THE PRIMARY MOULT OF WADERS ON THE ATLANTIC COAST OF MOROCCO

Data from 3659 waders of 23 species live-trapped in the years 1971-73 on the Atlantic coast of Morocco during the period of autumn moult and migration are analysed to estimate duration and timing of primary moult. Common Sandpiper was the only species to moult primaries in its first autumn (unless published ageing criteria are incorrect). Several species showed a low incidence of arrested primary moult and a higher incidence was observed in Ringed, Kentish and Grey Plovers. This is discussed in relation to breeding and migration. Similar rates of primary feather replacement relative to specific moult duration were observed in all species for which information was available. Comparisons between species and with published studies showed that variations in rate of moulting between species and between different geographical populations of the same species were largely due to differences in feather growth rate rather than in the numbers of primaries concurrently in growth. Variations in rate between individuals of the same population were achieved, at least in the first part of moult, by differences in feather dropping rate resulting in differences in the numbers of primaries growing concurrently. The timing and duration of moult in different populations and differences between breeding and non-breeding components were closely related to the requirements of other annual cycle activities, notably breeding and migration. Non-breeding birds summering in Morocco had started moult early. Locally breeding birds had an early start to a fairly slow moult which overlapped with breeding and which in some cases passed through an arrested stage. Birds breeding in cold temperate and arctic regions and wintering in Morocco moulted in a short time soon after arrival. In some cases, notably in Ringed Plovers, birds had commenced moulting on the breeding grounds and arrested moult during migration. Most Redshank and possibly Dunlin migrated in active wing moult. The fastest primary moult was achieved by high arctic breeding birds, Curlew Sandpiper and possibly Little Stint, which stopped to moult in Morocco before moving on to wintering areas further south. This situation is contrasted with that of populations of these two and other species wintering in the southern hemisphere where moult occurs over an extended period during the northern winter.     

Flexibility in the timing of post-nuptial moult among Red-billed Queleas Quelea quelea in Botswana in relation to the timing of breeding

The timing of primary moult of adult Red-billed Queleas Quelea quelea, captured as they were completing an unusually late breeding attempt at Francistown, northern Botswana, in June 2004, was compared with the timing of moult of birds breeding earlier in the season in north-west Botswana during two earlier years, 1971 and 1972. Differences between years in the dates when local colonies finished breeding (mid-March to late June) and between two localities in the same year (mid-March and late May) were matched by corresponding differences in the estimated dates of moult onset, ranging from mid-April to mid-June. Flexibility in the timing of moult among Red-billed Queleas in southern Africa evidently enables birds to take advantage of unusually late breeding opportunities by delaying moult onset and overlapping moult and breeding at the end of the nesting cycle. Such flexibility may also include moult interruption to permit late breeding, although its incidence in southern Africa is apparently low.     

Prolonged and flexible primary moult overlaps extensively with breeding in beach‐nesting Hooded Plovers Thinornis rubricollis

We present the first report of complete overlap of breeding and moult in a shorebird. In southeastern Australia, Hooded Plovers Thinornis rubricollis spend their entire lives on oceanic beaches, where they exhibit biparental care. Population moult encompassed the 6‐month breeding season. Moult timing was estimated using the Underhill–Zucchini method for Type 2 data with a power transformation to accommodate sexual differences in rates of moult progression in the early and late stages of moult. Average moult durations were long in females (170.3 ± 14.2 days), and even longer in males (210.3 ± 13.5 days). Breeding status was known for most birds in our samples, and many active breeders (especially males) were also growing primaries. Females delayed the onset of primary moult but were able to increase the speed of moult and continue breeding, completing moult at about the same time as males. The mechanism by which this was achieved appeared to be flexibility in moult sequence. All moult formulae fell on one of two linked moult sequences, one faster than the other. The slower sequence had fewer feathers growing concurrently and also had formulae indicating suspended moults. Switching between sequences via common formulae is possible at many points during the moult cycle, and three of 12 recaptures were confirmed to have switched sequences in the same moult season. Hooded Plovers thus have a prolonged primary moult with the flexibility to change their rate of moult; this may facilitate high levels of replacement clutches that are associated with passive nest defence and low reproductive success.     

Annual cycle of the Helmeted Honeyeater Lichenostomus melanops cassidix, a sedentary inhabitant of a predictable environment

The annual cycle of breeding, moult and weight variation in the Helmeted Honeyeater Lichenostomus melanops cassidix , a sedentary bird of temperate southeast Australia, is documented. Breeding and moult were sequential unimodal annual events, whose timing was highly consistent between years. However, overlap of breeding and moult was frequent, and some individuals even commenced primary moult before laying their final clutch. The timing of the post-juvenile moult was coincident with that of adults. Early-hatched young moulted within a few months of hatching, but late-hatched young deferred moult for a year. Helmeted Honeyeaters were heaviest in autumn and early winter, and lightest in spring and early summer, a cycle most consistent with the redirection of all available resources to reproduction. The long breeding season (seven-and-a-half months) of the Helmeted Honeyeater, extensive overlap of breeding and moult, and other life-history attributes including small clutch size, are more consistent with the described bio-rhythmic patterns for birds in the humid tropics than the temperate zone. However, the Helmeted Honeyeater has a fairly rapid primary moult rate, unusual amongst species that overlap moult and breeding. This combination of attributes reflects the stable, somewhat seasonal environment occupied and the resource monopoly established by this tightly territorial subspecies. We speculate that extension of the breeding season, by overlapping breeding and moult, is one of the few options available to vary life-history strategies amongst 'old-endemic' Australian birds of the temperate zone.     

Genetic and plastic responses of a northern mammal to climate change

Climate change is predicted to be most severe in northern regions and there has been much interest in to what extent organisms can cope with these changes through phenotypic plasticity or microevolutionary processes. A red squirrel population in the southwest Yukon, Canada, faced with increasing spring temperatures and food supply has advanced the timing of breeding by 18 days over the last 10 years (6 days per generation). Longitudinal analysis of females breeding in multiple years suggests that much of this change in parturition date can be explained by a plastic response to increased food abundance (3.7 days per generation). Significant changes in breeding values (0.8 days per generation), were in concordance with predictions from the breeder's equation (0.6 days per generation), and indicated that an evolutionary response to strong selection favouring earlier breeders also contributed to the observed advancement of this heritable trait. The timing of breeding in this population of squirrels, therefore, has advanced as a result of both phenotypic changes within generations, and genetic changes among generations in response to a rapidly changing environment.     

Plasticity of moult and breeding schedules in migratory European Stonechats Saxicola rubicola

Timing is crucial in seasonal environments. Passerine birds typically use a combination of physiological mechanisms and environmental cues to ensure that breeding, moult and migration occur without major temporal overlap and under the most favourable conditions. However, late in the breeding season some individuals initiate additional clutches , whereas others initiate moult. Such alternative strategies are thought to reflect trade‐offs between reproductive benefits and timely investment in maintenance and survival. The degree of seasonal plasticity differs between species, depending on the mechanisms that govern their annual routine. Migrants are generally under pressure to complete breeding and moult before the autumn departure and often show little plasticity. We studied seasonal plasticity of breeding and moult schedules in the European Stonechat Saxicola rubicola. This species, an obligate short‐distance migrant in Central Europe, sometimes initiates late clutches after typically at least two earlier breeding attempts. Based on life‐history theory and on observations in captivity, which revealed photoperiodic regulation of breeding and moult, we predicted relatively little seasonal plasticity in Stonechats. We further predicted that reproductive gains of late breeders should be offset by reduced survival. These predictions were tested on long‐term field data, using Underhill–Zucchini models to estimate moult. Late breeding occurred in c. 40% of pairs and increased their reproductive success by a third. Both sexes modified moult timing but in different ways. Late breeding females postponed moult approximately until chick independence without compensating for delay by faster moult. Males started moult on time and overlapped it with breeding, associated with markedly slowed plumage change. Sex differences in moult score increased with lay date, but due to their respective modifications, both sexes delayed moult completion. Nonetheless, we could not detect any evidence for survival costs of late breeding. Breeding and moult of European Stonechats appear relatively flexible, despite migratory schedules and photoperiodic programs for seasonal timing. Individuals can modify seasonal behaviour in late summer, presumably depending on their condition, and may profit considerably from extended breeding.     

The breeding biology and population dynamics of King Penguins Aptenodytes patagonica on the Crozet Islands

Among King Penguins Aptenodytes patagonica at Possession Island, one of the Crozet Islands, the length of the moult period, pre-laying period, incubating and brooding shifts were highly variable according to the year and to the stage of the breeding season. The moulting period was shorter in late breeders than in early breeders. Only half of the birds which successfully reared a chick bred the following cycle, but late in the season. Almost all these late breeders were unsuccessful. The reasons for the high variability in the breeding pattern observed in this species between years, as well as between colonies and between individuals are discussed. Breeding success was on average 30.6% and survival during the first year at sea could reach 50%. The survival of adult birds has increased during the past 10 years from 90.7% to 95.2% per annum. Despite an almost biennial breeding frequency and a very high rate of chick loss during the winter fast, the King Penguin population of Possession Island has doubled between 1966 and 1985 due to a high survival rate of adult and immature birds. The increase during the last decade in adult survival and in adult and chick condition suggests that the population increase could be the result of an improvement in food availability.     

Breeding status influences timing but not duration of moult in the Northern Fulmar Fulmarus glacialis

Seabirds are key marine top predator species that are often used as indicators of the environmental quality of the oceans. Their breeding phenology has been studied extensively, but their pelagic habits mean less is known about the phenology of other events during the non-breeding period. Here, we used miniaturized saltwater immersion light-based geolocators (GLS) to investigate moult phenology in individuals with known breeding histories in a population of Northern Fulmar Fulmarus glacialis in Orkney, Scotland. As seabirds spend more time on the water during moult, moulting periods can be identified from patterns of variation in the amount of time that birds are in contact with saltwater. Estimates of daily variation in this behaviour during the non-breeding period were based upon wet/dry sensors and then modelled to characterize the timing of the moult. Light-based geolocation provided information on the areas used by each individual during its moult period. Inter-individual variability in moult timing was investigated in relation to sex and breeding success in the previous summer. We found a sex difference in the location of the moult, but not in its timing. However, the timing of moult did differ between individuals that had succeeded or failed in their previous breeding attempt, with successful breeders moulting the latest. In contrast, the duration of moult did not depend on prior reproductive success, but there was evidence of inter-annual variation in moult duration. GLS studies have provided a step change in our understanding of the at-sea distribution of pelagic seabirds. Our work highlights how activity data from these devices can add value to such studies by identifying key phases of the annual cycle, and locations at these times, when seabirds may be at particular risk. Furthermore, our findings indicate that individual and inter-annual variation in breeding success may influence phenological patterns in other phases of the Northern Fulmar annual cycle.     

Annual variation in the timing of breeding and moulting in male and female Pied Flycatchers Ficedula hypoleuca

During five breeding seasons, the timing of breeding and moulting was studied in the Pied Flycatcher Ficedula hypoleuca. In central Sweden, on average 67% of the males and 41% of the females started moulting before the young fledged. The proportion of individuals with an overlap between breeding and moulting varied considerably between years, with the highest proportion of moulting males being recorded in the year when the females started egg-laying on the latest date. Despite a large annual variation in the proportion of individuals showing a moult/breeding overlap, the duration of this overlap varied insignificantly between years. The onset of moult in males seemed to be related to both calendar date and timing of the current breeding attempt. Most females postponed their moult until just before or just after the fledging of their young, independent of calendar date. There was no significant relationship between male and female moult scores and nestling weight at fledging or fledging success of their brood. Thus, in long-distance migrants such as Pied Flycatchers, it may be adaptive to have some overlap between reproduction and moult, but there seems to be a limit to how early in the breeding cycle they are able to start moulting.     

Moult of the giant petrels Macronectes halli and M. giganteus at South Georgia

Moult scores were collected from colour-ringed individuals of known reproductive status of the two species of giant petrel, Macronectes halli and M. giganteus , at Bird Island, South Georgia between 1978–81.
Both species showed a substantial overlap between breeding and wing-moult, unlike most other Southern Ocean seabirds. Males started moult before females and both sexes of M. giganteus moulted at an earlier stage of the breeding cycle than M. halli , which breeds six weeks earlier than its congener.
Changes in moult rate during the breeding season are documented for both species, with Id. halli showing a rapid increase as the chick nears fledging. Male M. giganteus show a notably different pattern to the other three species-sex groups, starting moult much earlier (at egg-laying), with greater individual synchrony and usually suspending primary moult throughout the main chick growth period, whereas only two male M. halli and no females of either species suspended moult. Differences in pattern, timing and rate of moult are interpreted in terms of availability of food resources and the competing energy demands of other activities, especially chick-rearing.
Completion of primary moult could not be observed in the field but was estimated using data frcsm non-breeding birds and failed breeders; the latter started a rapid moult almost immediately they failed. In both sexes of both species moult is probably concluded at least by early winter.
The general pattern of moult in giant petrels at Bird Island is contrasted with that of other populations and species of Southern Ocean seabirds. It is suggested that the unusually extensive overlap between breeding and moult in giant petrels is a consequence of the very abundant and easily available summer food supplies (especially carrion) and the much diminished winter resources, favouring a completion of moult by the beginning of the winter.     

Annual variation in breeding biology of gentoo penguins, Pygoscelis papua, at Bird Island, South Georgia

The breeding biology of the gentoo penguin, Pygoscelis papua , was studied over a three-year period (1986–1988) at Bird Island, South Georgia, with particular reference to birds of known age or breeding experience. Laying date varied significantly between all three years, being three weeks later in 1987, when the breeding population decreased markedly. Factors involved in the timing of breeding are discussed. Within years egg-laying was highly synchronous: 95% of clutches were initiated in 14·5 days or less. The incubation period was 35 days and the laying interval, between the two eggs, 3·3–3·4 days. Chicks creched when 25–30 days old, and this varied between years, possibly related to food supply and chick growth. Chicks left the colony for the first time between 75 and 85 days of age. The breeding population at Bird Island decreased by 20% and increased by 84% in successive years during the study period. Breeding success (chicks fledged per egg laid) varied between 0·33 and 0·65 within colonies, but for the whole island was very consistent over the three years: 0·45, 0·51 and 0·47. Overall, colony differences were not correlated between years. Disturbance from Antarctic fur seals, Arctocephalus gazella , is suggested as the cause of consistently lower breeding success at one colony. Mean egg weight varied annually, and with age of the breeding bird, nest location and, in one year, with laying date. Young, first-time breeders laid smaller eggs and had lower breeding success compared to older, experienced birds, similar to other seabirds. However, they differed from other species in laying on average earlier than older birds. The relationship between age, egg weight, laying date and breeding success is discussed in relation to predation and seasonal food supply.     

Sex‐specific patterns of fuelling and pre‐breeding body moult of Little Stints Calidris minuta in South Africa

The timing and duration of each stage of the life of a long‐distance migrant bird are constrained by time and resources. If the parental roles of males and females differ, the timing of other life stages, such as moult or pre‐migratory fuelling, may also differ between the sexes. Little is known about sexual differences for species with weak sexual dimorphism, but DNA‐sexing enables fresh insights. The Little Stint Calidris minuta is a monomorphic long‐distance migrant wader breeding in the Arctic tundra. Males compete for territories and perform elaborate aerial displays. Females produce two clutches a season. Each sex may be a bigamist and incubate one nest a season, each with a different partner. We expect that these differences in breeding behaviour entail different preparations for breeding by males and females, so we aimed to determine whether Little Stints showed any sex differences in their strategies for pre‐breeding moult and pre‐migratory fuelling at their non‐breeding grounds in South Africa. We used body moult records, wing length and body mass of 241 DNA‐sexed Little Stints that we caught and ringed between 27 January and 29 April in 2008–2018 at two neighbouring wetlands in North West Province, South Africa. For each individual we assessed the percentage of breeding plumage on its upperparts and took blood samples for DNA‐sexing. We calculated an adjusted Body Moult Index and an adjusted Wing Coverts Moult Index, then used the Underhill–Zucchini moult model to estimate the start dates and the rate of body moult in males and females. We estimated the changes in the sex ratio of the local population during their stay in South Africa, and also estimated the timing and rate of pre‐migratory fuelling and the potential flight ranges for males and females. The males started body moult on average on 7 February and the females on 12 February, but the sexes did not differ in their timing of wing covert moult, which started on average on 10 February. In January to mid‐February, males constituted c. 57% of the population, but their proportion declined afterwards, indicating an earlier departure than females. We estimated that both sexes began pre‐migratory fuelling on average on 15 March. The sexes did not differ in fuelling rate, but most females stayed at the non‐breeding site longer than the males, and thus accumulated more fuel and had longer potential flight ranges. These patterns of moult and fuelling suggest sex differences in preparations for breeding. We suggest that the males depart from South Africa earlier but with smaller fuel loads than the females to establish breeding territories before the females arrive. We conclude that for each sex the observed trade‐offs between fuelling and moult at the non‐breeding grounds are precursors to different migration strategies, which in turn are adaptations for their different roles in reproductive behaviour.     

Adjustment of pre‐moult foraging strategies in Macaroni Penguins Eudyptes chrysolophus according to locality,sex and breeding status

The annual moult creates the highest physiological stress during a penguin's breeding‐cycle and is preceded by a period of hyperphagia at sea. Although crucial to individual survival, foraging strategies before moult have been little investigated in keystone marine consumers in the Southern Ocean. The Macaroni Penguin Eudyptes chrysolophus demonstrates how individuals may adjust their foraging strategies during this period in line with constraints such as potential intraspecific competition between localities, foraging ability between dimorphic sexes and timing at sea between breeding and non‐breeding population components. We recorded pre‐moult behaviour at sea for 22 Macaroni Penguins from Crozet and Kerguelen Islands (southern Indian Ocean) during 2009 and 2011, using light‐based geolocation and stable isotope analysis. Penguins were distributed in population‐specific oceanic areas with similar surface temperatures (3.5 °C) south of the archipelagos, where they foraged at comparable trophic levels based on stable isotopes of their blood. Bayesian ‘broken stick’ modelling with concurrent analysis of seawater temperature records from the animal‐borne devices showed that within each population, females remained 6 days longer than males in the colder waters before heading back towards their colonies. Finally, 17 other non‐breeding individuals that moulted earlier had a higher mean blood δ¹⁵N value than did post‐breeding birds, meaning that early moulters probably fed more on fish than did late moulters. Our findings of such adjustments in foraging strategies developed across locality, sex and breeding status help understanding of the species' contrasted pre‐moult biology across its range and its ecology in the non‐breeding period.     

Effects of latitude on the trade-off between reproduction and moult: a long-term study with pied flycatcher

Long-distance migratory passerine birds are generally time constrained by reproduction and moult, which need to be completed before migration. Breeding and post-nuptial moult may overlap especially under time-constrained conditions (northern latitudes). Here, we analysed the timing of adult moult in relation to latitude, timing of breeding and reproductive effort in pied flycatchers (Ficedula hypoleuca) breeding in four widely separated populations (40-68° N). In males but not females, the proportion of moulting birds while provisioning nestlings increased with increasing latitude. This may suggest that a moult-breeding overlap is a strategy employed by male pied flycatchers to adjust to the short breeding season at northern latitudes. However, the moult-breeding overlap was more pronounced among males in the southernmost study population (Spain). In this population, males may decide not to invest more in reproduction, and start moulting at earlier breeding stage than in northern populations,or, alternatively, birds in the Mediterranean region are time constrained by the hot and dry summer. The trade-off between breeding and post-nuptial moult may be more important in some populations than in others, depending on the latitude of the breeding site. Our results show that a moult-breeding overlap imposes a fitness cost on males in terms of fecundity and breeding success.     

Breeding barnacle geese in Kolokolkova Bay,Russia: number of breeding pairs,reproductive success and morphology

We report the results of an expedition to a barnacle-goose (Branta leucopsis) breeding area in Kolokolkova Bay, west of the lower Pechora delta in northern Russia, undertaken in July 2002. In total, 6 breeding colonies were found within the study area, harbouring 1,324 nests. Mean clutch size was 2.77±0.10 but may have been underestimated because of nest predation. Nest predation was high and correlated with the density of breeding gulls, Larus. The 2002 season was relatively cold and peak hatch occurred late, on 14 July. More than 11,000 barnacle geese were found to moult in the area which, together with the large number of nests found, emphasises the importance of Kolokolkova Bay for barnacle geese. Adult barnacle geese (341) were captured, marked and measured during their annual wing moult. Birds with broods started to moult approximately 2 weeks later than non- and failed breeders. Weight loss during moult was 3 times as rapid as reported for barnacle geese breeding in the Baltic, and a large cost of reproduction seemed to exist in the form of reduced body weight at the onset of moult for birds leading broods. Work in the area will continue over the coming years to document and explain the differences in major life-history parameters, dynamics and environmental effects between arctic and temperate breeding barnacle-goose populations.     

Small changes in timing of breeding among subarctic passerines over a 32‐year period

Many bird populations in temperate regions have advanced their timing of breeding in response to a warming climate in recent decades. However, long‐term trends in temperature differ geographically and between seasons, and so do responses of local breeding populations. Data on breeding bird phenology from subarctic and arctic passerine populations are scarce, and relatively little data has been recorded in open‐nesting species. We investigated the timing of breeding and its relationship to spring temperature of 14 mainly open‐nesting passerine species in subarctic Swedish Lapland over a period of 32 years (1984–2015). We estimated timing of breeding from the progress of post‐juvenile moult in mist‐netted birds, a new method exploring the fact that the progress of post‐juvenile moult correlates with age. Although there was a numerical tendency for earlier breeding in most species (on average ?0.09 days/year), changes were statistically significant in only three species (by ?0.16 to ?0.23 days/year). These figures are relatively low compared with what has been found in other long‐term studies but are similar to a few other studies in subarctic areas. Generally, annual hatching dates were negatively correlated with mean temperature in May. This correlation was stronger in long‐distance than in short‐distance migrants. Although annual temperatures at high northern latitudes have increased over recent decades, there was no long‐term increase in mean temperature in May over the study period at this subarctic site. This is probably the main reason why there were only small long‐term changes in hatching dates.     

The timing, duration and pattern of moult and its relationship to breeding in a population of the European Greenfinch Carduelis chloris

Moult was studied in 1 year among Greenfinches trapped in a garden in east‐central England. Over the period June–December 2003, 333 captures of 179 individual adults provided information on breeding condition, moult, body weight, sex and age (yearling or older adult, equivalent to birds in their second or later calendar years, respectively). About 95% of all birds (sex and age groups combined) started primary feather moult from 2 July to 14 August, and finished from 10 October to 22 November. The mean date of moult onset in the population as a whole was 24 July. On average, males began 8 days before females, and yearlings began 6 days before older birds. The mean duration of moult was 100 days, whether the figure was calculated for the population as a whole or just for the 36 individual birds that were caught more than once during moult. However, moult rate was slightly slower, and moult duration slightly longer, in yearlings than in older adults of both sexes. No evidence was found for any systematic relationship between moult onset date and rate (duration). Breeding and moult overlapped by up to 5 weeks or more in individual birds, and some birds probably started to moult as early as the incubation stage of their last clutch of the season. The cloacal protuberance (taken as indicative of breeding condition) had regressed in all males by the time the fifth primary was shed, and the brood patch had regressed and re‐feathered in all females by the time the fourth primary was shed. The bulk of feather replacement in the secondary, tail and body tracts occurred in the second half of primary moult, and after cloacal protuberances and brood patches were completely regressed. In all birds examined near the end of primary moult the secondaries were still growing, and would have continued growth for up to another 19 days or more, extending the end of the moulting season into December. Body mass during moult was affected significantly by sex and age, as well as by time of day, amount of food in gullet, reproductive condition and date. No firm evidence emerged that body mass was affected by moult stage, after allowing for effects of date and other variables (although there was a non‐significant negative relationship between moult stage and body mass in males). In the population as a whole, the breeding season (from first egg‐laying to independence of last young) was spread over 21 weeks and moult over 24 weeks. With an overlap between the two events at the population level of up to 9 weeks, the two processes together took up to 36 weeks, some 69% of the year.     

Sex‐dependent response of primary moult to simulated time constraints in the rock sparrow Petronia petronia

There is growing evidence that moult speed affects plumage quality. In many bird species, males and females differ in terms of breeding effort, survival expectation and the relationship between fitness and plumage quality. Consequently, differences in moult strategies between the sexes can be expected. The aim of this study was to assess whether, under simulated time constraints and with no parental investment in the previous breeding season, males and females differed in: a) timing and duration of primary moult, b) growth rates of individual primary feathers, and c) number of concurrently growing feathers. We investigated the effect of time constraints generated by a treatment consisting of two decreasing photoperiods (slow changing photoperiod, SCP=2 min day^?1 and fast changing photoperiod, FCP=8 min day^?1) on the primary post‐nuptial moult of captive rock sparrows Petronia petronia. Females started to moult on average 14 and 15 days later than males in both experimental groups. Primary moult duration was 10 (FCP) and 24 (SCP) days longer in males than in females, and, within sex, 34 (females) and 48 (males) days longer in SCP birds than in FCP ones. Females renewed a larger number of primaries simultaneously (5.7% in FCP and 12.8% in SCP) and had a higher total daily feather mass grown (9.9% in FCP and 22.4% in SCP), even though daily growth rates of individual primaries did not differ between sexes. As a result, males and females completed their primary moult at the same time within treatment. The observed differences in timing, duration and energy allocation for primary moult between the sexes probably have a genetic basis, as birds did not engage in reproduction during the preceding breeding season.     

“THE BIRDS OF SOUTH AFRICA”

Jones, P. J. 1980. The timing of wing moult in the Greyhooded Kingfisher in Nigeria. Ostrich 51:99-106.

The post-nuptial and post-juvenile moults of the Greyhooded Kingfisher Halcyon leucocephala took place in northern Nigeria between May and November (the rainy season) after migration from the southern breeding areas. Moult of individual birds lasted between 92 and 176 days, those starting moult latest (mostly juveniles) moulting fastest. This variation may be related to food availability during moult; those starting early do so before the rainy season begins in the north and before insect numbers increase, whereas those moulting later do so during the full flush of rainy season insect availability. This variability appears to be adaptive in allowing the complete moult to be fitted into the period remaining between the end of the breeding season, which is variable, and the southward migration in the early dry season, whose timing is relatively fixed.