, are filter feeding as these sessile animals hitch a ride on a motile being.

Gulls squabbling for food and prime spaces were common sights and sounds.
Next obstacle. eating. 
An American Oystercatcher feeds on exposed mussels.
Shorebird beaks are not one-size-fits-all, they are varies in form and function, allowing different birds to specialize in different forms of feeding and different prey.
A very late long tailed duck, a male going through a molt, into his eclipse plumage (the plumage that is more camouflaged).
He was also super close to shore-- but these images are still super cropped. These are my favorite sea ducks, tiny and adorable, but capable of diving up to 200 feet below the surface.
A ceremonious pair of Forester's terns, and lunch.
One of two willets, foraging in the mud.

A new bird for me, happy to find and ID in the field a short-billed dowitcher (as opposed to, seriously, the long-billed). 
Tent caterpillars!
 If you are interested in volunteer opportunities with NYC Audubon, they have a whole bunch of stuff they do. I am looking forward to a few more volunteer nights with them, it's such a wild, fun, and unique experience, and it is all citizen science. You are helping to collect data, that leads to finding in trends that end up helping birds, other animals, and our local ecosystems! Find out more:

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