Moult Patterns Research Articles

Wintering location and moult patterns of juvenile Common Chiffchaffs Phylloscopus collybita

Capsule The pattern of moult of juvenile Common Chiffchaffs Phylloscopus collybita wintering in two distant localities of the Iberian Peninsula, Málaga (south) and Barcelona (north) differed. Individuals wintering in the northern locality moulted more contour than flight feathers, and vice versa, while sexes did not differ; individuals moulting more contour feathers arrived later and individuals moulting more flight feathers arrived earlier. Taken together, our results suggest that the pattern of moult of juvenile Common Chiffchaffs may depend on the location to which they migrate, in addition to the geographic origin and the time of breeding.

Moult topography and its application to the study of partial wing‐moult in two neotropical wrens

During partial moults birds replace a variable number or percentage of old feathers. This quantity, known as moult extent, has been a primary variable used in comparative studies. However, different spatial configurations of feather replacement may result from an equal number of renewed feathers. Few studies have addressed spatial aspects of moult, which may vary among species, among individuals of the same species and between episodes at the individual level. We present a novel approach to quantify the spatial configuration of a wing‐moult episode, hereafter referred to as moult topography, which comprises two elements, namely extent and vector, the latter condensing the spatial configuration of the replaced feathers on the wing plane. We apply this method to investigate preformative (post‐juvenile) wing‐feather moult pattern in the Spot‐breasted Wren Pheugopedius maculipectus and the White‐breasted Wood‐Wren Henicorhina leucosticta. We specified a null model of wing‐moult topography by which feather replacement follows a discrete anterior–posterior (vertical) axis between tracts and a discrete proximal–distal (horizontal) axis within tracts, and whereby wing feathers from a new tract are replaced only if all the feathers from the previous (anterior) tract have been replaced. Our sample of Spot‐breasted Wrens showed a strict single pattern of replacement that did not differ significantly from the null model. Our sample of White‐breasted Wood‐Wrens, however, differed significantly from the null model, showing prioritization of proximal wing feathers closer to the body. These differences might have biological relevance, for example in mate selection or in response to different environmental stressors, and might reveal the influence of these factors on the evolution of moult strategies. Overall, moult topography provides a new approach to future ecological and evolutionary studies of moult.

In Tundra Plovers the Frequency of Inner Flight Feather Replacement Varies with Length of Long-Distance Flights

The repair jobs that birds have to do to maintain high quality plumage take energy and time, so should be under intense selection. Recently, we have shown that secondary moult in the Eurasian Golden Plover Pluvialis apricaria is incomplete, irregular and asymmetric between wings, and argued that this reflected their ‘relaxed’ migratory habits. On the basis of this hypothesis, we predict that relatives of this species that have to make long flights between breeding areas and winter quarters would invest more in the moult of secondaries. To test this we collected data on moult patterns in two populations of Pacific Golden Plovers Pluvialis fulva (Siberia and Alaska), on American Golden Plovers Pluvialis dominica (Alaska) and Grey Plovers Pluvialis squatarola. Data were from the breeding, staging (Mongolia and Indiana) and wintering (Uruguay) areas. We found patterns consistent with our prediction: Pacific Golden Plovers from Siberia, and Grey Plovers have a similar moulting pattern to Eurasian Golden Plovers. Although both go to remote winter quarters, they migrate mainly over land, probably making short or moderate flights, as they are able to stage frequently. In contrast, the Alaskan populations of Pacific Golden Plovers and American Golden Plovers tend to renew all their secondaries from their second wing moult onwards. In line with their moult patterns, these two populations are known to make very long non-stop flights between breeding and winter areas. We argue that irregular moult and the partial renewal of secondaries is a primitive character in all four species. The full replacement of secondaries in the Pacific Golden Plovers and American Golden Plovers from Alaska may be considered as an adaptation for very long demanding flights. Regular moult patterns of secondaries, as found in many other shorebirds, could be a further refinement of this adaptation.

Moult of Flight Feathers in Darters (Anhingidae)

There is little information on flight feather moult in darters (Anhingidae). I used a combination of direct observations and photographs to confirm that the normal pattern of moult is to replace all remiges synchronously, but not all rectrices. I surmise that at least some rectrices are retained year-round because they are important for controlling body angle and depth while diving in shallow water. However, a few birds do not replace all their remiges at once, retaining some inner primaries and secondaries. The retained feathers are insufficient to allow flight, and the reason why these feathers are retained is unknown.

Seasonal male plumage as a multi-component sexual signal: insights and opportunities

Seasonal breeding plumage of male fairy-wrens (Malurus spp.) shows significant inter-and intra-specific variation in several potential signalling components that we systematically review here. There is extensive colour variation in the genus, possibly related to variation in visual sensitivity. In many species, males can delay development of their first complete breeding plumage for one or more years, although males in more complete breeding plumage appear to be reproductively more successful. An additional sexual signal, and an evolutionary innovation, is the timing of the pre-breeding moult. A mechanism regulating this moult is testosterone, which can stimulate initiation of moult and development of male breeding colouration and is presumably required for maintenance of the breeding plumage. Males undertake pre-breeding moult earlier as they age, and early pre-breeding moult appears selected by female choice for extra-pair mates. Few studies have addressed variation in colour quality or the role of plumage in aggressive interactions. Condition-dependence of moult or breeding plumage has not been experimentally investigated. We argue that the genus is particularly suited to comparative analyses, as it provides informative contrasts in colour, plumage development, patterns of moult, colour vision and mating system, offering many exciting opportunities for testing evolutionary theories on function and maintenance of sexual signals.

The Flight Feather Molt of Griffon Vultures (Gyps fulvus) and Associated Biological Consequences

Molt patterns are poorly understood in most large bird species; however, they are of paramount importance in the development of surveys in which age is a key parameter. From 2000 to 2011, we studied the body condition and molt patterns of 214 Griffon Vultures (Gyps fulvus) in Spain. Adult Griffon Vultures (“griffons”) demonstrated a poor body condition in winter during the incubation period, which then improved after hatching. Conversely, subadults were fairly uniform throughout the year, with their condition slightly inferior to that of adults throughout the year (except during the incubation period). The molt period lasted from April to December, ending in winter. Juveniles started their first molt in May of their second calendar year, beginning from the innermost primary (pp1) and proceeding outwards. Later, in midsummer, some individuals molted secondaries (only 17% of secondaries were molted in the first molt season) beginning at four foci: from the innermost (ss25) outwards, the outermost (ss1) and ss5 or ss6 inwards, and centrifugally from ss12. In the third calendar year, griffons continued molting primaries outwards in an orderly fashion and two new foci appeared in secondaries, apparently at ss6 and ss15. Most juvenile feathers were completely molted by the fourth calendar year, although some fifth-calendar-year griffons had retained juvenile secondaries. Subsequently, adults did not show a consistent molt pattern, but had a high degree of asymmetry between the two wings. Some quills were molted more often than others and this led us to hypothesize that adult griffons might molt quills on demand.El conocimiento sobre los patrones de muda de la mayoría de las grandes aves es aún escaso, sin embargo resulta de fundamental importancia para desarrollar investigaciones en las que la determinación de la edad es clave. Entre 2000 y 2011 estudiamos la condición corporal y el patrón de muda de 214 individuos de Gyps fulvus en España. Los buitres adultos mostraron una condición corporal baja en invierno, durante el periodo de incubación, la cual mejoró tras el nacimiento de los pollos. Por el contrario los sub-adultos mantuvieron una condición corporal uniforme a lo largo del año, un poco más baja que los adultos a lo largo del año, exceptuando el periodo de incubación. El periodo de muda duró desde abril hasta diciembre, finalizando en el invierno. Los juveniles comenzaron su primera muda en mayo de su segundo año de calendario, iniciándola desde las plumas primarias más internas (pp1) hacia fuera. Después, a mediados del verano, algunos jóvenes mudaron las plumas secundarias (sólo el 17% de las secundarias fueron mudadas en la primera sesión de muda), comenzando en cuatro focos, desde la más interna (ss25) hacia fuera, desde la más externa (ss1), desde la ss5 o ss6 hacia dentro y centrífugamente desde las ss12. En el tercer año calendario, los buitres continuaron la muda de las primarias de forma ordenada hacia fuera y aparecieron dos focos nuevos en las secundarias, en ss6 y ss15. Para el cuarto año calendario la mayoría de las plumas juveniles estuvieron completamente mudadas, aunque algunos buitres del quinto año aún presentaban secundarias juveniles retenidas. Tras esto, los adultos no mostraron un patrón consistente de muda, con un alto grado de asimetría entre ambas alas. Algunas rémiges fueron mudadas más frecuentemente que otras, lo que nos permite hipotetizar que los buitres adultos podrían mudar las rémiges cuando fuera necesario.

Primary Molt and Body Mass Changes in Least (Calidris minutilla) and Western (Calidris mauri) Sandpipers: Patterns from Ensenada de La Paz, México

Abstract. This study documents patterns of primary feather molt and body mass changes in Least Sandpipers (Calidris minutilla) and Western Sandpipers (C. mauri) in Ensenada de La Paz, Mexico. Both species use the same habitats and complete an uninterrupted primary feather molt between late July and October. Average timing of Least Sandpiper primary molt was from 29 July to 21 September (duration of 54 days), while Western Sandpipers molted from 29 July to 29 September (duration of 62 days). Molt models of individual primaries suggested that the molt of Least Sandpipers starts after all individuals have arrived in the study area, whereas the molt of Western Sandpiper starts before all individuals have arrived; the heavier Western Sandpiper tends to grow more feathers simultaneously than the Least Sandpiper. While Western Sandpipers are heavier than Least Sandpipers at the start of molt, both species decrease their body mass over the molt period. Although Least and Western sandpipers have similar natural hi...

Unique pattern of molt leads to low intraindividual variation in feather mercury concentrations in penguins

The authors hypothesized that the catastrophic annual molt of penguins (Sphenisciformes) would lead to reduced intraindividual variation of mercury concentrations in body feathers. While mean mercury concentrations varied significantly among 8 penguin species, intraindividual variability did not differ among species and was 3 times lower than values observed in other seabirds. The findings of the present study suggest that a single body feather collected at random per individual can be adequate to estimate mercury exposure at the population level in penguins.

Complete Post-Juvenile Moult in First-Year Blackcaps: Proximate Causes and Adaptive Implications

Moult is one of the most energy-demanding events in the annual cycle of a migratory bird. As a consequence, moult patterns have evolved that separate moult from other costly life-cycle stages and that exclude unnecessary replacement of the feathers. We studied two Spanish blackcap Sylvia atricapilla populations with the aim of elucidating variation and flexibility of their postjuvenile moult pattern. In contrast to most juveniles of this species, which normally undergo a partial moult both in captivity and in the wild, we found complete moult in 2 juvenile blackcaps. Complete moult was also inferred for another 7 birds, which were in active moult. Eight of these birds were trapped at a site in northern Spain and one originated from a partially migratory population from eastern Spain. This bird, held under the same environmental conditions as other 31 juveniles from the same population, moulted all primaries in captivity while the other 31 juveniles invariably undertook a normal partial post-juvenile moult. Therefore, it seems likely that complete post-juvenile moult observed in this bird was not induced by environmental conditions but had a genetic basis. Thus, we show that previously undetected variation among post-juvenile moult patterns is present in wild blackcaps and suggest that variation in the expression of important life-history traits could represent a potential reservoir for adaptive changes. This finding is in line with the great adaptive capacity of blackcap, repeatedly observed both in wild and in captivity.

Differences in the timing and extent of annual moult of black-browed albatrosses Thalassarche melanophris living in contrasting environments

Moult entails costs related to the acquisition of energy and nutrients necessary for feather synthesis, as well as the impact of reduced flight performance induced by gaps in the wing plumage. Variation in moult strategies within and between populations may convey valuable information on energetic trade-offs and other responses to differing environmental constraints. We studied the moult strategies of two populations of a pelagic seabird, the black-browed albatross Thalassarche melanophris, nesting in contrasting environments. According to conventional wisdom, it is exceptional for albatrosses (Diomedeidae) to moult while breeding. Here we show that black-browed albatrosses breeding on the Falklands regularly moult primaries, tail and body feathers during chick-rearing, and the majority of those at South Georgia show some body feather moult in late chick-rearing. The greater moult-breeding overlap at the Falklands allows the birds to annually renew more primary feathers than their counterparts at South Georgia. The results of the present paper, pooled with other evidence, suggest that black-browed albatrosses from South Georgia face a more challenging environment during reproduction. They also serve to warn against the uncritical acceptance of conventional ideas about moult patterns when using feathers to study the ecology of seabirds and other migrants for which there is scant information at particular stages of the annual cycle.

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.

Feather selection and replacement patterns demonstrate that Goldfinches Carduelis carduelis fix postjuvenile moult extent prior to moult initiation

Birds undergoing a partial moult have to make important decisions regarding moult extent, pattern and sequence. Moreover, since partial moults are usually subject to a great degree of individual variability, the mechanisms controlling and organising such moults can be particularly complex. In the present paper, I investigate the feather selection and replacement process involved in partial postjuvenile moult in the Goldfinch Carduelis carduelis. Moult patterns observed after moult completion indicate that birds select the feathers to be replaced according to a predetermined order of moult priorities. However, the sequence of feather replacement, both within and between feather tracts, differs markedly from this order of moult priorities, varying individually to be adjusted to the final moult extent. These results indicate that, prior to or at the beginning of moult, each bird fixes with precision which feathers will be replaced. These findings have important implications for the interpretation of partial and incomplete moult patterns and for our understanding of the underlying factors controlling moults.

Adaptations in primary wing moult of southern African Viduidae and their hosts (Estrildidae)

Primary wing moult patterns in southern African brood-parasitic viduines were compared with those of their estrildid hosts. We searched for similarities in the timing and duration of moult within these closely related species potentially arising from their linked breeding biology and geographical distributions. Contrasting patterns were found between summer and winter rainfall regions, suggesting that climate dominates over phylogenetic effects on moult. Within the summer rainfall region different patterns of moult also emerged, and these generally supported the colonisation hypothesis of the host–brood parasite system. Moult estimates are provided for these taxa for which, until now, data have been mostly descriptive.

Individual migratory patterns of two threatened seabirds revealed using stable isotope and geolocation analyses

AbstractAimIntraspecific variability in the migratory movements of seabirds is being revealed far more complex than hitherto recognized, and our lack of understanding undermines their effective protection. Our aim is to test whether the isotopic values of a single feather of two threatened seabirds, the Mediterranean (Puffinus yelkouan) and the Balearic (Puffinus mauretanicus) shearwaters allow the geographic assignment of birds to their non‐breeding areas.LocationThese two species are known to use three main non‐breeding areas: the NE Atlantic Ocean, the W Mediterranean and the Aegean‐Black seas.MethodsWe clustered in three groups the δ13C and δ15N values of the first primary feather (P1), inferred to be grown during the non‐breeding period, of 34 Mediterranean and 56 Balearic shearwaters accidentally caught by longliners. To link the isotopic values of P1 to its corresponding non‐breeding area, we performed a discriminant function analysis (DFA) based on the three clusters and applied this function to feathers of known origin: P1 from seven Mediterranean shearwaters from Hyères Archipelago (France) tracked with geolocators and body feathers from six chicks from Balearic shearwaters. To link the moulting patterns to the areas where the feathers were grown, we applied the DFA to a sequence of primary feathers of eight Balearic and five Mediterranean shearwaters (caught by longliners).ResultsIsotopic and tracking data indicate that none of the Mediterranean shearwaters migrated to the Atlantic. The cluster and discriminant function analyses revealed that 8% of Balearic and 54% of Mediterranean shearwater moulted P1 in the Mediterranean Sea. Migratory movements were reflected in the changing isotopic values of the primary sequences.Main conclusionsStable isotope analyses (SIA) are a powerful approach to reveal the intraspecific variability in the migratory patterns of seabirds that use distinct isotopic areas over their annual cycle. The assignment of birds to their non‐breeding areas by means of SIA is a simple and effective tool that can help to evaluate the impact of human activities in remote areas not only at population but also at individual level, which is an essential knowledge for the management and conservation of threatened species.

Assessment of Trace-Metal Concentrations in Western Reef Heron (Egretta gularis) and Siberian Gull (Larus heuglini) From Southern Iran

The objective of the present study was to investigate the levels of heavy metals, namely, chromium, copper, cobalt, nickel, and iron, in Western Reef heron (Egretta gularis) (n = 15) and Siberian gull (Larus heuglini) (n = 15) to (1) compare metal concentrations between two bird species with different trophic level, molting pattern, and life strategy; (2) examine species- and sex-related variations in trace-metal accumulation; and (3) determine the significance between heavy-metal concentrations in kidney, liver, and pectoral muscle. Bird samples were collected from November to December 2010 throughout the Hara Biosphere Reserve, and heavy metals were assayed by using a Shimadzu AA 680 flame atomic absorption spectrophotometer; the results were given as μg/g dry weight. Metal concentrations were different between the bird species as well as among bird tissues, but there was no difference (except chromium and iron in kidney) between sex (male vs. female). Mean levels in kidney of Western Reef heron and Siberian gull were chromium (0.96, 2.32 μg/g), copper (6.31, 10.55 μg/g), cobalt (0.12, 0.14 μg/g), nickel (1.13, 1.32 μg/g), and iron (37.92, 39.64 μg/g), respectively, whereas in liver they were chromium (1.05, 2.75 μg/g), copper (8.93, 12.63 μg/g), cobalt (0.09, 0.17 μg/g), nickel (1.1, 2.27 μg/g), and iron (34.03, 44.21 μg/g), respectively. Results showed that heavy-metal concentrations in Western Reef heron were decreased in the sequence iron > copper > nickel > chromium > cobalt, whereas in Siberian gull they were decreased in the sequence iron > copper > chromium > nickel > cobalt. Results also showed that in both species, the highest chromium and nickel concentrations were measured in female birds and the lowest in male birds, whereas the highest copper, cobalt, and iron (except iron in liver) concentrations were measured in male birds and the lowest in female birds.

Selection of flight feathers from Buteo buteo and Accipiter gentilis for use in biomonitoring heavy metal contamination

The concentrations of Hg were determined in all primary flight feathers from 20 specimens of Buteo buteo and 49 specimens of Accipiter gentilis, which had died in various Wildlife Recovery Centres in Galicia (NW Spain) between 2001 and 2009. The aim of the study was to standardize the feather or feathers that should be analyzed in each species to enable inter-individual comparison of the levels of contamination, taking into consideration any variability in the concentrations of Hg caused by the birds' molting patterns. For both species the results show a high degree of both inter (e.g. an individual of A. gentilis showed 426ngg−1 of Hg as median and 568ngg−1 as median absolute deviation, MAD) and intra-individual variability (e.g. primary feather number seven – P7 – of all the A. gentilis individuals showed 537ngg−1 of Hg as median and 1129ngg−1 as MAD). Although molting did not have a clear effect on the concentrations of Hg in the flight feathers, it was possible to identify the most representative feather in each individual, taking into account the amount of metal excreted in each feather and the intra-individual variability. For B. buteo use of flight feather P6 is recommended for Hg biomonitoring studies; the amount of Hg excreted to this feather was 509ng as median, which represents the 14% (from 10 to 20%) of the total Hg present in all the primary feathers. For A. gentilis the recommended feather is P7, which has a median of 86ng of Hg (corresponding to 12%, and varying between 5 and 22%).

Feather growth rate and mass in Nearctic passerines with variable migratory behavior and molt pattern

ABSTRACT. Bird species vary greatly in the duration of their annual complete feather molt. However, such variation is not well documented in birds from many biogeographic areas, which restricts our understanding of the diversification of molt strategies. Recent research has revealed that molt duration can be estimated in passerines from ptilochronology-based measurements of the growth rate of their tail feathers. We used this approach to explore how molt duration varied in 98 Nearctic species that have different migratory strategies and molt patterns. As previously documented for Palearctic species, migration was associated with a shortening of molt duration among species that molted during summer on their breeding range. However, molts of winter-molting migratory species were as long as those of summer-molting sedentary species, which suggests that winter molt also allows Nearctic migrants to avoid the temporal constraints experienced during summer. Our results also suggest that migratory species that un...

Timing and Pattern of Molt in Kuhl's Bat,Pipistrellus kuhlii, in Saudi Arabia

Kuhl's bat (Pipistrellus kuhlii) from Unizah Province, near the center of Saudi Arabia, was studied monthly from May 2005 to August 2006 to investigate the timing and patterns of molt. Adults and juveniles undergo a single molt extending annually over a five month period in summer from late April until September and following the breeding season. Few males of Kuhl's bat initiate molt before females but the majority of both sexes molt in July and terminated the molt almost simultaneously. Molting begins on the dorsum and then spreads to the ventrum once the dorsal molt is completed. Our findings provide comparable observations to previous studies on molt in bats suggesting that bats appear to exhibit a species-specific timing and sequence of molt.

Is the LCP Superfund Site an Ecological Trap for Clapper Rails?

Abstract Rallus longirostris (Clapper Rail) is considered a good indicator species for toxicants because of its strong site fidelity and predictable diet of benthic organisms. High levels of the rare PCB Aroclor 1268 have been found in Clapper Rail adults, chicks, and eggs from the marshes associated with the Linden Chemical Plant (LCP) in Brunswick, GA. Recently, sampling and testing feathers has successfully been used as a non-lethal tool to trace exposure and assimilation of Aroclor 1268 in rails from the LCP site. This approach allows us to infer how and when these birds are exposed to contaminants in the marsh due to predictable molting patterns coupled with the fact that a feather will accumulate the toxicant only at the time it is grown. This study is the start of a process to investigate the possibility that this ecosystem contamination is the foundation of an ecological trap for Clapper Rails at the LCP site. Aroclor 1268 was isolated in Clapper Rail feathers from all birds collected from the con...

Seasonal patterns of prolactin and corticosterone secretion in an Antarctic seabird that moults during reproduction

In avian species that have evolved life-history strategies wherein molt and breeding overlap, there are potential conflicts between the regulatory roles of baseline prolactin and corticosterone in parental care (positive) and moult (negative). We describe seasonal patterns of hormonal secretion, moult, and parental behaviour in sibling species of giant petrels ( Macronectes spp.) which begin moult during the incubation/early chick-rearing stage of reproduction. With the exception of male Southern giant petrels ( Macronectes giganteus), prolactin secretion and moult in Northern ( Macronectes halli) and female Southern giant petrels conformed to those observed in all other avian species, with the initiation of moult coincident with decreases from peak prolactin levels. However, male Southern giant petrels began moulting early in incubation when prolactin was increasing and had not yet peaked, which suggests a requirement of prolactin for incubation behaviour and a dissociation of prolactin from moult. Corticosterone showed little seasonal variation and no relationship with moult. When comparing prolactin, corticosterone, and moult in failed vs. active breeders, we found that failed breeding enabled a more rapid down-regulation of prolactin, thus facilitating a more rapid moult. We present specific examples of the behavioural ecology of giant petrels which we conclude help mediate any potential hormonal conflicts between parental care and moult.