OBSERVATIONS ON THE BEHAVIOUR OF BIRDS IN SOUTHERN RHODESIA

Maclean, G. L. 1974. The breeding biology of the Rufouseared Warbler and its bearing on the genus Prinia. Ostrich 45: 9–14.

The Rufouseared Warbler Prinia pectoralis, a common species of the Kalahari scrub, nests after rain at any time of the year. Nest construction and nest sites are described. The clutch is normally three or four eggs. Incubation takes 12 to 13 days and the nestling period is 11 to 13 days. Data suggest that the Rufouseared Warbler is not a member of the genus Priniu, the generic position it currently occupies.     

A SUMMARY OF THE BIRDS OF WESTMINSTER O.F.S. AND SURROUNDINGS (1953-1955)

Results are presented from point-counts at six sites in the Kalahari in Botswana. Counts were repeated three times: during a dry season following good rains (1991), during the next wet season when rains were far below average, and the following dry season (1992) when the area became drought-stricken. Compared to the wet season, bird numbers decreased during the drought by 37–81% and species by 8–52%; compared to the previous dry season, birds decreased by 5–71% and species by 2–47%. Bird diversity (relative to numbers) tended to increase during the wet season but was little affected by drought, except in the northern Kalahari, where a greater proportion of birds moved out in response to drought. This gave the northern Kalahari the most distinct bird community during a wet cycle, but it became again typically Kalahari during the drought. Thus, the typical Kalahari bird communities expanded their range during drought into the moister periphery. Changes in numbers, most probably resulting from (local) movements were found in many species. Most confirmed earlier reports on their nomadic nature but some, like Red-crested Lophotis ruficrista and Northern Black Afrotis afraoides Korhaan, Chestnut-vented Tit-Babbler Parisoma subcaeruleum, Ant-eating Chat Myrmecocichla formicivora, Tinkling Cisticola Cisticola rufilatus, Black-chested Prinia Prinia flavicans, Marico Flycatcher Bradornis mariquensis and Brown-crowned Tchagra Tchagra australis have not been or are not widely recognised as mobile species.     

THE FINE STRUCTURE AND FUNCTION OF THE CONTRACTILE AXOSTYLES OF CERTAIN FLAGELLATES

The axostyles of the flagellates Oxymonas, Saccinobaculus, and Notila are large ribbon-shaped structures which undulate actively in the cytoplasm. The form of their movements is described and illustrated. Axostyles consist of regular arrays of longitudinal fibres, the number of which varies between 100 and 5000 in different species. The fibres are about 240 A in diameter, apparently hollow, regularly cross-banded with a periodicity of about 150 A, and connected by delicate cross-links, also at regular intervals of about 150 A. They resemble very closely the central fibres of cilia and flagella. No other structural components are present, except at the anterior end, where the fibres are attached to one or more basal bodies, and at the posterior tip, where they are anchored to the plasma membrane. The relevance of the findings to an understanding of the mechanism of ciliary and flagellar movements is discussed.     

OBSERVATIONS ON THE BREEDING OF THE PINK-BACKED PELICAN PELECANUS RUFESCENS

This paper summarises observations on the breeding behaviour of the Pink-backed Pelican Pelecanus rufescens at Rakewa, Nyanza Province, Kenya, where the species has bred for at least 200 years. Observations covered most of one breeding season, November 1962 to April 1963. Of at least 250 nests, 35 were closely observed. The community consisted of about 815 pelicans of which about 540 were adults. The death rate is estimated at 13% per annum and the mean life-span at about seven and a half years. The breeding site, in trees above a small swamp, is 15 miles from the favoured feeding ground. The colony is protected by local Luo people. The pelicans feed and roost mainly at the Miriu Delta, 15 miles away, travelling between the two places so high up as to be unseen. They fish in the early morning, visiting the colony to feed young mainly between 09.00 and 13.00 hrs. Once the young are large both parents roost away from the colony at the Delta. The breeding season takes place from August, towards the end of the rains, to March, at the end of the dry season. The birds breed in synchronised groups, the breeding cycle for any group occupying five months. Nuptial display is performed on the nest trees, by single pairs or small groups. Two main displays are described, “pointing” and “bill-clapping”. Mating occurs on the nest, with little preliminary display. Nests are slight stick structures, repaired from year to year, and used by other pelicans if abandoned. The clutch is normally two eggs, occasionally three. Both sexes incubate, with infrequent change-overs, for 33–35 days. The chick is first brick-red, becoming covered with white down. Feathers break through at about 12 days and have covered much of the body by 30 days. At 40 days chicks can recognise their own parent. They fly at 70–75 days. Parents feed chicks by regurgitation, sometimes into the nest. They brood them closely at first, but after 10–12 days leave them much alone. Large chicks thrust the head far into the parental gullet, and injuries result from such feeding struggles. Feeding usually occurs before mid-day, each parent normally delivering two feeds with a rest between. Curious convulsive movements of the young are probably begging displays. Forty-two young hatched in 35 nests, an average of 0.6 chicks/egg laid. The heaviest mortality among young occurred between 10–30 days when 31% of all chicks died. Young which flew were produced at the rate of 0.47/egg hatched, 0.28/egg laid, and 0.57/pair.     

Embryonic behaviour in the lizard, Lacerta vivipara

The behaviour of embryos of the lizard Lacerta vivipara has been studied in cultured eggs, removed from the mother. Spontaneous movements begin at a time when the embryo is still unresponsive to touch, and about two days before the appearance of reflex responses. The earliest movements consist of lateral flexion which gradually gives place to dorsiventral flexion. Embryonic movements are not necessarily related to contractions of the amnion. The activity of the embryo, as measured by the number of times movements were initiated and the amount of time spent in activity during a half hour period, rises to a plateau and then decreases sharply as the time of hatching approaches. Activity of the tail is prominent, particularly at times when other movements occur in rapid succession. Serpentine movements were not observed in embryos younger than stage 39; some prematurely born animals showed such activity in response to contact with the substratum. During embryonic life any part of the animal may move individually or in combination with any other part, such combined movements being unco-ordinated. In these respects the spontaneous motility of the lizard embryo closely resembles that of the chick. Statistical analysis of the embryonic movements provides evidence of rhythmic activity within the developing central nervous system.     

THE BIRD POPULATION OF THE DAMS ON THE FREE STATE GOLDFIELDS

Taylor, P. B. 1987. A field study of the Spotted Crake Porzana porzana at Ndola, Zambia. Ostrich 58: 107-117. From 1974 to 1980 field observations were made of Spotted Crakes Porzana porzana at Itawa Swamps and Kanini Sewage Works, Ndola, Zambia. Field identification characters, behaviour, food and feeding methods, activity times, interspecific interactions, aggression and voice are described. Habitat at Ndola is seasonal and temporary: shallowly flooded or moist grass and other vegetation with patches of open water and mud, near swamps and at sewage settling ponds. Wintering crakes were itinerant from December to April with a February-March peak and remained at one site for up to 25 days, occupying temporary territories 210-315 m2 in extent. Arrivals were associated with heavy rainfall and most departures with major habitat changes. Local movements took place. Behaviour is similar to diat in the Palaearctic. Comparisons are made with the habitat, movements, dispersion and behaviour of other rallid species at Ndola. The Spotted Crake is ecologically separated from other wetland rallid species in habitats in Zambia and Kenya by its preference for very temporary habitats and also by differences in food and feeding methods. All Zambian records of this species up to the end of 1984 are reviewed.     

Isolation and analysis of the gene encoding the pyruvate-ferredoxin oxidoreductase of Desulfovibrio africanus, production of the recombinant enzyme in Escherichia coli, and effect of carboxy-terminal deletions on its stability.

Previous studies have shown that the pyruvate-ferredoxin oxidoreductase (POR) of the sulfate-reducing bacterium Desulfovibrio africanus is a homodimer that contains one thiamine pyrophosphate and three [4Fe-4S]2+/1+ centers/subunit. Interestingly, the enzyme isolated from a strictly anaerobic bacterium is highly stable in the presence of oxygen, in contrast to the other PORs characterized in anaerobic organisms (L. Pieulle, B. Guigliarelli, M. Asso, F. Dole, A. Bernadac, and E. C. Hatchikian, Biochim. Biophys. Acta 1250:49-59, 1995). We report here the determination of the nucleotide sequence of the por gene encoding the D. africanus POR. The amino acid sequence deduced from this nucleotide sequence corresponds to the first primary structure of a homodimeric POR from strictly anaerobic bacteria. The subunit of the D. africanus POR contains two ferredoxin-type [4Fe-4S] cluster binding motifs (CX2CX2CX3CP) and four additional highly conserved cysteines belonging to a nontypical motif. These 12 cysteine residues may coordinate the three Fe-S centers present in D. africanus POR. The thiamine pyrophosphate binding domain is located in the C-terminal part of the protein close to the four conserved cysteine residues. The D. africanus enzyme sequence appears homologous to the other POR sequences. However, the enzyme differs from all other PORs by a C-terminal extension of about 60 residues of its polypeptide chain. The two cysteine residues located in this additional region may be involved in the formation of a disulfide bridge associated with the activation process of the catalytic activity. The por gene has been expressed, for the first time, in anaerobically grown Escherichia coli behind the isopropyl-beta-D-thiogalactopyranoside-inducible tac promoter, resulting in the production of POR in its active form. The recombinant enzyme is stable toward oxygen during several days, and initial characterization of the recombinant POR showed that its activity increased in the presence of dithioerythritol. These properties indicate that the recombinant POR behaves like the native D. africanus enzyme. The study of carboxy-terminal deletion mutants strongly suggests that deletions in the C-terminal region of D. africanus enzyme can have dramatic effects on the stability of the enzyme toward oxygen.     

ASPECTS OF THE BREEDING STATUS AND ECOLOGY OF THE BATELEUR AND TAWNY EAGLE IN THE KALAHARI GEMSBOK NATIONAL PARK,SOUTH AFRICA

Herholdt, J.J., Kemp, A.C. & Du Plessis, D. 1996. Aspects of the breeding status and ecology of the Bateleur and Tawny Eagle in the Kalahari Gemsbok National Park. Ostrich 67:126-137.

The nesting success at 13 nesting territories of Bateleur Terathopius ecaudatus and 19 nesting territorites of Tawny Eagle Aquila rapax was monitored for seven successive years (1988–1994) in a protected area in the Kalahari desert of South Africa. On average Bateleurs laid one year in two (51/95 pair-years) and fledged 0.33 young/pair/year (31/95). Tawny Eagles laid, on average, in two out of three years (66/105), and fledged 0.4 young/pair/year (42/105). Most Bateleurs laid eggs in January and February, while Tawny Eagles mostly laid from May to June. Almost all Bateleur and Tawny Eagle nesting territories located were in the Acacia erioloba savanna in the dry Auob and Nossob riverbeds. Bateleur nesting territories were spaced at intervals of 7.2 km (2.5–14.6 km; n = 9) along the Nossob River. Tawny Eagle nesting territories were spaced at intervals of 17.6 km (6.1–32.7 km) in the Nossob River and 11.3 km (8–14 km) in the Auob River respectively. A total of 13 Bateleur and 30–40 Tawny Eagle nesting territories (27 known active nesting territories) respectively occurred in the Kalahari Gemsbok National Park during the study period. There was evidence of a 13% decline in active nesting territories of Bateleur during the seven year study, and at least a 40% decline over the previous 10 years. Vacated nesting territories were not reoccupied. There was no safe buffer zone around the Kalahari Gemsbok National Park and persecution in the adjacent farmlands, when foraging Bateleur from the protected Park enter these areas, as well as nesting site disturbance, could have been part of the reason for this decline. Poisoned and suspected poisoned Bateleurs have been found in the Park during the study period. There was no obvious decline in active Tawny Eagle nesting territories.     

THE SOCIABLE WEAVER,PART 5: FOOD,FEEDING AND GENERAL BEHAVIOUR

Maclean, G. L. 1973. The Sociable Weaver, Part 5: Food, feeding and general behaviour. Ostrich 44:254-261.

The food of the Sociable Weaver during the study period consisted of 78,9% animal material by weight; the rest was mainly seeds, mostly of green grasses. The young are fed entirely on animal food. The most important single source of animal food in the Kalahari is the harvester termite Hodotermes mossambica. Sociable Weavers are independent of drinking water under natural conditions. Members of a colony do not usually feed more than about 1,5 km from the nest mass.

Maintenance activities and other general behaviour patterns of the Sociable Weaver are described; they are typically passerine.     

THE STATUS OF THE DUGONG (DUGONG DUGON MOLLER); KENYA, 1961

The scarcity of dugong (Dugong dugon Miiller) throughout their former range and lack of knowledge of the species' ecology justifies this record of the opinions of the fishermen in the Lamu district of Kenya, where the species is still plentiful. The area and the programme of questioning are described. The social life, reproduction, movements and predators of the dugong are recorded as reported by the fishermen. The present distribution is contrasted with the past. My observations on the food plants and their distribution are given, as well as the fishermen's estimation of the part each plays in the dugong's diet. The need for calm water over feeding grounds, afforded by depth of water or shelter from winds, seems to be a controlling factor in the distribution of dugong. Man appears to be the main predator.     

NOTE ON THE LONGEVITY OF THE VULTURINE SEA.EAGLE,CYPOHIERAX ANGOLENSIS (Gm.)

Herremans, M. &; Herremans-Tonnoeyr, D. 1994. Seasonal patterns in abundance of Lilacbreasted Rollers Coracias caudata and Purple Rollers Coracias naevia inferred from roadside counts in eastern and northern Botswana. Ostrich 65:66-73

The relative abundance of rollers (Coraciidae) in 45933 km of roadside counts made in eastern and northern Botswana between May 1991 and April 1994 was assessed by season and biome. Lilacbreasted Rollers appeared to move from breeding grounds in the northern Botswana woodlands into the northern Kalahari, and north-westward from breeding grounds in the Transvaal into the Limpopo drainage system and adjacent eastern Kalahari, during winter. Purple Rollers showed an influx during autumn and winter over most of eastern Botswana, but birds did not remain during the drought winter of 1992. The pattern indicated a large scale west-east or southwest-northeast migratory movement, from breeding grounds in the drier parts of the Kalahari to wintering grounds in the more humid periphery of the Kalahari.     

THE BREEDING OF THE LESSER FLAMINGO IN THE MWERU WANTIPA, NORTHERN RHODESIA.

A hitherto unreported breeding site of the Lesser Flamingo Phoeniconaias minor is recorded in the Mweru Wantipa or Mweru Marsh, Northern Rhodesia. The site of the nesting colony, its structure, nest construction and behaviour of the birds is described. The importance of flooding in determining the site of the nesting colony is noted; adverse conditions caused by a rise in the water-level of Lake Mweru Wantipa appear to have completely destroyed the nests. The instability of such environments does not offer much chance of regular and permanent breeding, and may influence local movements on the part of the birds.     

Sensorimotor pathways processing vibratory signals from the femoral chordotonal organ of the stick insect

The femoral chordotonal organ of stick insects senses position and velocity of movements in the femur-tibia joint, as well as tibial vibration. While sensory information about large-scale tibial movements is processed by a well-known neuronal network and elicits resistance reflexes in extensor and flexor tibiae motoneurons, it is not yet known how sensory information about vibration of the tibia is processed. We investigated the transmission of vibration stimuli to tibial extensor motoneurons and their premotor interneurons. Vibration stimuli applied to the femoral chordotonal organ evoked responses in tibial extensor and flexor muscles. During ongoing vibration this response adapted rapidly. This adaptation had no effect on the motoneuronal response to large-scale tibial movements. Recording from premotor interneurons revealed that vibratory signals were processed in part by the same interneuronal pathways as (large-scale) velocity and position information. While only certain parts of the interneuronal reflex pathways showed little or no response during vibration stimuli, most neurons responded to both position or velocity stimuli and vibration at the femoral chordotonal organ. We conclude that sensory information about vibration of the tibia shares part of the interneuronal pathways that transmit sensory information about large-scale tibial movements to the motoneurons. Accepted: 25 April 1999     

蚕豆气孔运动中水通道和离子通道的作用和地位的探讨

 用不同浓度HgCl2、LaCl3和TEACl (Tetraethylammonium chloride)处理蚕豆(Vicia faba)叶片下表皮条,发现HgCl2能显著抑制气孔开闭,Ca2+通道阻塞剂LaCl3或K+通道阻塞剂TEACl处理也都有一定程度的抑制。三者的作用效果HgCl2>>LaCl3>TEACl。用HgCl2+LaCl3、HgCl2+TEACl或HgCl2+LaCl3+TEACl处理,则气孔开闭运动几乎完全被抑制。表明：蚕豆气孔运动中,保卫细胞胀缩主要是水通道直接参与保卫细胞与叶肉细胞间水流的调节引起的,离子通道起间接次要作用,二者共同引起保卫细胞体积变化而导致气孔开闭。     

OBSERVATIONS ON THE BREEDING OF THE WOOLLYNECKED STORK

Scott, J. A. 1975. Observations on the breeding of the Woollynecked Stork. Ostrich 46: 201–207.

Little is known about the breeding of the Woollynecked Stork Ciconia episcopus in Africa. This paper discusses breeding, adult and nestling behaviour, nests and sites. Seasonal movements are discussed briefly. Eight nests were studied during 1970 to 1974. At one nest incubation was established at 30 to 31 days and the fledging period 55 to 65 days. No feeding of the young was observed at any time, though one eight hour observation period was undertaken. Few mating displays were seen and none away from the nest.     

Australopithecine taxonomy and phylogeny in light of facial morphology

The beginning of specialization characterizing the robust australopithecines is manifested in almost every aspect of the masticatory system of Australopithecus africanus. Of particular significance is the presence of two massive bony columns on both sides of the nasal aperture that support the anterior portion of the palate. These columns--the anterior pillars--are viewed as a structural response to the greater occlusal load stemming from the beginning stages of molarization of the premolars and exerted on the more anterior part of the dental arcade. In A. africanus the molarization process is, indeed, just in its initial phase, but the still considerable protrusion of the palate relative to the more peripheral facial frame increases the need for pillars. The anterior pillars and the advancement of the inferior part of the infraorbital plate (the origin of the masseter) play a major role in molding the facial topography of A. africanus. The absence of the pillars and the common position of the masseteric origin lead us to define the face of A. afarensis as the most primitive of the australopithecines and allow us to discriminate between its facial morphology and that of A. africanus. The presence of anterior pillars in the face of the latter places it clearly in the robust australopithecine clade.     

THE RATE OF GROWTH OF THE DOMESTIC FOWL

This paper points out the fact that the growth period of the domestic fowl is analogous to that of the mammal, being composed of three, or perhaps four, cycles; two of these cycles are postembryonic with maxima at about 8 and 18 weeks varying somewhat with the breed and two or at least one, are embryonic with maxima at 11 to 12 and 15 to 16 days of age. Hatching occurs during the first part of the second or third cycle resembling in this respect the guinea pig rather than the mouse. The velocity curves of each of these cycles are similar to and can be represented by the equation of an autocatalytic monomolecular reaction.     

Plant community structure in relation to grazing and environmental changes along a north-south transect in the western Kalahari

Sixteen vegetation types were described from a north-south transect in the western Kalahari. Pronounced differences were found between communities on the nutrient poor red Kalahari sand, covering most of the area and those on fine soils and white calcareous sand. Syntaxa resulting from severe overgrazing by livestock were in most cases clearly distinguished from the less disturbed vegetation. The communities on red sand consisted mainly of shrub savanna dominated by perennial tufted grasses, whereas in the vegetation on calcareous material and on overgrazed land, forbs, dwarf shrubs and shrubs played a more important role. The major communities on red sand showed a clear geographical zonation roughly corresponding to the gradient in mean annual rainfall and its interannual variation. In the northern and central Kalahari these syntaxa were dominated by species of Sudano-Zambezian origin and in the southern Kalahari by species showing Karoo-Namib affinities.     

Resistance to Ditylenchus africanus present in peanut breeding lines

Peanut is an important cash crop both for commercial and small-scale farmers in South Africa. The effect of Ditylenchus africanus on peanut is mainly qualitative, leading to downgrading of consignments. This nematode is difficult to control because of its high reproductive and damage potential. The objective of this study was to identify peanut genotypes with resistance to D. africanus that would also be sustainable under field conditions. Selected peanut genotypes were evaluated against D. africanus in microplot and field trials. The inbred lines PC254K1 and CG7 were confirmed to be resistant to D. africanus. The resistance expressed by these two genotypes was sustainable under field conditions. The breeding line PC287K5 maintained low nematode numbers in some trials, but its level of resistance was not as strong or as sustainable as that of PC254K1 or CG7. However, PC287K5 could still play an important role in the peanut industry where lower D. africanus populations occur.