Contributed by Roland C. Clement
[Published in 1968: Smithsonian Institution United States National Museum Bulletin 237 (Part 3): 1273-1291]
The tremendous energy which drives small birds toward their breeding grounds in spring is well illustrated by the way in which some of them overshoot their destination. Witness the occurrence of the eastern race of the white-crowned sparrow on Fletcher's Ice Island (T-3) on June 16, 1957, when it was at 82o37' N., 99o50' W., only 150 miles from the North Pole and some 2,000 miles beyond the nearest nesting habitat of the species, as reported by Spencer Apollonio (1958).
Because unusual observational opportunities are required to recognize such events, we are less aware of them than the facts probably warrant. But it is this sort of random exploration of extralimital territory that helps account for the ability of so many species to colonize new territory as soon as it becomes suitable. We know, today, that the margin of the tundra which forms the northern limit of the white-crown's range has been both farther north and farther south during the last10,000 years, and that the range and the population of this species have varied accordingly.
The eastern white-crown is best described as a subarctic and alpine zone bird, but so extensive is its range that only ecological characterization is really helpful. This has seldom been done and as a result "life zone" pigeon-holings are rampant with apparent contradictions. The only full awareness of the ecology of this bird in all the material before me is Harrison F. Lewis' excellent description, in a letter of July 1,1963: "In coasting along the north shore of the Gulf of St. Lawrence from west to east, in latitude slightly north of 50o, one enters the breeding range of the white-crowned sparrow abruptly on passing Saint Genevieve Island, the easternmost of the Mingan Archipelago. The reason for the abruptness of this boundary is that the Mingan Islands, which border the coast for some 50 miles, are formed of limestone, as is, also, much of the adjacent coastal mainland. Eastward from Saint Genevieve, the mainland and the coastal islands are of acidic pre-Cambrian rocks, such as granite and gneiss. The vegetation of the limestone belt is much superior to that which grows on the adjacent pre-Cambrian rocks, and the bird life reflects this; for example, the ovenbird nests on the limestone of the Mingan region, but not beyond. West of Saint Genevieve I have only a few records of sporadic occurrence of the white-crown in the nesting season."
This Mingan region is an outlier of Paleozoic rocks. In his monumental photo-reconnaisance of the vegetation and physiography of the Labrador-Ungava peninsula, F. Kenneth Hare (1959) marks it as the eastern terminus of the Laurentide massif and considers it an outlier of the coastal tundra that fringes the southeast coast of Labrador. Climatologists bring the 55o F. July isotherm, which transects the peninsula from west to east, to the coast just east of this region, and forms a rough boundary between the open subarctic woodland to the north, the closed-crown forest to the south and west, and the scrubby forest characteristic of the eastern tip of the peninsula at this latitude.
It is open, stunted tree growth and brush that attracts nesting white-crowned sparrows. At Goose Bay, Labrador, for example, I found them nesting only in the open, often burned, black spruce and dwarf birch on the high, sandy delta of the airport plateau. In better sites nearby, white-throated sparrows nested. An awareness of such temporary ecological changes in distribution allows me to view with interest the nesting reports of white-crowns at North Bay, Ontario, and at Baie Comeau and Godbout on the north shore of the St. Lawrence, as well as near Godthaab, Greenland, in 1824 (Salomonson, 1950); though I cannot credit them for lack of corroborative details on the ecology of the site.
Despite the fact that it was the first known and is the most widely distributed race, the eastern white-crown has been one of the least studied. No one has yet reported in any detail on the biology of the alpine populations of the Rocky Mountain massif, and the eastern group has only recently begun to attract the attention it deserves. In a study of geographic variation in the entire leucophrys group, Richard C. Banks (1964) reduces Harry C. Oberholser's (1932) Cordilleran race oriantha to synonymy with the eastern race, discounts W. E. Clyde Todd's (1953) proposal of the name nigrilora for the "ultratypical" Labrador peninsula population, and considers the slightly larger, reddish-backed and black-lored nominate leucophrys to be the ancestral population. "The species," he writes, "appears to be essentially a northern one which has extended southward only where summer conditions approximate those found in subarctic regions. Thus, in the western. . .United States, White-crowns are found only in high mountains and along the cool Pacific coast."
Spring.--The interaction between internal and external factors in the eastern population remains almost unreported. Only Marshall B. Eyster (1954) has shown that, compared to such congeners as the white-throated sparrow and the junco, the white-crown is much more prone to pre-migratory nocturnal unrest (zugunruhe).
Viewed from the central wintering grounds of the southern Great Plains, the spring migration involves a radiation northward. One population segment goes northwestward into the Rocky Mountain uplands, another more or less due north to the Cypress Hills of Saskatchewan and the Hudson's Bay country, but the largest segment trends far to the east of north, to summer in northern Quebec and western Newfoundland.
In an analysis of 198 recoveries and 9,107 returns from nearly 232,000 white-crowns banded between 1920 and 1963, Angelo J. Cortopassi and Richard L. Mewaldt (1965) show that migration is of a broad-front type and not oriented to landmarks--of 6,000 birds banded while on migration, not a single individual returned to the place of banding. Migration is by hops of at least 200 miles, with one 310-mile hop recorded in spring, and with a daily mean of about 50 miles. One bird banded by Ralph K. Bell at Clarksville, Pa., May 6, 1962, was recaptured 1,500 miles to the north at Battle Harbor, Labrador, on June 12, having averaged 40 miles per day.
The rapid northward surge of this species results in "a high fidelity of timing" as Cortopassi and Mewaldt put it--94 percent of the birds pass through 1,000 miles of the northeast's most populous countryside between May 2 and 18, with May 11 the median date for banding migrants in this region. Milton B. Trautman (1956) gives the principal movement at Buckeye Lake, Ohio, as May 8 to 20. In a letter to Ralph K. Bell, Gordon Wilson of Bowling Green, Ky., who has chronicled the birds of his region for 45 years, gives average departure as May 10, with May 28 as a late date.
The only evidence of physiographically-controlled spring migration I have seen is a letter from Clark S. Beardslee to Mr. Bent in 1951, reporting that in spring northbound white-crowns move eastward through Ontario, cross into New York State in the Buffalo-Niagara isthmus, then presumably circle eastward around the south side of Lake Ontario before moving northward into Quebec. Harold D. Mitchell has kindly confirmed these observations for me.
Dispersal into the subarctic breeding grounds on the interior Quebec-Labrador plateaus normally occurs during the last week of May, though late ice and snow may sometimes delay arrival a whole week. I was impressed by the influence of seasonal conditions when I arrived at Knob Lake in interior Quebec on May 18,1957. A raging blizzard made it plain that winter's grip was still firm. Returning to within 15 miles of the St. Lawrence above Seven Islands, I found white-crowns abundant and obviously "dammed up" by weather, for they were occupying all sorts of habitats that are not usual for them. They sang softly while awaiting better conditions for concluding their migration. The first birds arrived at Knob Lake on May 23 that year, but even so, they had to spend several days feeding along plowed roadsides until the snow melted from the territories they were to occupy. Harrison F. Lewis' notes show that conditions were even more severe a decade earlier; his June 4, 1947 journal entry records that this "was an abnormally cold, late spring, with consequent heavy loss of life among small migrant passerines." He recorded 120 obviously delayed migrant white-crowns at Seven Islands, south and west of the breeding range.
Territory.--Territorial behavior has not yet been described for this race of the white-crown. I have twice seen fights in early June in the Knob Lake region, the birds facing each other breast to breast, then jumping, clawing, and flying at each other. Such jousts are usually short-lived.
The white-crown does best in "hybrid" habitats, where disturbance of the surface by fire or mechanical means has increased diversity and the shrub growth is still young. Under such conditions I have found two nests only 300 feet apart, and computed territory sizes as between .88 and 1.85 acres each. On the other hand, a breeding bird census of 18 1/2 acres of open lichen woodland--the most extensive vegetative type of central Labrador--revealed a low density of two nests, or about 1 territory per 9 acres. This would be about 70 pairs per square mile, but Thomas H. Manning (1949) estimated that in western Ungava the population was between 10 and 30 pairs per square mile, the higher counts being in burnt areas.
Courtship.--The sexes being alike, it is difficult to follow territorial disputes and courtship until birds have been color-marked. No one has yet done this early enough in the season to unravel this phase of the life history of the eastern subspecies.
Within a week after arrival on the breeding grounds a good deal of territorial song is heard from about 5:00 a.m. to 10:00 a.m. and again in the evening. For a week or so thereafter the birds utter much high-pitched trilling with depressed crowns, either from the ground or from no more than 4 feet above it. This trill is quickly communicated to the whole nearby group, several other birds then repeating it. The trilling bird often attracts a companion who approaches with crest high and loud pete notes, as though alarmed, and they fly off together. Three-party nuptial chases are common at this season. More specifically, the bird that emits the high, trilling dreeeee note often crouches low, with head up, and flutters its wings as though rotated from the "wrist." I did not notice the tail-spreading and the spasmodic wing opening and closing that caught the attention of Francis Harper (1958) in this same area. As I proved by collecting, the female gives a loud chatter during these mating chases (this female contained oocytes up to 1 millimeter in diameter). Two weeks after the population arrived, while trilling was going on everywhere, I saw a female crouch and trill (I wrote whimper), and the male then mounted quickly three times. Soon afterward song fell off noticeably.
The male of the eastern white-crowned sparrow seems to share some notes and postures heretofore (Nice, 1943, and Blanchard, 1936) ascribed to the female only. On June 13, 1957, I collected a trilling, wing-flipping bird that turned out to be a male. Error is easy under the stress of collecting in close quarters, and a male that entered unobserved may have been the inadvertent victim of my search during the few seconds involved; but, again, on June 24, 1958, I saw a color banded male, the mate of a female with eggs in the nest, rotate its wings "at the wrist," in the slow wing-flutter that the female gives while trilling in invitation to copulation (Blanchard, 1936).
Nesting.--Whereas Alfred O. Gross (1937) could write that "the height of the breeding season of the White-crowned Sparrow on the Labrador coast is during the first two weeks of July," for the Labrador peninsula as a whole, most eggs are laid by mid-June. This varies greatly from season to season, however, and from region to region; the season in the higher southern third of the vast peninsula, for example, is usually later than in the lower areas farther north.
In mid-morning on June 16, 1957, I surprised a bird forming a nest. It had pulled out mixed hairy-cap mosses and Cladonia lichens for a proper cup in the shade of a dwarf birch. From a total of some 30 nests examined in situ, it seems safe to consider my description (in Todd, 1963) as typical: "four inches in outside diameter and two and five-eighths inches inside. The inside depth was one and one-half inches. The main body of the nest is woven of fine grass stems, the outside is made up of mixed moss stems, and the bottom is lined with very fine root fibers, or in one case with white ptarmigan body-feathers." Harrison F. Lewis (in litt.) once found a nest lined with light gray hair, perhaps that of a dog. Most nests set into the moss-lichen or lichen-crowberry mat are partly concealed by overhanging branches of dwarf birch or Labrador tea; not infrequently a nest is neatly tucked into the lower side of a moss or crowberry (Empetrum) mound. Much less frequently, nests are built into moss hummocks on a string of heath shrubbery some distance out in a sphagnum bog. Although I have never seen an elevated nest, Arthur A. Allen wrote me that whereas all the nests he had found in the Churchill region were on the ground, on the Labrador Coast (North Shore) "the few nests I saw were in small firs." Earlier, Oliver L. Austin, Jr. (1932) had quoted Moravian missionary Perrett's notes from Makkovik, Labrador, concerning a nest "about three feet from the ground in bushes thrown over a boat to protect it from the sun."
On June 30, 1957, I found an otherwise typical white-crown nest in a "hybrid" habitat near the airport at Schefferville (Knob Lake), Quebec, which contained 8 eggs and had 3 birds in attendance. On July 2 the eggs and the two birds that came to incubate between 10:45 a.m. and 1:30 p.m. were collected by Don R. Oliver of the McGill University Subarctic Laboratory and shipped to me at Brown University, where William Montagna dissected them. Both birds were females in comparable stages of gonadal regression, with equally developed brood patches. One bird showed two clear follicles and what appeared to be two coalesced follicles; the other had three clear follicles and one questionable follicle. Although polygyny has been reported in Emberizines before (e.g., corn bunting) this appears to be the first American record and is unusual in that only one nest was involved.
Some pairs may mate a second time. On July 10, during their 7th day of caring for young, the banded pair I had under observation at Schefferville, Quebec, performed elements of the nuptial display. The female trilled and fluttered her wings as she left the nest; later I heard her trill while out of sight behind my blind and thought that the sounds indicated a mating chase; that same day the male twittered on crossing her in flight as they exchanged visits to feed the young. E. P. Wheeler, II (in litt.) once found a bird with unhatched eggs as late as July 30 on the Labrador coast.
Eggs.--The white-crowned sparrow lays three to five, and rarely six eggs. They are ovate, though some may tend toward either short or elongate ovate, and are slightly glossy. The ground is pale greenish or creamy white and is heavily marked with spots and blotches of reddish browns such as "Natal brown," "Mars brown," "chestnut," "Verona brown," or "russet." There is quite a range of variation; frequently the spottings obscure the entire ground, while in other cases considerable ground is showing with the markings concentrated toward the large end where they may become confluent. On eggs with much ground showing, undermarkings of "pale neutral gray" may be discernible.
The measurements of 50 eggs of Z. l. leucophrys average 21.5 by 15.6 millimeter; the eggs showing the four extremes measure 24.1 by 16.5, 21.6 by 17.0, 18.9 by 15.8, and 19.8 by 14.5 millimeters.
Of 29 sets recorded, 23 sets had four eggs, 5 had five eggs, and only one had six eggs. I therefore assume the three-egg clutches occasionally reported are probably incomplete.
A color-banded pair had four eggs on June 24, 1958, when discovered, and hatching occurred July 4, so incubation is at least 11 days. The female did all the brooding of the young, so it seems likely that she also did all the incubating of the eggs, as I found her on the nest after dark. Another bird was so bothered by the wind flapping my blind during a 3-hour watch that she was off the nest as much as she was on; she changed every 1 1/2 minutes as a rule, and her longest periods on the eggs were 6 to 7 minutes.
Young.--I found that for the first and second days after hatching, the female turns the young, just as she turned the eggs earlier, at 10- to 20-minute intervals. Her brooding schedule is controlled by the male's visits, for she gets off the nest when he brings her food. He comes silently and directly to the nest, whereas she lands10 to 15 feet away, always on the same side, then hops in slowly, nearly always using the same perches. On reaching the nest she gives a few alerting chips, to which the young make no vocal response until the 5th day, and the male responds to their trilling only after the 7th day. In 1957 I noted:
"It is surprising to see how well the pale lining of the female's feathering causes her to blend unobtrusively with the straw border of the nest as she broods. The young grow so quickly that on the third day they push up the female, beg, and gape without parental provocation. They nestle deeply into the nest when the sun dips in late afternoon. On the fourth day their eyes are open during shady intervals, and fully open the next day. They hug the nest when the female scolds and no longer gape at my touch. The tail feathers are now one quarter inch long.
"By the seventh day the female has trouble brooding since the young toss and turn. The next day they scratch and preen for the first time, and anticipate the parent's return by trilling."
Feeding and nest-sanitation are shared almost equally by the parents, the male making slightly more than half the feedings, and removing slightly more than half the fecal sacs. Usually the old birds carry the fecal sacs away, but they occasionally eat the small ones. On their 8th day the young receive feeding visits on an average of one every 10 minutes. On the 9th day they will leave the nest if disturbed, but probably stay on another day or two when not pressed.
My Labrador notes contain a description of a fledgling about 2 days off the nest. It had dark brown eyes, the bill was brown, and the gape and most of the commissure corn-yellow, the tarsus lilac, and the toenails light horn gray. Francis Harper (1958) describes a young bird as having vermillion mouth linings, with commissure and tomia corn-yellow.
Richard R. Graber (1955) describes in detail the juvenal plumage on the basis of a bird from Colorado and another from Labrador:
"Forehead and crown streaked throughout with black. Crown and forehead white medially, brown laterally. Occiput dark, mottled brown and black. Nape mottled, white and black. Back streaked, black and buff. Rump and upper tail coverts rusty-buff, streaked with black. Rectrices and remiges black. Primaries edged with buff, secondaries and tertials with dull rust color. Uppermost (proximal) tertials edged and tipped with buffy white. Lesser coverts gray; medians black, edged with white; greater coverts black, edged with buff, tipped with white. Two white wing bars. Lores dark, brownish or gray. Narrow white supra-ocular stripe from eye to nape. Auriculars buff-tinged gray, post-auriculars like nape. Chin and throat white, flecked with black, and with black "mustache" marks. Under parts white, or lightly tinged with buff on chest, sides, and crissum. Chest, sides, and flanks heavily streaked with black. Belly and crissum immaculate. Leg feathers dark brown, edged with white."
Jonathan J. Dwight (1900) presumes that the first winter plumage is "acquired by partial postjuvenal moult, probably in August on its breeding grounds, which apparently involves the body plumage and the wing coverts partly but not the rest of the wings nor the tail." This is the "brown Livery," the conspicuously more buffy immature plumage, in which the head is marked by broad reddish-brown stripes instead of the black and white of the adult.
Dwight also writes that first nuptial plumage is "acquired by a partial prenuptial moult beginning the end of March which involves chiefly the head and chin and a few scattering feathers elsewhere. The black and white crown is assumed, which soon shows nearly as much wear as the rest of the plumage. This becomes grayer and the stripes clearer. Old and young become practically indistinguishable" at this stage. Furthermore, "adult winter plumage is acquired by a complete postnuptial moult."
Robert A. Norris (1954) reports an extensive prenuptial molt during March and April, except for "the alulae, the primaries, secondaries and their greater (outer) coverts, the ten outside tail feathers, and some of the feathers of the "wing lining." He felt it was "fairly certain that nonmolting birds such as my mid-March specimens would show. . .overlap between periods of molt and migration," assuming that completion of the molt requires 2 months.
Amelia R. Laskey of Nashville, Tenn., wrote Mr. Bent that she noticed unusually early beginning of crown molt during the first week of November 1932 and again in1934. In the experience of both Mrs. Laskey and Ralph Bell, crown molt is normally complete by late April. Bell's notes show that crown molt takes at least 20 days.
Food.--Perhaps the most interesting item on the food of white-crowns is Francis Harper's (1958) discovery that in spring on the breeding grounds, these birds eat the green capsules of Polytrichum juniperinum, the hairy-cap moss. In 1957 I watched one bird pick and eat 120 capsules in exactly one minute. A female collected on June 8 had nothing but these capsules in her crop, and though all the white-crowns were utilizing this food at the time, some birds also picked up small brown seeds, a few sand grains, and black flies (Simulium sp.).
Like other terrestrial passerines, the white-crown is an opportunist. The hairy-cap moss capsules it consumes in late May and early June, when snows have just melted but before many insects emerge, are at that time the most available food. I have watched them eat the new green catkins of willows. The young are fed insects as nestlings, and themselves catch flies, mosquitoes, and spiders, as everyone who has studied them has noticed. In winter they are primarily seed eaters, and in spring or any other time these are available, they take fleshy fruits such as the red mulberry or the crowberry.
Behavior.--The white-crown has long had the reputation of being an aristocrat among the Emberizines. His neat attire, striking crown, and his habit of stretching his head upward to look around have probably combined to earn him this title.
But nobility should imply natural dominance. It was not until I saw white-crowns nesting adjacent to white-throated sparrows at Redmond Lake south of Schefferville, Quebec, that I realized that the white-crown is more mousy than regal in bearing, at least in summer. I found white-throats more deliberate, less upset by intrusion, their alarm notes a quiet announcement of awareness, and their flights shorter. White-crowns, on the other hand, were much more high-strung, always running while on the ground--even if they did this by hopping with both feet--and their alarm notes were more insistent, sharp, or nervous. These differences have an environmental basis, as the white-crowns occupy open country where they are more exposed to potential enemies and pressed by the wind, whereas the white-throats occupy the sheltered brushy borders of the closed crown, Canadian-zone woodland that here reaches a northern limit.
This demeanor changes on the wintering grounds. Albert F. Ganier of Nashville, Tenn., who has studied their ways since the turn of the century, writes me that in his region the white-crowns remain in compact groups of 10 to 20 birds, hugging the same habitat week after week, either in a weed- and brush-grown fence row along some little frequented road, or in an abandoned piece of farmland where plant succession is throwing up clumps and patches of herbaceous and sapling growth. "Here," he writes, "they feed quietly on the ground, but when intruded upon rise to the top of the low growth and eye the intruder with apparent curiosity, rather than with fear. They crane their necks to get a better look and it would appear that they have not yet evolved a fear of man to the extent of most other birds." They are apparently not easily flushed out of these preferred coverts, as are the white-throats that fly ahead of the intruder.
Woodward H. Brown (1954) was impressed by the aerial feeding of white-crowns and saw them "occasionally spring 15 -18 inches in the air, returning to former positions on grape vines, catching gnats or other small insects."
In Quebec-Labrador I was impressed by the fact that females when disturbed always sneaked off the nest for 10 or 20 feet in a sort of "mouse run," but without the wing-dragging display that shore birds and other species often add before sounding any alarm. On July 3,1958, while crossing a very wet sedge bog near Lake Matamace north of Schefferville, I watched a white-crown, which I took to be a male, catch insects by running in water up to its "knees," throwing up its tail, raising its white crest high, and "flashing" its wings much as a mockingbird does to flush out the insect life from the bog mat.
On July 10,1944, at Goose Bay, Labrador, I flushed a pair of anxious adults and after 10 minutes of hunting finally drove out a close sitting fledgling which a companion and I captured with difficulty. It was interesting that three adults drove at us frantically as we chased the young bird. They decoyed boldly with the "broken wing" feint, and drew me 40 feet from the young one, returning to me each time I hesitated in following.
In 1958 at an elevation of 2,600 feet on Irony Mountain in central Quebec-Labrador, Henri Ouellet of the Canadian National Museum watched a white-crown feed a still-downy willow ptarmigan. E. P. Wheeler II, who has shared notes made during many years of patient field work in Labrador, noticed that white-crowns sometimes scratch for food very vigorously, using both feet at once as the fox sparrow does. This trait, and the tendency of white-crowns to take easily to man's newly created habitats in the northern wilderness, as song sparrows and their western congeners do farther south, raises interesting questions about the relationship of all these species. Raymond A. Paynter, Jr. (1964), in the course of a review of some North American Emberizinae, reaffirms the view that the basic differences between the song sparrows, the fox sparrows, and the crowned and white-throated sparrow groups are not clear-cut, and therefore urged that the genera Melospiza, Passerella, and Zonotrichia be merged. The existence of hybrids among the white-crowns (Miller, 1940), between the white-crown and the white-throat (Abbott, 1958), and between the white-crown and the song sparrow and the white-throat and the junco (Dickerman, 1961) lends impressive weight to the Paynter proposal.
Voice.--Often as I sat in the dusk in my tent or some miner's shack in the iron ore belt of interior Labrador in 1957, the song of the white-crown reminded me of that of a diminutive eastern meadowlark. "Especially is this so in chorus," I wrote, "and the first two notes are often like the black-capped chickadee's sweet-ee call." I syllabified one common version as, "teu-dee. . .et tu aklavik," a phrase which will mean more if pronounced in French. Everyone recognizes this song as like an imperfect white-throated sparrow song. To Ludlow Griscom it had the quality of a black-throated green warbler song, while Francis H. Allen wrote Mr. Bent that to him the song was "doleful rather than plaintive--the sweet expression of a state of utter boredom, as if the bird were saying, 'Oh, well, what's the use?"'
Harrison F. Lewis told Arthur A. Allen that he rendered the song as "Oh gee--it was the whiz-whiskey," to which the fox sparrow, so often a neighbor in the northland, would answer, "Well, my dear, why did you take it?" The open, windy nature of the semibarrens that the white-crowns occupy in summer diminishes the impression their song makes on human visitors; so many songs are wafted away on the wind that only dominant phrases force themselves on the traveler's attention. The word renditions given above are the subjective efforts of pre-technological field ornithology. Today's field students use tape recorders and analyze their input from the visual record of a sound spectrograph that allows direct reading and comparison of duration and pitch. Donald J. Borror (1961) has analyzed a number of white-crown song recordings made by W. W. H. Gunn in northern Ontario and has provided the following objective description:
The song usually begins with one to three clear whistled notes that are steady in pitch, and ends with three buzzy notes, the last lower in pitch than the two preceding. The first note is about 0.5 sec in length; if there are two or three similar introductory notes the second and third are a little shorter. The final buzzy notes are uttered at three to four per sec. Sometimes there are short clear notes or two-note phrases in the middle of the song and sometimes the second or third note of the song is slurred. One or two of the final buzzes (except the last) may begin with a short sharp note or be slightly up-slurred or both. Some songs end in a low trill rather than a low buzzy note. The songs of a given bird are usually very similar, but those of different birds often vary slightly.
The pitch of the white-crown's song is between 2,600 and 7,200 cycles per second.
Morning and evening song periods usually involve 15 to 20 minutes of uninterrupted song, and as each song is of 2-second duration and the interval between songs is 9 to10 seconds, the total output during such a burst may be 100 or more songs. I have counted 194 consecutive songs.
Francis Harper (1958) writes the principal call note as "a tsit, which, when heard near at hand, seems to have a slight metallic rasp." Charles W. Townsend and Glover M. Allen (1907) distinguished a metallic chink call note from a sharper chip alarm note. In my field notes I described the call note as pete, identical by both sexes, and the alarm notes as higher pitched than the ordinary scold note.
Amelia R. Laskey (in litt.) mentions a ventriloquial song of the immature as follows: "At first the songs, coming at intervals, seemed to emanate from shrubs some 15 feet behind the bird, but as it came closer I could see its bill open and close. It was a lengthier song than the adults give in spring, and the bird erected its crown feathers as it sang."
Mortality.--It seems to me better to get away from the connotations of the word "enemy" and simply to point out that the white-crown is subject to the usual factors that cause attrition in animal populations, whether disease, the complex of factors engendering winter mortality, or direct predation by accipitrine hawks, shrikes, weasels, and the like.
It has its normal share of parasites, both external and internal. Oscar M. Root has kindly furnished a note on the identification of Hippoboscid louse-flies, Ornithomyia fringillina, found on immature birds by Gary C. Kuyava in Minnesota; Francis Harper (1958) has taken a mite of the genus Lealaps from a juvenile specimen in Quebec; and Robert A. Norris (1954) found biting lice (Mallophaga) on dried skins and also found that four out of nine specimens examined in Georgia had protozoan infections of the blood (Leucocytozoon), and one of these, a smallish individual which had not begun its prenuptial molt on March 17, was doubly infected with the malarial parasite, Plasmodium. One adult was heavily infected with abdominal helminths, the filarid nematode Diplotriaena. The individual infected with Plasmodium also had foot tumors caused by the virus Epithelioma contagiosm. Alfred O. Gross (1937) reports the mallophagan Philopterus subflavescens (Geof.) from young on the Labrador coast, and Herbert Friedmann (1938) reports parasitism by the cowbird at Okotoks, Alberta.
Of greater population significance, probably, is the loss of young birds during the first migration. For the Quebec-Labrador segment, especially, this must be a significant decimating factor because the young of the year are often wind-drifted out to sea, where they perish unless they are fortunate enough to reach an island from whence they can return. I have been particularly impressed with this problem in their lives at Block Island, R.I., where hundreds of white-crowns appear in autumn, when cold fronts pass out to sea, all of them immatures.
Fall and Winter.--Young were on the wing as early as July 11, 1945, at Indian House Lake in northern Labrador, and Austin (1932) saw young flying on July 16, 1928 on the coast, although late July is a more normal date there. In August at Indian House Lake they were in loose family groups, feeding and playing in the alder strand that fringes the George River, and by mid-September when they leave the region, they are usually restricted to dwarf birch thickets in timberline areas on the slopes. On July 31 and again on August 3, 1957, at Scheffeville, Henri Ouellet noted a goodly number of both adults and young in the open, "feeding very little, and seemingly on the move." E. P. Wheeler's last date for Kutsertakh on the Atlantic slope of Labrador is Oct. 5, 1934.
At Buckeye Lake, Ohio, Milton B. Trautman (1940) records first arrival as October 1 to 8, with the peak of migration October 10 to 27, and the last departure November 3. White-crowns first wintered there in 1953. The ratio of immatures to adults, M. B. Trautman reports, was usually 2 to 1, though in some years there were 97 immatures to 3 adults. As earlier mentioned, on Block Island, 10 miles off the Rhode Island shore, immature birds are almost or quite alone, which suggests that adults are too experienced to allow themselves to be wind-drifted out to sea during migration. Robert A. Norris (1954) reports a wintering flock of 30 immatures to 1 adult in Georgia; he considered the sex ratio balanced.
Concerning autumn habitats, Milton B. Trautman (1940) writes, "As in spring, the birds were found in brushy situations, but many were also present in dense patches of high weeds, and in weedy uncut cornfields. Autumn sparrows were somewhat more secretive than were spring birds, and it was only by remaining quiet in a dense weed patch or brushy thicket and giving a Screech Owl whistle that a true indication of numbers could be obtained."
Robert A. Norris (1954) writes that white-crowns do not flock with other species and that on the Georgia wintering grounds he studied, the birds are "found in more open country with less cover and also farther from water than is typically the case with White-throated Sparrows." The March-April weights of his Georgia birds ranged from 23.7 grams for the smallest female to 31.2 grams for the largest male, the 13-bird sample averaging 30.05 grams. In a larger sample, however, Paul A. Stewart (1937) found that 21 adults ranged from 19.9 to 37.1 grams, with a mean of 31.26 grams; 31 immature birds ranged from 23.5 to 32 grams, with a mean of 27.56 grams.
Cortopassi and Mewaldt's (1965) plot of the distribution of this species from the Christmas Bird Counts of Audubon Field Notes shows that the wintering population has two centers of concentration, one in western Texas and southeastern New Mexico and the other in the Appalachian plateau and its western extension, the interior low plateaus and Ozark plateaus. In these two broad belts the bird-watcher may expect to see from 1 to 10 birds per hour afield during a full day's quest. They warn, however, that the Texas-New Mexico area of concentration may be the result of the oasis-like nature of suitable habitat, and the special attention this receives from the bird counters. According to their analysis of banded bird data, only the eastern race of the white-crown is regular east of the 90o parallel. Between 90o and 105o (the Great Plains region) the eastern and Gambel's races migrate and winter together. Intergrades from the west side of Hudson Bay winter mostly in the Dakotas.
The eastern white-crown has apparently been extending its
winter range both eastward and northward since about 1950. A very
few now winter fairly regularly as far northeast as the New York
City region (John Bull, 1964), where winter reports were hardly
credible 20 years earlier (Cruickshank, 1942), and quite unknown
when Ludlow Griscom (1923) summed up the status of that region's
bird life. The climatic amelioration of the first half of the
century may have facilitated this range expansion, but such new
land-use practices as the planting of multiflora (Rosa
multiflora) hedges and the great number of bird-feeding
stations that have come into vogue during this period have
unquestionably helped tide over individual birds.
White-crowned Sparrow* Zonotrichia leucophrys [Eastern White-crowned Sparrow]
*Original Source: Bent, Arthur Cleveland and collaborators (compiled and edited by Oliver L. Austin, Jr.). 1968. Smithsonian Institution United States National Museum Bulletin 237 (Part 3): 1273-1291. United States Government Printing Office