Primary moult,mass and movements of the Rock Pigeon Columba guinea in the Western Cape,South Africa

Underhill, L.G. & Underhill, G.D. 1997. Primary moult, mass and movements of the Rock Pigeon Columba guinea in the Western Cape, South Africa. Ostrich 68 (24): 86–89.

Rock Pigeons Columba guinea in the Western Cape, South Africa, take an estimated 7.2 months to complete primary moult. The mean starting and completion dates are 26 December and 2 August, with 95% of birds starting and completing within two months of these dates. The overall mean mass was 344 g, but birds were heaviest in winter (356 g) and lightest in spring and summer (334 g). Twenty-four of 48 recoveries of Rock Pigeons ringed in the Western Cape were more than 2 km from the ringing site. These recoveries demonstrate movements of Rock Pigeons between the mountains of the Cape Peninsula and the wheat-growing areas to the northeast.     

Return to Robben Island of African Penguins that were rehabilitated,relocated or reared in captivity following the Treasure oil spill of 2000

Following an oil spill from the Treasure off the coast of South Africa in June 2000, about 19 000 oiled African Penguins Spheniscus demersus, including 14 825 from Robben Island, were caught for rehabilitation and subsequent release. A further 19 500 penguins that were not oiled — mostly birds in adult plumage, including 7 000 from Robben Island — were relocated some 700km to the east, to prevent them becoming oiled. Additionally, 3 350 orphaned chicks, including 2 643 from Robben Island — were collected for rearing in captivity and release to the wild. Some four years later — by the end of December 2004 — 70% of rehabilitated adults, 40% of relocated birds and 34% of captive-reared chicks had been seen back at Robben Island. Another 7% of birds relocated from Robben Island had been sighted at other localities. Rates of resighting rehabilitated birds were similar at Robben and Dassen Islands, but a greater proportion of relocated birds was seen at Dassen Island, where birds collected for relocation were mostly from breeding areas. The lower proportion of relocated birds seen at Robben Island is thought to result from this intervention causing some pre-breeding birds to move to other colonies. All three conservation interventions are considered to have been successful, but it is premature to assess their relative contributions to the conservation of the species. Three relocated birds tracked by satellite took 15–21 days to return to their home colonies. This rapid return may have resulted from breeding attempts being interrupted. After remaining at their home islands for 4–5 days, two of the tracked birds then left these islands for 19–36 days. We surmise that, after they had searched unsuccessfully for their mates, they abandoned breeding for the year 2000.     

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.     

THE POPULATION,ECOLOGY AND CONSERVATION OF THE BLACK OYSTERCATCHER HAEMATOPUS MOQUINI

Summers, R. W. & Cooper, J. 1977. The population, ecology and conservation of the Black Oystercatcher Haematopus moquini. Ostrich 48:28-40.

The population of Black Oystercatchers Haematopus moquini in the southwestern Cape, South Africa, was estimated to be 2 942 birds. Birds occurred most abundantly on coastal islands and were also abundant on mixed (sandy and rocky) shores of the mainland. Sandy shores and coastal wetlands supported few birds. Black Oystercatchers bred mainly from December to February with the number of clutches present reaching a peak in the first half of January. The most frequent clutch size was two eggs, the mean clutch size was 1,81. No significant differences were found in either linear dimensions or mass between the first and second eggs. The mean proportion of juveniles in groups of birds in July was 3,6 % suggesting a low recruitment to the adult population. The breeding population at Marcus Island is apparently sedentary throughout the year. The primary moult season for adults extends from March to October (eight months). Introduced mammalian predators should be controlled on islands and important mainland breeding sites should be protected by the creation of nature reserves and restricting human access during the breeding season.     

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.     

NOTES ON THE PEARL-BREASTED SWALLOW HIRUNDO DIMIDIATA IN THE SOUTH-WESTERN CAPE

Earlé R. A. &; Herholdt, J. J. 1988. Breeding and moult of the Anteating Chat Myrmecocichla formicivora. Ostrich 59: 155–161.

The general breeding biology and moult of the Anteating Chat Myrmecocichla formicivora was studied in open grassveld over a two-year period. During the winter (July), groups were significantly smaller than during summer (December) (1,81 ± 0,50 versus 2,85 ± 1,35 birds per group). There was a large turnover of individuals in the study area but the total population stayed the same. The breeding season in the study area lasted from September to February but analysis of nest record cards from a larger area gave a breeding season of August-April. Two types of nests were used: 90,6% were burrows in sand banks or other excavations, but 9,4%were in the mud pellet nests of Greater Striped Swallows Hirundo cucullata (n = 53). Consecutive breeding attempts were never made in the same burrow. Clutches consisted of three, four or five eggs ([Xbar] = 3,73 ± 0,67). Incubation lasted 14–14,5-15 days. The nestling period lasted 15–18 days. Fledgling/egg breeding success was 41,8% with 48,2% of all eggs not reaching the hatching stage. Juveniles showed an unequal sex ratio of 0,57 ♂ ♂: 1,0 ♀ ♀ but adults had a nearly equal ratio (0,9 ♂ ♂: 1,0 ♀ ♀). There was a significant positive correlation between the primary moult score and the week of the seven months in which moult was recorded. Juveniles underwent a complete body moult and partial primary moult 3–4 months after fledging.     

MEASUREMENTS AND MOULT OF FIVE SPECIES OF BULBUL FROM MOÇAMBIQUE AND MALAŴI

Summary

Hanmer, D. B., 1978. Measurements and moult of five species of bulbul from Moçambique and Mala?i. Ostrich 49:116-131.

The wing length, weight and moult of five species of bulbul, Blackeyed Pycnonotus barbatus, Sombre Andropadus importunus, Yellowbellied A. flaviventris, Terrestrial Phyllas-trephus terrestris and Yellowspotted Nicator Nicator gularis, are given for two localities in tropical lowland (Mopcia, Moçambique and Nchalo, Mala?i). The characters identifying immatures and the length of time these are retained, are given with reference to skull pneumatization, retrapped birds and the breeding season, for Pycnonotus barbatus, Andropadus intportunus and Phyllastrephus terrestris. Weights are compared with some published for other parts of Africa. The months during which moult occurred are given. Duration and timing of primary moult and its relation to the breeding season, are given for Pycnonotus barbatus, Andropadus importunus and Phyllastrephus terrestris. The age at which immatures moult is given for these three species. Instances of interrupted moult are mentioned.     

Conditions at the breeding grounds and migration strategy shape different moult patterns of two populations of Eurasian golden plover Pluvialis apricaria

Events in the life cycle of migrant birds are generally time‐constrained. Moult, together with breeding and migration, is the most energetically demanding annual cycle stages, but it is the only stage that can be scheduled at different times of the year. However, it is still not fully understood what factors determine this scheduling. We compare the timing of primary feather moult in relation to breeding and migration between two populations of Eurasian golden plover Pluvialis apricaria, the continental population breeding in Scandinavia and in N Russia that migrates to the Netherlands and southern Europe, and the Icelandic population that migrates mainly to Ireland and western UK. Moult was studied at the breeding grounds (N Sweden, N Russia, Iceland) and at stopover and wintering sites (S Sweden, the Netherlands). In both populations, primary moult overlapped with incubation and chick rearing, and females started on average 9 d later than males. Icelandic plovers overlapped moult with incubation to a larger extent and stayed in the breeding grounds until primary moult was completed. In contrast, continental birds only moulted the first 5–7 primaries at the breeding grounds and completed moult in stopover and wintering areas, such as S Sweden and the Netherlands. This overlap, although rare in birds, can be understood from an annual cycle perspective. Icelandic plovers presumably need to initiate moult early in the season to be able to complete it at the breeding grounds. The latter is not possible for continental plovers as their breeding season is much shorter due to a harsher climate. Additionally, for this population, moulting all the primaries at the stopover/wintering site is also not possible as too little time would remain to prepare for cold‐spell movements. We conclude that environmental conditions and migration strategy affect the annual scheduling of primary feather moult in the Eurasian golden plover.     

Unexpected weight gain in resident Antarctic Terns Sterna vittata during the austral winter

Antarctic Terns Sterna oittata (Fig. 1) may display two very different migratory behaviours. According to Cooper (1976), the terns breeding on Tristan da Cunha in the South Atlantic fly thousands of kilometers to the coasts of Africa where they moult. Antarctic Terns that inhabit the more southern and colder Antarctic Peninsula region moult on their breeding grounds. An early account of these seemingly resident peninsular terns (Holdgate 1963) leaves little doubt that at least part of the tern population wintered in the vicinity of Arthur Harbor (64°46′S 64°03′W), Anvers Island, west of the Antarctic Peninsula. Watson (1975) stated that adult Antarctic Terns are generally sedentary around many insular breeding stations, moving only to the nearest open water in winter. During the year 1975 through 1978, 19 tern specimens of different sexes and ages were collected at Arthur Harbor in the non-breeding season near U.S. Palmer Station. An additional eight terns were collected at a sea short distance from Anvers Island during the non-breeding season in 1985 (Pietz & Strong, in press). I found that the adult birds taken at the height of winter weighed significantly more than the 150-180g of a normal breeding Antarctic Tern. This unexpected discovery prompted me to examine the weights of an additional 34 specimens that had been collected at or near Anvers Island during several breeding seasons. By comparing the weights of adult terns by sex, age, and collection date (Fig. 2, Table 1) I found that both males and females weighed significantly more in the winter non-breeding season (April-September) than in the summer breeding season (October-March) (t₂₄= 6.57, P < 0.001, and t₁₆= 5.71, P < 0.001, respectively). No significant differences were detected between male and female weights in summer(t₂₃=0.76, P >0.20) or winter (t₁₇=1.16, P0.20). In short, it appears that body-weights of adult terns rise rather dramatically following breeding, attain a peak in mid-winter, and then fall at the approach of the next breeding season (Fig. 2). I suggest that this increased body-weight is an adaptation to the austral winter rather than simply a recovery from weight loss due to energetic costs of breeding and moulting.     

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.     

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.     

Unexpected weight gain in resident Antarctic Terns Sterna vittata during the austral winter

Antarctic Terns Sterna vittata (Fig. 1) may display two very different migratory behaviours. According to Cooper (1976), the terns breeding on Tristan da Cunha in the South Atlantic fly thousands of kilometers to the coasts of Africa where they moult. Antarctic Terns that inhabit the more southern and colder Antarctic Peninsula region moult on their breeding grounds. An early account of these seemingly resident peninsular terns (Holdgate 1963) leaves little doubt that at least part of the tern population wintered in the vicinity of Arthur Harbor (64°46'S 64°03'W), Anvers Island, west of the Antarctic Peninsula. Watson (1975) stated that adult Antarctic Terns are generally sedentary around many insular breeding stations, moving only to the nearest open water in winter. During the years 1975 through 1978, 19 tern specimens of different sexes and ages were collected at Arthur Harbor in the non-breeding season near U.S. Palmer Station. An additional eight terns were collected at sea a short distance from Anvers Island during the non-breeding season in 1985 (Pietz & Strong, in press). I found that the adult birds taken at the height of winter weighed significantly more than the 150–180 g of a normal breeding Antarctic Tern. This unexpected discovery prompted me to examine the weights of an additional 34 specimens that had been collected at or near Anvers Island during several breeding seasons. By comparing the weights of adult terns by sex, age, and collection date (Fig. 2, Table 1) I found that both males and females weighed significantly more in the winter non-breeding season (April-September) than in the summer breeding season (October-March) (t₂₄ = 6·57, P < 0·001, and t₁₆ = 5·71, P < 0·001, respectively). No significant differences were detected between male and female weights in summer (t₂₃ = 0·76, P > 0·20) or winter (t₁₇ = 1·16, P > 0·20). In short, it appears that body-weights of adult terns rise rather dramatically following breeding, attain a peak in mid-winter, and then fall at the approach of the next breeding season (Fig. 2). I suggest that this increased body-weight is an adaptation to the austral winter rather than simply a recovery from weight loss due to energetic costs of breeding and moulting.     

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.     

SOME INTERESTING RHODESIAN RECORDS—IV

Austin, G. T. 1979. Pattern and timing of moult in penduline tits (Anthoscopus). Ostrich 49:168-173.

Moult was examined in species of Anthoscopus. Second and subsequent prebasic moults were complete. Primary and rectrix moult was typical of passerines, but secondary moult was some what irregular. Moult was largely non-overlapping with breeding, although some body moult was noted during the breeding season. In southern Africa there was some regional variation in timing of moult. First year birds moulted after adults had largely completed feather replacement. This first prebasic moult was incomplete.     

THE BIOLOGY OF THE WAVED ALBATROSS DIOMEDEA IRRORATA OF HOOD ISLAND, GALAPAGOS

As a nesting species, the Waved Albatross Diomedea irrorata is restricted to Hood Island in the Galapagos archipelago where 12,000 pairs bred in 1971. Outside the islands the species occurs over the northern parts of the Humboldt Current. Two colonies were studied in detail (1970–1971). At the start of a season, males returned first to the colonies and defended a small territory. Copulation occurred without any elaborate ceremony and the female spent little time on land before laying. There was no fixed nest-site, even within a season, and birds moved their eggs considerable distances. This resulted in heavy egg losses. Younger birds bred later than older birds and laid longer but narrower eggs. The average incubation spell varied from four to five days at the extremes of the incubation period to 19 days in the middle. The average incubation and fledging periods were 60 and 167 days respectively. Pairs which lost an egg sometimes adopted the abandoned egg of another bird and successfully reared the chick. Most pairs nested in both seasons. Nesting success was extremely variable, both between years and between colonies. Between 1961 and 1971 at Punta Suarez, virtually no young were reared in four seasons. Even in 1970–71, where nesting success was good, some groups of birds deserted their eggs en masse whereas in neighbouring areas up to 80% of the pairs reared young. The main foods of the young were squid and fish. Birds did not moult wing and tail feathers at the breeding colonies, and about 50% retained some primaries for more than one season, suggesting that successful pairs had difficulty in fitting in a complete moult between breeding attempts. Old feathers were normally found among the inner primaries and at the next moult were preferentially replaced, though adjacent newer feathers were sometimes retained for another season. Some birds bred in their fourth years, but most not until a year or two older. Immatures were present at the colonies late in the breeding cycle, the youngest returning latest and remaining until the last young fledged. Survival of adults and young averaged at least 95% and 93% per annum over many years. Adults and young ringed in 1961 survived equally well. The significance of the timing of the return of immatures and of the large-scale desertion of eggs, apparently not due to food shortage or disturbance, is discussed.     

A comparison of breeding and moult cycles and life histories in two tropical starling species: the Blue-eared Glossy Starling Lamprotornis chalybaeus and Rüppell's Long-tailed Glossy Starling L. purpuropterus

The Blue-eared Glossy Starling Lamprotornis chalybaeus and Rüppell's Long-tailed Glossy Starling Lamprotornis purpuropterus were investigated in the field and in aviaries at Lake Nakuru National Park, Kenya for seasonality in reproductive activity and moult. The former species was found to be a seasonal breeder which nests after the onset of the heavy rains in April. Although some birds had large gonads prior to the rains in the dry season no nesting occurred. The rains were contemporary with increases in gonadal size and the plasma titres of LH, testosterone (T) in males and estradiol (E2) in females. These hormones are associated with the initiation of breeding activity. As breeding ceased in July and the moult began, the plasma titres again decreased. There was a bimodal breeding pattern which paralleled a change in biotope preference for nesting. Early nests, in the heavy rains, were on the open savanna and later nests were in the acacia forest. Late nesting birds also had delayed peaks in gonadal size, plasma titres of LH, T and E2 and a delayed moult onset. Data on individual captive birds demonstrate that these annual cycles have a distinctly individual character superimposed on the seasonal trends. In Rüppell's Long-tailed Glossy Starlings no seasonality in breeding was found although the flight feather moult commenced and was completed in all individuals at about the same time. The moult extended over about ten months, so a great deal of breeding-moult overlap was present. The absence of seasonality in field birds was reflected in the aviary birds, which had no pronounced cycles in the reproductive parameters measured (gonadal size, LH, T and E2 plasma titres). Breeding in field birds was regulated on a pair basis and correlated with increases in duetting. The striking differences in the seasonal organization between this species and Blue-eared Glossy Starlings were presumably due to the different biotope preferences and social behaviour of the two species.     

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.     

THE BREEDING BIOLOGY OF AN URBAN POPULATION OF ROCK PIGEONS COLUMBA GUINEA

Elliott, C. C. H. & Cooper, J. 1980. The breeding biology of an urban population of Rock Pigeons Columba guinea. Ostrich 51:198-203.

The breeding biology of the Rock Pigeon Columba guinea was studied for three seasons from 1972 to 1975 at the University of Cape Town, southwestern Cape, South Africa. Nests were visited at approximately weekly intervals. The breeding season (September to February) coincided with the end of the winter rainy season and the presence of cereal crops. Clutch size was two eggs in 99% of cases. Mean incubation period was 14,8 days. Incubation was shared as two continuous shifts per day. Growth rate was similar to that in other studies. The mean nestling period was 23,6 days. Second broods after the successful departure of chicks were frequent, the interval between nest departure and re-laying being as little as five days. Hatching success was 66%, chick rearing success 83% and overall breeding success 49%, similar to other Columba pigeons. It is suggested that the production of pigeon's milk is the limiting factor controlling the invariable clutch size.     

Moult in Black-browed and Grey-headed Albatrosses Diomedea melanophris and D. chrysostoma

We recorded the age of individual wing and tail feathers of Black-browed and Grey-headed Albatrosses Diomedea melanophris and D. chrysostoma of known age and breeding status at Bird Island, South Georgia. Breeders and non-breeders of both species moult their rectrices annually. Non-breeders moult primaries biennially. In the first year of a cycle, the outer three and some inner primaries are moulted descendantly; in the next year the inner primaries are moulted ascendantly, starting from primary seven. There is a general progression to moulting equal numbers of primaries in each half of the cycle by the time breeding starts at about 10 years of age. Grey-headed Albatrosses usually moult fewer primaries than Black-browed Albatrosses, particularly as 3-year-olds, when they undertake substantial plumage change in body moult. Most secondaries in Black-browed Albatrosses have been replaced once by age 4 years. Breeding Black-browed Albatrosses continue the moult pattern established as immatures whether they fail or not, as do failed Grey-headed Albatrosses. Successful Grey-headed Albatrosses, which breed again 16 months later, moult their three innermost primaries after breeding in the remainder of the current year and, after a period when moult is interrupted, renew the remaining primaries the following year. Comparisons between species and between failed and successful birds within species indicate that moult rate is not closely linked to the length of the interval between breeding attempts. Interspecies differences are better explained by breeding latitude, with tropical albatrosses moulting twice as fast as sub-Antarctic species, possibly reflecting food availability outside the breeding season.     

SHORT NOTES

Laycock, H. T. 1982. Moulting and plumage changes in the Thickbilled Weaver. Ostrich 53:91-101.

Thickoilled Weavers were studied in captivity, in the wild and as museum specimens. Moulting follows the normal passerine pattern, but a difference from related species is that there is no post-fledging moult of the flight feathers. Methods were devised for identifying isolated feathers and for aging trapped birds, this being easier in the male. After the breeding season the male undergoes eclipse, which has apparently not been described before, and loses his white forehead patches. Adult males and females moult about the same time, but second-year males moult six or eight weeks earlier. The duration of post-nuptial moult is about four months and is timed to occur during the season when there is maximum food availability. The use of a “moult score” is avoided in this account and the timing of feather loss substituted as having more real meaning.