Occurring in scattered portions of the southwestern U.S. where it is a year-round resident, the Rufous-crowned Sparrow is inconspicuous and has been little studied. Rufous-crowned Sparrows prefer to walk or run rather than fly, and often stay out of sight under vegetation.
It is thought that Rufous-crowned Sparrow pairs may stay together year-round, but more study of this is needed. Outside of small family groups, the Rufous-crowned Sparrow is seldom seen in flocks. Its nests are rarely parasitized by Brown-headed Cowbirds.
While most of its range lies in Mexico, the Rufous-winged Sparrow does reach portions of southern Arizona where there is appropriate bunchgrass habitat. The breeding season of the Rufous-winged Sparrow in its arid environment typically begins with the summer monsoon rains in southern Arizona.
Although historical reports of Rufous-winged Sparrows included references to nest parasitism by Brown-headed Cowbirds, few modern examples exist. Cowbird egg laying is typically coming to an end by the time the Rufous-winged Sparrow begins breeding each summer.
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Description of the Rufous-winged Sparrow
The Rufous-winged Sparrow has a gray head with a reddish eye line, and a black malar stripe on each side of the face. It has a dark upper mandible and paler lower mandible, and reddish lesser wing coverts.
Seasonal change in appearance
Juveniles resemble adults but have streaked breasts.
Insects and seeds.
Forages on the ground or in low shrubs.
Rufous-winged Sparrows are resident in southern Arizona and Mexico.
Rufous-winged Sparrows defend territories year-round.
Male Rufous-winged Sparrows sing year-round.
The song consists of chip notes followed by a trill.
- Rufous-crowned Sparrows have reddish crowns.
The nest is a cup of plant material placed in a bush or cactus.
Incubation and fledging:
– Young hatch at 11-12 days.
– Young fledge (leave the nest) in 8-9 days after hatching but remain with the adults for some time.
Bent Life History of the Rufous-winged Sparrow
Published by the Smithsonian Institution between the 1920s and the 1950s, the Bent life history series of monographs provide an often colorful description of the birds of North America. Arthur Cleveland Bent was the lead author for the series. The Bent series is a great resource and often includes quotes from early American Ornithologists, including Audubon, Townsend, Wilson, Sutton and many others.
Bent Life History for the Rufous-winged Sparrow – the common name and sub-species reflect the nomenclature in use at the time the description was written.
AIMOPHILA CARPALIS CARPALIS (Coues)
One of the several confusing, obscure species of southern Arizona and Mexico, the rufous-winged sparrow, like most of its close relatives, looks like “just a sparrow.” It sports no striking black tail nor cravat, no showy pattern on crown or tail. It has no brilliant song nor striking call. It is just a trim little bird, much like a chipping sparrow in general appearance, but with different striping on the head. It does not gather into prominent flocks. The casual observer would probably vote it among our birds least likely to be of any interest, especially if he were aware that it is sedentary and presents no problems of migration.
How wrong he would be! The rufous-winged sparrow is far more than “just a sparrow.” It is a bird of exceptional interest, particularly for its history and the strange interrelations of its life cycle and molts. Besides, it can well claim the title of the most misunderstood bird in the United States. As R. T. Moore (1946) aptly says: “few species have suffered so much from conjecture and inspired guessing.” Moore himself, unfortunately, here adds his share of inaccuracies.
Historically, the last two really distinct species of United States birds to be discovered (except for the nocturnal Caprimulgus ridgwayi) were found by the redoubtable Charles E. Bendire on the Rillito near Tucson, Ariz., in 1872: Bendire’s thrasher and the rufous-winged sparrow. To be sure, a few other local and well-marked races of birds were yet to be discovered, but probably none deserves the rank of a full species. When the now historic Fort Lowell was removed from Tucson to the Rillito, both C. E. Bendire and Henry W. Henshaw promptly found the rufous-winged sparrow abundant there; yet ~within a few years it vanished completely. Herbert Brown took a specimen at or near Tucson early in 1886; thereafter not a single Aimophila carpalis was found in the Tucson area for half a century. Finally E. C. Jacot secured a pair in 1936 well away from the original points of discovery, and some time later took a third specimen. Unaware of these details, I found the birds late in 1938. In the late 1930s most or all of the birds in the Tucson area were in grassy swales on the desert east and southeast of town. Later I found others in brushy bottomlands south of town. About 1951 the species began to spread out in the valley, and in 1956 an extraordinary expansion of range carried the species into areas of almost solid grassland and even into one wooded mountain canyon to the south, well above its usual desert or Lower Sonoran Zone haunts. Few species have sbown such drastic fluctuations in habitat and numbers. It is small wonder that A. carpaiis was considered extinct in the United States by some authors, including the American Ornithologists’ Union (1931) especially as no one understood the bird’s requirements and everyone looked for it in the wrong places (Swarth, 1929; van Rossem, 1931, 1936; Phillips, Marshall, and Monson, 1964).
The genus Aimophila, with certain close allies, forms a large group of sparrows centered in the southern half of Mexico. A few species extend northward well into the United States, but only one, A. aestivalis, is limited to this country. In their life histories, most or all of these sparrows react markedly to factors other than the calendar and the photoperiod. Thus, the customary way of presenting life histories must, in these cases, be modified to obtain a clear understanding.
Habitat and phenological background: The essential parts of the normal habitat of the rufous-winged sparrow, as already stated (Phillips, 1955), are grass and brush (thorny, dense, or preferably both). The grasses favored in Arizona are of bunching types, not plain low Bouteloua, though in recent years areas with very sparse grass and low weeds have been inhabited. The brush: grass combination and the birds are common and widespread over much of Sonora; they give way southward to taller, denser thorn forest in Sinaloa, and northward to deserts devoid of grass and to unbroken, brushless desert grasslands in Arizona. In both Sinaloa and Arizona the birds thus seem to be in rather restricted, isolated colonies. Even these, however, are not uniform ecologically, at least near Tucson (the only point whence we have detailed data on the life history). To discuss these data, we must distinguish at least five types of habitat:
SwALE HABITAT: Areas where flood waters seep into desert soils, not yet b&lly gullied, producing wide stands of grass in the bottom, chiefly tobosa (Hilaria mutica). Around these stands the better drained edges support leguminous brush and low trees, and usually desert hackberry (Celtis tala var. pallida) bushes which may be of considerable density and circumference, and over 2 meters tall, when the soil is still healthy. Moisture comes entirely from rains over the local drainage area; no underground water is within reach of the roots.
DESERT WASH HABITAT: Similar, but gently sloping, without seepage or the consequent stands of tobosa; the bottom is plain sand, completely drained and usually gullied shallowly. Dominant trees are usually palo verde and mesquite, and there is an understory of brush, cacti, weeds, and what little grass escapes the inevitable cattle. This is marginal habitat for Aimophila, but it was definitely occupied in 1958.
RIPARIAN HABITAT: Here water still flows more or less throughout the year. High waters flood the bottomlands occasionally, producing originally “bunches of tall rye 1=sacaton] and mesquite grasses” (Bendire, 1882). These habitats were soon grazed to destruction in Arizona, but many remain in Sonora, where they have not been studied. The closest approach in Arizona now (in the range of our sparrow) is lower Sabino Creek, leaving the Santa Catalina Mountains. Near its rocky bed, this creek has some broad-leafed riparian trees (willow, cottonwood, ash, etc.); farther back, lower mesquite trees dominate, with considerable tangles of weeds and grass in ungrazed spots.
Originally, C. E. Bendire (1882) found his new sparrow “particularly partial to a strip of country . . then covered with good sized mesquite trees interspersed with sage and thorn bushes, small undergrowth,” and grasses. They were “seldom any great distance” from these woods “in the dry and arid cactus covered plains.”
FARMLAND HABITAT: Back from the now-dry bed of the erstwhile Santa Cruz River, Papago Indians have for years farmed fields in what was once, centuries ago, a dense thicket of mesquite woods. Irrigation ditches border the fields; along them grows a profusion of weeds, grass, and often a hedgerow of mesquite trees, elderberries, and brush, chiefly Condalia lycioides. The principal study area here is that of Joe T. Marshall, Jr., near the silted-over Indian Dam (see map, fig. lb, in Marshall, 1960). Here the birds inhabit the edges of the brushy and cleared parts. After the early 1950s, with the rnness and death of the owners, these fields were not irrigated and received only normal rainfall. The nearby river, not visited by the sparrows, ceased trickling regularly in the late 1940s and is now dry.
DEEP-soIL HABITAT: This is very near the farms just mentioned, but on the east rather than the west bank of the river and perhaps 200 meters farther north, below the dam site. The mesquite trees are somewhat more cut over and spaced apart, though rather taller; often they are overgrown with vines or have weedy tangles below. Many clumps of tall sacaton grass, in the openings between trees, are a sad remnant of the day when the river slowly sank into the soil here, to reappear below. With the subsequent deep channeling, this is now the driest of the occupied habitats, the most dependent on day-to-day rainfall.
Because the time of nesting may vary widely from year to year at the same spot owing to ecological factors, most or all of which depend on rainfall, we must understand both the normal climate and the rainfall pattern of the abnormal years when the birds reacted differently. Usually almost no rain falls between March and the end of June. Tradition has the rains starting on San Juan’s day, June 24, but they seldom do. Early July is a more usual time for rains to start. These, in summer, tend to be very local: a downpour here today, another there later, and mere drizzles elsewhere. Accurate measurements of water available to plants in each area are obviously impossible, and were not attempted. Even for the University of Arizona campus, I cannot consider the figures given (see below) as strictly accurate, but they show the trends of rainfall.
Rainfall at Tucson, Arizona (University of Arizona station) Fine dots=normal (median) Short dashes== calculated arithmetic mean, all years Solid line= 1951: 1952 Longer dashes= 1957: 1958
The climatic picture of the fall, winter, and spring of 195 1: 52, though quite similar to that of 1957: 58, was strikingly dillerent from normal. The weather remained hot through Oct. 20, 1951, then cooled off. Storms at the end of each fall month brought less rain in September than later, but added up to a very wet fall in southwestern and central Arizona. It stayed cool and rainy through Christmas, but 1952 opened with a long spell of warm, dry weather from January 10 through February 29. This gave way abruptly to a cold, rainy period from March 1 to 17; intermittent rains continued through at least April 28, though the weather warmed to normal after March 25.
Thus, since the start of weather recording at Tucson in 1868, only two previous years (1905 and 1926) approached 1952 in the quantity of rain that fell in March and April, and only 1870, 1924, and 1925 were drier in January and February. The total rainfall was normal or greater from July ii to December 25, 1951, except in the period August 29 to October 24; but only 7 millimeters (0.27 inch) fell from Dec. 26, 1951, through Feb. 29, 1952, which is normally the winter rainy season.
Naturally, this abnormal weather produced an unusual reaction in the habitat. Most obvious, though probably not important to our sparrow, was a veritable plague of greasy cutworm moths and other adult Noctuidae at the end of March and later. Robert H. Crandall (in litt.) noted several other unusual features near Tucson; the usually dry- and dead-looking “burro-brush,” (Hyrnenoclea pentalepis and perhaps also H. salsola and H. monogyra), a thin wiry next-tonothing, was green and succulent about the first of April; evidently it was well supplied with minute inchworms (Microlepidoptera), whose pupae he found about April 20. In late April he saw some big caterpillars of a sphinx moth which usually appear only after the summer rains start; and from early to mid-May (approximately) many inchworms appeared on the native palo verde trees.
The rainfall pattern of 1957: 58 was generally similar to that of 1951: 52. After Sept. 1,1957, no rain fell until October, which was very wet. Light rains continued to December 7, but from December 16 through February 3 no measurable rain fell. Then a succession of storms wet the valley from February 4 through April 9, with later sprinkles on April 16 and May 11. The summer rains began on June 20 and 26.
I have little information on the ecological picture of 1957: 58, for Robert Crandall had moved away. A plague of big grasshoppers, Trimerotropis pallidipennis, occurred in and near Tucson from May 5 to about May 10 (and later?); at the same season Floyd G. Werner noted a plague of false chinch-bugs, Nysius raphanus. A lesser infestation of the same (?) grasshopper invaded the city later, on June 28: 29. We may probably safely conclude that small insects were present in unusual quantities in both springs, but that the species were different. (Westward, in the California deserts, at least one butterfly was exceptionally common from November 1957 to May 1958: C. H. Abbott, 1959.) From late March through April the swale habitat was quite well covered with herbs, even on the desert away from the bottoms; most of those flowering in late March were Compositae. Notable among these was a purple-rayed Erigeron which was rare or absent in the desert wash habitat. Also scarce in the latter habitat were grass clumps and weedy Aplopappus-sized shrubs; otherwise, the vegetation there was rather similar to that of the outer part of the swale habitat, dominants being palo verde and Opuntia Julgida, with considerable mistletoe, desert hackberry (most of which had been partly killed back earlier), whitethorn, and low composite herbage, but somewhat less mesquite.
In the bottom of the swale habitat, the thriving tobosa grass nearly excludes other plants. There on May 20, 1952, I saw little else than a few flowering Erigeron divergens and the crucifer Descuraini,a pinnata.
Factors that induce Nesting: Jt does not seem, however, that mere abundance of plants or insects or a given amount of rain will per se cause the rufous-winged sparrow to nest. Nesting depends on the readiness of the female, because in most if not all years the male seems to be in breeding condition long before actual nesting occurs. (A reverse situation, with the male in full breeding condition away from the usual breeding grounds long after nesting, occurs in the same region in A. cassini: A. R. Phillips, 1944.) Nesting by the female is apparently triggered by additional factors which, at present, we can only guess. Thus in 1959: 60, rainfall was again above normal in December and January; this was followed, April 10 to 20 and later, by a plague of army cut-worm moths, Chorizagrotis auxiliaris (lide William X. Foerster). The weather, of course, always becomes very warm by May and June at Tucson. Neither Robert Crandall nor I was there in 1960, but several friends kindly looked in vain for evidence of unusually early nesting of A. carpalis. Some factor, apparently, was missing.
Certainly a most important aspect of the rufous-winged sparrow’s nesting is the lack of concordance between different areas, and prob-. ably even between close neighbors within the same little colonies, in the breeding activities of the females. A proper understanding of the factors that trigger nesting will thus require the amassing of more detailed data over long periods of time. Based on data as of 1963, the only reasonable conclusion is that nesting depends on certain unclear ecological conditions within the pair’s territory. Obviously no fashionable all-inclusive theory can possibly explain the strange facts about to be presented; these do not coincide with dates, photoperiods, amounts of cloud cover, darkness or sunshine, cyclonic or anticyclonic weather, temperature variations, or other current phenomena.
The rufous-winged sparrow responds, instead, to the most potent of several perhaps conflicting environmental factors, like the responses of certain nesting passerine birds in Latvia (Vilks, 1958), and its individual variability parallels that of some Australian ducks (Frith, 1957). Both it and other Aimophilae (ritficeps herein; see H. Wagner, 1955), as well as all the birds of the arid parts of Australia (Keast, 1960), afford overwheiming evidence against the automatic photoperiod hypothesis expounded by A. Wolfson (1960), A. H. Miller (1960) and D. S. Farmer and A. Oksche (1964). (For an excellent review of this subject see A. J. Marshall, 1951.)
A particularly interesting problcm, which would require far more time to investigate than I could devote to it, is whether nests built when conditions first begin to look favorable are abandoned if the weather turns hot and dry again, as Paul Schwartz and E. T. Gilhiard believe may occur normally with Venezuelan birds (Gilliard, 1959).
Spring: As the rufous-winged sparrow neither migrates nor often gathers into flocks that are obviously larger than family size, the changes in its behavior and local distribution in spring are not striking. By mid- or late March most of the birds seem to be in pairs, but this is not universal. For one thing, the apparent pairs may not be true pairs. Thus on Mar. 24, 1940, I collected one bird from an apparent pair which on skinning later, I found to he a male (testes somewhat enlarged, left 2.8X1.8, right 1.7X1.7 millimeters); yet while I was preparing it to take home its supposed “mate” sang. Therefore, either the female may sing or (more likely) some apparent pairs are not of opposite sexes, a condition that was proved, also in March, in the case of a wren, Uropsila leucogaster brachyurus in Yucat~in (Chapman, 1896b).
For another thing, even in wet springs some birds remain in small flocks through March. On Mar. 29, 1958, my ornithology students saw two groups of three birds each near Tucson in the swale habitat. More exceptional was a flock of about five or six sparrows that I saw in the desert wash habitat on Apr. 27, 1958; at least four birds, if not the whole flock, were rufous-winged sparrows; yet, in the same area, some pairs already had eggs in the nests. Farther south in southern Sonora according to A. J. van Rossem (1945a) the birds were not yet paired in late May and even up to June22 ,1937; while Joe T. Marshall, Jr. (MS.) could find no nests there from May 8 to 12, 1958, on which dates some pairs near Tucson had young nearly ready to leave the nest (in desert wash) or actually on the wing (in riparian habitat). In northwestern and central western Sonora I found at least some birds paired,, though not yet nesting, Apr. 20 and 28, 1947.
Territory: As might be expected, the size of the territory evidently varies inversely to the desirability of the habitat. In the farmland habitat Patrick J. Gould (MS.) found a pair holding about ~ hectare (2 acres); most of this was not contiguous to the territories of other pairs. The favored swab habitat may support as many as 8 to 10 pairs per % kilometer (~ mile), the swale being perhaps 50: 100 meters wide on an average (A. R. Phillips, 1955); probably most territories here do not greatly exceed % hectare. On Mar. 29, 1958, flights here seldom exceeded 15 meters; and in a cholla cactus flat I saw two “pairs” perched in chollas not over 10 meters apart with no apparent friction. Whether these birds had yet established territories at that date, however, is uncertain.
In the original riparian habitat, their density must have been rather spectacular. In 1872 in a strip of mesquite trees, brush, and grass measuring about 1500X400 meters, C. E. Bendire (1882) “found not less than forty-three of their nests with eggs and a still larger number of those of the Black-throated Sparrow * * * besides a number of nests containing young.”
Courtship: Twice I have seen billing or possibly courtship feeding. On Mar. 12, 1952, in the Coyote Mountains (eastern edge of Papago Indian Reservation, southwest of Tucson), I saw a pair billing, but could not see whether any food was actually passed; collecting the birds, I found them to be male and female with gonads slightly enlarged: testes averaged 2.4X1.8 millimeters, the largest ovum was about 0.6 millimeter in diameter. The other occasion was on Mar. 29, 1958, in the swale habitat near Tucson. After one of the two pairs in nearby chollas had flown, the remaining pair then billed several times; the upper bird reached down and slightly to its left, while the lower one seemed to reach up, to the right, and a bit forward. I feel sure that they were only billing, for I saw nothing in their bills and no swallowing actions, nor had they apparently been feeding just before. Neither this one pair nor the other in the chollas was collected.
Nesting season: Customarily we confine our main discussion of nesting to the location and construction of nests, relegating the dates to a few lines at the very end, after the migration dates and casual records. To do so with the rufous-winged sparrow, however, would be to pass over one of the most fascinating aspects of its life history, which sets it (and most of the other Aimophila sparrows) off from the general run of birds of northern latitudes.
The nesting season corresponds in all cases with a season of rainfall and warm to hot temperatures. In normal years, though the testes of males enlarge greatly in late April or May, no eggs are laid near Tucson until the end of June or early July, and perhaps later in years and areas of delayed rains. Gale Monson and I found nests with one and four eggs (incubation of the latter just starting) on June 30, 1940.
On June 29, 1954, 4~ days after the big rains began, Joe T. Marshall, Jr. (MS.) found two nests in the same state of construction in swale habitat. “Herbaceous vegetation is now very definitely sprouting: tiny cotyledons are up everywhere, and green is starting to appear on the perennials.” One of these nests seemed ready for eggs on July 2, but was unlined. Similarly, Herbert Brandt (1951) never found nests in his years in Arizona, for he usually left about the end of June.
Thus it came as a tremendous surprise when Eliot F. Porter discovered rufous-winged sparrows with large young on the wing on May 19, 1952. This occurred in a swalelike habitat 6l~ kilometers north of Vail, after heavy March and April rains. He also found apparently full-grown young in a weedy desert wash on May 24, 1952, more than a month before the first eggs are usually laid.
On May 20, 1952, E. F. Porter and I took a census of % kilometer (~ mile) of a broad swale. We found three or four families of young on the wing, which had recently left the nest or were somewhat larger (two juvenal females had the tail 21 and 37 millimeters long); one pair with two eggs (incubating); another pair at an apparently completed but empty nest; and at least three other males were heard singing near by, but their mates (if any) were not found.
Three days later I checked the deep-soil habitat. Here three or four males were singing, but I found no nests or young. To verify this surprising difference between two localities about 25 kilometers (15 miles) apart, I revisited the deep-soil habitat on July 13. Again no young were found, and it seemed that nesting had started normally in late June; for the most advanced birds detected were a pair with the male singing and the female carrying small grasshoppers, presumably to young in the nest. Another nest was found with one broken egg.
In 1958 unseasonal nestings occurred in the swale habitat, though apparently less commonly or successfully. Arthur Twomey, Jr., and I could find no active nest on April 20, though one looked completed. (A cracked egg was later found just below, but the nest was apparently abandoned.) Some early nests did succeed, however, for I took a female just out of the nest (tail 11.2 millimeters) on May 10, and Robert W. Dickerman and I took grown young, possibly from two different families, on June 12, well into the post-juvenal molt.
More conspicuous, however, were the unseasonal nestings discovered in the marginal desert wash habitat by James M. and Eugenia W. Gates (MS.). On Apr. 20, 1958, they found a nest with four eggs, subsequently deserted, plus two possibly new nests; and on revisiting the area on April 27, we found more nests with and without eggs. One nest the Gates followed up later had three very small young and one egg on IVIay 3; another was apparently successful, the young presumably leaving on May 15 or 16. At this time rufouswinged sparrows were also nesting in other places. In the riparian habitat I found a nest with four eggs (later deserted?) on April 30, and Eliot F. Porter (MS.) found another which four young left, prematurely in his judgment, on May 7,1958. In the farmland habitat Joe T. Marshall, Jr. (MS.) found two nests, with two and three eggs, respectively, on May 2. The former had an apparently newly hatched chick on May 17, when the latter’s young appeared to be about 6 days old. These were still being brooded on the 18th.
Another exceptionally wet year was 1940: 41. In the Wilson C. Hanna collection (Jide W. G. F. Harris) is a set of eggs Oscar F. Clark took on May 4, 1941, at Sells on the Papago Indian Reservation, Arizona, where the desert wash is the principal habitat.
Nesting continues in Arizona into September. C. E. Bendire (1882) “found fresh eggs as late as Sept. 1, 1872.” These are presu.mably the same eggs reported (Baird, Brewer, and Ridgway, 1874) as taken September 11 and still preserved in the U.S. National Museum (fide W. G. F. Harris). Nevertheless Elliott Coues (1873b) does not include this species among birds C. E. Bendire found “still laying September 13,” 1872. Farther s6uth in Sonora, a family of three young was “at most two or three days out of the nest” on Nov. 1, 1946 (Pitelka, 1951); and even near the Arizona border a “small juvenile” was taken September 29 (Miller et al., 1957). Likewise R. T. Moore (1946) reported heavily incubated eggs found by C. C. Lamb in Sinaloa, Oct. 2, 1933.
There is, unfortunately, no sure evidence of just when the birds in the old Tucson riparian habitat normally nested. We kiiow only that C. E. Bendire (1882) found the first eggs “about June 14, 1872, although I believe these birds commence to breed about a month earlier, their nests having been previously overlooked by me”: an understandable possibility, as the species itself was undescribed. Also, Frank Stephens (Brewster, 1882a) found a nest with three eggs May 25, 1881, a year of better-than-average March and April rainfall. So all this is very inconclusive.
Charles E. Bendire (1882) thought that two or three broods were raised in the riparian habitat in 1872. Likewise in 1958, some pairs probably raised two broods in the desert wash habitat. Here the Gates (MS.) found two new nests with eggs on July 6; one of these, with one egg, was only about 7 or 8 meters from the site of the apparently successful nesting in May.
Nesting: The nest site preferred in the swale habitat is the edge of a thick, tall desert hackberry bush (Celtis tala, var. pallida), 0.6 to 2 meters above the ground. In the desert wash habitat where most of these bushes were partly bare due to the increasing desiccation of the country, the birds showed a marked preference for the edges of or open parts within palo verde trees (Cereidium) 1.3 to 2.5 meters above the ground. Sometimes the nests were in the less dense clumps of mistletoe on the palo verde trees, or in cholla cacti (Opuntiajulgida): in one case in a cholla growing within the shelter of a palo verde. In the farmland habitat, where none of these plants grows, the favored site is 1 to 1.3 meters up in a thorny (‘ondalia lycioides bush. In the old riparian habitat nests were “firmly fixed into a fork, or crotch” 0.15 to 1.5 meters up “in low bushes, preferably small mesquite bushes” (Bendire, 1882).
The building of two nests in swale habitat on June 29, 1954, was accomplished as follows (Marshall, MS.): “The male gets up and sings a bit while the female brings a big bundle of the pale, curly, basal leaves of tobosa grass. She comes down to the nest from above, enters, and works there 15: 30 seconds; then she climbs out, hops up higher, and both birds fly down to feed 30: 40 meters away.”
The nest itself is a conspicuous, solid, deep cup of old, dead (usually gray) plant stems, lined with fine grass and usually (at least on the bottom) with horsehair. In the swale habitat, as in the old riparian habitat, the shell is made of coarse grasses (sometimes mixed with weeds), chiefly the stems but including leaves and the fine stalks of inflorescences. Elsewhere the outer shell is built of similar material (much of it is not grass): weed-stems, at times with the top of the root or with what seem to be strips of some thin, gray plant cortex such as fine bark. Except for this last and the leaf-blades, most of this outer material is largely from }~ to 1 millimeter thick, and more often below than above these limits. The usc of a fine thorny twig (Acacia con.stricta?) seems unusual in the swale habitat, though twigs are the common component of nests in farmland habitat. A conspicuous component at times, because it is easily identifiable, is the stalk of an Eriogonum.
Over-all outside dimensions of the shell are usually 8.5 to 12 centimeters in diameter, and 6 to 8 centimeters in depth; sometimes larger in nests of tobosa grass (swale habitat), or with grasses straggling beneath. The inner cup is usually 4 to 5.5 centimeters in diameter and 5 to 6.5 centimeters deep. C. E. Bendire (1882) describes the nest in the old riparian habitat as “three inches [7.5 centimeters] deep in the inside, so deep in fact that nothing but the tip of the tail of the bird is visible when setting.”
Eggs: The set usually comprises four eggs. Recent extremes show a bird incubating two eggs, May 1958 (Marshall, MS.), and a nest with five fresh eggs (one a cowbird~s) taken on Aug. 8,1959 (Patrick J. Gould), both in farmland habitat. But in C. E. Bendire’s time, sets of five were not unusual, and three eggs were rare or unknown. The eggs are slightly glossy, ovate, very pale bluish white, and unmarked. W. G. F. Harris’ measurements of 50 eggs average 19.1 by 13.9 millimeters; the eggs showing the four extremes measure 20.3 by 14.7, 18.8 by 15.0, 17.8 by 14.0, and 18.8 by 13.0 millimeters. C. E. Bendire (1882) gives somewhat larger figures, while my own attempts give smaller ones; doubtless this reflects differences in individual techniques and measuring equipment.
Incubation: The female is a close sitter, even when the eggs are fresh. One whose eggs were hatching on September 1 refused to fly when I was less than a meter away. The male on such occasions of danger seems usually to be singing near by. One bird in the desert wash habitat came onto the nest so secretively that I never saw her, though I was watching for her, until she was incubating. While I have never captured incubating birds, I have no reason to suppose that males incubate. The length of the incubation period is unknown.
Young: A young bird I thought to be newly hatched on May 17, 1958, had sparse dark down. Young seem to remain in the nest 9 or 10 days. A nest found with two eggs and two newly hatched but dry young on Sept. 1,1939, was empty on September 12. but two of the four young were caught and banded near by. This nest was also found independently by A. H. Anderson on September 10, when it appeared to contain only two large young. On September 6 when I rustled the bottom of the nest, the young with eyes open popped their head up to be fed, but their voices were still hardly audible.
Both parents attend and doubtless feed the young. They do not regularly clean the nest, which becomes filthy. Only once did I see an adult carrying a fecal sac, which it deposited on a branch.
The young, or at least the last brood, remain with or near their parents through the fall, if not the winter. One of the young banded Sept. 12, 1939 was seen not far from its native hush 2% months later on November 25.
Plumages: There seem to be no specimens of the natal down. The juvenal plumage is of the usual streaky sparrow type, but the dusky streaks below are unusually coarse. Robert Ridgway (1901) describes it as: “Upper parts, including pileum, light grayish brown, broadly streaked with blackish; lesser wing-coverts dusky centrally, broadly margined with pale brownish buff; under parts whitish, the chest and sides streaked with dusky.” The head markings are at first all dusky on a brownish-buff background, but rufous soon appears behind the eye in the postocular streak. The iris is a grayer brown, less rusty or reddish than the tan or rufous eye of adults and the lower mandible is almost wholly dusky, like the upper and not pinkish. The mouth varies from flesh color to whitish; the gape is pale huffy to creamy whitish. The feet are somewhat more lavender and purplish-tinged than those of adults, and are sometimes even grayish. The adult’s feet are more pinkish or yellowish.
The first prebasic or postjuvenal molt may occur at any time from June to October or even November, depending on the date of hatehing. It starts to replace the short: lived juvenal plumage early on the anterior parts and the wing coverts. Two young taken in swale habitat on June 12, 1958, were already largely in first basic (first winter) plumage, especially the male taken by Robert W. Dickerman. Normally the juvenal flight feathers (except the tertials) are retained as are the primary coverts and alula. It would be interesting to trace the molt in early hatched birds that molt in June to see whether they molt again in September or October, and if so how fully. One September immature was found to he molting primaries and rectrices (A. R. Phillips, 1951b). This molt produces a definitive, adultlike plumage, though the sides of the head are usually a more buffy and less grayish brown. The best distinguishing marks are the broader, less pointed tip to the alula and the usually browner, less dusky and whitish primary coverts.
A. R. Phillips (195 ib) discusses the normal (dry year) molt sequence in some detail. Briefly, a prealternate (or prenuptial) molt in May and June renews the body plumage, tertials, and central rectrices, even if these are juvenal rectrices. In Arizona the later prebasic (postnuptial) molts occur mainly from mid-September into October; they are notable for the apparently aimless, disorganized order of the tail feather molting. Females seemingly lag behind males in all molts. (Molt of juvenal feathers in birds in spring is unusual, according to Humphrey and Parkes, 1959.)
Molt between November and May seems to be a most exceptional event in Arizona. I have seen but one molting specimen: the male of a pair taken in swale habitat by J. A. Munro on Jan. 31, 1952. It was molting on the throat and on the middle (median) part of the breast and especially of the belly.
Farther south in Sonora, a smaller race was still in worn alternate plumage at the end of October 1946, with the males only just starting the prebasic molt (Pitelka, 1951). Nesting here is apparently later than in Arizona. If R. T. Moore (1946) is correct in saying that “some July and August birds are in the midst of molt,” the prealternate molt must often be correspondingly late in Sinaloa. But Moore’s statement that the species molts at any time of year in the Tropical Zone is not supported by the material I have examined. Nor can I believe that “many March individuals have completed their prenuptial [=prealternate] molt” there, as Moore states.
Just as the timing of the prebasic (postnuptial) molt is evidently affected by the timing of the nesting period, so also is the extent, timing, or perhaps even the very occurrence of the prealternate (prenuptial) molt. In years of unusually early nestings in Arizona, the latter is often curtailed or postponed until after the young leave the nest. I know of no clearer illustration of the undesirability of tying the names of plumages and molts to the breeding cycle in the classic Dwightian tradition.
Particularly instructive is a small family group taken on June 12, 1958, in swhle habitat. The young one, a female, was fully grown, with the tail 65.2 millimeters and not sheathed at base; she was well into the first prebasic (postjuvenal) molt. The parents were both adults more than a year old. Except for one of the outer, longer tertials in each wing, the prenuptial molt of the father had been postponed and was just starting, chiefly on the back but also on the breast and belly. The mother, on the other hand, had molted normally, or nearly so, even while incubating, and was now well into the prealternate or prenuptial molt. Her oviduct was now small, and the brood patch no longer vascular; her largest ova were 1.5 and 1.8 millimeter in diameter. That the molt is a prenuptial one seems certain. The primaries and secondaries show no molt, though that of the tertials is near completion, and the only short rectrices are the central pair, now 34.5 and 44.6 millimeters long. One outer rectrix is missing, and the other appears fresh. All other tail feathers are old, and the longer ones are more or less worn and frayed. Curiously the secondaries, longest tertial, and innermost two primaries are all new in the right wing, though old in the left. Molt of the greater and especially middle wing coverts is also markedly asymmetrical.
Most of the few specimens taken in years of atypical nestings point to a partial or complete suppression of the prealternate (pre-. nuptial) molt by the developing ecological conditions that ultimately induced nesting. Thus parents of small young taken in swale habitat on May 20, 1952 (adults, male and female, of diII~erent families) and June 21, 1952 (first: year female) are not molting and have not replaced many feathers. The male has lost several flight feathers, chiefly secondaries, but shows few new feathers (inner right scapulars; left central and next-to-central tail feathers). The females are even more worn, but the first-year one has started to molt on the breast, lower chest, and back. On the other hand, an adult male of the same date (June 21), but whose nest had fresh eggs, has molted almost normally, is largely in fresh feather, and still shows some molt, mostly on the breast and lower chest.
In the deep-soil habitat no early nestings were observed. In the most advanced nesting noted, an adult female was carrying grasshoppers to young on July 13, 1952; she had molted parts of the wing coverts, most of the forecrown, back, and chest, and some remiges in the right wing (tertials and innermost primary); she also had some new feathers in the rump, and perhaps elsewhere, but she retained the old nape, upper and under tail coverts, rectrices (except the outer pair), flanks, sides of the neck, and part or all of the throat, malar area, and lores. An admit male was seemingly in an earlier part of the breeding cycle; he was singing near a nest containing an egg shell. Some molt was still in progress, and he retained some old plumage, including the greater wing coverts and part of the crissum; but the prealternate molt was nearly complete. In fact, even the two innermost pairs of primaries had been replaced. Thus molt in this population had been less affected by the unusual weather and ecological conditions.
Aside from the scanty data provided by Frank A. Pitelka (1951), no information is available which would suggest whether or not rainfall also affects the timing and extent of the molts of the more southern races in Mexico.
Food: Field observations show that during the nesting season a good deal of the food consists of small green caterpillars of the inchworm type. Other blackish caterpillars and small grasshoppers 7 to 10 millimeters long are also taken. The adults feed largely in the desert hackberry bushes at this time. Earlier in the summer the birds catch low-flying insects in short sallies while on the wing and glean others from the stems of small plants such as burroweed,
Haplopappus tenuisectu.s. The young soon start to eat seeds; one female in first prebasic molt as early as June 12, 1958, had chiefly small seeds and gravel in her stomach and only one or two small insects. Food at other seasons presumably consists largely of grass and weed seeds. Henry W. Henshaw (1875) found them in September “hopping about in search of small seeds and insects.” C. E. Bendire (1882), possibly referring to the winter food, wrote that it “seems to feed principally on various kinds of small seeds.”
The strangely molting female of June 12, 1958, however, had fed largely on small ants, determined by Floyd G. Werner to be workers of Solenopsis (zyloni?). Her stomach also held some small seeds, a little gravel (and bits of glass?), and one large, blackish mandible which probably came from a grasshopper.
Beluwior.: In its favorite haunts the rufous-winged sparrow is a bird of modest habits and is easily observed. When disturbed, it flies up into a bush or low tree from which it watches the observer’s approach. Only once have I seen it run like a mouse through the grass in the exasperating manner of its relatives, such as A. cassini. On the other hand I have never seen it burst into a flight song as cassini commonly does in summer, though C. E. Bendire (1882) mentions it singing “while hovering a few feet in the air, generally in close proximity to” its nest, in the crowded population of the old riparian habitat.
On one occasion, early in June 1951, I did see a rufous-winged sparrow several meters above the ground. This bird was singing from a telephone wire by a road that separated homes with lawns and citrus and Eucalyptus trees from the desert mesa. At that moment a Harris’ hawk was sitting in a tree not far off, and I suspected that the hawk’s presence may have accounted for the unusually high perch the rufous-winged sparrow chose.
For a small bird, the species shows much courage at nesting time. While I was examining a replacement nest with two fresh eggs, a bird came very near me in the lower part of the same bush and “chipped,” with its wings somewhat spread as if trying to drive me away. It is not so approachable at other times, but (like Scott, 1886) I have always found it less shy than others of its genus. Both C. E. Bendire (1882) and H. W. Henshaw (1875) liken it to the blackthroated and chipping sparrows in behavior.
In marginal, overgrazed areas it may be less confiding. Near Sells, Ariz., in June W. L. Dawson (MS.) writes that “the birds themselves are very shy, and IC. I.] Clay spent half an hour securing a pair.” R. T. Moore (1946) also called them “extremely shy” at Fresnal, east of Sells, but seemingly had no difficulty in collecting specimens. Doubtless the birds tend to retreat farther when they can do so without entering the territory of another pair. Even where fairly common, however, most rufous-winged sparrows seem unusually secretive when laying and incubating.
Voice: The rufous-winged sparrow has a wide variety of calls and songs. The characteristic “location note” is a shrill, piercing seep, or as C. E. Bendire puts it, “a lisping ‘tzip,’ ‘tzip,’ frequently repeated.” It differs from those of such Spizellae as the chipping sparrow and of most other sparrows in its somewhat higher pitch and loudness, and its firmer, more metallic quality. The song is variable, one frequent type being a monotone. More often the opening notes, commonly three in number, vary in pitch from the closing series, and generally among themselves as well. In any event, the song ends in a rapid, almost trilled series of notes identical with the call and on a single pitch. The opening notes are more widely spaced and seem to be held a bit longer, but are scarcely more musical. The usual song is thus much like that of a canyon brown towhee, but sometimes the second of the opening notes is lower-pitched and sounds rather different. One such song is rendered in my notes as chip burr chee-hehe-he-he-he; another as f-ce yoor tee te-te-te-te-te the yoor being reminiscent of the call of Say’s phoebe. There are other variations, too.
Altogether I consider the song pleasing, if hardly pretentious, but I cannot scold C. K Bendire for calling it “rather weak and monotonous.” While I admit that the bird is no musician, I think Dawson (MS.) uses some poetic license in stating that “its sharp iterative staccato notes” are “utterly destitute of musical quality.” He continues: “The song * **~5 curiously like that of the Abert or California [brown] towhee, lightened, quickened, and continued, teip, f-sip, f-sip, f-sip, teip, f-sip, f-sip, tsip, f-sip.” A less common chattering note, much like a brown towhee’s or a black-throated sparrow’s, of a tinkling quality, is possibly used only when the birds are excited.
The main season of song in normal (dry) years is from June or July to mid-September. Singing may be heard at almost any time, though I have not specifically noted hearing it in December. When singing, the bird prefers a perch several feet up on top of a mediumsized cactus or thorny bush.
Field marks: The rufous-winged sparrow resembles the chipping sparrow on its upper parts, with its rufous crown and black-striped back. The white malar area, however, is bordered above and below by thin black stripes, separating it from the throat and cheeks; and the line through the eye is rufous rather than black. Thus the headstripings resemble more closely those of the rufous-crowned sparrow, which is found at higher altitudes, but the back and mustache-cheek markings are more pronounced, and the whole bird is more slender and trim. The ground color of the side of the head is somewhat paler, so that there is no obvious whitish ring around the eye. In fresh plumage, a hint of white at the outer corners of the dark tail when spread, will help distinguish it from both the rufous-crowned and the chipping sparrow. The rufous bend of the wing can be seen only under favorable circumstances. Voice and habitat are the best clues, especially in early summer when chipping sparrows are not apt to be present in the Lower Sonoran Zone.
Enemies: Little is known of those enemies of the rufous-winged sparrow that man conventionally (or conveniently) discusses. In the old mesquite thickets, C. E. Bendire (1882) found that its “nest appears to be one of the most favored by” the brown-headed cowbird; about one-half of the nests were parasitized, and in a number of these the owner’s (but not the parasite’s) eggs were “minutely punctured in one or more places,” presumably by the cowbird. In the swale habitat, however, I have found little parasitism by cowbirds, which are scarce there.
Undoubtedly the most important enemy of the rufous-winged sparrow is the unscrupulous cattleman. The distribution of the bird in the Tucson Valley during the 1930s and 1940s made this clear. Those areas where colonies survived were never heavily grazed; furthermore, they were in places where the grass derived its water from rainfall in the immediate vicinity and was not dependent on a healthy range above. The late J. J. Thornber of the University of Arizona informed me that light grazing in the opening decades of the century had largely replaced the once-dominant grama grass (Bouteloua Rothrocki) with Ari.stida in these areas. But there was always some sort of grass cover. The most flourishing colonies were around meadows of tobosa (Hilaria mutica). This is good evidence that the general abuse of thecountrybyovergrazing exterminated the bird about Fort Lowell and Oracle and sadly reduced its numbers along the Santa Cruz River, so that the once marginal colonies became the species’ only strongholds in this region.
Fall and Winter: After the young are grown, small (probably family) groups of rufous-winged sparrows are generally found associating with such other sparrows as the black-throated, chipping, and Brewer’s. ‘Where it was densely congregated in the mesquite thickets, C. E. Bendire (1882) found the species “sociable and gregarious at all times,” especially in winter, when “it is found in small flocks.” W. E. D. Scott (1887) found winter flocks of 4 to 20 individuals, but some of these would seem to be exceptionally large. Recent observers usually find only family-sized groups, which may associate with other sparrows such as Spizellae.
Occasionally this sparrow may show signs of some sexual activity in fall. On Oct. 9, 1938 I watched one snuggle down into an old nest in a desert hackberry, but I am not sure that this nest was originally of a rufous-winged rather than a black-throated sparrow. J. T. Marshall, Jr. (MS.) saw one enter a cactus wren’s nest in farmland where it remained for 15 seconds on Nov. 16, 1956. Such actions have not been noticed in winter.
Range: Southern Arizona south to central Sinaloa; nonmigratory. The rufous-winged sparrow ranges north to Pinal County, Arizona (Oracle Junction and Oracle); east to central southern Arizona (Oracle and Tucson regions, sporadically near Sonoita), eastern Sonora (Rio Bavispe, Santa Rosa, and Guirocoba), and northeastern Sinaloa (Colmoa, Rancho El Padre, Tab ala. on Rio San Lorenzo); south to central Sinaloa (Elota); west to the coasts of Sinaloa and Sonora (north to Estero de Tasiota and Rancho Costa Rica, and west of Caborca), and Arizona (western part of Papago Indian Reservation at Menager’s Dam and Ventana Ranch).
The entire species as outlined has been divided into three subspecies, of which only one (A. c. carpalis) enters the United States.
Egg dates: Arizona: 25 records, April 20 to September 11. Sinaloa: September 11, October 2.