ARQUATELLA PTILOCNEMIS PTILOCNEMIS (Coues)
PRIBILOF SANDPIPER
HABITS
As explained under the Aleutian sandpiper, this bird is probably not a subspecies of the purple sandpiper; so the name maritima can not be used for either ptilocnemis or couesi. I have therefore thought it best to follow Ridgway (1919) in the use of his names for the Pribilof and Aleutian sandpipers, rather than use the Check List names.
The Pribilof sandpiper has the most restricted distribution of any North American sandpiper. In summer it is confined to the chilly and foggy uplands of the Pribilof Islands, the equally cool, damp lowlands of St. Matthew Island, Hall Island, and perhaps St. Lawrence Island, all in Bering Sea. And its known migration range is limited to a few localities on the mainland of Alaska and in the Aleutian Islands, where it probably winters. It may breed more extensively on St. Lawrence Island than it is now known to do, but it has not yet been found breeding anywhere on the mainland. G. Dallas Hanna (1921) says:
I strongly suspect that the birds have some other extensive breeding ground than St. George, St. Paul, and St. Matthew Islands, because in September and October large flocks come to the two former islands; these appear to contain many more individuals than are in existence on all three. Whether St. Lawrence Island supplies the extra number or not remains for future determination. The winter range of the species is practically unknown, the only records being from Portage Bay, southeast Alaska, and Lynn Canal, between Alaska and British Columbia. The appearance of the birds at the former locality in flocks in spring (if identifications were correct) indicates that they wintered farther south, probably on Vancouver and other islands of British Columbia. They could hardly have come from beyond these localities and have remained undiscovered.
Spring.—The same writer says:
Spring migration takes place the latter part of April and the first half of May. My earliest record for St. Paul Island is April 15 (1915) when a flock appeared at Northeast Point. The height of migration is a little later than that date and may usually be expected from the 1st to the 15th of May. Birds are almost invariably paired upon arrival. Very few spring flocks have been seen on the Pribilofs, and they do not tarry by the beaches, but go directly to the upland nesting sites. It seems to be uncommon for more than the resident population to land upon an island in spring. The birds seem to go directly to the chosen breeding grounds, wherever they may be. This fact is of wide application among the northern shore birds. Only rare stragglers of such species as golden plovers, turnstones, and pectoral and sharp-tailed sandpipers stop at the Pribilofs on their way north, but large numbers of some of them come in fall.
Courtship.—Dr. E. W. Nelson (1887) writes:
The male of the pair seen by me on St. Lawrence Island in June kept flying up some 10 or 15 yards, its wings beating with a rapid vibrating or tremulous motion, while the bird thus poised trilled forth a clear, rather musical and liquid but hard, whistling note, which is probably the same note which Elliott likens to the trill of the tree frog. The short song ended, the musician glides to the ground upon stiffened wings and resumes his feeding or stands silently for a time on a projecting rock or knoll.
Nesting.—We found Pribilof sandpipers very common in July on the low tundra at the south end of St. Matthew Island, where they were evidently breeding just back of the beaches. They were also common in the interior at the north end of this island and on the highlands of Hall Island. We collected a few specimens of the birds, but had no time to hunt for nests. We are indebted to Mr. Hanna (1921) for his excellent account of the nesting habits of this bird, from which I quote as follows: