Tag: beach ecosystem

Endangered

Earlier this week, Carol and I walked on a beach in Maine where we saw two endangered bird species, Piping Plovers (Charadrius melodus) and Least Terns (Sternula antillarum).

Small sand-colored bird, standing in the sand, covering a chick with its wing.
Piping Plover with a nestling
Small gray and white bird nestled in the sand, perhaps sitting on a nest.
Least Tern — this bird remained stationary while we watched it, and may have been on a nest

Both these species nest on the beach above the high water mark. Nesting in the sand was a useful evolutionary adaptation for most of these birds’ existence. However, in the last hundred years as humans have used beaches more and more heavily. Many former nesting sites have either been eradicated. Other nesting sites see such heavy human use that nesting success has dropped precipitously.

Take the Piping Plover. The main strategy they use to evade predators is their cryptic coloration — when threatened, they squat down in the sand and are almost invisible. But this adaptation is counterproductive when the birds encounter over-sand vehicles (the birds and their nests get smushed), or off-leash dogs (the birds are found by smell, not sight) or oblivious humans playing on the beach (again, the birds get smushed). Then when some humans try to enact regulations to protect the birds — like restricting dog-walkers’ access to nesting areas, or prohibiting over-sand vehicles near nesting areas — many humans don’t comply with the regulations. So at another location in Maine this week, I saw a human with an unleashed dog standing right next to a marked nesting area where a few hours I had earlier seen a Piping Plover.

This is an example of how land use change and human overpopulation have caused rapid species decline over the past several decades. Now we can add another threat to these two species. Global climate change is already causing rising sea levels. If sea level rise continues, the preferred nesting locations for these birds is going to disappear.

It’s easy to sink into despair and imagine that these two species will be extinct in the next couple of decades. But while I’m not optimistic, there is still hope. Because even though humans are pushing these species to extinction, it’s also possible that they can be saved from extinction by careful human management. For that reason, I’ve decided that “management” is my new synonym for “hope.”

Intestine seaweed

There’s a species of seaweed that grows along the coast here in Cohasset with the scientific name Ulva intestinalis; so named because it looks like intestines. A common English name for it is Gutweed, though I’d rather call it Intestine seaweed.

Anyway, it’s one of my favorite seaweeds. How could I not like something that looks like little green intestines?

Strands of green tubular seaweed lying on a rock.

Limantour Beach

Photos from our trip to Point Reyes National Seashore:

American White Pelicans (Pelecanus erythrorhynchos) feeding in Estero de Limantour, watched by a Great Egret (Ardea alba)

Moonglow Anemone (Anthopleura artemisia) in a tidal pool formed from a ship’s engine block on Limantour Spit

One of about 145 Giant Bell Jellies that we saw stranded on Limantour Beach. Not a true jellyfish, this organism is actually a colony of smaller hydrozoans. The purple spots are ocelli, or primitive eyes.

Kelp

Bull Kelp, Nereocystis luetkeana, Half Moon Bay State Beach

This is apparently an air bladder of Bull Kelp (Nereocystis luetkeana), but with a much shorter stipe (or stalk) than that usually associated with this species of macroalgae. Carol found this beautiful organism when we were on a walk at Half Moon Bay State Beach late this afternoon (I walked right by it because I was too busy looking at Sanderlings and Mew Gulls).

References:
Peter Alden and Fred Heath, National Audubon Society Field Guide to California, p. 87.
A. L. Baker, An Image-Based Key: Algae (PS Protista), Cyanobacteria, and Other Aquatic Objects, Nereocystis.
Washington State University, Intertidal organisms EZ-ID Guide, Nereocystis luetkeana (Bull Kelp).

Rensselaer, N.Y., to Saco, Maine

A short drive today, so by three o’clock I had set up my tent, and started walking up the beach. Very light rain fell off and on, but that didn’t reduce the number of people on the beach by very much. In the short stretch of beach between Ferry Beach Camp and Conference Center, and the entrance to Ferry Beach State Park, I passed a dozen families set up with towels, three different guys casting bait in hopes of a striper coming by, a dozen people walking up or down the beach, and half a dozen people tossing a frisbee around.

As soon as I got away from the beach, and onto the trails in the woods of Ferry Beach State Park, I didn’t see another human being. Probably the mosquitoes kept them away. There is plenty of open water in the woods behind the dunes this year, plenty of places for mosquitoes to breed. And then I heard a Veery singing, that strange downward spiraling song that is one of the most haunting and beautiful bird songs I have ever heard: a bird song worth driving three thousand miles to hear.

Three predators

This afternoon, we went for a walk at Purissima Creek Redwoods Open Space Preserve in the Santa Cruz Mountains southwest of San Mateo. It was a stunning afternoon, warm but not too hot, with fog beginning to roll in up the canyons from the ocean.

As we hiked down into the preserve, we kept hearing a hawk screaming somewhere in the distance, but we never saw it. And then when we were hiking back up to the parking lot, there it was overhead: an accipter flying over the ridge we were on, then turning and riding the breeze coming up the canyon to our right. And what kind of accipter was it, a Cooper’s Hawk or a Sharp-shinned Hawk? I’d say it was perhaps a little larger, the neck a little longer, the tail a little more rounded, the wingbeats a little more deliberate: probably a Cooper’s Hawk, but I’m not good enough at field identification to be sure. It wheeled around, high above the canyon floor but at eye level for us; a couple of Band-tailed Pigeons came over the ridge, saw the accipter, and quickly ducked into the trees below us. Then the fog rolled up the canyon, and it was gone.

As we continued up the trail, Carol got about a hundred feet in front of me. Suddenly we both froze: walking the trail well up the hill in front of us was a dog-sized canid: a Gray Fox, its long tail behind it, its head turning from side to side, giving us a flash of the rufous fur up the side of the neck. It didn’t seem to notice us; it was busy watching the undergrowth on either side of the trail, and at least once it pounced at something.

We got back to the car a little after seven, and decided to go down to the beach to eat dinner. It was a beautiful foggy evening, and we walked along past Heerman’s and California Gulls, but the real attraction of the beach was the Velella velellas. When I was reading up on this species last night, I found a Web page by Dr. David Cowles that gave a possible reason why so many Velella velellas have washed up on northern California beaches:

“The angled sail makes it sail at 45 degrees from the prevailing wind. Some have a sail angled to the left, others to the right. Off California the right-angled form prevails, and these remain offshore in the prevailing northerly winds. Strong southerly or westerly winds, however, may bring huge aggregations ashore.”

We walked down the beach, making an unscientific survey: of the dozens of individuals we saw — ranging in size from less than two inches long to one that was as long as my notebook or approximately four inches (10 cm) long — all the sails had the same handedness (according to Dr. Cowles’ terminology, right-angled sails). Here’s a sketch from my notebook:

BlogAug0214

I picked one up by its sail to look at the tentacles hanging down underneath. The velellas, like the fox and accipter, are predators, feeding on smaller organisms with their dangling tentacles. The tentacles seemed to descend from the central oval, and were of varying lengths. The sail itself felt smooth, flexible, and slightly rubbery; I dropped it back into the waves after I had looked at it.

Three very different predators — but each one a fabulously beautiful organism.

Dinner for gulls

Walking down the beach this afternoon, I paused to watch a Herring Gull flying along with something in its mouth. It landed near me, and dropped a good sized crab on the sand. The crab landed on its legs and started to scuttle away, but after fumbling once, the gull expertly flipped the crab on its back. The crab weakly waved its legs in the air while the gull tilted its head on one side so it could look at the crab with one eye.

I walked over so I could better see the crab. The gull kept an eye on me, and when I got within ten feet of it, it flapped its wings, rose in the air, and settled down twenty feet away, screeching at me. The body of the crab was a good four or five inches across — perhaps a foot across with the legs. With the toe of my shoe, I flipped it over to get a better look. The upper side of the carapace was a reddish-brown color, so it was probably Cancer irroratus or Cancer borealis. The crab plowed its head end into the sand and began to move slowly and feebly along. I walked about twenty feet away, and turned to watch.

When I was a safe distance away, the gull flew back in. Again, it expertly flipped the crab onto its back. Then it stabbed sharply into the crab’s vulnerable underside; the crab’s legs waved feebly; the gull stabbed again; and once more, on this last stab bringing a chunk of flesh up. The crab’s legs twitched a little. The gull flipped its head back and swallowed the piece of flesh, then stabbed again and again. The gull was a messy eater, and little chunks of carapace and flesh and bits of leg got scattered around on the sand. The crab had stopped moving by this point. I left the gull to its dinner, and walked on down the beach.