SYSTEMATIC NOTES ON EMBERIZA CABANISI IN THE SOUTH AFRICAN SUB-REGION

Dean, W. R. J. &; Skead, D. M. 1979. Moult and mass of the Redknobbed Coot. Ostrich 50: 199–202.

The Redknobbed Coot Fulica cristata has a flightless moult throughout the year at Barberspan, but mainly during April and October/November. The flightless period is about 54 days. The plumage on the upper and under parts of the body and of the tail is replaced continually. The habitat of moulting Redknobbed Coots appears to be large open lakes; flightless birds occur singly or in small groups among full winged birds well out on open water. The mean mass of 4 016 adult Redknobbed Coots was 737 g and of 741 juveniles was 579 g, with an annual peak in adult mass in March.     

WATERFOWL (ANATIDAE) ON IRRIGATION LAKES IN THE ORANGE FREE STATE

Geldenhuys, J. N. 1975. Waterfowl (Anatidae) on irrigation lakes in the Orange Free State. Ostrich 46:219-235.

The incidence and population size of fifteen duck species were determined on nine irrigation lakes in the Orange Free State, South Africa, during August 1972 to July 1973. Allemanskraal supported the highest average number of Egyptian Goose, South African Shelduck and Yellowbilled Duck. Redbilled Teal and Spurwinged Goose favoured Bloemhof. Cape Shoveller and Cape Teal concentrated on Kalkfontein, and Southern Pochard frequented Erfenis. The most common species were the Egyptian Goose, South African Shelduck, Yellowbilled Duck and Spurwinged Goose, in thit order according to average number of birds per count, Black Duck, Whitefaced Duck, Whistling Duck, Whitebacked Duck, Hottentot Teal, Knobbilled Duck and Maccoa Duck occurred sporadically. Relatively high seasonal population nuctuations were found in the South African Shelduck, Cape Teal, Southern Pochard and to a lesser extent in the Spurwinged Goose and Cape Shoveller.     

Do captive waterfowl alter their behaviour patterns during their flightless period of moult?

Many different behavioural changes have been observed in wild waterfowl during the flightless stage of wing moult with birds frequently becoming inactive and reducing time spent foraging. Increased predation risk, elevated energetic demands of feather re-growth and restriction of foraging opportunities are thought to underlie these changes. By studying captive populations of both a dabbling and a diving duck species at the same site, we determined whether captive birds would reflect the behavioural responses of wild waterfowl to moult. The time-budgets of 42 Common Eiders, Somateria mollissima, (a diving duck) and 18 Garganeys, Anas querquedula, (a dabbling duck) were recorded during wing moult (July–August) and non-moult (January) with behaviour recorded under six categories. Despite captivity providing a low predation risk and constant access to food, birds altered their behaviour during the flightless period of wing moult. Time allocated to foraging and locomotion decreased significantly during moult compared to non-moult periods, while resting time increased significantly. Moulting Eiders underwent a greater reduction in time spent foraging and in locomotion compared with Garganeys, which is likely to be in response to a higher energetic cost of foraging in Eiders. It is possible that increased resting in both diving and dabbling ducks reduces their likelihood of detection by predators, while allowing them to remain vigilant. We demonstrate that there is much potential for using captive animals in studies that can augment our knowledge of behaviours of free-living conspecifics, the former being a hitherto under-exploited resource.     

Greater energy stores enable flightless moulting geese to increase resting behaviour

Many species of waterfowl undergo a post‐breeding simultaneous flight feather moult (wing moult) which renders them flightless and vulnerable to predation for up to 4 weeks. Here we present an analysis of the correlations between individual time‐budgets and body mass states in 13 captive Barnacle Geese Branta leucopsis throughout an entire wing moult. The daily percentage of time spent resting was positively correlated with initial body mass at the start of wing moult. Behaviour of individual birds during wing moult is dependent on initial physiological state, which may in turn be dependent on foraging ability; the storage of energy before the start of wing moult will help birds to reduce exposure to the dangers of predation.     

SEX RATIOS,MORPHOLOGY AND GROWTH OF THE AFRICAN BUCK DUCK

Frost, P. G. H., Ball, I. J., Siegfried, W. R. & McKinney, F. 1979. Sex ratios, morphology and growth of the African Black Duck. Ostrich 50:220-233.

Black Ducks Anus sparsa were trapped regularly in the Eerste River Valley near Stellenbosch, South Africa. The sex ratio of adult Black Ducks did not differ significantly from parity. Males were larger and heavier than females and also had proportionately larger wing spurs which are used when fighting over mates and territories. Body mass fluctuated seasonally, being lowest during summer and highest in autumn-winter. In the southwestern Cape breeding took place from July to December after the peak of the early winter rains. Ducklings hatched when waters were dropping and there was an increase in the emergence of aquatic insects. The growth rate of ducklings in the Eerste River Valley was severely retarded compared with that of ducklings reared in captivitly. Black Ducks moulted their body feathers twice a year, the moults corresponding to the pre- and post-nuptial moults of northern hemisphere waterfowl. Moults were not accompanied by any change in plumage coloration. Body and rectrix moult took more than five weeks to complete while remex replacement required about 30 days. Males began wing moult about a month earlier than females which delayed moulting until after their young had been reared. Forty-six percent of Black Ducks trapped had noticeable plumage aberrations; individual recognition among Black Ducks appears to be an important element in their social behaviour.     

ACTIVITY BUDGETS OF SPURWINGED AND EGYPTIAN GEESE AT BARBERSPAN DURING WINTER

Halse, S. A. 1985. Activity budgets of Spurwinged and Egyptian Geese at Barberspan during winter. Ostrich 56:104-110.

Daily behaviour of Spurwinged and Egyptian Geese was studied during winter at Barbers an, a large lake in the Transvaal. Non-moulting Spurwinged and Egyptian Geese spend about 2 h and 1,5h, respectively, feeding in farmland surrounding the lake in the early morning and about 20 min and 30 min, respectively, feeding there in the evening. They return to Barberspan during the day.

Activity budgets were calculated for all Spurwinged and all Egyptian Geese, including both moulting and non-moulting birds, at the lake during the day. Both species spend most of the day sleeping on the shore and relatively little time feeding. Both species spend a large proportion of this limited feeding time on open water picking at floating Potamogeton pectinatus. Closer to the shore the feeding habits of the species differ, Egyptian Geese feeding mostly along the shoreline in water a few centimetres deep, immersing only the bill, while Spurwinged Geese upend or submerge their heads and necks in deeper water.

An energy budget was calculated for Spurwinged Geese using the activity budget data. An averag-sized non-moulting goose (5,2 kg) requires about 2000 kJ/day for maintenance. During moult energy requirements increase 30 per cent to 2500 kJ/day because of the extra energy required for feather growth.     

Pre‐moult patterns of habitat use and moult site selection by Brent Geese Branta bernicla nigricans: individuals prospect for moult sites

In environments where habitat quality varies, the mechanism by which individuals assess and select habitats has significant consequences on their spatial distribution and ability to respond to environmental change. Each year, thousands of Black Brent Geese Branta bernicla nigricans migrate to the Teshekpuk Lake Special Area (TLSA), Alaska, to undergo a flightless wing‐moult. Over the last three decades, moulting Brent Geese have changed their distribution within the TLSA, redistributing from inland, freshwater wetlands towards coastal, brackish wetlands. To understand better the mechanism by which Brent Geese select a moult site, as well as reasons behind the long‐term shift of moulting distributions, we examined movements and habitat use of birds marked with GPS‐transmitters during the pre‐moult period. Brent Geese did not generally migrate directly to their moulting site during the pre‐moult period, defined as the time from arrival at the moulting grounds to the onset of flightlessness. Rather, individuals used an average of 3.7 ± 0.6 (se) wetland complexes and travelled a minimum of 95.14 ± 15.84 km during the pre‐moult period. Moreover, 69% of Brent Geese visited their final moult site only to leave and visit other sites before returning for the flightless moult. Brent Geese spent significant time in both inland freshwater and coastal estuarine habitats during the pre‐moult, irrespective of the habitat in which they ultimately moulted. Whereas previous research suggested that Brent Geese choose moult sites based largely upon the experience of previous years, our observations suggest a mechanism of moult site selection whereby Brent Geese ‘prospect’ for moult sites, visiting multiple potential moult sites across varied habitat types, presumably gathering information from each site and correspondingly using this information to choose an appropriate moult site. By allowing individuals to adjust their distributions in response to habitat quality cues that may change annually, such as forage type and availability, prospecting may have influenced the long‐term shift in moulting distributions of Brent Geese in the TLSA.     

NOTICES

Schmitt, M. B., Baur, S. &; Von Malitz, F. 1980. Observations on the Steppe Buzzard in the Transvaal: Ostrich 51:151-159.

During a three year study 247 Steppe Buzzards Buteo buteo vulpinus were captured in the Transvaal, South Africa. Density, mensural data and moult are discussed and compared with findings from the Cape Province. Linear density is 7,3 times lower in the Transvaal as compared with the Cape. Identification criteria for second-year birds are given. Second-year birds moult primaries descendently and symmetrically, secondary moult is mainly ascendent and symmetrical, tail moult irregular but symmetrical. Adult birds moult irregularly. Recorded food items are listed.     

Non‐breeding Cackling,Ross's and Snow Geese on Baffin Island show no loss of body mass during wing moult

Non‐breeding Cackling Branta hutchinsii, Ross's Anser rossii and Lesser Snow Geese Anser caerulescens caerulescens captured during remigial moult on Baffin Island in 2015 showed no loss of body mass with moult stage, and individual variation in mass was largely explained by sex and measures of body size (tarsus length). Exceptional conditions in 2015 resulted in almost no reproductive effort or success in that year, so captured geese of all three species were likely to have been non‐breeding individuals that initiated moult early, whereas there were almost no failed or successful breeders, which would normally moult later. This suggests that in a non‐breeding year (i.e. in the absence of competition from large numbers of goslings), locally moulting geese can obtain sufficient exogenous energy to meet their needs during the flightless wing moult period without losing body mass. This also is consistent with the hypothesis that in other species of geese, accumulation of fat stores prior to, and depletion of such stores during, wing moult is adaptive and likely to be a feature of individual plasticity to meet particular needs, such as undertaking moult migration to remote sites where precise foraging and predation conditions cannot be anticipated, or where competition from more dominant individuals may restrict their access to a reliable food supply.     

Species‐specific habitat use of wing‐moulting waterbirds in response to temporary flightlessness

The choice of the moulting habitat is of paramount importance for wing‐moulting waterbirds that have to cope with a flightless period of several weeks. However, some species might have more restricted habitat requirements during moult than others, for example due to a highly specialized feeding ecology. The moult‐related habitat use of five species (Gadwall Anas strepera, Red‐crested Pochard Netta rufina, Common Pochard Aythya ferina, Tufted Duck Aythya fuligula, Coot Fulica atra) was compared at a European inland moulting site that offered a variety of water bodies characterized by different levels of nutrient concentration, water depth, shoreline vegetation density and disturbance. To determine location‐ and species‐specific densities, birds were regularly counted throughout the moulting seasons of 2010 and 2011. In 2011, additional data on Gadwalls were used to assess differences in requirements between the flightless phase of moult and the periods before and after. Furthermore, habitat choice of 38 tagged Gadwalls was compared among two to four successive years. During the moulting season, all species showed clear preferences for specific levels of nutrient content, suggesting an active choice of suitable food sources in both food specialists and generalists. Species showing the strongest attachment to shallow water (Gadwall and Coot) were most sensitive to human disturbance and increasing water depths, and species averse to diving (Gadwall) used ponds with dense shore vegetation while flightless. For Gadwalls, habitat conditions rather than nutrient supply became increasingly important during the flightless phase. Average return rates of 59 and 54% were recorded for male and female Gadwalls, respectively, and the repeated use of familiar locations could be demonstrated in the majority of returning birds (65%). Familiarity with the habitat apparently plays an important role and may enable individuals to compensate for suboptimal conditions at the moulting site.     

Microhabitat nest‐site selection by ducks in the boreal forest

The boreal forest is one of the North America’s most important breeding areas for ducks, but information about the nesting ecology of ducks in the region is limited. We collected microhabitat data related to vegetation structure and composition at 157 duck nests and paired random locations in Alberta’s boreal forest region from 2016 to 2018. We identified fine‐scale vegetation features selected by ducks for all nests, between nesting guilds, and among five species using conditional logistic regression. Ducks in the boreal forest selected nest sites with greater overhead and graminoid cover, but less forb cover than random sites. Characteristics of the nest sites of upland‐ and overwater‐nesting guilds differed, with species nesting in upland habitat selecting nests that provided greater shrub cover and less lateral concealment and species nesting over water selecting nests with less shrub cover. We examined the characteristics of nest sites of American Wigeon (Mareca americana), Blue‐winged Teal (Spatula discors), Green‐winged Teal (Anas crecca), Mallards (Anas platyrhynchos), and Ring‐necked Ducks (Aythya collaris), and found differences among species that may facilitate species coexistence at a regional scale. Our results suggest that females of species nesting in upland habitat selected nest sites that optimized concealment from aerial predators while also allowing detection of and escape from terrestrial predators. Consequently, alteration in the composition and heterogeneity of vegetation and predator communities caused by climate change and industrial development in the boreal forest of Canada may affect the nest‐site selection strategies of boreal ducks.     

Wing moult and mass change in free‐living mallard Anas platyrhynchos

Captured free‐living male mallard Anas platyrhynchos at Abberton in southern Britain showed peak mass gain immediately prior to simultaneous remex moult. Individuals of both sexes were heavier before shedding wing feathers than when flightless confirming literature accounts that show mallard accumulate fat stores in anticipation of moult to contribute to meeting energy needs during remex re‐growth. Over the course of four seasons, males lost 13 17% of initial body mass on average during re‐growth of flight feathers, females 13 23%. Based on energy expenditure of 1.3 times BMR, male mallard were estimated to be able to fulfil 42 60% and females 41 82% of their energy needs throughout moult from stores. Free‐flying male mallard fed ad libitum in a predator‐free environment did not differ in starting body mass or rate of mass loss during wing moult compared to free‐living Abberton birds, suggesting depletion of fat stores, irrespective of available sources of exogenous energy. Based on this evidence, we reject that the hypotheses that mass loss in moulting mallard is due to 1) simple energy stress and 2) restrictions on feeding and consider that 3) attaining the ability to fly at an earlier stage on incompletely grown flight feathers is not the primary factor shaping this trait. Rather, we consider the accumulation and subsequent depletion of fat stores, together with reductions in energy expenditure, enable mallard to re‐grow feathers as rapidly as possible by exploiting habitats that offer safety from predators, but do not necessarily enable them to balance energy budgets during the flightless period of remex feather re‐growth.     

THE MIGRATION SYSTEM OF THE CURLEW SANDPIPER CALIDRIS FERRUGINEA IN AFRICA

Elliot, C: C. H., Waltner, M., Underhill. L. G., Pringle, J. S. & Dick, W. J. A. 1976. The migration system of the Curlew Sandpiper Calidris ferruginea in Africa. Ostrich 47:191-213. Data on ringing and recoveries of Curlew Sandpiper, mainly from the Cape, South Africa are presented. Possible migration routes to the breeding grounds are considered in the light of these and other recoveries from the rest of Africa. Retraps show that the species exhibits ortstreue and some evidence is presented which suggests that some birds may travel together and stay in the south in the same flock during one and subsequent migrations. Sex ratio statistics show an excess of females. Adults complete a full primary moult in the Cape between September and February, taking about 140 days but there is a lot of individual variation. Data from Mauritania show primary moult starting faster, a month earlier than in the Cape, and arrested moult in a few adults. The difference may be because Mauritanian birds move on further south while the Cape is the end point of the migration. Kenyan moult records from the Rift Valley follow the Cape pattern except that some birds arrest moult and finish later. Juvenile moult is shown to be different from that of adults, involving only a moult of the outer primaries and taking place during the overwintering period, April to August. All juveniles in the Cape are thought to overwinter and the modified moult to be an adaptation to this behaviour. The weight of adults but not juveniles increases markedly in the six weeks before migration. Fat and protein analyses suggest that the increase is entirely due to deposition of migratory fat. Kenyan birds have lower mean weights and deposit fat about two weeks later than those at the Cape. The nearer the non-breeding quarters are to the breeding grounds, the earlier moult starts and the later fat deposition takes place.     

Circumpolar variation in morphological characteristics of Greater White-fronted Geese Anser albifrons

Capsule Greater White-fronted Geese show significant variation in body size from sampling locations throughout their circumpolar breeding range.

Aims To determine the degree of geographical variation in body size of Greater White-fronted Geese and identify factors contributing to any apparent patterns in variation.

Methods Structural measures of >3000 geese from 16 breeding areas throughout the Holarctic breeding range of the species were compared statistically.

Results Palearctic forms varied clinally, and increased in size from the smallest forms on the Kanin and Taimyr peninsulas in western Eurasia to the largest forms breeding in the Anadyr Lowlands of eastern Chukotka. Clinal variation was less apparent in the Nearctic, as both the smallest form in the Nearctic and the largest form overall (the Tule Goose) were from different breeding areas in Alaska. The Tule Goose was 25% larger than the smallest form. Birds from Greenland (A. a. flavirostris) were the second largest, although only slightly larger than geese from several North American populations. Body size was not correlated with breeding latitude but was positively correlated with temperature on the breeding grounds, breeding habitat, and migration distance. Body mass of Greater White-fronted Geese from all populations remained relatively constant during the period of wing moult. Morphological distinctness of eastern and western Palearctic forms concurs with earlier findings of complete range disjunction.

Conclusions Patterns of morphological variation in Greater White-fronted Geese across the Holarctic can be generally attributed to adaptation to variable breeding environments, migration requirements, and phylo-geographical histories.     

THE NEST OF THE KNYSNA SCRUB WARBLER (BRADYPTERUS SYLVATICUS) AND SOME NOTES ON PARENTAL BEHAVIOUR

Von Maltitz, F., Schmitt, M. B., &; Biggs, H. C. 1984. Measurements, moult and abundance of the Lizard Buzzard in the Transvaal. Ostrich 55: 177–181.

During a 12-year study 51 Lizard Buzzards Kaupifalco monogrammicus were captured in the Transvaal. South Africa. They occurred sporadically, with peaks in the years 1972, 1975, 1979 and 1983 and were significantly more common in winter. Moult was completed between January and June. Mass is given and recaptures documented.     

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

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

Changes in body mass and organ size during remigial moult in common scoter Melanitta nigra

The “cost‐benefit” hypothesis states that avian body organs show mass changes consistent with the trade‐off between their functional importance and maintenance cost, which may vary throughout the annual cycle. Flightless moulting common scoter Melanitta nigra in Danish marine waters select rich undisturbed offshore feeding areas lacking predators, suggesting active feeding during moult. We tested four predictions relating to organ size during flightlessness in moulting male common scoter under this hypothesis. Namely that (i) pectoral muscles would show atrophy followed by hypertrophy, but that there would be no change in (ii) leg muscles and heart (the locomotory architecture required to sustain diving for food), (iii) digestive organs and liver (required to process food), or (iv) fat deposits (because birds could fulfil daily energy requirements from locally abundant food resources). Dissection of scoters collected at different stages during wing moult south of the Danish island of Læsø provided data on organ size that were consistent with these predictions. Pectoral muscle mass showed a c.23% atrophy during the middle of the flightless period relative to that at the end of moult. There was no significant loss in leg muscle, heart, digestive organs (except gizzard mass), liver, fat reserves or body mass with remigial growth. These findings are consistent with the hypothesis that common scoter moult in a rich feeding area, and rely on their diet to meet the nutritional requirements of remigial moult. These results differ in detail from those of a similar study of terrestrial feeding moulting greylag geese Anser anser, but because of the widely differing ecology of the species concerned, both sets of findings provide strong support for the hypothesis that variations in phenotypic plasticity in size of fat stores, locomotor and digestive organs can be interpreted as evolutionary adaptations to meet the conflicting needs (feather growth, nutritional challenges and predator avoidance) of the flightless moult period in different Anatidae species.     

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.     

Marine moult migration of the freshwater Scaly‐sided Merganser Mergus squamatus revealed by stable isotopes and geolocators

Scaly‐sided Mergansers Mergus squamatus breed on freshwater rivers in far eastern Russia, Korea and China, wintering in similar habitats in China and Korea, but nothing was known of their moulting habitat. To investigate the moult strategies of this species, we combined wing feather stable isotope ratios (males and females) with geolocator data (nesting females) to establish major habitat types (freshwater, brackish or saltwater) used by both sexes during wing moult. Although most Scaly‐sided Mergansers of both sexes probably moult on freshwater, some males and non‐breeding and failed breeding females appeared to undertake moult migration to brackish and marine waters. Given the previous lack of any surveys of coastal or estuarine waters for this species during the moult period, these findings suggest important survey needs for the effective conservation of the species during the flightless moult period.     

青海湖湿地鸭科鸟类群落结构

2007 ～2010年每年4～10月,采用直接计数法对青海湖周边6种典型生境包括河口湿地、湖泊、淡水沼泽、淡水泉、岩石湖岸、沙滩中的鸭科鸟类群落进行了调查.共记录到鸭科鸟类9属21种,采用频率指数法确定的优势种有斑头雁( Anser indicus)、赤麻鸭(Tadorna ferruginea)、针尾鸭(Anas a...