Primary Moult Research Articles

Moult of three Palaearctic migrants in their West African winter quarters

Some theories about moult strategies of Palaearctic passerine migrants assume that birds adapt timing of moult to environmental conditions such as rainfall on their African wintering grounds. Species wintering in the northern tropics should limit moult to the period shortly after their arrival at the end of the rainy season. Passerine migrants wintering in West Africa should also moult more rapidly compared to related species or conspecific populations that moult elsewhere. We investigated the moult of melodious warblers Hippolais polyglotta, willow warblers Phylloscopus trochilus and pied flycatchers Ficedula hypoleuca wintering in Comoe National Park, Ivory Coast, between October 1994 and April 1998. In contrast to previous studies we did not restrict our analyses to moult of flight feathers but also included moult of body feathers. The results differed partially from the general assumptions of previous authors. Melodious warblers moulted twice: a complete moult shortly after their arrival, and a moult of body feathers and in some cases some tertials and secondaries in spring. Willow warblers moulting flight feathers were found between December and March with the majority moulting in January and February. Primary moult was not faster compared to populations moulting in central Africa and South Africa. Body feather moult varied strongly among individuals with birds in heavy moult between December and April. Pied flycatchers moulted body feathers and tertials between January and April. Birds with growing feathers were found throughout the whole period including the entire dry season. Moult strategies are thus not readily related to a few environmental factors in general and our results show that factors other than mere resource availability during certain times on the wintering grounds are likely to govern the timing of moult.

Polymorphic Flight-Feather Molt Sequence in Tufted Puffins (Fratercula Cirrhata): A Rare Phenomenon in Birds

Abstract Previous reports have stated that Tufted Puffins (Fratercula cirrhata) lose all of their flight feathers simultaneously (or nearly so) during flight-feather molt and replace them in no apparent order. In contrast, we found that captive second-year (SY) Tufted Puffins (1) typically require 15 and 10 days to lose their primaries and secondaries, respectively, during their first flight-feather molt, and an average of 21 days to lose all of their remiges; and (2) replace their primaries in either of two discrete sequences. In 9 of 13 birds, primary molt began at the innermost primary, P1, and progressed distally to the outermost functional primary, P10. However, in the remaining four birds, primary molt began in the middle of the primaries (P5-P7) and progressed both distally to P10 and proximally toward P1. Before the proximal wave reached P1, a second wave of molt was initiated at P1 and progressed distally, typically replacing P2 and P3 before reaching the proximal wave. Such polymorphism in flight-feather molt sequence is rare in birds, having been reported previously only in a few passerine species. Secondary molt began about 13 days after onset of primary molt and finished at about the same time as primary molt, resulting in a total duration of flight-feather molt of ∼54 days and a flightless period of ∼40 days.

POLYMORPHIC FLIGHT-FEATHER MOLT SEQUENCE IN TUFTED PUFFINS (FRATERCULA CIRRHATA): A RARE PHENOMENON IN BIRDS

Abstract Previous reports have stated that Tufted Puffins (Fratercula cirrhata) lose all of their flight feathers simultaneously (or nearly so) during flight-feather molt and replace them in no apparent order. In contrast, we found that captive second-year (SY) Tufted Puffins (1) typically require 15 and 10 days to lose their primaries and secondaries, respectively, during their first flight-feather molt, and an average of 21 days to lose all of their remiges; and (2) replace their primaries in either of two discrete sequences. In 9 of 13 birds, primary molt began at the innermost primary, P1, and progressed distally to the outermost functional primary, P10. However, in the remaining four birds, primary molt began in the middle of the primaries (P5-P7) and progressed both distally to P10 and proximally toward P1. Before the proximal wave reached P1, a second wave of molt was initiated at P1 and progressed distally, typically replacing P2 and P3 before reaching the proximal wave. Such polymorphism in fligh...

Habitat use, moult and biometrics in the Manchurian Reed Warbler Acrocephalus tangorum wintering in Thailand

Manchurian Reed Warblers Acrocephalus tangorum wintering at Khao Sam Roi Yot, Thailand, were largely restricted to mature Phragmites reeds. The mean wing length (± sd) of 105 Manchurian Reed Warblers was 54.5 ± 1.41 mm. There was no evidence of differences in body weight in spring, autumn or winter. Both adults and first‐winter birds underwent a complete moult soon after arrival in their winter quarters. Primary moult duration was estimated to be 59 days. Moult of secondaries was suspended in approximately one‐third to one‐fifth of birds, the few retained, old, unmoulted feathers usually being replaced later in the winter. No further moult was usually detected prior to northward spring migration.

Aspects of Breeding, Molt, Measurements and Population Trend of Hartlaub’s Gull in Western Cape, South Africa

Abstract In South Africa’s Western Cape, the main breeding season of Hartlaub’s Gull (Larus hartlaubii) is from January or February until May. At southern localities, there may be a second peak in breeding in August and September. Primary molt of adults mostly starts between August and December and lasts on average 115 days. In each of nine body measurements, averages were higher for males than for females, but values overlapped. In Western Cape during 1990-2001, the species bred at nine localities where breeding had not previously been reported. The maximum number recorded breeding at all localities in this region in any one year was about 5,500 pairs in 1995, less than the 10,000-11,000 pairs estimated for the region in the 1980s. Because the timing of the peak in breeding varies from year to year, it is considered that the 5,500 pairs represent an under-estimate, but it is likely that numbers did decrease after the 1980s. There are substantial inter-annual fluctuations in numbers of birds breeding, sug...

Biometrics, moult and migration of Grey Plovers, Pluvialis squatarola, at Mida Creek, Kenya

Ringing data for 269 Grey Plovers, Pluvialis squatarola, caught between 1977 and 1988 were analysed. Adults started primary moult soon after arrival in August and September. Mean starting date of adult primary moult was estimated to be 13 September, primary moult duration as 130 days. First-year birds had not started primary moult by early May. Body mass of adults in primary moult was stable from September to February, averaging 205 g, but increased at the end of the moult in March and April. Pre-migratory body mass was estimated at 268 g and would allow a non-stop flight as far as the southeastern Mediterranean or the northern Persian Gulf. Mean wing length increased in March and April, possibly due to the arrival of longer-winged migrants from southern Africa or an earlier departure of males. A decrease in numbers was observed from the second half of April and by mid-May all adults had left the area. In June/July, the number of first-year birds was c. 25% of the total summer population.

A simple method for estimating timing and duration of avian primary moult using field data

A simple method for estimating timing and duration of avian primary moult using field data

MOLT PATTERNS AND MOLTING GROUNDS OF LUCY'S AND VIRGINIA'S WARBLERS: SIMILAR YET DIFFERENT

Using museum specimens, we documented the molt cycles and molting grounds of adult Lucy's (Vermivora luciae) and Virginia's (V. virginiae) warblers. During prebasic molts, both species replace all body plumage. Prebasic primary molt takes a mean of 71 days for Lucy's Warblers, but a mean of just 42 days for Virginia's Warblers. Prebasic molt occurs exclusively on the breeding grounds. We found no evidence of a prealternate molt in Lucy's Warblers, and limited evidence of a prealternate molt in Virginia's Warblers. In both species, the seasonal change in crown color is a function of the freshly replaced gray-tipped feathers acquired during the prebasic molt being abraded during the winter, such that the basal red coloration of those same feathers is exposed during spring. These species differ from other western-breeding passerines in that they do not appear to directly exploit the late season food resources in the southwestern United States and northwestern Mexico. This difference is suggested by the lack of a shift from northern parts of their breeding range to molt in those potentially more productive regions of the southwestern monsoon region. The possibility of winter territoriality may play a role in the rapid prebasic molt exhibited by Virginia's Warblers. On the other hand, the lengthy prebasic molt of Lucy's Warblers may be explained by the use of poor nutritional resources during late summer, and/or the lack of territoriality during late summer and winter. We conclude that our data, in conjunction with data from previous studies, suggest multiple contrasting molt migration strategies among breeding passerines in western North America.

Moult strategies in the Common Whitethroat Sylvia c. communis in northern Nigeria

Moult strategies in the Common Whitethroat Sylvia c. communis trapped in northern Nigeria in April 1999 are analysed. Differences in the extent of moult between age and sex classes are presented. The secondary moult of adult birds is considered to belong to a new pre‐breeding moult or an arrested moult, beginning at the normal starting positions on the wing, and not as a continuation of a suspended post‐breeding moult. Eccentric moult of primaries was found in nearly 19% of the yearling birds, a pattern that is unusual for Western Palearctic passerines. Some individuals showed resemblance to the split moult pattern described for the Barred Warbler S. nisoria.

Duration of primary moult affects primary quality in Grey Plovers Pluvialis squatarola

Feather wear is the natural degradation and breakage of feather structure during the interval between moults. Different rates of feather wear have been observed for primaries of free‐living populations of several species of passerines and waders, and this variability has been linked to different concentrations of melanins. In this study primary moult duration explained 59% of the variation in annual rates of primary abrasion (percentage wing length loss) of seven Grey Plover wintering populations, while migration distance explained 14%. The analysis suggests that primary moult duration plays a key role in determining primary durability and hence primary quality. Long distance migrants might evolve more durable primaries, despite the higher predation risks and energetic costs of a prolonged moult. Partial or complete pre‐breeding primary moults of first‐year waders and complete biannual moults of some passerines might have evolved under selective forces favouring migration with unabraded primaries.

Molt of the Ivory Gull

-Molting is a fundamental biological process common to all birds, and understanding molt strategies is an integral part of studying any species' life history. Molt of the monotypic Ivory Gull (Pagophila eburnea) has received variable and often contradictory treatment in the literature. Based upon examination of 152 museum specimens, the unique molt strategy of this species is clarified. Juveniles molt directly into definitive (= adult) basic plumage via a complete molt during April to August of their second calendar year. Adults have only a single molt per cycle, a strategy unique among gulls: their prebasic molt starts in March and April, progresses quickly, and is mostly completed before the pre-laying to hatching period (mid June to early August); adults typically suspend primary molt at this time and conclude molt of outermost primaries in late August or September. Thus molt and breeding overlap broadly in the Ivory Gull, presumably an adaptation to the constraints of its high-latitude winter range and the brief Arctic summer. Received iJuly 2001, accepted 12 August 2001.

The timing and duration of moult in adult Starlings Sturnus vulgaris in east‐central England

The timing and duration of primary moult were estimated for wild adult Starlings Sturnus vulgaris near Monks Wood in 1977‐78, and for captive birds in 1999. The model of Underhill and Zucchini (1988) was modified to allow for a non‐linear increase in the moult score, based on scores of captive birds. For wild birds, estimates of moult duration in 1977 and 1978 were 100 days and 98 days, with mean and standard deviation in start dates of 6 June and 7.3 days in 1977, and 2 June and 9.7 days in 1978. For captive birds, moult duration was 85 days, with mean and standard deviation of 31 May and 4.1 days. Differences between these estimates and those reported for other wild and captive Starling populations are discussed.

Life History Implications of Complete and Incomplete Primary Molts in Pelagic Cormorants

Abstract We describe the rules of primary flight-feather replacement for Pelagic Cormorants (Phalacrocorax pelagicus), and contrast the completeness of primary replacement in individuals from Asia and North America. In adult Pelagic Cormorants primary replacement is stepwise, with multiple waves of molt, each initiated at the innermost primary (P1), proceeding simultaneously toward the tip of the wing. Shugart and Rohwer's (1996) ontogenetic model for generating and maintaining stepwise primary replacement depended upon incomplete molts. In each new episode of molt, waves of primary replacement were thought to be initiated at P1 and at each arrested wave that had failed to replace all old feathers in the preceding molt. Because most adult Pelagic Cormorants from North America completely replace their primaries but maintain stepwise primary molts, the latter assumption must be relaxed. In contrast to the present-day situation in North America, Pelagic Cormorants from northeastern Asia have incomplete molts of their primaries, and may be forced to skip breeding in some years to clear their wings of overworn primaries. Young birds from Asia start the replacement of their juvenile primaries later than North American birds and replace more feathers simultaneously. Implicancias de la Muda Primaria Completa e Incompleta en la Historia de Vida de Phalacrocorax pelagicus Resumen. Describimos las reglas de reemplazo de plumas primarias para Phalacrocorax pelagicus y contrastamos la totalización del reemplazo de primarias entre individuos de Asia y América del Norte. En individuos adultos, el reemplazo de primarias ocurre en varias etapas, con múltiples secuencias de muda cada una iniciada en la primaria más interna (P1), procediendo simultáneamente hacia la punta del ala. El modelo ontogenético de Shugart y Rohwer (1996) para la generación y mantenimiento del reemplazo en etapas de las plumas primarias depende de mudas incompletas. Se pensaba que en cada nuevo episodio de muda las secuencias de reemplazo de primarias eran iniciadas en P1 y en cada punto de interrupción de la muda precedente que hubiera impedido el reemplazo de todas las plumas viejas. Debido a que la mayoría de los individuos adultos de P. pelagicus de Norteamérica reeemplazan completamente sus primarias pero aún lo hacen en etapas, la última suposición debe ser re-evaluada. En contraste con la situación actual en Norteamérica, individuos del noreste de Asia tienen mudas incompletas de sus primarias y pueden verse forzados a no reproducirse en algunos años para despojarse de la presencia de primarias desgastadas. Las aves juveniles de Asia comienzan el reemplazo de sus primarias más tarde y reemplazan más plumas simultáneamente que las aves de Norteamérica.

Moult and ageing of storm petrels hydrobates pelagicus

Current published ageing criteria for Storm Petrels, Hydrobates pelagicus appear to be unreliable, so fledged birds are not aged to a high degree of accuracy, restricting the scope of age‐specific studies. Analyses of moult and feather wear were carried out on 28 specimens of Storm Petrels which were washed ashore on the southern coast of Portugal during January 1996, and on a further 780 live individuals which were trapped during May‐July 1998, also on the southern coast of Portugal. Differences in the pattern of wear and bleaching of the primary feathers between those grown simultaneously in the nest and those grown sequentially over a long period by older birds, allows fledged individuals to be aged as in their first year, or older. Using primary wear to age individuals, the shape of the outermost long primary feather can then also be shown to be a reliable ageing criterion. Some birds in active primary moult can be aged even more specifically by a combination of primary wear and the shape of the outermost primary.

Biometrics and moult of Grey Plovers, Pluvialis squatarola, in Australia

Data on 299 Grey Plovers, Pluvialis squatarola, banded in north-western Australia (NWA) and in Victoria, south-eastern Australia (SEA), in 1980–99 were analysed. Sightings of birds leg-flagged in SEA indicated refuelling sites in Japan on both northward and southward migration. A POSCON discriminant analysis on biometrical data suggested that Grey Plovers caught in Australia originated from populations breeding in Siberia east of the Lena River and that the discrete population of Wrangel Island was better represented in SEA. In NWA, departures to the breeding grounds occurred mainly in April, with an average departure body mass of 311 g. This would allow a non-stop flight of c. 4200–5400 km, enough to reach the coasts of northern Vietnam or China. Primary moult duration and mean starting date were 128 days and 5 October in SEA, and 121 days and 10 September in NWA. Grey Plovers departed northwards with little or no breeding plumage.

MOLT DURING SPRING MIGRATION: A COMPARISON OF FOUR SPECIES OF RAPTORS

We quantified the extent of molt in Steppe Buzzards (Buteo buteo vulpinus), Marsh Harriers (Circus aeruginosus), Levant Sparrowhawks (Accipiter brevipes), and Eurasian Sparrowhawks (A. nisus) caught during spring migration 1985–1988 in Elat, southern Israel. Ten percent of yearling Steppe Buzzards (58 of 550) and four percent of yearling Marsh Harriers (3 of 77) were actively molting their remiges while on migration. These findings are contrary to suggestions that birds do not molt their flight feathers during migration when they should avoid extra energy expenditure and maintain flight performance. Active molt of primaries and secondaries, however, was not found among adult buzzards and harriers, or in any individual of the two Accipiter species. Molt strategies may be related to differences in flight mode during migration between species that primarily soar (buzzards and harriers) and species that flap more (sparrowhawks). Body condition was not related to the state of molt. This, and the fact that only yearling birds were in active molt of remiges, suggest that a delay in arrival on the breeding grounds may be a significant cost of molt during spring migration.

LIFE HISTORY IMPLICATIONS OF COMPLETE AND INCOMPLETE PRIMARY MOLTS IN PELAGIC CORMORANTS

Abstract We describe the rules of primary flight-feather replacement for Pelagic Cormorants (Phalacrocorax pelagicus), and contrast the completeness of primary replacement in individuals from Asia and North America. In adult Pelagic Cormorants primary replacement is stepwise, with multiple waves of molt, each initiated at the innermost primary (P1), proceeding simultaneously toward the tip of the wing. Shugart and Rohwer's (1996) ontogenetic model for generating and maintaining stepwise primary replacement depended upon incomplete molts. In each new episode of molt, waves of primary replacement were thought to be initiated at P1 and at each arrested wave that had failed to replace all old feathers in the preceding molt. Because most adult Pelagic Cormorants from North America completely replace their primaries but maintain stepwise primary molts, the latter assumption must be relaxed. In contrast to the present-day situation in North America, Pelagic Cormorants from northeastern Asia have incomplete molts...

Migration patterns and moult of Common Terns Sterna hirundo and Sandwich Terns Sterna sandvicensis using Teesmouth in late summer

Count, recovery and biometric data were analysed to assess the conservation status and use of Teesmouth by Common Terns Sterna hirundo and Sandwich Terns Sterna sandvicensis in late summer. The recognition of the international importance of Teesmouth to migratory Sandwich Terns was endorsed. Peak late summer counts for 1990–1997 averaged 1,835, over 1% of the international population. Analysis of information from both Common and Sandwich Terns ringed or recovered in late summer at Teesmouth identified the existence of a trans‐Pennine migratory pathway of Common Terns between Teesmouth and Merseyside. Trans‐Pennine migration of Sandwich Terns is also suspected from visual observations of departures from Teesmouth. 55% of adult Common Terns using Teesmouth have yet to initiate primary moult. This, and the recovery patterns, are consistent with the involvement of a substantial Baltic contingent of non‐moulting adults amongst the late summer Teesmouth population. Of those adults in active wing moult, primary moult had progressed less far than for birds in the Wadden Sea at the same time of year. This suggests a cline through northern European breeding populations in the timing of moult. Visible migration, retrap data, arrival dates of different populations and the progression of primary moult, all identify rapid turnover amongst the late summer Common Tern population at Teesmouth, suggesting that over 1% of the UK breeding population, with their young, migrate through Teesmouth

Cases of serial descendant primary moult (Staffelmauser) in the Black‐shouldered Kite Elanus caeruleus

The primary moult of small Accipitridae normally follows a single descendant sequence, while serial descendant primary moult (Staffelmauser) is typical in large raptors. Elaninae are considered to moult in a single descendant sequence. During a study of Black‐shouldered Kites in the Western Cape, South Africa, six sub‐adult birds (9%) and two adults (5%) replaced the primaries in a serial descendant pattern. Only a minority of juveniles underwent a complete post‐juvenile moult; most replaced only contour feathers during the first moult.

Primary moult, biometrics, mass and age composition of Grey Plovers Pluvialis squatarola in southeastern India

Little is known about the biology of waders wintering in southern Asia; this paper deals with the Grey Plover Pluvialis squatarola, a species extensively studied only in western Europe. Adult Grey Plovers wintering in southeastern India underwent primary moult in autumn; the duration was estimated to be 127 days, with mean starting date 1 September and mean completion date 5 January. Some first-year Grey Plovers initiated primary moult in late winter and spring, and completed this moult the following spring. The average mass of adults on arrival in September was 200 g, fluctuated close to 220 g from October to February, and increased to 280 g near the end of May. The mass variation did not show the January peak observed in western Europe. Breeding productivity, measured as the percentage of first-year birds in winter catches, varied between 5% and 70% over six years, and showed a positive correlation with that of Dark-bellied Brent Geese Branta b. bernicla in western Europe and Curlew Sandpipers Calidris ferruginea in South Africa.