Migrators need staging areas

Recently I’ve been rewarded with a few sightings of migrating shorebirds. Last week I recounted seeing a lone least sandpiper among the rocks at high tide at a small beach I frequent. This past Tuesday, after a day of almost torrential rain, I again found myself heading to the ocean.

Dusk was fast approaching; the sky was still gray and ominous, but there was a change in the air that signaled the approach of a cold front. The sea, gunmetal gray, was quiet now; the sand underfoot speckled with raindrop imprints.

Tendrils of mist rose from the islands offshore.

I had the beach entirely to myself. As I enjoyed this somber, mysterious mood brought on by the change in weather systems, I noticed small forms moving along the sand flats exposed by low tide.

At first, I only noticed a few birds, but as I looked more carefully, several more popped into view. I noticed three more least sandpipers, as well as six semipalmated plovers and four semipalmated sandpipers.

The least sandpipers scurried among the rack at the high tide line, probing underneath clumps of seaweed and among small grassy tussocks for their food. These diminutive shorebirds were so small and moved so quickly that at times they looked like mice running on the sand.

The plovers and semipalmated sandpipers frequented the wet sand farther down the beach, but each had different foraging techniques. The plovers rely more on sight and tended to search near pebbly areas. Twice I saw one grab a fat sandworm and tug it out from among the stones.

The sandpipers, however, rely less on sight in procuring food. The tips of their bills have tactile and chemo-sensitive nerve receptors which allow them to locate prey beneath the sand by touch, smell, and differences in pressure.

None of these shorebirds breed in Maine; they are transient visitors during migration.

Another migrant sandpiper – which I haven’t seen – is the red knot. This beautiful shorebird with the robin-like red breast breeds in mid-to-high Arctic regions spanning the globe. Migration for one subspecies of this bird means a 10,000-mile trip from the top of the world to “the world’s end” – Tierra del Fuego, the southernmost point of South America.

As I had mentioned in a previous column, habitat conservation for migratory bird species is challenging and daunting. Long-distance migrants such as this shorebird (among others) often rely on “staging areas,” areas that supply concentrated, super-abundant food in a relatively short period of time. Such staging areas enable the birds to fatten up in preparation for nonstop flights of thousands of miles to their final destinations.

If the productivity of such staging areas is compromised – either because of habitat loss and degradation or overharvesting by humans – bird populations that depend on them will suffer. This appears to be the case with the rufa subspecies of red knot, according to a report by the Defenders of Wildlife, which cites a new status assessment from the U.S. Fish and Wildlife Service.

The FWS assessment states the rufa red knot has declined so radically as to possibly face extinction “within the next decade.”

For years now, I’ve been reading dire predictions of what would happen if we didn’t smarten up and improve our stewardship of the planet. I never expected to hear that a species would become extinct in my lifetime, but yet it looks as if this may be exactly the case – and not only for this one species of shorebird. The red knot’s drastic decline is just the latest in a long line of troubling changes which have taken place in many different animal populations the world over.

As I think about the plight of the red knot, I remember the shorebirds I had the pleasure of observing earlier this week. How long before extinction is predicted for them?

For more information, visit Defenders of Wildlife, at www.defenders.org ]www.defenders.org, or view the FWS status assessment at www.fws.gov/northeast/endangered/Red%20Knot%20Assessment%20May%202007.standard.pdf.

BDN bird columnist Chris Corio can be reached at bdnsports@bangordailynews.net