Moult of Malayan Barn Owls Tyto alba

Moult in Malayan Barn Owls Tyto alba was studied in two pairs of wild collected captive birds and from feathers taken from nest sites throughout peninsular Malaysia.
Post-juvenile captive birds moulted nearly to completion prior to first breeding, beginning with P6 at a mean age of 301.5 days. This contrasted with the only other study of moult in captive Barn Ow-Is in Germany when moult began at an age of 400 days, and then continued for a protracted period of two years separated by a suspension of moult during the normal breeding season.
The complex sequence of moult in primaries and secondaries both in the Malayan and German birds was similar.
Moult among adult Malayan birds in the wild showed a broad and somebyhat irregular seasonal trend With lower incidence during peak breeding periods.     

THE BREEDING OF THE GREATER FLAMINGO AND GREAT WHITE PELICAN IN EAST AFRICA

This paper brings together observations on the breeding of the Greater Flamingo Phoenicopterus ruber and Great White Pelican Pelecanus onocrotalus, mainly at Lake Elmenteita, Kenya, 1951–1971. The Greater Flamingo bred at Lakes Elmenteita and Nakuru in 11/21 observed years and at Lakes Natron and Magadi in 5/12 observed years. On average, it breeds about every second year, but a succession of breeding years is followed by several years in which no breeding occurs. A history of 21 years' breeding at Lakes Nakuru and Elmenteita is given. At Elmenteita three sites have been used, the main site in every breeding year, the others less often. The number of pairs breeding in any year has varied from 500–9,250, but in 1968 flamingos bred three times, involving perhaps 8,500 pairs which made about 15,700 nests, some pairs perhaps laying twice or even thrice in a year. Losses of eggs (38.2% overall) were caused by rising water (16.2%), competition for nest space with Great White Pelicans (6.9%, after 1968 only), human interference (3.5%), Marabou Stork predation (1.8%) and other natural causes (9.8%). Losses among chicks totalled 68.3% overall and were mainly due to Marabou Storks (36.5%), undiagnosed disease (8.6%), and rising water (6.6%). Disease caused serious loss only in 1966, and after 1968 losses from Marabous rose from 2.7% to 76.5%, resulting in an increase in overall mortality from 48.7 to 92%. This was perhaps associated with the establishment of a fish factory at Lake Naivasha. When attacking flamingo colonies Marabous did not actually eat many eggs or chicks, but simply caused wholesale desertion by alarming the flamingos. In 1968 total desertion of a colony of 4,500 pairs was caused between 18 and 26 March by a maximum of 17 Marabous, and similar wholesale desertion was caused in later years. The overall breeding success among Greater Flamingos at Elmenteita was about 19% of eggs laid, but without the excessive post-1968 Marabou predation would have been about 30%. At such a rate Greater Flamingos require at least 24 years of adult life to replace themselves, but if the mortality caused by Marabous since 1968 continues they will require about 58 years, and the population will inevitably decline. Breeding success at Lakes Magadi and Natron has been higher, about 44% of eggs laid; but figures available are much more approximate than at Elmenteita. Some new data on display, nest-site selection, laying dates, clutch-size, hatching and creche behaviour are given for the Greater Flamingo. The Great White Pelican bred at Lake Elmenteita from 1968 to 1971 without a break, some birds laying in every month, but with reduced laying November–December. They bred on the same islands as, and in association with the Greater Flamingo, and caused heavy losses among the latter, not through aggressiveness, but simply because of their superior size and weight. Although food supply must ultimately have controlled the pelican's ability to breed, an adequate food supply was available for 6 years before they did and continued after they had ceased. Their breeding was finally triggered by the Greater Flamingo colonies, with which the pelicans associated. When a flamingo colony was deserted because of Marabou Storks the pelicans, unafraid themselves of the Marabous, also deserted. They also associated with, and wiped out, a colony of Sacred Ibis. From July 1968 to June 1969 about 2,600 pairs of pelicans bred at Elmenteita, rearing about 2,200 young to the flying stage. The breeding colony apparently comprised most of the adults from Lake Nakuru and Lake Naivasha, the main feeding areas. From July 1968 to January 1971 certainly 7,200 and probably 8,000 pairs of pelicans bred at Elmenteita. Some pairs may have bred twice or thrice in this period. Breeding ceased suddenly in January 1971, eggs, and small and large young being alike abandoned for no established reason, although food supply was certainly still plentiful. Additional information on pair formation, incubation and fledging periods, nest-relief, etc. is given. The best available record of the incubation period is 35–36 days. Nest relief takes place on average about once every 48 hrs, and is dependent on thermal activity enabling the pelicans to soar. At Elmenteita large young ate quantities of putrefying matter, including the corpses of other young pelicans. They also ate living young hatching from eggs, and up to 14 days old. Touch probably plays an important part in helping them to locate possible food in opaque water.     

MOULT OF BUDGERIGARS MELOPSZTTACUS UNDULATUS

In captive Budgerigars Melopsitticus undulatus moult of primaries started in the middle of the tract and moved progressively inwards and outwards, the inner feathers being replaced faster than the outer ones. Full replacement of primaries took six to eight months and a new cycle of moult usually started before completion of the old cycle. Moult of secondaries followed no clear pattern and occurred less frequently than moult of primaries. Moult of rectrices started with the middle pair and moved progressively outwards on both sides. Complete moult of rectrices took about six months and a new cycle often started before completion of the old. Moult of the head and body occurred intermittently throughout the year. Birds fledged in juvenal plumage, they passed into first basic plumage with a partial moult (head and body feathers) and into definitive basic plumage with a moult of all contour feathers.
In the field in inland mid-eastern Australia, there were some birds replacing feathers and some with complete plumage in most months of the year. Birds with complete plumage may have been between moults or within a moult and between replacement of feathers. The proportion of birds in moult did not increase in intensity after breeding, or cease during breeding or before movements. Some birds of both sexes with gonads in a reproductive condition were replacing feathers. Rirds that were replacing feathers had similar lipid deposits to birds that had a complete plumage.     

THE MOULT OF THE BULLFINCH PYRRHULA PYRRHULA

The distribution of feather tracts and their sequence of moult in the Bullfinch is described. The adult post-nuptial moult, which is complete, lasted 10–12 weeks, and the post-juvenile moult, which is partial, 7–9 weeks. Adult moult began with the shedding of the first (innermost) primary and ended with the replacement of the last. Variations in the rate of moult in the flight feathers were mainly achieved, not by changes in the growth rates of individual feathers, but in the number of feathers growing concurrently. The primaries were shed more slowly, and the onset of body moult delayed, in birds which were still feeding late young. In 1962, the onset of moult in the adults was spread over 11 weeks from thc end of July to the beginning of October, and in the two following years over the six weeks, from the end of July to the beginning of September. The onset of moult was delayed by late breeding, which itself occurred in response to a comparative abundance of food in late summer, markedly in 1962. In all years, the first juveniles to moult started at the end of July, and the last, three weeks after the latest adults. Juveniles moulting late in the season retained more juvenile feathers than those moulting earlier. During moult, adult and juvenile Bullfinches produce feathers equivalent to 40% and 33% respectively of their dry weights. In both, for much of the moult, an average of nearly 40 mgm. of feather material—some 0.6% of their dry-weight–is laid down each day. The remiges of the adult comprise only a seventh of the weight of the entire plumage, and it is suggested that their protracted moult results not so much from their energy requirements, as from the need to maintain efficient flight. Variation in the rate of moult in the remiges was much less pronounced than in the body feathers. Bullfinches were less active during moult than at other times of the year. The weights of both adults and juveniles increased during moult. The food during the moult period is described. In all years, most Bullfinches finished moulting just before food became scarce, even though this occurred at different times in different years. In one year, adults moulting latest in the season probably survived less well than those moulting earlier; the same was apparently true of the juveniles in all years. The timing of moult in the Bullfinch, and the factors initiating it, are discussed in relation to the breeding season and foodsupply near Oxford.     

Body weight, gonad development and moult in the Tawny owl (Strix alum)

Gonad development, moult and seasonal changes in body weight and composition in the Tawny owl Strix aluco were studied by examining the carcasses of 369 owls (mostly road casualties) supplemented by 112 weights of live birds. In breeding females laying was preceded by the accumulation of fat and to a lesser extent protein which meant that they weighed more at this time (February/March) than at any other. Females declined in weight after laying but were still heavy during incubation. In contrast, males and non-breeding females did not increase in weight before the start of the breeding season. Juveniles reached or even exceeded adult weight well before independence due to the deposition of fat. Even after the exclusion of diseased or contaminated individuals, 9·4% of the birds examined were identified as starving; most of these were in the autumn and were probably newly-independent young wandering in search of territories. In both sexes gonad maturation was of brief duration coinciding with the period (mid-March to mid-April) in which eggs are normally laid. Ovarian growth was biphasic. In the three months prior to the breeding season ovarian condition in different birds was positively correlated with body weight and it appeared that the largest ovarian follicles of females in poor condition failed to attain the size from which rapid growth to final ovulation occurs. in males testis size in the breeding season was correlated with pectoral muscle weight (an index to protein condition) but not body weight. The majority of adults commenced wing moult in June. The average duration of primary moult was estimated to be 77 days. Healthy birds replaced the primaries of both wings at the same rate but most diseased birds moulted asymmetrically and/or out of season. First-year birds renewed their body feathers between September and November. In the Tawny owl territory establishment, breeding and moult are temporally separated.     

Moult in adult Fiery-necked Nightjars Caprimulgus pectoralis ringed on Ranelia Farm,Cashel, Zimbabwe

Nothing has been published on the moult of the Fiery-necked Nightjar Caprimulgus pectoralis in Zimbabwe. However, most of the birds handled on Ranelia Farm, Cashel, during a study of nightjar breeding biology over four seasons, were examined for moult. Fiery-necked Nightjars were examined on over 70 occasions. Their annual moult occurs between late October and early March, commencing with the primaries, which moult descendantly. The secondaries, which moult ascendantly, follow after P5 has been shed, and so do the rectrices, which moult centrifugally, but R5 precedes R4. Body moult, which starts about the time that R1 is shed, progresses from the head across the neck to the rest of the dorsal plumage, and then over the throat and flanks to the ventral surface. The rictal bristles moult descendantly in time with the primaries. Several birds, some with primary moult scores as high as 18, had commenced moult while still tending young from the first brood, or incubating the eggs of a second, or replacement, clutch. The moult season overlaps the breeding season by about two months.     

Influences of status and recent breeding experience on the moult strategy of the yellow-nosed albatross Diomedea chlororhynchos

The primary moult of individually colour-ringed, adult yellow-nosed albatrosses at nests on Gough Island was examined in 1983 and related to the status of each bird and its breeding history in the previous year. Adults renew only about half of their primaries each winter and suspend moult while breeding. Birds that bred successfully renewed fewer primaries than did unsuccessful birds or nonbreeders. There were no differences in primary moult between the sexes or in relation to size. Yellow-nosed albatrosses show complex wave moult as an adaptation to slow renewal of flight feathers. The energy, nutrient or time requirements for feather renewal may conflict with breeding annually so that there is a trade-off between the extent of moult desirable to maintain flight efficiency and the benefits of breeding in successive seasons.     

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.     

FOOD AS A FACTOR CONTROLLING THE BREEDING OF PUFFINVS LHERMINIERI

A study of Puffinus Iherminieri on Plaza Island, Galápagos, showed that, although eggs were laid in all months, there were marked peaks and troughs of laying. Intervals between successive layings varied with the success or failure of the first egg, an average of nine months for successful pairs, eight months for pairs which lost a young, and 6–5 months for those which failed to hatch an egg. However the breeding success did not influence the time between the end of one breeding attempt and the next laying. This suggests that birds were breeding as quickly as possible. The critical factor preventing more frequent breeding appeared to be the time required to replace the wing and tail feathers.
Details are given of the breeding biology, all aspects of which were strongly influenced by frequent and unpredictable food shortages. The average incubation period was 49 days but this was prolonged by temporary desertion due to food shortages. Chick growth and fledging periods (62 to 100 days) were variable. There was no well–defined desertion period and birds were experimentally induced to feed young for up to 120 days.
Overall nesting success was low (26%) and adult survival between breeding attempts was high (92–95%).
Food, planktonic fish larvae and Crustacea, appeared to be rarely abundant and details are given of the effect of food shortage on the breeding.
The breeding synchrony was brought about by food shortages. The ultimate factor controlling breeding appeared to be the availability of food for egg formation and there was no possibility of birds timing breeding so that young were being fed at a time of food abundance.
A comparison is made of the breeding of eight Puffinus species.     

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.     

FACTORS AFFECTING EGG-WEIGHT, BODY-WEIGHT AND MOULT OF THE WOODPIGEON COLUMBA PALUMBUS

The heaviest clutches (2 eggs) laid by Woodpigeons Columba palumbus in a Cambridgeshire study area weighed 30% more than the lightest. Yet the variation in egg-weight within clutches was less than 1 %. Irrespective of initial weight, eggs lost weight at the same constant rate during incubation. Heavy eggs hatched more successfully than light eggs and none weighing less than 16 g hatched. There was no correlation between chicks' weight at hatching and their weight at day 6 during the July-September part of the breeding season. The ability to feed crop milk at this stage could compensate for low chick-weight, but this might not be true early in the season. Weight at day 6 was correlated with the weight at day 16 or 17. The growth pattern is discussed. Chicks in broods of one achieved a higher weight at day 17 than those in broods of two. The survival rate both in and after leaving the nest was the same in both brood-sizes. Chick-weight in artificially created broods of three was almost as high as in broods of two, but again data refer to the July-September period when abundant cereal food is available. Survival before and after fledging was lower in broods of three. Clutch- and egg-weight declined from April until September. It is suggested that this is adaptive, in that the adults produce heavier eggs when food supplies are most difficult to collect. The critical period probably occurs during the few days when the adult must produce crop milk and the young cannot be left unattended. Thus egg-weight depends on the female's capacity to acquire nutrients, and is related to the needs of embryonic development and the amount of compensation in nutrient supply which can be provided immediately after hatching. But clutch-size is more related to the bird's ability to feed and rear young to the point of fledging, thereby influencing the number of offspring which survive to leave progeny. Egg-weight and female body-weight were positively correlated in females weighing less than 480 g but not in heavier females. First-year birds did not acquire adult weight until midsummer and they would probably produce light eggs if they could breed before this month. However, their gonads do not recrudesce until July and this prevents them breeding in the spring. Seasonal changes in body-weight and fat content of adults and first-year birds are described and discussed; differences were noted between adult males and females which were considered to be adaptive. The moult is described. It begins in April and continues until November, approximately one pair of primaries being replaced per month. The moult ceases during the winter months, when it is known that food supplies become limiting. Woodpigeons lay light eggs relative to their body-weight but can achieve the extra parental care needed for the altricial chicks by producing crop milk. Because the moult is extended, the energy demands of moulting and breeding combined are relatively low and this enables the Woodpigeon to have a long breeding season and to moult coincidentally.     

The influence of age on laying date,clutch size,and egg size of the white-fronted tern,Sterna striata

Abstract

The age at first breeding and the influence of age on laying date, clutch size, and egg size of white-fronted terns were studied at the Kaikoura Peninsula, New Zealand, between 1971 and 1976. Of the 134 banded birds recovered breeding at Kaikoura, 63% were marked as nestlings at Kaikoura; the remainder came from colonies within 104 km. The bird is extremely capricious in its choice of nesting locality, and there are indications that it is not consistently philopatric. A small number bred as 3-year-olds, but the majority did not commence breeding until after they were 6 years old. Most pairs (73%) were of partners with an age difference of 1 year or less. Laying date and egg size varied with the age of the parent, but clutch size showed no significant change in relation to age. Mean egg volume did not vary between one-egg and two-egg clutches, but in two-egg clutches the first egg laid was significantly the larger in length, breadth, and volume. Single-egg clutches were the most common, but as the season progressed the proportion of two-egg clutches increased. There was no significant seasonal change in egg size.     

THE MOULT OF REMIGES AND RECTRICES IN GREAT BLACK-BACKED GULLS LARUS MARZNUS AND GLAUCOUS GULLS L. HYPERBOREUS IN ICELAND

The moult of primaries, secondaries, and rectrices in two closely-related gulls, the Great Black-backed Gull Larus mavinus and the Glaucous Gull L. hyperboreus, was studied in Iceland. Both gulls moult their primaries in an extremely regular sequence, starting with the 1st (innermost) and ending with the 10th (oiltermost) feather. Usually two, less often one or three, primaries are growing per wing during the primary moult, which lasts for about six or seven months. Growlng primaries were estimated to lengthen on the average by 8.7 mm per day in marinus and 7.8 mm per day in hyperboreus. The secondaries, usually 24 in number, are shed in two moult waves, one starting with the innermost feather soon after the start of the primary moult and then progressing slowly outwards, the other beginning with the outermost secondary after the primary moult is about half completed and then progressing rapidly inwards. The moult is completed just before the end of the primary moult as the two moult waves meet at about the 16th secondary. There are no marked differences between the two gulls in the moult of secondaries. The moult of rectrices shows large variations in both species, some feathers being much more irregular than others in their time of shedding. In both species, indications of an obscured centrifugal pattern of replacement are seen, although the 5th (next to the outermost) rectrix is usually the last one to be shed. Significant differences were observed between the two species in the degree of regularity of shedding of some feathers and in the average position in the moulting sequence of others. The moult of rectrices starts soon after the moult of primaries is half completed. The feathers are then shed in rapid succession, and the moult is completed some time before the end of the primary moult. The need for good powers of flight at all times is undoubtedly the reason for the protracted primary moult. This in turn causes the moult to start early, in adults sotnetimes before the eggs are laid; immatures moult even earlier than this. The rectrix moult and the main part of the secondary moult do not begin in adults until the young have fledged, but then progress very rapidly. Presumably, the loss of some of these feathers would impair the flying ability to an extent sufficient to make it difficult for the gulls to care for their young, while the rapid moult is necessary in order for the replacement of these feathers to be completed by the time the primary moult is over.     

OBSERVATIONS ON THE BREEDING OF THE PIED CROW AND GREAT SPOTTED CUCKOO IN NORTHERN NIGERIA

Mundy. P. J. & Cook, A. W. 1977. Observations on the breeding of the Pied Crow and Great Spotted Cuckoo in northern Nigeria. Ostrich 48:72-84.

The breeding cycle of the Pied Crow Corvus albus was studied in 1971. The birds bred in the wet season and all of 23 pairs were single-brooded. They appeared to nest territorially, and mostly close to human habitations. Average clutch size was 4.8 eggs and the greenish eggs were either pale and lightly marked, or darker and heavily marked. The average incubation and fledging periods were 181/2 and 38 days respectively. Chicks hatched asynchronously. Five crow nests were found parasitised by the Great Spotted Cuckoo Clamator glandarius and it appeared that only one hen cuckoo was responsible. The cuckoo apparently did not remove, or even crack, host eggs. One instance of an adult cuckoo feeding a juvenile was seen. In terms of growth increments a cuckoo chick substituted for one-half a crow chick but developed faster and fledged in nearly one-half the time. The cuckoo reduced host breeding success practically to zero apparently by indirect means, which contrasts with its situation in Europe.     

PTERYLOGRAPHY, PLUMAGE DEVELOPMENT AND MOULT OF JAPANESE QUAIL COTURNIX C. JAPONICA IN CAPTIVITY

Japanese Quail were kept in small cages under controlled conditions of temperature and light, and their pterylography and moult are described. There are 10 primaries, 14 secondaries and corresponding numbers of greater upper and lower wing coverts. The alula has four feathers and the tail from five to six pairs of feathers. There is an apterium in the dorso-pelvic tract similar to that in other quail genera. The arrangement of feathers in the ventral and cervical tracts appears to differ from that described for some North American quail.
The chicks hatch with a covering of natal down. Pre-juvenile moult can be seen when the chicks are three days old. Juvenile body plumage is complete in about 30 days; the sides of the face, around the eyes, are the last places to acquire feathers. The tenth and last juvenile primary to grow is mature when the chicks are 41 days old.
The moult in which the juvenile plumage is replaced overlaps the post-natal moult and in part of the ventral tract natal down is replaced by the first adult feathers. This makes it possible to sex the quail at 14 days old. The first adult moult is complete, in the body tracts, by the time the birds are five to six weeks old. The dropping of juvenile primaries commences at about three weeks old and ceases when about eight weeks old. Only from three to six primaries are replaced; most birds studied replaced five. The significance of this difference from other Galliformes is discussed; it is thought to be associated with the species' migratory behaviour. Quail which remained in the controlled laboratory environment did not undergo any further moult. All birds moulted when both temperature and light period were reduced and most birds moulted when the light period alone was reduced. Adult birds housed in small cages in an unheated, unlit shed underwent a complete moult between August and December in which all primaries were replaced. This moult took 8–14 weeks to complete.     

Identification and breeding of yearling Piping Plovers

ABSTRACT Age of first breeding is an important life history trait. Many Piping Plovers (Charadrius melodus) do not breed as yearlings, but little information is available concerning the age of first breeding. From 2000 to 2006, we marked 991 chicks in three areas in Saskatchewan, Canada, and subsequently determined when 102 (49 females and 53 males) first bred. Females bred significantly earlier, on average, than males. More females (68%) bred as yearlings than did males (41%; P= 0.04), with most others first nesting when 2‐yr old (29% of females and 50% of males). As expected from differences between the sexes in age of first breeding, younger females were more likely to pair with older males than were younger males with older females. Chicks that hatched early in the breeding season did not breed at an earlier age than those that hatched late in the year. Unlike older birds, juvenile Piping Plovers do not replace flight feathers during their first winter. As a result, 18 of 27 yearlings (67%) had worn outer primaries, whereas only one of 123 (1%) older birds had worn primaries. In addition, whereas 20 of 24 yearlings (83%) retained a few buff‐tipped median coverts, none of 119 known older birds had such coverts. As a result, we were able to identify all yearlings by their worn primaries, buff‐tipped median wing coverts, or both. Wing lengths of yearling Piping Plovers were 3% shorter than those of older birds, presumably due to wear. Because there is no evidence of differences in adult survival rates between the sexes and breeding habitat is available, we speculate that fewer yearling males than females breed because primary wear may reduce the ability of yearling males to perform aerial breeding displays.     

The ‘chaotic’ flight feather moult of the Steppe Buzzard Buteo buteo vulpinus

Steppe Buzzards breed in Eurasia and spend the non-breeding season in Africa. Adults moult some flight feathers during the breeding season and some during the non-breeding season. Moult is arrested during migration. The extent of moult of flight feathers in adults is highly variable between individuals in southern Africa, with the renewal of two primaries, three secondaries and five rectrices as the most frequently encountered pattern. Time spent on the non-breeding grounds in South Africa is too short to allow for a sequential moult. Moult of flight feathers is restricted to the almost synchronous dropping of a number of feathers upon arrival, with few being replaced subsequently. Any of the flight feathers can be replaced in southern Africa, and the pattern of renewal in primaries and secondaries cannot be distinguished from random. Tail feathers are replaced in an alternating (transilient) pattern. Moult in the non-breeding areas may primarily be complementary to moult on the breeding grounds, but these two partial moults per year are insufficient to renew all flight feathers annually. Middle secondaries and central tail feathers are regularly carried over to a third moult, but this is rare for primaries.     

Interrelation between moulting and breeding in a tropical population of the House Sparrow Passer domesticus

Under the tropical regime in Rajkot, India, the House Sparrow Passer domesticus had a prolonged breeding season, so that breeding and moulting of the primaries overlapped. The moult was interrupted commonly in the nesting birds and was observed more frequently in females than in males. It is concluded that moult initiation was not controlled by reproductive hormones in any way. It is also suggested that the reproductive hormones may not be directly involved with moult interruption.     

AUTUMN MOVEMENTS, MOULT AND MEASUREMENTS OF THE LESSER REDPOLL CARDUELIS FLAMMEA CABARET

The annual cycle of Lesser Redpolls breeding in Northumberland is described. Birds return in late April and could rear at least two broods, in the absence of predation, before they begin to moult in early August. The complete moult of both sexes usually begins just after the last brood of young reaches independence. Moult ends in late September and the adults then move southwards immediately. Juveniles also finish their partial moult before they migrate, but those which finish moult well before the adults, apparently wait for the latter before undertaking extensive southward movements, though some disperse over short distances in early September. Some adults and juveniles caught during moult at one site returned to moult there in later autumns, even though they did not breed there. Movement in autumn from Britain to the Continent takes place only at the short sea-crossings. More recoveries are obtained abroad in years of poor birch seed crop in southern England. Moult of the remiges and rectrices of the adults is described, and its progress recorded by a numerical scoring system whose merits are discussed. The moult score of the primary feathers follows an approximately linear relationship with date, and the moult scores of all individuals of each sex in each year have been used in regression analyses to yield averages of the duration, start and end of moult, an average daily increase of primary moult score, and the spread of the start of moult within each sample of birds. The results are discussed in relation to breeding and migration. The rates of moult of the primaries, secondaries and tail are not independent of each other, though, in contrast to the primaries, the secondary moult score does not increase linearly with date. The average daily increase of primary moult score is closely correlated with the number of primaries growing simultaneously. Each primary took about 16 days to complete growth in each year, but the duration of moult varied between 43 and 56 days in different years. Variation in the timing and duration of moult of Redpolls in Norway, Iceland and Britain is discussed in relation to the breeding season. Plumage sequences of the Lesser Redpoll are reviewed, with emphasis on their application to separation of sex and age classes. Wing lengths of the males and females of a given age overlap considerably, and abrasion alters these lengths only slightly. Older birds have longer wings. Weight changes of adults and juveniles in autumn are examined in detail. Weight variation of individual birds in August and September is more often due to hourly changes in response to feeding than day-to-day changes in response to temperature. Weights of adults, but not first-year birds, decrease at the start but then increase towards the end of the moult, but apparently there is no deposition of fat for migration. Weights of birds caught during their southward movement also show no increase, nor did a group of Lesser Redpolls caught near Oxford in December. It is suggested that day length may be an additional reason for southward migration, besides a reduction in food supply.     

THE BIRDS OF BLYTHSWOOD AND SOME NOTES ON BIRDS OF THE DISTRICT

Wintle, C. C. &; Taylor, P. B. 1993. Sequential polyandry, behaviour and moult in captive Striped Crakes Aenigmatolimnas marginalis. Ostrich 64:115-122.

Captive Striped Crakes showed sequential polyandry, the female laying for a second male when the clutch of her first mate was about to hatch. Where aviary space permitted each male set up a breeding territory and each female defended a larger area encompassing the territories of one or two males. Non-territorial subordinate males and females did not breed. The female initiated breeding by attracting the male and soliciting copulation, and the male incubated the eggs and cared for the young. Incubation took 17–18 days, the chicks left the nest at 4–5 days of age and were fully grown and capable of flight at 46–53 days. Breeding occurred from September to March and males normally reared two broods per season. Territoriality was evident only during the breeding season. Juvenile plumage was a duller version of the sexually dimorphic adult plumage; post-juvenile moult bean at 13–15 weeks and was complete at 21 weeks. Remex moult was simultaneous and a complete moult regular1 occurred twice a year in adults, in December and April (males) and September and March/April (females).