Part 59

The species is unknown from Canada. During the international boundary survey, Doctor Coues found mountain plover on Frenchman Creek and obtained a specimen that is now in the British Museum. This is reported as being labeled “forty-ninth parallel,” but the point of collection was probably well within the present State of Montana.

Egg dates.--Colorado and Kansas: 74 records, April 30 to June 16; 37 records, May 14 to 26. Montana and Wyoming: 4 records, May 22 to July 9.

Family APHRIZIDAE. Surf birds and Turnstones

APHRIZA VIRGATA (Gmelin)

SURF BIRD

HABITS

From its summer home in the mountains of central Alaska the surf bird migrates down the Pacific coasts of North and South America as far as the Straits of Magellan. Twice each year some individuals make this long journey, while others are scattered along the coasts from southern Alaska southward. Consequently it may be found, chiefly on migrations but occasionally at other seasons, by those who seek it on the outlying rocky ledges, reefs, and promontories all along the Pacific coast. As its name implies, it is a bird of the surf line, associated in its rocky habitat with turnstones and wandering tattlers, unmindful of the flying spray. It well deserves its generic name, which is taken from two Greek words, aphros, meaning sea foam, and zao, I live.

Spring.--The spring migration is directly north along the coasts of both continents. It is difficult to trace the dates, as the winter range is so extensive. The latest recorded date for the Straits of Magellan is March 3; and the earliest date of arrival at the Kobuk River, Alaska, is May 29. The main flight along the California coast seems to come in March. Dr. Joseph Grinnell (1909) reports a flight at Admiralty Island, Alaska, on May 12, “a flock estimated to contain 300 waders, fully two-thirds of which were of this species.” Harry S. Swarth (1911) says that, at Kuiu Island, Alaska, between April 25 and May 6, “it was abundant and in large flocks, feeding in company with the numerous other waders frequenting the mud flats.” H. B. Conover saw it only once at Hooper Bay, Alaska, on May 18.

Nesting.--The breeding grounds and the nesting habits of the surf bird long remained unknown. The birds vanished from the coast of Alaska about the first of June and were not seen again for six weeks or more, when they appeared again with their young. Rumors suggested that they bred in the mountains in the interior. O. J. Murie (1924) gave us the first definite information, when he discovered the breeding ground of the species in the Mount McKinley Park region of central Alaska. On July 13, 1921, he was descending a slope above timber line, “when two surf birds were flushed and circled about making an outcry.” He was “presently rewarded by seeing a downy young one striding away bravely over the rough ground.” The young bird was secured and one of the parents, which proved to be the male, thus establishing the first breeding record for the species.

Five years later Joseph Dixon (1927) spent considerable time in this same region and succeeded in finding, on May 28, 1926, the first nest of the surf bird. He took some excellent photographs and made a thorough study of the bird and its habits, thus completing the picture very satisfactorily. I shall quote freely from his excellent published account of it. Regarding the nesting site and the nest he writes:

One of the most striking things about the surf bird is the remarkable difference between its winter and summer habitat. Near the end of their northward migration in the spring these birds abandon the seacoast and take up their summer residence far in the interior, from 300 to 500 miles from salt water. This involves a great altitudinal shift. Instead of living at sea level as they do at other seasons, during nesting time they are to be found on barren, rocky mountains high up above timber line. During the entire summer we never found these birds below 4,000 feet elevation.

The rocky character of the surf birds’ surroundings appears to remain fairly constant throughout the year. In summer the birds are to be found most frequently near the summits of the rock slides where the broken rocks are much the same as the rugged reefs they inhabit during the winter. We found in the Mount McKinley district that the summer range of the surf bird was almost identical with that of the mountain sheep and that it was useless to look for surf birds outside of “sheep” country.

When standing on a barren wind-swept ridge late in the afternoon of May 28, searching a nearby hillside with binoculars, Mr. Wright’s attention was attracted to a grayish bird that was sneaking hurriedly along over the rocky ground. As he watched, the bird apparently faded out of sight some 600 feet away. Marking the point of disappearance he hurried over to the spot where the bird was last seen and, falling to find the bird, began to think he was mistaken. But, upon his taking one more step, the bird flew up suddenly right into his face, startling him mightily. As the bird flew away, the large white rump patch, together with a white patch on either wing, brought realization that this was the long-sought-for surf bird. A hasty glance at his feet revealed the nest and contents of four eggs. Another step forward and he would have placed his foot directly in the nest! To George M. Wright belongs the honor of being the first white man, of which we have any record, to lay eyes on the nest and eggs of this rare bird.

The surf bird’s nest was located 1,000 feet above timber line on a rocky ridge that faced southwest and lay fair to the sun and hence was relatively free from snow. The nest site was on dry rocky ground and not on the wet tundra which was plentiful nearby. The rocky ground about the nest was clothed with a thin carpet of alpine-arctic vegetation, the tallest of which were a few creeping arctic willows less than 2 inches high. The most conspicuous plant about the nest was the white-flowered Dryas integrifolia. The nest was entirely out in the open with no bushes that afford the least concealment. In fact it was almost “out in the street,” since the eggs were within a foot of a frequently traveled trail of the white Alaska mountain sheep (Ovis dalli). There was no fabricated nest such as the wandering tattler makes. Instead, the eggs were deposited in a natural erosional depression, the sides of which had been lined with a few bits of dried-up grayish-green lichens and caribou moss. The bottom of the nest was composed of the dead emarginate leaves of Dryas integrifolia, which only partially covered the crumbling serpentine outcrop that formed the backbone of the ridge. The nest, which was barely large enough to hold the four eggs, which were placed as close together as possible, with little ends down, measured 4 inches in diameter and an inch and a half in depth. The eggs in the nest blended so well with the reddish brown moss of the tundra that it became difficult to make them out at a distance of more than 8 or 10 feet.

The nest was found at nearly 9 o’clock in the evening. They built a crude shelter of rocks near it and kept a careful watch over it all that night and half of the next day. During this time Mr. Dixon (1927) made these observations:

When it began to rain the surf bird merely fluffed up and then spread out the feathers on his back so as completely to cover the nest. This proved an effective method, because the melting snow and the rain ran readily off the surf-bird’s back and was absorbed by the moss outside the nest. We were not so well protected and were soon shivering and wet to the skin.

At 4 o’clock a female mountain sheep appeared, silently, like a ghost, out of the mist that came drifting over the mountain peaks in great white swirls. She did not see us at first, but when she was within 6 feet of and headed directly toward the surf-bird’s nest she became suddenly aware of our presence and took a step or two forward. When the ewe was about to step on the nest the surf bird suddenly “exploded” right in the astonished animal’s face. This unexpected movement and the sudden noise and flash of white of the bird’s spread wings and tail caused the mountain sheep to jump back quickly; then she whirled around and bounded off back up the trail. This sudden movement of the surf bird at the critical moment doubtless serves to prevent sheep and caribou from trampling upon its nest and eggs. We found through repeated experiments that this was the bird’s regular reaction. When we approached, whether fast or slow, the bird would stay on the nest until the last minute, and then, instead of sneaking off low to the ground like most birds do, would fly directly up into our faces. Even after we knew that the bird would do this the psychological result on our part was the same. A person would involuntarily recoil when the bird “exploded” like a firecracker right in his face.

When first frightened off the nest by Mr. Wright the previous afternoon the bird, which we later thought might have been the female, after “exploding,” ran away with wings half spread and the tail spread out fanlike and dragging on the ground. This displayed conspicuously the white rump patch. Now and then this bird would nestle down as though covering a nest. When about 100 yards distant from the nest the bird began to wander about, pretending to feed. It exhibited no concern whatever when Mr. Wright returned to the nest and examined the eggs. It made no attempt to return to the nest even after the observer had retired to a distance and waited for a period of 10 minutes, during which interval rain began to fall.

In marked contrast with this rather indifferent attitude, the bird which was watched on the nest for 16 hours, behaved in an entirely different manner. This second bird, when forced off the nest, would fly directly up into the intruder’s face, and then run off to one side, a distance of 8 or 10 feet, where it would perch on a rock, fluff out its feathers like a “sitting” hen and utter a low plaintive call, tee-tee-teet! The call would often be repeated two or three times after a slight pause of half a minute between calls. When we started after this bird it would lead us adroitly away from the nest; but if we stood still it would soon hustle directly back, even when we were standing only 10 feet distant. In going on to the nest the bird was very careful not to step directly upon the eggs. It would trot up to within a foot or so of the eggs and then sneak cautiously down to the edge of the nest. Here it would stop, inspect the eggs, and reach out with its bill and turn the eggs about, keeping them little ends down. Following this inspection the bird fluffed out the feathers on its breast and sitting down gently on the edge of the nest, slid its body forward with great care, until the eggs were completely covered.

Eggs.--I have not yet seen these eggs, so I will quote Mr. Dixon’s (1927) excellent description of them:

The eggs of the surf bird are not easily confused with the eggs of any other North American sandpiper or plover. In shape they are pyriform but, though similar in form to eggs of other birds of the order Limicolae, in color they appear more like eggs of the falcons, particularly certain eggs of the sparrow hawk and prairie falcon.

In the type set, which is now safely housed in the well-known Thayer collection, there is considerable variation both in the ground color and in the markings of the eggs. Three eggs of this set have an intensely buffy ground color, while the fourth egg is of the same color but decidedly lighter. The markings on the three eggs are bold, varying in color from fawn to bay. The markings on the fourth egg are small and evenly distributed. The four eggs may be described as follows: The first egg has a light ground color which equals tilleul-buff. In this egg the marking consists of fine splashes, one-half to two millimeters in length. There is but slight tendency for the markings to form a wreath on the larger end. A few small dark brown spots on its larger end identifies this egg, which resembles slightly certain eggs of the yellow-billed magpie. In egg number two the ground color is rich tilleul-buff, while the markings consist of bold bay-colored spots and splashes from one-half to three millimeters in length. These spots are concentrated about the larger end of the egg, where in places they are so dense as completely to obscure the ground color. A few deep-seated lavender under-shell markings are apparent on this egg. Egg number three is similar both in ground color and in markings to egg number two, except in egg number three the heavy bay markings form a decided wreath 21 millimeters in diameter about its larger end. Egg number four has the richest ground color of all, while its markings are fawn, but the markings are not so sharply defined as in the other eggs.

The four eggs measure =43.7= by 30.5, 41.5 by =31.5=, 43.3 by 31.2, and =42.4= by =31=, and they average 42.7 by 31 millimeters.

Young.--Mr. Dixon (1927) demonstrated most conclusively that the male does most, if not all, of the incubating. The bird that they had under observation for 16 hours and the only one seen near the nest proved to be the male. All of the five males collected had bare incubation patches, while none of the females had these. Mr. Murie (1924) found both parents attending the young bird which he captured; and the one shot, probably the more solicitous one, was the male. Evidence is accumulating all the time to show that with more shore birds than we realize, perhaps with all, the males perform the greater part of the domestic duties.

Plumages.--The young bird taken by Mr. Murie is still in the downy stage. The upper parts are variegated and mottled with “cinnamon buff,” brownish black, “sepia,” and buffy white; the forehead and sides of the head are buffy white, boldly spotted and striped with black; the crown is mainly spotted with black; the buffy tints are mainly on the upper back, wings, thighs, and rump; the under parts are grayish white, whitest on the chin and belly.

When the young birds come down to the coast of Alaska, in August, they are in full juvenal plumage. In this the crown is streaked with “fuscous” and brownish black, the feathers having white edgings; the chin and throat are white, with shaft streaks of “hair brown”; there is a broad band of “hair brown” across the breast, with white edgings, running into spots below, which are lacking on the white belly; the mantle is “hair brown,” with very narrow whitish edgings, giving a scaled appearance; the scapulars also have a subterminal “fuscous” bar; the lesser and median wing coverts are broadly or conspicuously edged with grayish white.

A partial postjuvenal molt in the early fall produces a first winter plumage which is like the adult winter, except that there are fewer and smaller spots on the under parts; and the juvenal wing coverts and some scapulars are retained.

Two specimens, collected in Peru on June 30, illustrate the first nuptial plumage. These are doubtless birds which do not migrate north to breed during their first year. Apparently a nearly complete molt has taken place, as the wings and tail appear fresh, but some of the old scapulars and wing coverts are retained. The adult nuptial plumage is suggested, but all traces of cinnamon are lacking; the feathers of the mantle are “fuscous” or “hair brown,” broadly edged with grayish white and subterminally bordered with brownish black; the crown is grayish white, streaked with dusky; the scapulars are “fuscous” to brownish black, broadly tipped, notched, or spotted with pale grayish; the breast and flanks are less heavily marked than in the adult. I have not seen this plumage described elsewhere. At the next molt the adult winter plumage is assumed.