Greater Coverts Research Articles

Moult intensity constraints along the complete moult sequence of the House Sparrow (Passer domesticus)

Sequence and intensity are two essential components of bird moult. While the moult sequences of remex tracts are highly homogenous across passerines, other tracts apparently show a high variability. Moreover, order of moult activation among tracts are insufficiently known. Likewise, dynamics of moult intensity as moult progresses remains poorly known. Here, we provide detailed quantitative description of moult sequence and intensity in the House Sparrow (Passer domesticus). To understand their role, we tested two hypotheses on the: 1) protection function of moult sequence, and 2) aerodynamic and physiological constraints on moult intensity. We scored percentage growth of 313 captured sparrows using the mass of the feathers of each tract (also length for remiges) to monitor moult intensity throughout the complete moult progress, which is defined as the fraction of new and growing feathers in a moulting bird relative to the total plumage. Moult sequence was highly variable both within wing coverts and among feather tracts, with moult sequence differing among all birds to some degree. We only found support for the protection function between greater coverts and both tertials and secondaries. Remex-moult intensity conformed to theoretical predictions, therefore lending support to the aerodynamic-constraint hypothesis. Furthermore, remex-moult speed plateaued during the central stages of moult progress. However, overall plumage-moult speed did not fit predictions of the physiological-constraint hypothesis, showing that the remex moult is only constrained by aerodynamics. Our results indicate that aerodynamic loss is not simply the inevitable effect of moult, but that moult is finely regulated to reduce aerodynamic loss. We propose that the moult of the House Sparrow is controlled through sequence and intensity adjustments in order to: 1) avoid body and wing growth peaks; 2) fulfil the protection function between some key feather tracts; 3) reduce detrimental effects on flight ability; 4) keep remex sequence fixed; and 5) relax remex replacement to last the whole moult duration.

Molt Strategies by Age and Subspecies in the Willow Flycatcher

We clarify the molt strategies of the Willow Flycatcher (Empidonax traillii) by subspecies through the examination of 455 museum specimens. Most and typically all juvenile primary coverts are retained during the preformative molt in fall and winter, allowing yearlings to be distinguished from older birds from their first spring through their second fall. In addition to replacing the body feathers and some to (usually) all secondary coverts and tertials, the preformative molt can include no other remiges or rectrices (46% of specimens), all remiges and rectrices (33%), or some remiges in an “eccentric” sequence (21%). During the prealternate molt, replacement of upper wing coverts and tertials is much less extensive than in the preformative molt, varying from replacement of no feathers in 27% of specimens to replacing more than half of the median and greater coverts and all three tertials in other specimens. Both the preformative and the first prealternate molts are significantly more extensive in eastern E. t. traillii than in the three western subspecies (brewsteri, adastus, and extimus). The definitive prealternate molt is also significantly more extensive than the first prealternate molt in the western subspecies but not in traillii. These differences between traillii and the other subspecies may result from longer migration distances, hence more solar exposure on an annual basis, and different molt-strategy dynamics between eastern and western North American passerines, perhaps relating to preferences for moister habitats. Further investigation is needed on the timing of molts on the winter grounds and the extent of body-feather replacement during the prealternate molt.

Preformative molt, plumage maturation, and age criteria for 7 species of manakins

We developed aging criteria for 7 species of manakins (Pipridae) from the Manu Biosphere Reserve, Peru, based on patterns of plumage maturation and wing-feather replacement following their preformative molt, and summarize information on their morphological characteristics. Each species underwent a partial preformative molt, which could be identified using the presence of molt limits in the greater coverts. Some male Band-tailed Manakin (Pipra fasciicauda), Round-tailed Manakin (Ceratopipra chloromeros), Cerulean-capped Manakin (Lepidothrix coeruleocapilla), and Yungas Manakin (Chiroxiphia boliviana) showed evidence of delayed plumage maturation, allowing for age classification up to the third annual cycle, whereas Blue-crowned Manakin (L. coronata caelestipileata), Fiery-capped Manakin (Machaeropterus pyrocephalus), and Green Manakin (Cryptopipo holochlora viridor) appeared to attain definitive plumage after their second molt cycle. Morphometrics showed strong overlap and were less useful for separation of age and sex classes. Our findings add to the growing list of studies that suggest many tropical passerines can be aged using primarily molt limits. Data on molt and plumage maturation are still needed for the vast majority of tropical birds in order to inform conservation-based research and studies of avian life history.

Wing-feather moult of the White-backed Woodpecker Dendrocopos leucotos lilfordi

ABSTRACT Determining the age of specimens is of great help in wildlife management, especially for rare or threatened species in which each individual has a high value. In birds, differences in moulting pattern between juveniles and adults may in some cases allow determination of a bird’s age from the examination of its plumage. In the present study, we analyse the moult of 19 breeding individuals of White-backed Woodpecker Dendrocopos leucotos lilfordi captured for GPS tagging in the Pyrenees, in order to describe, for the first time, the moulting pattern of this endangered woodpecker. Two well-differentiated groups of adult birds were identified: those that underwent a partial moult, and were classified as second-calendar-year birds, and those that performed a complete one and were classified as older. The first group had renewed most lesser and median coverts, all primaries and the innermost greater coverts, thus showing clear moult limits between the primaries and secondaries and within the greater coverts. Some individuals also replaced up to two more greater coverts (GC5–6). Individuals classified as older birds showed all feathers to be of a single generation, indicating that they had undergone a complete moult. A few individuals in this category retained a few unmoulted secondaries and primary coverts, however. A recapture of a bird with a complete moult, which had been captured a year before showing a partial moult, would confirm these moult sequences to be age dependent. This moulting pattern is very similar to that described for other spotted woodpeckers, and allows researchers to determine the ages of breeding individuals during the nesting season.

Remigial and rectricial molt sequences in a captive Ryukyu Scops-Owl (Otus elegans)

We describe the remigial and rectricial molt sequences of a Ryukyu Scops-Owl (Otus elegans) held in captivity on Minami-daito Island, Nansei Islands, southern Japan. The owl completely shed its remiges and rectrices during its preformative molt as well as during its definitive prebasic molts in 3 consecutive years. In the preformative molt, the primaries were all shed during October, November, and December, in distal order from P1. Although all 4 groups of secondaries were shed in proximal order, the sequence may have been caused by adventitious shedding under captive conditions. During definitive prebasic molt, the primaries were shed in distal order during the period from June to September. The secondaries were shed from 3 nodes in 4 feather groups; 3 groups were shed in proximal order, but the remaining group was shed in distal order. The primary coverts were shed in exact sequence with their corresponding primaries during the definitive prebasic molt, but in a different sequence during the preformative molt. Whereas the greater coverts were shed irregularly during the early part of the primary covert molt, the median coverts were shed during the first half of the primary covert molt. The alula feathers were shed distally over a period of weeks. The right rectrices were shed in irregular order over a short period (12 days) and the left rectrices were shed over a long period (at least 82 days). The shedding sequence of the captive Ryukyu Scops-Owl basically followed the known pattern previously observed in Strigidae species. The captive individual underwent a complete molt when it was a juvenile as a result of being provided with sufficient food, and presumably because of the lower energy demands of being in a cage.

Non-moulted primary coverts correlate with rapid primary moulting

Time constraint is a main factor which affects the moult strategies in passerines, mainly during the first year of life. The variability of moult strategies between species is associated with the extent of the moult. In the first year of life, the extent of the moult is highly variable between species and individuals. In most passerine species, juveniles only renew some of their feathers, but the factors that govern which feathers are renewed and which are retained have been largely overlooked. Here we examine the common pattern of non-moulted primary coverts (PC) in passerines during the first-year moult cycle (post-juvenile and first-year pre-breeding moults). On the interspecific level we found that among 63 species of passerines, PCs are the least commonly moulted feather tract. For five species (Hirundo rustica, Pycnonotus xanthopygos, Prinia gracilis, Acrocephalus stentoreus and Passer moabiticus) which perform a complete post-juvenile moult, we found that the PC moult occurs over a longer period than greater coverts (GCs) and is sequential (non-simultaneous). At the intraspecific level, we found that the main difference between a partial and complete moult in Prinia gracilis is the moulting or non-moulting of the PCs. We also demonstrate that for Prinia gracilis 1) juveniles which do not moult their PCs, moult their primaries at a higher speed than those which moult their PCs and 2) area/mass ratio of PCs is lower than of GCs. These two findings may explain why many passerines skip PC renewal during the first year of life. Because the PC moult lasts a long time, forgoing this moult enables long term resource savings that allow for dealing with time constraints. Our results highlight the adaptive advantages of non-moulted PCs in cases of time constraints.

Age and sex determination of Mallards Anas platyrhynchos in autumn

Male and female mallards Anas platyrhynchos are easily told apart, whereas ageing is problematic, due to individual timing of moult and lack of easily defined age criteria. From examination and photographic documentation of mallards caught at Ottenby Bird Observatory (56°12′N, 16°24′E), we describe nine characters of plumage and bare parts to be used for ageing in autumn. The reliability of these characters was tested by letting experienced bird ringers determine putative age of birds from photos. Age determination from any single character proved to be uncertain, as correctly assigned mallard photos of each character was in the range of 51–85% for males and 48–89% for females. For both sexes, the lowest figure represented post-humerals and the highest represented tertials. Rectrices, tertial coverts, and greater coverts had high scores (71–85%). Using all characters, 91% of the males and 95% of the females were correctly aged. As young mallards, with the progress of pre-breeding moult (completed from October onwards), acquire tail and tertials identical to adults, untypical individuals are better not assigned to an age category.

Thamnophilidae (antbird) molt strategies in a central Amazonian rainforest

ABSTRACT Avian molt, or the regularly scheduled replacement of feathers, is an important life history event, particularly in central Amazonian rainforest birds for which a relatively high proportion of the annual cycle can be dedicated to this process. Here, we detail molt strategies of 18 antbird species (Thamnophilidae) based on 2,362 individuals captured from lowland tropical rainforest at the Biological Dynamics of Forest Fragmentation Project near Manaus, Brazil. All species exhibited a molt strategy consistent with the Complex Basic Strategy, in which birds undergo an inserted preformative molt within the first cycle, but apparently lack prealternate molts. The preformative molt and resulting formative plumage aspect of the 18 antbird species can be grouped by three distinct patterns: 1) a complete molt resulting in an adult-like formative plumage without molt limits; 2) a partial molt involving body feathers, lesser coverts, at least some or all median and greater coverts, and sometimes tertials or...

Ageing Dunnocks Prunella modularis using plumage characteristics

Iris colour has long been regarded as the only reliable way of ageing Dunnocks Prunella modularis. There are limitations with this method, namely that it can only be used during late summer and autumn when a difference in iris colour exists between young (first-year) and adult birds. By late autumn, the method is no longer reliable and many Dunnocks are thus left unaged. Differences in plumage exist between young and adult birds. These differences have an advantage over iris colour since they are observable year-round. A number of differences between young and adult birds have been found, notably in the greater coverts and primary coverts. These features allow Dunnocks to be reliably aged when ageing by iris colour is not possible.

Wing feather moult and age determination of Snowy Owls Bubo scandiacus

Moult of primary and secondary flight feathers of Snowy Owls Bubo scandiacus was studied from 53 museum specimens retaining some juvenile feathers. There were no ringed Snowy Owls of known age in the skin material, and the moult pattern has thus been interpreted using the moult of Eagle Owls Bubo bubo as a model. The difference between juvenile and adult primaries is described. Greater coverts may facilitate age determination of single flight feathers. Snowy Owls start their first flight feather moult M1 by shedding the innermost 2-6 secondaries during their second summer (as 2C birds). A majority of the owls also shed primary P7 during this first moult, occasionally also P8. This moult progresses at a faster pace than seen in Scandinavian Eagle Owls. During their second flight feather moult M2, moult of secondaries advances outwards, including moult from the two focal points S2 and S5, as in the Eagle Owl. Both P7 and P8 are moulted and fresh after M2, and some owls even moult P6 or P9. After the third flight feather moult M3 it is very hard to distinguish juvenile secondaries from old M1 secondaries, and a specific moult pattern is most easily recognized in primaries. On sharp images of the upper side of wings on a flying Snowy Owl, or on birds in hand, it should be possible to age birds up to four calendar years (4C) in autumn and five calendar years (5C) in spring, before onset of the fourth flight feather moult M4.

Variation in deuterium (δD) signatures of Yellow Warbler Dendroica petechia feathers grown on breeding and wintering grounds

Stable isotope analysis of feathers may help track populations of migratory birds throughout their annual cycle. We use deuterium isotope ratios in feathers (δDf) to confirm that Yellow Warblers Dendroica petechia go through both a prebasic molt on or near their breeding grounds and a prealternate molt on their wintering grounds, and evaluate whether δD analysis of different feather types can help assign birds to breeding and winter origins. We show that primary coverts and tail feathers have δDf values that reflect long-term average deuterium isotope ratios in precipitation (δDP) on the breeding grounds. Most greater coverts and crown feathers, however, have δDf values that are more enriched than predicted based on the δDP of their wintering distribution. We also found significant interannual variation in the δDf values of tail feathers, greater coverts and crown feathers. Interannual variation in δDf of winter-grown feathers may be explained by El Nino/La Nina conditions that influence rainfall and thus δDP; feathers were more depleted following an El Nino year (2005) than a La Nina year (2006). Gender had no effect on the δDf values of any feathers sampled. Age influenced the δDf values of crown feathers but not greater coverts. This study therefore confirms that δDf of summer-grown feathers can be used to identify breeding locations, but suggests that the ability to use δDf of winter-grown feathers to assign individuals to winter locations is limited by weak spatial gradients and temporal variation in δDP.

Ageing and sexing Marsh Tits Poecile palustris using wing length and moult

Ageing and sexing Marsh Tits Poecile palustris presents some difficulties for ringers. Wing length has previously been found to be useful for sexing English Marsh Tits, although the replacement of all juvenile rectrices and greater coverts by first‐year birds made ageing difficult. We examined Marsh Tits of known age and sex and found that 93.5% of birds could be sexed correctly using wing lengths of ≤ 62 mm for females and ≥ 63 mm for males. Wing length was also an indicator of age: many first‐years had shorter wings, but most also retained some juvenile rectrices and greater coverts after the post‐juvenile moult, and could be readily aged using these features. We found a primary moult period of 67 days for adult Marsh Tits, with a mean onset of 27 May.

Post‐juvenile and post‐breeding moult of Savi's Warblers Locustella luscinioides in Portugal

We describe the sequence and extent of the complex and little understood post‐juvenile and post‐breeding moults of Savi's Warblers Locustella luscinioides. In contrast to previous studies, the post‐juvenile moult occurred in at least 44% of the birds, 5% of which moulted some or all tertials and greater coverts. The timing of overlap between the filling and the post‐juvenile moults, and the fact that later‐moulting birds had no post‐juvenile moult, strongly suggests that the moult extent is dependent on fledging date. From July onwards, all adult males overlapped breeding and moult, whereas only 11% of the females did so. The start of moult varied from 6 June to 25 August, and was significantly earlier in males. Only 18% of the birds completed the moult, whereas the remaining individuals retained a variable number of inner primaries and/or secondaries. Interestingly, not only was the number of retained primaries positively associated with the date of moult, but so too was the primary number of birds in which the moult started. We view this as an adaptation allowing the replacement of the most important feathers for flight when the time available for moult is short. Body condition did not vary with the progress of moult when date was taken into account, but fat reserves still tended to decrease and then increase. The body condition was correlated positively with the wing raggedness, so Savi's Warblers do not compensate for an increasing wing load during moult.

Some aspects of chaffinch fringilla coelebs biology, based on an analysis of individuals ringed during 1991 to 2003 in Norfolk, England

From 1991 to 2003, 2,954 Chaffinches Fringilla coelebs were caught and ringed, year‐round, at Hilborough, Norfolk, England. The age and sex composition of Chaffinches varied between winters, but no systematic pattern was apparent. The age and sex composition of Chaffinches caught during winter did not vary significantly from that of Chaffinches caught during the breeding season. Chaffinch wing lengths and body weights did not vary significantly between seasons. Male Chaffinches had wings that were on average 6 mm longer than females and adult wings were on average 2–3 mm longer than immatures and juveniles. Male Chaffinches were on average 2 g heavier than females. Approximately 40% of juvenile Chaffinches retained unmoulted greater coverts after their post‐juvenile moult, retaining 1.47 ± 0.04 and 1.67 ± 0.09 formales and females respectively. Compared to immature females, twice as many immature males retained juvenile greater coverts. Overthe period of study, Chaffinches showed relatively consistent annual productivity, with captures of between 1.5 and 2 times as many juveniles or immatures as adults during the months following the breeding season. The higher productivity in some years was notexplained by variations in average monthly temperature during the breeding season. The mean duration between initial and final capture on the study site was between 1.6 and 2.3 years, and the longest period between initial capture and last recapture was over ten years. Only 0.14% of Chaffinches were recorded moving distances greater than 5 km from the site of capture, confirming the sedentary nature of the species. This study shows that few, if any, continental immigrants supplement the local Chaffinch population atthe study site in Norfolk.

Age and sex composition, biometrics, site fidelity and origin of Brambling Fringilla montifringilla wintering in Norfolk, England

We analysed data collected from approximately 2,600 Brambling Fringilla montifringilla caught while attracted to artificial food at a site in Norfolk, England over seven winters. The age and sex composition of trapped birds varied between winters in relation to the total number of birds caught, but no systematic pattern was apparent. During invasion years, when a higher number of birds were present on the study site, the proportion of males was higher. In any one winter, 38–70% of the Brambling were male and 63–86% were juvenile. Very few adult females visited the study site. Males had longer wings than females, by an average of 5–6 mm and the wings of adults averaged 1–2 mm longer than juveniles. There was sexual dimorphism in body weight, with males being on average 2 g heavier than females. Adults were on average 1 g heavier than juveniles. Within winters, mean body weights were higher in warmer months. Between winters, there was significant variation in wing length and body weight, which may have been associated with variation in the geographical origin of the birds or food availability. Approximately 70% of juveniles had undergone a partial moult of the greater coverts, with an average of between 2.7 and 3.4 old greater coverts being retained. Annual variation in the progression of moult was probably due to food availability and weather conditions on the breeding grounds or where the juveniles moulted. The mean proportion of Brambling retrapped within‐winters was 5.7% (range 0–15%) and there was no evidence to suggest that site fidelity was different in invasion years. Recoveries of ringed birds suggest that Brambling over‐wintering in Norfolk originate from Scandinavia and pass through the Low Countries on migration.

BODY MOLT OF MALE LONG-TAILED DUCKS IN THE NEAR-SHORE WATERS OF THE NORTH SLOPE, ALASKA

We examined the timing and intensity of body molt in relation to stage of remige growth for postbreeding adult male Long-tailed Ducks (Clangula hyemalis) off the coast of northern Alaska. During this period, remige and rectrix feathers are molted simultaneously with body feathers during the prebasic molt, which results in a period of increased energetic and nutritional demands. We collected birds from late July through mid-August and recorded intensity of molt in eight regions: head and neck, back and rump, greater coverts, lesser coverts, flank and sides, breast, belly, and tail. Using nonlinear regression, we estimated the peak intensity and variation for each region in relation to ninth primary length. We found little evidence of molt in the head and neck region. The greater and lesser coverts, and back and rump reached peak molt intensities earliest and were followed by tail, breast, and belly. Molt intensity in the flank and side region was highly variable and indicated a more prolonged molting pattern in relation to other regions. While body molt occurs simultaneously with wing molt, we found that molt among regions occurred in a staggered pattern. Long-tailed Ducks may employ this staggered molting pattern to minimize the energetic and nutritional requirements of molt.

Four fledglings of partial albinistic-plumage in two families of the Carrion Crow, Corvus corone orientalis

Four partly albino fledglings were observed in two Carrion Crow Corvus corone orientalis families in Hirosaki City, Aomori Prefecture, Japan, from 30 June to 9 August 2002. They all had white parts on the subterminal regions of the upper and under primary coverts, upper and under greater coverts, primaries, secondaries, and tertiaries. Two fledglings in one family had white in the subterminal regions of the rectrices as well as in the remiges. The latter two birds stayed with their parents for about 20 days longer than their single normally plumaged sibling.

Three new species of the ectoparasitic mites of the genus Syringophiloidus Kethley, 1970 (Acari: Syringophilidae) from passeriform birds from Slovakia.

Three new quill mite species of the genus Syringophiloidus Kethley, 1970 (Acari: Syringophilidae) from Slovakia are described and figured: S. bombycillae sp. n. from the waxwing Bombycilla garrulus (L.) (Passeriformes: Bombycillidae), S. schoeniclus sp. n. from the reed bunting Emberiza schoeniclus L. (Passcriformes: Emberizidae) and S. montanus sp. n. from the tree sparrow Passer monlanus (L.) (Passeriformes: Ploceidae). A key to all known species of the genus Syringophiloidus is given.

Ptilochronology proves unreliable in studies of nestling Pied Flycatchers

Ptilochronology does not appear to be a reliable measure of the daily growth rate of contour feathers or the nutritional state of nestling Pied Flycatchers Ficedula hypoleuca. Growth bars on primary remiges, which according to ptilochronology represent a day’s increment of feather growth, are only about half as wide as the actual daily increase in the length of these feathers while they are growing. The average width of the growth bars on primaries was also uncorrelated with other commonly used measures of growth or nutritional status (increase in body mass or in the size of the wing or tarsus), although these were highly correlated with each other. In adult flycatchers, the average width of the growth bars on tertials was unrelated to the average bar width on greater coverts, although both feathers are replaced during the winter (prenuptial) moult. This suggests that the growth bars either do not reflect the nutritional status of adults during normal periods of moult or that contour feathers in different tracts vary in their sensitivity to the nutritional status of the moulting bird. To our knowledge, this is the first time that anyone has attempted to apply ptilochronology to nestlings. It is noteworthy that a method of measuring growth and nutritional state that has shown promise when applied to induced feathers of adult birds seems to be unreliable when applied to the developing plumage of nestlings, and perhaps the normal (not‐induced) replacement plumage of adults.

AGE AND SEX DETERMINATION OF THE MAUI PARROTBILL

Abstract We determined the best plumage and morphometric variables for ageing and sexing the Maui Parrotbill (Pseudonestor xanthophrys), an endangered Hawaiian honeycreeper found only on east Maui, Hawaii, by examining and measuring 30 museum specimens and 71 live birds captured in mist nets. Juvenal plumage was identified by the presence of pale-tipped wing bars on the middle and greater coverts, grayish olive dorsal plumage, and dingy white underparts and superciliaries. Birds undergoing first prebasic molt retained the juvenal remiges, rectrices, and wing coverts. Birds in first basic plumage possessed juvenal wing bars and a dull juvenal-like plumage. Subsequent molts were complete, and adults lacked wing bars. Adult males had bright yellow plumage on the cheeks, throat, and superciliaries, as did 27% of adult females. All other adult females had less yellow in the underparts. The dorsal plumage of adult females was more variable than adult males and was either yellow-olive like the males or grayish o...