2017-02-17 Isla Socorro, A Day At The Beach

Yesterday was a big day exploring the higher elevations on Isla Socorro. To investigate as much diversity as possible, we visited a beach on the opposite side of the island where the sheep never grazed. The crew found a small cove for us to explore on the northern tip of the island. We travelled along the eastern flank of the island and got great views of this part of the island’s shoreline. It was a beautiful sunny day, and the sea was mild-wild. There were signs that the calm seas that had blessed the voyage to this point may be ending.

We encountered at a distance, some whales which I believe were Humpbacks. Bottlenose Dolphins came into view this day as well. Diane Alps, our marine mammal expert explained that the population of Bottlenose Dolphins found here were darker in color than their counterparts elsewhere in the Eastern Pacific Rim.

When we left the mountain the previous day, several members of our party elected to spend the night on the mountain. The insect team was part of this group, so several of us captured bugs for them in their absence. There were antlion cones all over the island. I grew up with these insects and knew how to catch them, so I relived part of my childhood this day. If you’ve never seen, or recognised one of these traps, let me describe one to you <Wikipedia-Link>. The bug (actually it’s the larval stage that constructs these traps) excavates the trap by digging with its head and flipping the scooped dirt some distance. Eventually it will end up and the bottom of a conic hole with the steepest sides the fine substrate will allow. The creature sinks its body below the visible surface and waits for an ant to fall into the trap. When an ant falls into the trap, it will try to climb out, but the antlion tosses fine sand above its victim, causing the hapless insect to fall until the antlion can capture the prey and suck out its insides. By scooping up the entire structure in my hand, I’m able to feel the creature burrowing down to escape. By removing the sand from my hand, a little at a time, I can capture this interesting little animal. Not all the cones have an antlion at the bottom. By taking a fine, hair-like tool (such as a small stick or blade of grass) and simulating the disturbance and ant would cause, and watching for the antlion kick dirt over its suspected victim, you can determine which hole is occupied. While I did not photograph the antlions, I collected one for Jim Berrian and Ida Naughton, our insect team.

Behind the sand berm that stood beside the beach was a line of mangroves that anchored the sands. Behind these mangroves was a small saltpan, dry on the surface, but wet and gooey just below. Here I found a Sanderling and a couple dozen Least Sandpipers. Both, I’m told, were first records for these species on the island. This was my final landing on this remarkable island.

Images from this day are shown below: