Thursday, July 16, 2015

Trip report: Breton Sound islands

This past Friday I had the great pleasure of visiting three of the islands on the east edge of Breton Sound:  Gosier (now two islands), and Breton Island.  Steven Liffman piloted us out in his fast boat and also took the photos that appear below, and Dave Muth and Dan Purrington rounded out the party.

The islands are low and sandy, easily overwashed by storms.  There was essentially no vegetation on North Gosier, sparse patches of grasses on South Gosier, and a mixture of low dense scrub (north end) and scattered grassy growth (southern) on Breton Island.

The large numbers of nesting seabirds on these islands has long been recognized, and is a reason that Breton NWR was an early member of the wildlife refuge system.  They did not disappoint!  We visited North Gosier first, where there were thousands of terns, dominated by Royal and Sandwich, along with Black Skimmers.  They were along the water's edge, and packed densely into colonies in the slightly higher interior of the island.  Generally, Royals and Sandwiches nested together, and Black Skimmers were grouped off by themselves with a handful of Gull-billed Terns mixed in.  Some Caspian Terns were mixed in.  As we walked the beach of North Gosier, skimmers gave distraction displays to try and draw us away from the colony, by flying by so low their breasts touched the sand, wiggling their bodies as they did so- a ruse to look injured. 

top:  Caspian Tern settling into Royal Tern nesting colony
bottom:  Sandwich Tern nesting colony

Terns and skimmers were also abundant on South Gosier.  We rescued four Caspian chicks that were swimming in the surf, and carried them onto the beach.

As great as these islands were, they did not hold a candle to our next stop, Breton Island.  There were tens of thousands of terns crowded on the beaches of the north end, and scattered liberally elsewhere along the perimeter.  Thousands of Brown Pelicans were loafing along the shore, and the heads of more on nests were poking up from the scrub.  Scanning the sky over the island as we approached showed 3300 terns in the air, not spooked, just going about their activities.  As we walked through the interior, creches of 100-200 large but still flightless tern chicks scuttled out of our way.  We decided it prudent to not approach too closely, and headed back for the boat.  At that point our first unexpected bird of the day flew by, headed out to the water:  Neotropical Cormorant, a bird normally confined to Baton Rouge and points west.   We boated a bit south and pulled on shore again, and while disembarking spotted the trophy bird of the day:  Arctic Tern.  It allowed close approach and study for the next half hour or so, showing the full suite of marks:  solid blood red bill, gray underparts separated from black cap by a white line, pencil thin black line on ventral and dorsal surfaces of transparent primaries, short legs.

Other interesting aspects of these islands included the prevalence of Reddish Egrets- we had ten or so, the only large waders except for a single Great Blue Heron.  Hundreds (thousands?) of Black Terns were loafing, apparently summering on the islands despite not breeding in the state- half or so were in black breeding plumage.  Scattered shorebirds included Marbled Godwits, Avocets, an Oystercatcher, and a Black-necked Stilt with three downy young.  Frigatebirds appeared now and then cruising overhead.

What a great day!


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