8. THE NIVEN FAMILY VISITS NYASALAND

Species worldwide are threatened due to various factors including habitat transformation and degradation. The Gurney's Sugarbird Promerops gurneyi is a bird species endemic to southern Africa. It is a nectarivorous species that is highly dependent on Protea woodland areas in the eastern parts of southern Africa and makes seasonal migrations between these localities. Although many of these habitats have been destroyed by human development activities, the start of commercial Protea farms in the KwaZulu-Natal Midlands may provide alternative habitat and year-round food resources for sugarbirds. Presence/absence of Gurney's Sugarbird on seven KwaZulu-Natal Protea farms were recorded monthly for one year (2006–2007) and compared to past distributions from 1980 and 1992. Sugarbirds were found to be resident for the entire year on some farms and breeding. The total distribution of Gurney's Sugarbird has extended with the development of Protea farms, as has its seasonal distribution and its breeding range. Our results also highlight the reliance that sugarbirds have on Protea whether indigenous or exotic species. More research on the interactions between Gurney's Sugarbirds and the commercial Protea farms is needed.     

MINUTES OF THE ANNUAL GENERAL MEETING OF THE SOUTH AFRICAN ORNITHOLOGICAL SOCIETY,HELD AT CAPE TOWN ON 17 May 1969

Earle, R.A. &; Oatley, T.B. 1983. Populations, ecology and breeding of the Orange Thrush at two sites in eastern South Africa. Ostrich 54:205-212.

The two populations of the Orange Thrush Turdus gurneyi studied represented two races, the nominate gurneyi in Natal and disruptans in Transvaal. In the Transvaal there was a large influx of individuals during the winter but numbers stayed constant during the breeding season with one pair/ha. Natal birds were more sedentary. Food seemed to be a major factor in regulating the winter population size of both the Orange Thrush and the Olive Thrush T. olivaceus in the Transvaal forest as the number of earthworms showed a peak just before the bird numbers peaked. In Natal the Orange Thrush showed a higher degree of specialization in diet than the Olive Thrush which his a mixed diet. Clutches consisted of two eggs and incubation lasted IS days. Chicks were brooded frequently, virtually to the time of fledging, thus protecting them from the cool, wet conditions of the forest. The nestling period was 15–18 days. The Orange Thrush preferred areas in the forest where little vegetation occurred at 1,0-1,5 m and where a good layer of leaf litter was present.     

Survival and life expectancy of the tree Protea roupelliae subsp. roupelliae in a montane grassland savanna: Effects of fire regime and plant structure

Survival and life expectancy are key demographic determinants of population dynamics. Using data collected in a field experiment monitored over 14 years in montane grassland of the Ukhahlamba‐Drakensberg Park, South Africa, we determined the effects of components of fire regime and plant structure on the survival and life expectancy of the tree Protea roupelliae subsp. roupelliae (Proteaceae). The field experiment comprised six plots (0.2–0.5 ha in area) from which the survival and life expectancies of 1567 juveniles (non‐reproductives) and 329 adults (reproductives) were estimated in response to differences in fire frequency, biennial seasonal fire, flame height, juvenile height, adult height, basal area and canopy vigour. Juvenile survival and life expectancies were highest when fires were excluded for 8 years. However, a fire after 12 years of fire exclusion and another fire 2 years later eliminated all juveniles. Over the same 14‐year period of biennial fires, juvenile survival was 5%. Juvenile survival and life expectancy were higher after biennial, winter fires than after annual, winter fires. Flame height had no effect on juvenile survival and life expectancy. Both survival and life expectancy of juveniles increased as plants got older and grew taller. Adult survival was unaffected by fire frequency, flame height or tree size, but the survival of adults in response to fire seasonality was inconclusive. Adults with low canopy vigour (<25%) were negatively affected by fire. Juvenile survival and life expectancy are critical bottlenecks in the demography of P. roupelliae. This species is neither a reseeder nor a resprouter. It avoids lethal fire damage by being restricted to rocky habitats with low fire intensities. Biennial winter fires least threaten the survival and life expectancy of P. roupelliae and impact least on its role in the summer feeding and breeding of Gurney's sugarbird.     

Do floral syndromes predict specialization in plant pollination systems? An experimental test in an “ornithophilous” African<Emphasis Type="Italic"> Protea</Emphasis>

We investigated whether the ornithophilous floral syndrome exhibited in an African sugarbush, Protea roupelliae (Proteaceae), reflects ecological specialization for bird-pollination. A breeding system experiment established that the species is self-compatible, but dependent on visits by pollinators for seed set. The cup-shaped inflorescences were visited by a wide range of insect and bird species; however inflorescences from which birds, but not insects, were excluded by wire cages set few seeds relative to open-pollinated controls. One species, the malachite sunbird (Nectarinia famosa), accounted for more than 80% of all birds captured in P. roupelliae stands and carried the largest protea pollen loads. A single visit by this sunbird species was enough to increase seed set considerably over unvisited, bagged inflorescences. Our results show that P. roupelliae is largely dependent on birds for pollination, and thus confirm the utility of floral syndromes for generating hypotheses about the ecology of pollination systems.     

OCCURRENCE AND MOVEMENT OF MIGRATORY SPECIES IN RHODESIA AND SOUTHERN AFRICA DURING THE PERIOD 1950-1953

Summary

Seiler, H. W. &; Pr?s-Jones, R. P. 1989. Mate competition, mate guarding, and unusual timing of copulations in the Cape Sugarbird (Promerops cafer). Ostrich 60:159-164.

Focal observations on two breeding pairs of the Cape Sugarbird were undertaken in the Cape Peninsula, South Africa. During the presumed fertile period of the female the male was significantly less likely to become separated from his mate than during other stages of the breeding cycle. This is interpreted as mate paring, which might be triggered by the female well in advance of her actual fertile period. The presumed fertile period was closely accompanied by a sharp increase in territorial intrusions by other males. Copulations were observed only outside the presumed fertile period.     

Isolation of highly polymorphic autosomal microsatellite loci and a sex‐linked locus from sugarbirds

We describe the isolation of six tetranucleotide microsatellites from the Cape sugarbird (Promerops cafer) using an enrichment protocol. All loci were highly variable with number of alleles ranging from nine to 26 and values of observed heterozygosity ranging from 0.534 to 0.931. All loci were in Hardy–Weinberg equilibrium with the exception of Pro66 and Pro86. Further analysis of Pro86 indicated it was Z‐linked. All loci amplified and were variable in the congeneric Gurneys sugarbird (Promerops gurneyi). These loci will be used in mating system and phylogeographic studies of Cape sugarbirds in South Africa.     

Sugar preferences of some southern African nectarivorous birds

Three southern African nectarivorous passerine birds, Gurney's Sugarbird Promerops gur-neyi , the Malachite Sunbird Nectarinia famosa and the Black Sunbird Nectarinia amethystina , were tested to determine their hexose and sucrose preferences. All three species preferred sucrose when offered a choice of 0.25 M solutions of glucose, fructose and sucrose. However, when the concentrations were increased to 0.73 M, the three species showed no preference for any of the three sugars. The choice made at low concentrations (equivalent to the lower limit of the range of nectar concentrations of preferred nectar-producing plants) may reflect preference for the sugar with the highest energy reward. We also examined the proposition that birds offered a choice of different concentrations of one sugar would show ranked preferences and maximize their rate of energy return by selectivity. In contrast to expectations, Gurney's Sugarbird and the Malachite Sunbird showed no preference for the highest concentrations. We suggest that dietary choices in these species indicate the birds had either reached a limit where they had sufficient energy intake or were affected by post-ingestion constraints.     

Evidence for altitudinal migration of forest birds between montane Eastern Arc and lowland forests in East Africa

Burgess, N.D. & Mlingwa, C.O.F. 2000. Evidence for altitudinal migration of forest birds between montane Eastern Arc and lowland forests in East Africa. Ostrich 71 (1 & 2): 184–190.

In this paper we assess the evidence for altitudinal movements of forest birds from the montane forests of the Eastern Arc mountains of East Africa to nearby lowland forest patches. For 34 montane species, including all the Eastern Arc endemics except Banded Green Sunbird Anthreptes rubritorques there is no evidence that they undertake seasonal movements to lower altitudes. An additional 26 montane species, of somewhat wider distribution, have been recorded at low (<500 m) altitudes during the cold/dry season (June to September). Most records of these montane birds at lower altitudes are from sites adjoining montane forest areas, although a few records are from lowland coastal forests at 100–240 km distance from montane areas. Only five of the 26 species (White-chested Alethe Alethe fulleborni, White-starred Forest Robin Pogonocichla stellata, Orange Ground Thrush Zoothera gurneyi, Evergreen Forest Warbler Bradypterus mariae and Barred Long-tailed Cuckoo Cercococcyx montanus) are regularly and commonly reported in the lowlands. They are also found in the lowlands in small numbers during the warm/wet season (October to February), when they may breed. The abundance of at least four, and probably more, of the forest birds with a more widespread distribution in the lowland and montane forests of East Africa declines greatly at high altitudes from the onset of the cold/wet season (February) and only increases again at the start of the warm/wet season (September). It is not known how far these species move as they cannot be easily separated from resident populations in lowland forests, and there are no ringing recoveries in different forests. Altitudinal migration of a proportion of the Eastern Arc avifauna is the most likely explanation for available data, although source-sink metapopulation theories may be helpful to explain the distributions of some species. As the movement of forest birds from the Eastern Arc to the lowland forests does not involve the rare endemics, they are of lower conservation concern, but the presence of montane and lowland forest may be important for the long-term survival of some more widely distributed forest species.     

Biometrics,possible breeding origins and migration routes of South African Grey Plovers,Pluvialis squatarola

Data on 355 Grey Plovers, Pluvialis squatarola, ringed in South Africa in 1971–1997 were analysed. Biometrics could not identify well-defined origins in the Siberian breeding grounds, but suggested the presence of birds from east of the Gydan Peninsula. Comparisons with populations spending the non-breeding period elsewhere did not allow a clear definition of the flyways used, although ringing recoveries indicated a migration route crossing the Mediterranean/Black Sea region during both southward and northward movements. First-year birds were on average smaller than adults. Bill length increased during the first year, reaching adult length by June. First-year wing length decreased by 4% before the outermost primary was shed, adult wing length did not change with season.     

Seasonal variation in honeyeater foraging behaviour,infloresence abundance and fruit set in Banksia spinulosa (Proteaceae)

Seasonal variation in the foraging behaviour of honeyeaters and the production of fruit were examined in relation to the flowering intensity of Banksia spinulosa over two flowering seasons. The abundance of inflorescences was greater in the mid than in the early and late periods of the flowering season. In the mid period, many plants were blooming and each plant had many flowering inflorescences. Inflorescences received most visits by honeyeaters in the early flowering period; the visitation rate declining as flowering progressed. Eastern spinebills were the most common floral visitors at all times during the season. The number of foraging probes made at inflorescences by eastern spinebills did not differ throughout the season. Foraging movements between inflorescences on the same plant were more frequent in the mid period than in the early and late periods. Long distance movements between plants (more than 10 m apart) were promoted by aggressive interactions between honeyeaters. Inflorescences flowering in the late period were less likely to develop follicles because there were fewer visits by birds and/or because resources had been allocated to inflorescences pollinated earlier in the season. The number of follicles produced per infructescence did not differ between flowering periods. Overall, the number of inflorescences produced per plant, the number of visits received per inflorescence and the proportion of inflorescences that developed follicles were greater in 1987 than in 1988.     

Population fluctuations in relation to seasonal habitat preferences of the Swainson's spurfowl, Pternistis swainsonii

Counts on Swainson's spurfowl Pternistis swainsonii were made during 1998–1999 within an intensive, fine‐grained, agricultural landscape to estimate population parameters, seasonal dispersion and habitat preferences. Radio‐transmitters were fitted to four birds to note habitat use and home ranges within the Summer breeding season. During Winter, population densities peaked, and birds exploited agricultural crops extensively. At the onset of Spring, densities dropped as birds paired to establish non‐overlapping breeding territories over a number of habitats with apparently sufficient cover and ‘natural’ food. Expanding grazed grassland appears to be the greatest threat to Swainson's spurfowl due to a lack of cover and food. The matrix of habitats within the landscape plays important roles in the success of this opportunistic spurfowl. Agricultural crops in the Winter sustain the population until the following Summer when natural savanna and ungrazed grasslands provide complementary foraging, nesting and roosting sites.     

Ringing or colour-banding does not increase predation mortality in redshanksTringa totanus

The use of metal and colour‐rings or bands as a means of measuring survival, movements and behaviour in birds is universal and fundamental to testing ecological and evolutionary theories. The practice rests on the largely untested assumption that the rings do not affect survival. However this assumption may not hold for several reasons, for example because the ‘oddity effect’ predicts predators select prey that appear different to their neighbours in order to avoid the ‘confusion effect’. We compared the foraging behaviour and the death rates of redshanks Tringa totanus conspicuously marked with six colour rings and one metal ring each to unmarked birds in a study system, where routinely up to 50% of the total population are killed by avian predators during a winter. If avian predators selectively target and/or have a higher capture success of ringed birds then we would predict the proportion of colour‐ringed birds in the population to decline through a winter. The proportion of colour‐ringed birds in the population did not change over the course of three separate winters, and in one winter the ratio of marked:unmarked birds found killed by sparrowhawks Accipiter nisus was the same as the ratio of marked birds alive in the population. In the year with largest sample size, power was sufficient to detect a greater than 2.2% difference in predation rate between ringed and unringed groups. The average kill rate difference between ringed and unringed birds across the three winters was less than 1% (0.73±2.2%) suggesting that even if there were differences in predation rate that were not detected because of low statistical power they were extremely small. There were no differences in any foraging measures comparing ringed and unringed birds, suggesting that the rings did not affect the ability of birds to meet their daily energy budgets. The results showed that colour‐ringed birds were not preferentially targeted or killed by avian predators, and suggest that the presence of a metal and even several large colour‐rings is unlikely to affect behaviour and predation mortality even under extreme selection.     

REMARKS ON THE DISTRIBUTION OF BIRDS COLLECTED IN MASHONALAND AND EASTERN SOUTHERN RHODESIA (Part I)

Oatley, T. B. 1983. Twenty-third ringing report for southern Africa. Ostrich. 54:141-149.

Bird ringing activities in southern Africa are summarized for a two-year period from July 1979 to June 1981. A total of 42 374 birds were ringed. Much ringing effort was devoted to marine buds. Palaearctic migrants comprised nearly 12% of the birds ringed, with waders, swallows and warblers being the most frequently ringed families. There were 747 recoveries or recaptures reported during the reviey period, of which 73 were foreign-ringed birds. The remainder involved 103 species of birds, only nine of which contributed 10 or more recoveries to the total. Five of the nine are marine birds and collectively account for 55% of all recoveries and recaptures. A selected list of recoveries and recaptures of southern African-ringed birds is given.     

Farming with native bees (<Emphasis Type="Italic">Apis mellifera</Emphasis> subsp. <Emphasis Type="Italic">capensis</Emphasis> Esch.) has varied effects on nectar-feeding bird communities in South African fynbos vegetation

Outside their natural range, honeybees (Apis mellifera) are known to have detrimental effects on indigenous pollinators through exploitative or interference competition, but little is known about the effect of honeybee farming in areas where honeybees occur naturally. In the Cape Floristic Region of South Africa, where honeybees are indigenous, managed hives potentially elevate the abundance of honeybees far above natural levels, but impacts on other floral resource-dependent species have not been studied. Here we use experimental manipulation of honeybee density to test whether honeybee farming affects nectar-feeding birds. We selected the common sugarbush (Protea repens), utilized by both birds and bees, and analysed the time (before/after) by treatment (control/experiment) interaction to explore changes in bee abundance, nectar availability and bird abundance at three sites. Hive addition increased honeybee abundance in inflorescences of P. repens above expected levels. Despite experimental increase in honeybee numbers, there is no reduction in nectar sugar availability relative to the control areas. Where honeybee density was highest, sugarbird (Promerops cafer) numbers declined relative to expected, but sunbirds (Nectarinidae) were not affected at any of the sites. We conclude that stocking rates of more than one honey bee per P. repens inflorescence have detrimental effects on bird abundance due to interference, rather than resource competition.     

PLUMAGE CHANGES IN THE MALE MACCOA DUCK

Clark, A. 1974. Plumage changes in the male Maccoa Duck. Ostrich 45: 251–254.

Maccoa Duck Oxyura mi ccoo counts made at various waters in the Transvaal and Orange Free State, South Africa, in which the numbers are separated according to plumage, are presented and discussed in the light of the work done by Siegfried (1968, 1970) on this species. Males invariably outnumber females and the indications are that Transvaal birds move out of the area during winter when most males are in non-breeding plumage. There is little difference in the pattern of plumage changes between Transvaal and Cape birds.     

Geographical and environmental factors affecting the distribution of wintering black storks Ciconia nigra in the Iberian Peninsula

Here we explore the environmental and geographical factors affecting the winter distribution of the black stork Ciconia nigra in the Iberian Peninsula, where an increasing number of individuals have remained to winter in the last two decades. We recorded 179 locations of 54 ringed individuals between 1988 and 2011 to map the species habitat suitability with MaxEnt, a machine‐learning technique based on the principle of maximum entropy. The migratory movements of 25 birds equipped with satellite transmitters were used to define the autumnal migratory flyway used by most storks crossing the Peninsula as well as to define the wintering period. The aim was to test if the number of wintering storks was positively correlated to habitat suitability and negatively correlated to the flyway distance. Data provided by an extensive count across Portugal and Spain during the 2012–2013 winter supported the findings that black storks were more abundant in areas of high habitat suitability close to the migratory flyway. This agrees with previous evidence on the role of migratory flyways in determining the distribution of some wintering birds in Iberia. A gap analysis reflected that just 12.3% of the suitable areas and 18.8% of individuals recorded during the 2012–2013 winter were included within the Special Protection Areas network of Portugal and Spain. Most of these birds were crowded in unprotected areas covered by rice fields (68% of individuals), a key habitat for the species.     

6.—DATA OF BIRDS' EGGS IN MY COLLECTION

Van Zyl, A.J, Jenkins, A.R. &; Allan, D.G. 1994. Evidence for seasonal movements by Rock Kestrels Falco tinnunculus and Lanner Falcons F. biarmicus in South Africa. Ostrich 65:111-121.

Patterns of seasonal movement by Rock Kestrels Falco tinnunculus and Lanner Falcons F. biarmicus in South Africa were determined using data from the Southern African Bird Atlas Project, road transect counts, ringing recoveries and other sources. Both species were found to be partial, facultative migrants, and Lanner Falcon movements involved mostly immature birds. Rock Kestrels were found to concentrate in the southwest of the country in the breeding season, and to move north and east in the non-breeding season. Lanner Falcons concentrated in the east of the country during the breeding season, and moved into the west in the non-breeding season. The movement by both species into the arid northwest of the country is probably associated with dramatic increases in prey abundance, in turn associated with summer rah events. Lanner Falcon movement into the southern Cape apparently coincides with cereal farming practices, affecting the availability of prey (granivorous birds and rodents). Rock Kestrel movement into the east of the aunt is probably to exploit increases in insect abundance mated with summer rain. The pattern of Rock Kestrel movements suggests that it does not compete for food with the Lesser Kestrel F. naumanni. a Palearctic migrant to the east of the country.     

GENE FLOW IN CHAMAECRISTA FASCICULATA (LEGUMINOSAE) I. GENE DISPERSAL

Both pollen and seed dispersal components of gene flow were examined in the annual plant Chamaecrista fasciculata (Leguminosae) and quantified in terms of Wright's neighborhood area. Pollen dispersal was estimated by measuring pollinator flight movement throughout the flowering season and the contribution of pollen carryover to pollen dispersal was determined by comparing pollinator flight movement with dispersal of electrophoretic markers in an experimental transect. Phenological effects on the probability of fruit set were measured to determine whether pollinations should be weighted differentially across the flowering season. The outcrossing rate, a major determinant of the role of pollen dispersal in gene flow, was estimated from electrophoretic analysis of progeny arrays and by measuring the proportion of nongeitonogamous pollinator flight movements. Seed dispersal was measured in a prairie habitat and in experimental plots without surrounding vegetation. Seed dispersal was small in comparison to pollen dispersal in both environments. Fruit set was low at the beginning and end of the flowering season, periods when flower density is low and pollinator flight distances are large. Although the outcrossing rate was high (t = 80%) and pollen carryover substantial, pollen dispersal was limited. Averaged over 4 years, neighborhood area, based on both seed and pollen dispersal, was 17.6 m², and corresponds to a circle of radius 2.4 m. The observed limited gene dispersal suggests the population of C. fasciculata is genetically subdivided into small breeding units of related individuals.     

ON THE RACE OF CARDINAL WOODPECKER Dendropicos fuscescens (Vieillot) OCCURRING IN THE EASTERN TRANSVAAL

Summary

Hustler, K. &; Marshall, B.E. 1996. The abundance and food consumption of piscivorous birds on Lake Kariba, Zimbabwe-Zambia. Ostrich 67:23-32.

About 40 species of piscivorous birds have been recorded on Lake Kariba (Zimbabwe-Zambia) but only 26 were observed during this study, carried out in 1986–87. The Reed Cormorant Phalacrocorax africanus was the most numerous and made up 51.4% of all the birds seen, followed by the Whitewinged Black Tern Chlidonias leucoptera (26.7%), and the Darter Anhinga melanogaster (10.8%). Several species roosted or bred in the drowned trees which project above the lake surface but gently sloping shores were the most important feeding grounds. Relatively few birds were seen on steeply sloping shores or in open water. There was a distinct pattern of seasonal abundance, with birds being most numerous in the rainy season (November-April). The relative abundance of some fish species also was greatest during this period. There was a positive relationship between the numbers of some bird species and the relative abundance of these fish. The mean density of piscivores (0.05 ha^?1) was low compared to some other African waters. This is attributed to the fact that Lake Kariba is relatively deep and its shoreline is mostly steep. The mean population of 25 000 birds consumed less than 1000 t of fish per annum, compared to almost 40000 t taken by the commercial fisheries. A considerable portion of the birds' diet was fish that were not taken commercially.     

Distribution and movements of Buller's albatross (Diomedea bulleri) in Australasian seas

Abstract

The distribution and movements of Buller's albatross in Australasian seas are analysed using results of shipborne surveys (13 238 10‐min counts), counts from trawlers, banding data, recoveries on beaches and fishing vessels, and records from the literature. Patterns of marine distribution are documented by monthly accounts and maps. During the breeding season, highest abundances are recorded over shelves and slopes off southern New Zealand (The Snares shelf to 41–43°S off the South Island, D. b. bulleri), around the Chatham Islands and over oceanic subtropical waters east of New Zealand (probably D. b. platei), with marked seasonal variations observed off southern New Zealand. Both subspecies disperse mostly outside Australasian waters during the non‐breeding season. Birds banded on The Snares were recovered off south‐eastern New Zealand (Stewart Island to Cook Strait) and in the eastern tropical Pacific. Immatures accounted for only 0.25% of birds censused during the ship‐borne surveys; they are recorded around the New Zealand mainland in August‐October and February‐May, off south‐eastern Australia and in the Tasman Sea in November‐December, February, and June‐July. Around New Zealand, males predominate among birds recovered along the eastern seaboard, whereas the sex ratio in south‐western waters tends to vary according to water depth and season. Distribution patterns and movements in New Zealand and Australian seas are discussed in relation to breeding events and breeding status.