Juvenal Plumage Research Articles

Notes on Molt and Juvenal Plumage in the Acorn Woodpecker

Notes on Molt and Juvenal Plumage in the Acorn Woodpecker

The effect of the postjuvenal molt in the house sparrow on infestations of the quill mite, Syringophiloidus minor (Berlese) (Acarina: Syringophilidae).

Syringophiloidus minor (Berlese) was recovered from House Sparrows, Passer domesticus L., ranging in age from nestlings to adults. Of 492 sparrows examined, 402 (82%) were infested. The primaries, major primary coverts, secondaries and rectrices were the most frequently infested feathers. Colonization of the primary coverts and secondaries of the juvenal plumage is selective, with mites favoring those feathers which occupy positions near the end of the molt sequence. Postjuvenal molt alters the frequency of infestation of feathers within a tract and also the frequency of infestation of entire tracts or combinations of tracts. The selective value of the infestation patterns in the juvenal and nuptial plumages and the probable sources of the dispersants which colonize the nuptial feathers during the postjuvenal molt are discussed.

THE BREEDING ECOLOGY OF ROYAL TERNS STERNA (THALASSEUS) MAXIMA MAXIMA

SummaryThe breeding ecology of the New World race of the Royal Tern Sterna maxima maxima was studied at colonies in Virginia and North Carolina, U.S.A., from 1967 to 1970.Colony sites are quite varied, but isolation, good distance visibility and (especially) freedom from quadruped predators seem important if not essential prerequisites.In Virginia, most adults arrive at the colony site in the last few days of March. Courtship, displaying and copulation take place at, near, and some distance from the colony site. In this the Royal Tern differs from its near relative S. sandvicensis sandvicensis which carries out these activities away from the colony site, presumably as an anti‐predator device.Courtship displays are not described, but in their essentials are similar to those of other terns. Copulations continue throughout incubation and gradually disappear when the eggs hatch. No post‐copulatory displays are known. Some synchrony of egg‐laying is evident, but no “mass laying” occurs, the colony increasing in size steadily over a period of weeks and months. Defaecation on the nest is normal and probably serves to strengthen the nest rim against flooding by high tides.Contrary to published reports, the normal clutch is one; the largest is two, probably often from two different females. All incubating adults examined had two brood patches.Average egg measurements are 63 × 44‐5 mm, and average egg weight is 64.3 g. Egg colour varies greatly, and evaluation is difficult. Eggs are probably not cryptically coloured and individual variation, as well as nest‐site, are used by returning adults to identify their own eggs.Average maximum nest density is c. 7/m2. Sterna sandvicensis acuflavida nests regularly, if not obligatorily, with m. maxima; interactions between the two, and possible benefits accruing to each, are discussed. Unhatched eggs were significantly nearer other nests than were successfully hatched eggs, and possible explanations are given.Incubation lasts about 30–31 days, a week longer than in most terns; both sexes incubate.Broken eggshells are never removed by the adults. Instead, after 2–3 days, the chicks leave the nest permanently to join a creche that roams freely about the immediate vicinity of the colony. Chicks remain in the creche for about 25–30 days, leaving it at fledging, approximately 30 days after hatching.While in the creche, chicks are normally fed only by their parents, who probably recognise them both vocally and visually, using the extensive variation in voice and colour of chicks characteristic of the species. Sandvicensis acuflavida chicks also are highly variable, and join Royal creches, adults of both species attending. Variation also occurs in Royals' juvenal plumage, and seems associated with extended parental care.Feeding adults normally wander up to 40 km from their colony, and this probably facilitates the intercolonial exchange of breeding birds we recorded. They feed inshore, in shallow waters, taking small fish by dives which do not go below the surface. They regularly take small soft‐shell crabs in this way, and frequently water‐skim like skimmers Rynchops spp., sometimes capturing food while doing so. A relationship between crab capture and water‐skimming is established for the first time, and water‐skimming in non‐feeding contexts is mentioned.Besides the quadruped predators which they normally avoid by fleeing the colony site, Royals have no known predators beyond the egg stage. Eggs, although not chicks, are readily taken by Laughing Gulls. Relationships between the two species are discussed, emphasising their constant association the year round.

The Juvenal Plumage and Relationships of Lophostrix cristata

The Juvenal Plumage and Relationships of Lophostrix cristata

An Improved Method of Sexing Ring-Necked Pheasant Chicks

An Improved Method of Sexing Ring-Necked Pheasant Chicks

Molts and Plumages of the Red-Winged Blackbird with Particular Reference to Fall Migration

Tordoff and Mengel (1956) have summarized a number of findings on the relationship of molt to migration in passerine birds and have concluded that there is strong evidence to support the contention of various authors that molt does influence at least the time of migration. The present study was undertaken to determine whether a correlation could be found between the onset or migration and the completion of molt in Red-winged Blackbirds (Agelaius phoeniceus). As a prerequisite to such a determination, we found it necessary to record the sequence, duration, and completion of molt of each feather tract leading to the Basic or fall and winter plumage. The results of this study are recorded in the following pages. For the sake of completeness we also are showing the succession of molts and plumages acquired by both sexes of Red-winged Blackbirds from juvenal plumage to the Definitive Basic or second winter plumage.

Incubation and Nestling Periods of the Horned Puffin

As in the case of many alcids, the basic features of the breeding biology of Horned Puffin (Fratercula corniculata) have remained relatively unknown. While studying breeding biology of plankton-feeding alcids on St. Lawrence Island, Alaska, in 1966 and 1967, I obtained data on two phases of this puffin's breeding cycle-the durations of incubation and nestling periods. All nests studied were on Sevuokuk Mountain in the Northwest Cape area of the island. Laying-hatching intervals were determined in 1967 for the single eggs in five nests, where both events were known to the nearest day. This interval averaged 41.4 with a range of 40-43 days. For the Common Puffin (F. arctica), Lockley (Puffins, 1953) gave periods of 40, 42 and 43 days; Myrberget (Medd. Statens Viltundersok, 11:1, 1962) gave it as 40-45 and averaged 41.8 days; and Kartaschew (Die Alkenvogel des Nordatlantiks, p. 85, 1960) stated that this period was usually 35-37 days but may be 40-42. One observation of the nestling period of Horned Puffin on St. Lawrence Island in 1967 was 38 days; the chick departed for sea during the night or early morning and possessed complete juvenal plumage. For the Common Puffin, Lockley (op. cit.) observed nestling periods of 47, 49 and 51 days; Kartaschew (op. cit.) gave it as 38-45 days; Myrberget (op. cit.) reported an average of 47.7 days; and Uspenski (The Bird Bazaars of Novaya Zemlya, Transl. of Russian Game Reports, 4:1, 1958) recorded two observations, 36 and 37 days. This work was supported by a National Research Council of Canada grant to M.D.F. Udvardy.

The Relationships of Sparrows in the Genera Ammodramus, Passerherbulus, and Ammospiza with a Description of a Hybrid Le Conte's × Sharp-Tailed Sparrow

THE first and second editions of the A.O.U. Check-list (1886, 1895) list the Henslow's Sparrow (now Passerherbulus henslowii) and the Le Conte's Sparrow (now Passerherbulus caudacutus) in the subgenus Coturniculus of the genus Ammodramus with the Grasshopper Sparrow (now Ammnodramus savannarum). When Ridgway (1901) raised the subgenera (Passerculus, Centronyx, Coturniculus, and Ammodramus) of Ammodramus to generic rank, he separated the Henslow's and Le Conte's Sparrows from the Grasshopper Sparrow and placed them with the former members of the subgenus Ammodramus, the Sharp-tailed Sparrow (now Ammospiza caudacuta) and the known Seaside Sparrows (now Ammospiza maritima and nigrescens), a treatment later followed by the A.O.U. (1903). The Ammodramus group remained intact, despite being renamed Ammospiza (Oberholser, 1905) and then Passerherbulus (Stone, 1907), until Oberholser (1917) split the group into four genera: Thryospiza for the Seaside Sparrows, Ammospiza for the Sharp-tailed Sparrow, Passerherbulus for the Le Conte's Sparrow, and Nemospiza for the Henslow's Sparrow. Subsequently the A.O.U. (1931) recognized the genus Ammospiza containing the Sharp-tailed and Seaside Sparrows, the genus Passerherbulus containing the Le Conte's and Henslow's Sparrows, and the genus Ammodramus, containing the Baird's (A. bairdii) and Grasshopper Sparrows. No changes have been made since, and as yet no diagnoses exist for these genera as presently constituted. More recently Tordoff and Mengel (1951) questioned the present classification when they discovered that the prealternate molt of the Le Conte's Sparrow was extensive and thus more like that of the Sharp-tailed Sparrow than that of the Henslow's Sparrow. Graber (1955) actually transferred the Le Conte's Sparrow to Ammospiza on the basis of the similarity of the juvenal plumages of the Le Conte's and Sharp-tailed Sparrows. With the discovery of a hybrid between the Le Conte's and Sharp-tailed Sparrows (described below), it seems appropriate to consider the evidence of molt, plumage, and voice bearing on the relationships of these species. Molt.-The descriptions of the molts of the species being considered are generally incomplete or erroneous. Detailed studies for most species have yet to be made. The best that can be done now is a brief comparison of what is known.

Notes on the Plumages and Generic Status of the Little Blue Heron

THE juvenal plumage of the Little Blue Heron (Florida caerulea) has always been described as white with dull brownish gray tips to the primaries (Palmer, 1962: 428, and earlier authors). In September 1962, when Dickerman was collecting blood specimens from nestling herons in a large mixed colony at San Blas, Nayarit, Mexico, an assistant brought to the boat for bleeding a large ambulatory nestling, 20-25 days of age, which because of the chestnut suffusion on the crown and back was considered at the time a between the Little Blue Heron and Louisiana Heron (Hydranassa tricolor). In October 1963 both authors visited the same heronry and found several juveniles showing a gradient of characters approaching the earlier specimen. Additional collecting at San Blas in 1964 and 1965 showed that this type of variation was relatively common and regular in occurrence. A total of 13 juveniles was collected. The San Blas specimens vary from those fitting the classical description of the juvenile Little Blue Heron to in.dividuals with the top of the head predominantly chestnut mixed with gray, and with a dingy chestnut cast to the interscapular area and lesser wing coverts. The primaries in such individuals are more extensively tipped with dusky than those of typical juveniles, the alula is marked with black, and the inner secondaries and scapulars are flecked with gray. Intermediate individuals have lesser amounts of chestnut or gray in these areas. The theory was initially suggested by the prominence of chestnut in the extreme individuals, as juvenile Louisiana Herons are extensively chestnut (see the excellent colored illustration by Eckelberry (in Pough, 1951: pl. 15). A total of 15 adult Little Blue and 14 adult and juvenile Louisiana herons collected in the San Blas colony shows no sign of hybrid or intermediate characters. The plumage variation shown by the San Blas nestlings stimulated us to examine all Little Blue Heron specimens in a number of major museums (see Acknowledgments). We found a few juveniles with grayish crowns and interscapulars that approached some of the San Blas birds ,and occasionally a specimen with black markings on the alula (characters not mentioned in literature descriptions of the juvenal plumage), but no juveniles with the chestnut coloration of the extremes among the San Blas population. As our sample of adult and juvenile Louisiana Herons showed no evidence of introgression, we can only conclude that the chestnutcrowned juvenal plumage represents a localized color phase, thus far known only from San Blas.

Interspecific Communication Signals in Parasitic Birds

Dull plumages prevail among parasitic birds. Parasitic cuckoos are significantly less brightly marked than are nesting cuckoos. Dull parasitic birds are less readily seen and recognized by hosts, and dull plumages also appease the hosts by absence of releasers of aggressive behavior. Inconspicuousness and appeasement increase the vulnerability of hosts to the brood parasites. The dull juvenal plumages in some parasitic birds may have been incorporated into the adult communication signals by neoteny. Evidence of neoteny among brood parasites includes prolonged retention of juvenal plumage, juvenal-adult-like species pairs, and the retention of juvenal-like incomplete skull ossification throughout adult life. Polymorphism and an unusual degree of variation in plumage are adaptations in parasitic cuckoos which reduce the probability of recognition by hosts. Polymorphism in Cuculus canorus and other parasitic cuckoos is considered to be the result of apostatic selection for deviant phenotypes. Polymorphism of cuckoo eggs is mimetic, and the tendency for the eggs of Chrysococcyx caprius to be laid in nests with matching eggs is statistically significant. Aggressive mimicry which deceives host species occurs in all stages of the life cycle of parasitic birds but mainly during the period of host parental care.

Feeding Behavior and Food-Consumption Rates of a Captive California Murre

Detailed studies of the underwater feeding behavior of Common Murres (Uria aalge californica) do not appear to have been reported. We had the opportunity to make such a study beginning in September 1964, when school children found an apparently uninjured murre on the beach near Humboldt Bay, California, and brought him to Humboldt State College. The bird was a nearly full-grown young male in juvenal plumage with fully developed flight feathers. Throughout the study, from 16 September 1964 to 19 January 1965, the murre was housed in a 620-gallon, indoor salt-water aquarium in the Wildlife Building at Humboldt State College. The aquarium tank is 66 inches long, 48 inches wide, and 45 inches deep and is constructed of concrete with a glass window in front 60 inches wide and 44 inches high through which detailed observations of the murre's underwater activities were made. The water was aerated with an air pipe, and filtering and refrigeration systems maintained the water temperature at 110 C. An overflow pipe opened at the surface, allowing the bird's fecal material to settle to the bottom where it could be collected for analysis. All pipes were near the tank walls and did not interfere with' the murre's activities. During most of the study period the aeration system was kept at a low enough level so that there was essentially no surface turbulence. The murre was fed live cull rainbow trout (Salmo gairdnerii) from the college hatchery. These fish averaged 25 per pound at the beginning and 10 per pound at the end of the study. Twice daily, the bird was placed in a paper bag and weighed to the nearest 5 g. Weights were usually taken about 0800 and in the late afternoon. We wish to thank the following for help with various phases of the study: R. I. Bonn, J. A. Gast, R. L. Jarvis, R. L. Ridenhour, Marilyn Sanford, R. A. Wallace, and E. A. Whitaker. R. E. Genelly and A. S. Mossman critically read the manuscript.

Identification of the Flycatchers of Eastern North America, with Special Emphasis on the Genus Empidonax

Among eastern birds, the flycatchers are notoriously difficult to identify. Vague identifications or unqualified errors occur not infrequently in the genus Empidonax, and we have personally seen banders identify wood pewees as Empidonaces and vice versa. Part of the problem lies in the fact that most of us are more familiar with birds in the field than we are with birds in the hand, where they give none of the behavioral clues that aid us in field identification. For this reason, banders have a special need for useful keys. But unfortunately the available texts and keys often lack vital information on when and where to expect a given species, and they commonly neglect juvenal plumages and plumage sequences. Some keys in common usage place undue emphasis upon single characters which, because of their variability, should only be used as corroborative evidence. A case in point is the often-quoted distinction between two groups of Empidonaces based solely on back coloration, which has inadvertently led to the misidentification of some green-backed Traill's Flycatchers as Acadian Flycatchers. Banders should thus find useful a new key and summary of pertinent information which covers all plumages of all eastern flycatchers, i.e. those species normally found anywhere east of the Great Plains and north of southernmost Texas, and including those extralimital species for which there are a number of specimens taken in the east. The nomenclature used is that of the A. 0. U. Check-list of North American Birds (1957). The key emphasizes characters visible in the living bird but not often mentioned in the literature, such as color of mouth lining, and also considers the times and places where certain species are not to be expected. Its use requires no more than an accurate caliper and a millimeter ruler. With these aids, and a careful reading of all the characters, we believe that 98 per cent or more of all the fullgrown birds netted can be readily keyed out, even in the difficult genus Empidonax.

The Nomenclature of Plumages and Molts

IN The Auk of 1959 (76: 1-31) there appeared an article by P.S. Humphrey and K. C. Parkes entitled "An approach to the study of molts and plumages," which will be the subject of this paper. Some readers may not be familiar with Humphrey and Parkes's paper and therefore would welcome a summary of the principal points discussed by these authors. Feeling unhappy with the terminology of molts and plumages as proposed (in 1900) by Dwight, and which has been, to use their words, the foundation of most, if not all, subsequent work, they decided to replace it with an almost completely new nomenclature. In their opinion (p. 14) "there is clearly a need for a semantically 'clean,' independent, uniform, and practical terminology applicable to plumages and molts of all birds," and therefore they endeavored to introduce a nomenclature which might assist in clarifying homologies of molts and plumages. With that aim in mind, they do not spare a single one of the expressions which are in current use, except the term juvenal plumage. They do away with adult, subadult, immature, annual (or perennial) plumage, nuptial plumage, off-season or non-breeding plumage, and so with Dwight's whole system of molt nomenclature, because they believe that molts should be named in terms of the incoming, and not of the replaced, generation of feathers. They introduce the new term basic plumage to designate what we used to call annual or, following Lynes (1930: 38), perennial, plumage. The molts by which this basic plumage, as well as the juvenal plumage, are replaced should henceforth both be called prebasic molts, no longer the annual and the postjuvenal molt, respectively. In birds which have as adults two plumages per cycle, as, for instance, the Scarlet Tanager (Piranga olivacea), the complete molt is, in their

An Approach to the Study of Molts and Plumages

During the course of studies of the molts and plumages of certain waterfowl and other birds, it has become apparent to us, as it has to a number of other workers, that the description of plumage successions has often been hampered by the lack of a uniform and practical terminology. It was our original intent to introduce a new terminology applicable, as far as possible, to all birds, in order to eliminate some of the semantic difficulties of the past. As this project progressed, it became obvious that knowledge of the plumage stages of many species is sadly incomplete or poorly understood; further study revealed the need of a reexamination of many long-held concepts of plumage succession and of more precise definitions of widely but ambiguously used terms. The subject is too large to be covered in a single paper. We propose here to discuss plumage succession beginning at the time of loss of the juvenal plumage, i.e., the bird's first covering of true (in some cases modified) contour feathers. We hope in a later paper to analyze the development of the plumages from the embryo through the completed juvenal plumage. We have adopted this reversed chronological sequence because of the complexity of the question of the natal downs and their origin, which we intend to investigate at some length. We hope in this paper to throw new light on concepts of plumage and molt, and we present a framework within which descriptive and comparative studies may be made. In spite of the vast progress made by many workers in recent decades in understanding some of the factors which affect the physiology of molt (genetic control, hormonal balance, photoperiod, temperature, diet, etc.), it must be remembered that such information is available for but a small fraction of the species of birds of the world. We believe it is greatly desirable to have

On the Juvenal Plumage of North American Pipits

On the Juvenal Plumage of North American Pipits

Notes on Panamanian Birds

WHEN E. A. Goldman visited eastern Panama to collect birds and mammals for the U. S. Biological Survey in 1911 and 1912, that part of Central America was still virtually unexplored ornithologically. The explorations of the Italian naturalist, Festa, in the Rio Tuyra Valley, in 1895, seem to have been the only previous work. After Goldman brought back his fine collection from Porto Bello, Cerro Azul, Chepo, Rio Tuyra Valley, Mt. Pirri, and Cana, the late E. W. Nelson began its study and described many interesting new forms from it. Unfortunately, he was never able to complete his study and no comprehensive report was ever written on the birds, although some information about them was included incidentally in the report on the mammals of Panama by Goldman (1920: 25-42). Since that time several other collectors have worked in eastern Panama, and the region has become much better known. Nevertheless, there seem to be a few things left in the Goldman collection that have escaped more recent investigators. In his lists of species characteristic of the Arid Lower Tropical Life Zone of Panama, Goldman (1920: 35) included 'Ammodramus savannarum obscurus,' which was then the name used for the grasshopper sparrows breeding in southern Mexico. This publication, as well as the specimens on which it was based, have apparently been overlooked by subsequent investigators of the Panamanian avifauna, since there is no mention of the species as occurring in that country by either Hellmayr (1938: 495-501), or Griscom (1935). The three specimens of grasshopper sparrow, on which Goldman's (1920: 35) citation was based, were taken by him near Chepo, at the eastern end of the Pacific coastal savannas in eastern Panama. These include an immature male and a non-sexed adult specimen collected on the Rio Pacora, ten miles west of Chepo, altitude 100 feet, March 28, 1911; also an adult female taken ten miles northwest of Chepo, March 20, 1911. The immature male is interesting in that it is in process of molt from the juvenal plumage to the adult dress. Much of the head and back

Juvenal Plumage of the Evening Grosbeak

Juvenal Plumage of the Evening Grosbeak

The Juvenal Plumage and Postjuvenal Molt in Several Species of Michigan Sparrows

The Juvenal Plumage and Postjuvenal Molt in Several Species of Michigan Sparrows

The Juvenal Plumage of Townsend's Warbler (Dendroica Townsendi)

The Juvenal Plumage of Townsend's Warbler (Dendroica Townsendi)

Natal down and Juvenal Plumage of the Acadian Sharp-Tailed Sparrow

Natal down and Juvenal Plumage of the Acadian Sharp-Tailed Sparrow