Part 60

Adults have a complete postnuptial molt in August; I have seen one with primaries and secondaries molting as early as August 27. In adult winter plumage the upper parts are uniform “fuscous,” with only slightly lighter (“hair brown”) edgings; the chin and throat are white, spotted with “hair brown”; there is a broad band of “hair brown” across the chest and below it the under parts are marked on the breast and flanks with hastate spots of “fuscous.”

A partial prenuptial molt of the body plumage takes place in April and May, but some of the old winter feathers are generally retained. In full nuptial plumage the head and neck are grayish white, everywhere boldly streaked, or spotted, with black and slightly suffused on the crown with “pinkish cinnamon”; the feathers of the back are centrally black, broadly edged with white and tinged with “pinkish cinnamon”; but the most striking features of this plumage are the scapulars, boldly patterned with “pinkish cinnamon” and black, with narrow whitish tips; the white under parts are boldly marked, especially on the breast and flanks, with hastate, subcordate, or crescentic spots of brownish black. The cinnamon colors fade during the breeding season to pale buff and eventually to white in July birds.

Food.--On its breeding grounds in summer the surf bird feeds almost entirely on insects, mainly flies and beetles. The analysis of the stomach contents of eight birds, taken in Alaska and examined by the Biological Survey, shows the following proportions: Diptera, 55.2 per cent; Coleoptera, 36 per cent; Lepidoptera, 3.8 per cent; Hymenoptera, 3.3 per cent; Phalangidea, 1 per cent; snails, 5 per cent; and seeds, 2 per cent. Mr. Dixon (1927) says of its feeding habits:

Three days later seven surf birds were found feeding in company at midday near this same spot. This time they were foraging near the top of a very steep talus slope that lay fair to the sun. Only a few scant flowers grew amid the rocks, but insects were numerous and active. One surf bird which, when later collected, proved to be a male stood guard while the others fed. The slightest movement on my part was sufficient to cause a warning note to be given by this sentinel. When feeding, these birds ran hurriedly over the rocks, traveling as fast or faster than a man could walk. When an insect was sighted the pursuing surf bird would stretch out its neck as far and as straight as possible. Then moving stealthily forward the bird would make a final thrust and secure the insect in its bill, much in the same manner that a turkey stalks a grasshopper.

At other seasons the surf bird feeds along the water line on ocean beaches, preferring the rocky or stony shores, or reefs exposed at low tide; here it extracts the soft parts of barnacles, mussels, or other crustaceans and small mollusks, or picks up other minute forms of marine life. It also feeds to some extent at the surf line on sandy beaches or on mud flats, where it picks up similar food from the surface without probing for it. At such times the birds are quite pugnacious unless sufficiently scattered.

Behavior.--Mr. Dixon (1927) writes:

On June 18 three surf birds were seen close under the summit of a mountain. Here they occasionally ran about and picked up insects, but more often they stood still on exposed rocks and preened their feathers. One of these three birds frequently raised both wings willet fashion over its back until they almost met. These individuals were exceedingly shy and would not allow the naturalist to approach closer than 100 yards. We found that this timidity was customary during the nesting season, when the birds were encountered away from the immediate vicinity of the nest.

At 8 o’clock on the evening of June 24 I climbed to the crest of a sharp ridge of one of the lower spurs of the main Alaskan Range. As I reached the highest peak four surf birds flew in from a distance. As they circled about the peak they called, tee, tee teet loudly. Their flight was swift and plover-like. As they turned the white basal portions of their tails together with the white bars of their wings formed four white V’s which stood out vividly in the strong glow of the evening sun. They circled the peak several times, calling loudly and evidently seeking for others of their kind. Soon there was an answering call from the ground and the four birds settled down on a rocky spur where three other surf birds were already feeding. When I crawled up to within 50 yards of them all seven birds ceased feeding and began to call loudly. After a period of several minutes they began to feed again, one remaining on guard while the others ran hither and thither chasing insects over the rocks and tundra.

Florence M. Bailey (1916) says of the behavior of surf birds on the California coast:

At high tide one day two of the surf birds were standing on the sand ridge just above the water resting from their labors, one with its back to the incoming waves staring ahead of it as if lost in reverie. On the beach one of the silent, solitary Aphrizas would often stand facing me, as if studying me intently, when, though I could not read its innermost thoughts, I had a good chance to note its light forehead and eye line, its white underparts, and streaked chest. Two of the droll birds were found one day engaged in an amusing performance that suggested the sparring of boys. One turned sideways to the other as if on guard, then dropped the wing on that side and spread its tail till the white rump showed. The other in turn spread its tail and they hopped over each other, doing this a number of times. They would also dip their bills menacingly, and one of them sat down several times as part of the play. As they flew off they gave their wild key-wé-ah.

When wanting to move down the beach one often flew close along under the green wall of the combing surf. When it alit its wings would be held out for an instant showing the clear white line down their length and the broad white base of the tail with the dusky tip. When on shore they stood around so much with their preoccupied dreamy gaze that, when one took wing and flew with swift strong wing strokes out across the surf and over the ocean, a disappearing white spot, you stood bewildered. Your idle dreamer was a child of the sea! Perhaps when it stood on the sandy beach with preoccupied gaze it was dreaming of its rocky surf-dashed home to the north, or of its rocky surf-dashed winter home to the south. How well its wild, keen, plaintive key-ah-wee tells the story!

Field marks.--While standing on rocks, at a distance or when the light is poor, surf birds might be mistaken for black turnstones, but they are somewhat larger. They are more stockily built and generally darker colored than other shore birds. But in flight they may be easily recognized by the broad white band in the wing, and by the white upper tail coverts and basal half of the tail; they lack the broad white patch in the center of the back and white stripes, which distinguish the turnstones.

Fall.--The birds apparently leave their breeding grounds in July and move down to the coast of Alaska; some reach Oregon before the end of July and California early in August. Apparently the adults come first. Young birds have been taken on the coast of southern Alaska as early as August 27 and have been noted at St. Michael up to the last of September. During the fall they move gradually down the coast, lingering for the winter at favorable places.

Winter.--The surf bird winters in small numbers, occasionally if not regularly, as far north as Wrangell, Alaska. Carl Lien has sent me the following notes from the coast of Washington:

Destruction Island lies 50 miles south of Cape Flattery and 3 out from the mainland. It is 35 acres in extent and surrounded by extensive reefs which are uncovered at low tide. There are numerous rocky ridges that are well above the water at high tide, these ridges forming little protected bays and harbors.

I first went to this island in December, 1910. On nice days when the sea was smooth it was my custom to row around the reefs observing the birds. I found the surf birds generally in company with Aleutian sandpipers and black turnstones. There would be a half dozen on this reef and similar bunches on neighboring reefs. Their actions were very lively, now running to a higher point on the rock as the wash from the swell came rushing up, now running down again as the water receded, feeding busily. The only thing I ever found in their stomachs was small mussels about an eighth of an inch long, occasionally up to a quarter of an inch. The following autumn they returned though I did not note the date. I saw them from time to time during the winter in the winters of 1912–13, 1913–14, 1914–15, 1915–16, 1916–17. They would arrive the last week in October or the first week in November. The flock on its first arrival would number about 200 birds. They would begin to leave the island the 1st of April and by the 1st of May there would be none left. They did not visit the high parts of the island but confined themselves to the reefs and gravel bars. They were very wary and hard to approach on foot though they would sometimes allow a boat to come within 10 yards.

DISTRIBUTION

Range.--Western North and South America.

Breeding range.--The breeding range of the surf bird is evidently in the higher mountains of the interior of Alaska. The nest and eggs have been found on one occasion only, in the Mount McKinley district (Dixon, 1927), but Murie (1924) found young, apparently about a week old, at the headwaters of Forty-mile River. There also seems a strong probability that the species breeds in the Selawik Range on the south side of the Kowak Valley (Grinnell, 1900), and in the region around the head of the Savage River in the Alaska Range (Murie, 1924).

Sharing a trait with other shore birds, some nonbreeders frequently remain through the summer at points far south of the breeding grounds. During this period they have been noted in California (Santa Barbara and the Farallone Islands); Oregon (Newport); and Washington (Destruction Island and Camp Mora, Clallam County).

Winter range.--In winter the surf bird is found on the Pacific coast both of North and South America. It has been detected south to the Straits of Magellan (Van Island in Trinity Channel), and at other points on the coast of Chile (Valdivia, Paposo, and Atacama); and Peru (Pisco Bay). At this season in North America it has been collected or observed in California (Monterey and probably San Francisco Bay region); Oregon (Cape Meares, Cannon Beach, and the entrance to Yaquina Bay); Washington (Jefferson County and Destruction Island); and Alaska (Wrangel and Craig). These latter records would appear to indicate that some individuals are only partially migratory.

Migration.--Because of the extensive areas that may be occupied by the species, particularly in winter, and in view of the scarcity of existing data, it is difficult to present an adequate picture of its migrations. The following dates may, however, throw some light on its movements.

Spring migration.--Early dates of arrival are Lower California, San Geronimo Island, March 15; California, San Diego, March 19; Oregon, Newport, March 21; Washington, Puget Sound, March 8; and Alaska, Admiralty Island, April 17, Forrester Island, April 20, Kuiu Island, April 25, Craig, May 9, and Kobuk River, May 29.

Late dates of spring departure are Chile, Van Island, March 3; Lower California, San Geronimo Island, April 13, Turtle Bay, April 14, and Abreojos Point, April 19; California, Los Angeles, May 1, Santa Barbara, May 4, Point Pinos, May 10, and San Nicolas Island, May 15; Oregon, Newport, May 3; and Washington, Jefferson County, April 28.

Fall migration.--Early dates of fall arrival are: Alaskan coast, Sitka, July 21, and Nushagak, August 9; British Columbia, Porcher Island, July 12, and Queen Charlotte Islands, August 2; Oregon, Newport, July 24; and California, Monterey Bay, August 3, and Point Pinos, August 5.

Late dates of fall departure are: Alaska, Craig, September 4, Sitka, September 5, and Nome, September 9; British Columbia, Comox, September 2; Oregon, Netarts Bay, November 19; and California, Berkeley, October 24.

Egg dates.--Alaska: One record, May 28, 1926.

ARENARIA INTERPRES (Linnaeus)