Fewer Shorebirds Migrating Along Atlantic Coast
Bird surveys have recorded declines in shorebirds passing through eastern North America during fall migration. An analysis of regular shorebird surveys found no clear trends in recent years for bird numbers in the midwestern United States, but did discover widespread losses in Atlantic Canada and northeastern US.
The surveys were conducted from 1972 to 1998 at 168 sites scattered from Newfoundland in the northeast to Texas in the south.
Overall, populations of sandpipers, plovers and other shorebirds travelling south through coastal states and provinces during July to October have decreased by 2.2 percent annually. For some species the rate is substantially higher. Solitary sandpiper, upland sandpiper and stilt sandpiper have each declined by over 6 percent a year. No shorebirds in the north Atlantic region increased significantly during the study period.
Out of 30 species that were intensively surveyed, 22 had declined in the north Atlantic region, including nine significantly, while in the Midwest, 11 species declined. The drops occurred among birds from various ranges and habitats, but were largest for those migrating along the Atlantic coast and breeding in temperate areas.
For many species, the trends were not consistent in both regions. Some that decreased near the coast, increased modestly farther inland. Populations of five species did dwindle in both regions though: piping plover, lesser yellowlegs, solitary sandpiper, Hudsonian godwit, marbled godwit and semipalmated sandpiper.
One anomaly, American golden plover, decreased significantly along the Atlantic, but actually increased significantly in the Midwest. This observation could be due to the plover shifting away from coastal to inland migration stopovers.
It's possible the other declining trends picked up in fall surveys result from birds passing through the region more quickly. This paper's authors infer though, that the lower bird counts in eastern North America mostly reflect smaller populations, since other studies more directly document recent declines of shorebirds.
Jonathan Bart, Stephen Brown, Brian Harrington and R.I. Guy Morrison. 2007. Survey trends of North American shorebirds: population declines or shifting distributions? Journal of Avian Biology. 38(1): 73-82.