A FIELD STUDY OF THE CALFBIRD PERISSOCEPHALVS TRICOLOR

The Calf bird Perissocephalus tricolor was studied in the Kanuku Mountains of southern Guyana for three months (January-April 1970), during which time almost daily visits were paid to a lek of four adult males. The adult males owned perches about 30 ft up in understorey trees, where they displayed and called throughout much of the day. Four immature males also visited the lek, particularly in the morning and evening. The immatures also wandered, feeding and occasionally calling together, over an area of forest of approximately 3 miles by half a mile. There was a hierarchy among the adult and immature males, the dominant males owning the most coveted perches at the lek. The male's most far-reaching call, the “moo call”, is a co-operative advertising call, in that birds calling together adjust the timing of their calls so as to follow each other and not overlap. The adult males perform a number of silent agonistic displays on their lek perches. Periodically, adult and immature males and sometimes a female invade the vicinity of a lek perch, usually that of the dominant male. Once a female was briefly mounted by the dominant male on his lek perch during an invasion. On other occasions females visited the lek but no mating occurred. The food of the males attending the lek was recorded by the daily collection of a total of 2,500 regurgitated fruit seeds (mostly drupes) from below the perches. Males also regularly take insects, but in smaller quantities. Three nests were found. The nest is an extremely light structure built entirely of fine twigs. A single egg was laid in each nest. All the nests (and two old ones) were within half a mile of the lek. Two of the nests were only 5 yards apart and the eggs were laid in them within 10 days of each other. The incubation period at one nest was 26–27 days and the fledging period approximately 27 days. The chick on hatching was covered in bright orange-chestnut down. It was fed mostly on insects (predominantly Orthoptera) brought by the female in her beak. There was no evidence of a male attending the nest. The Calfbird's nesting and lek behaviour is compared with that of other species of Cotingidae.     

SOME OBSERVATIONS ON THE DIDRIC CUCKOO

Earlé R. A. 1986. The breeding biology of the South African Cliff Swallow. Ostrich 57: 138–156.

The South African Cliff Swallow Hirundo spilodera breeds in dense colonies usually under man-made concrete bridges. The clutch size is 1–4 eggs but most 4-egg clutches are probably the result of conspecific brood parasitism. The incubation period averages 14,6 days and the fledling period 24,1 days. Although only the female Cliff Swallow has a featherless brood-patch, both males and females incubate effectively. Nestlings reach a maximum weight of up to 31 g between 19 and 22 days, about 10 g more than average adult weights. This weight increase of nestlings is mostly the result of an increase in water content of the body. Both parents feed the chicks, with the highest rate of feeding during the midday hours. In all, 56% of all eggs laid produced flying young, with a recruitment rate of 0,9 young: 1 adult per season.     

BREEDING BIOLOGY OF THE BEARDED VULTURE IN SOUTHERN AFRICA,PART I: THE PRELAYING AND INCUBATION PERIODS

Brown, C. J. 1990. Breeding biolo of the Bearded Vulture in southern Africa, Part I: The pre-laying and incubation periods. Ostrich 61: 24–32.

In southern Africa the Bearded Vulture Gpaetus barbatus lays its eggs in mid-winter. between the second half of May and the first week of July. Pairs became more active in their nesting areas about six weeks before laying and usually roosted there at night. Courtship flights were less frequent and demonstrative than in Eurasian birds and took place mainly in the late afternoons. During the pre-laying period most nest visits (77%) were to bring nesting material, 92% by the male. All nesting material was arranged by the female. Copulation was always preceded by allopreening, and occurred most frequently in the mornings. No copulation or courtship display took place after the first egg had been laid. Of 18 clutches, 16 (89%) contained two eggs and the remainder one egg. The laying interval was usually 3–5 days (range 2–9 days). Incubation started with the first egg and was evenly shared by both parents during the day, but only the female incubated at night, individual pairs maintained distinctive nest attendance and foraging period timetables, which allowed sufficient time for self-foraging by both parentes. No food was brought into the nest during the pre-laying and incubation periods, but in some pairs food was cached in nearby potholes in cliffs. The incubation period was 56–57 days.     

OBSERVATIONS ON THE BREEDING OF THE PALILA PSITT1ROSTRA BA1LLEUI OF HAWAII

The behavioural ecology and breeding biology of the endangered Palila Psittirostra bailleui was studied from 1971 to 1975. The most intensive breeding occurred from June to August, and coincided with peak production of mamane Sophora chrysophylla seeds, the bir?s major food source. The Palila was able to make adjustments in its breeding to compensate for yearly differentiation in the timing and abundance of this food supply. Sexual chasing and courtship feeding were the most frequently encountered pre-nesting behaviours. Territory was a mate-defended area, which later in the nesting sequence was confined to the nest site. A total of 26 nests was found; most were placed on larger branches of mamane trees. Nest construction occurred primarily in the morning hours and lasted up to 20 days. Both sexes took part in nest construction, albeit the male role was minimal. Unless the nest was placed in the terminal fork of a tree, it usually contained a large stick base. The modal clutch size was two; eggs were laid early in the morning and in all cases one per day. Incubation sometimes began with the first egg and lasted 15–16 days. Only the female incubated, and she covered the eggs for about 75% of the daylight hours and throughout the night. Egg hatching was asynchronous, with the first young emerging early in the morning and the second not until later that same day. Only the female brooded, and the rate declined until day 15 when essentially it stopped. Both parents fed the young by regurgitation, and the number of feedings per hour decreased slightly over the nestling period. It is thought that insects and finely masticated plant material formed the bulk of the nestling diet until about day 5 when mamane seeds became important. Helpers were found at one nest. Young developed slowly and did not leave the nest until 21–27 days old. It is believed that these prolonged nestling periods were able to evolve because of the (former) absence of ground predators. After fledging, young remained with their parents for at least 30 days. Productivity was regulated by small clutch size, low population numbers and by the length of an individual nesting sequence (in that a pair could potentially raise only one brood each year). The primary reason for the endangered status of this bird appears to be the effect of habitat alteration upon a specialist, coupled with the fact that the small effective breeding population and low dis-persability of the species may have resulted in decreased genetic fitness.     

EDITORIAL

Olver, M. D. &; Kuyper, M. A. 1978. Breeding biology of the Whitebreasted Cormorant in Natal. Ostrich 49:25-30.

From 1972–1975 Whitebreasted Cormorants Phalacrocorax carbo bred at the Cedara Dam, Natal, South Africa (29 32S, 30 17E), and from 1973 they fished for food at Midmar Dam, 5 km away and carried the food back to the nestlings. Breeding occurred from April to October and was preceded by a period of courtship. Nesting material was collected by the males and the nests built by the females. The mean clutch size for 1972–1973 was 3,1. Both parents incubated the eggs and guarded the nest and chicks. Growth of the chicks was studied in 1972–1973. The mean number of chicks reared was 1,6 per nest although seven nests contained three nestlings. At 28 days they left the nest when alarmed, but could not fly until 49 days old. The average flying age appeared to be about 53 days. The height of the nests above the ground seemed to determine the nest leaving age. Of the 186 eggs laid in the 60 nests observed over two years, 74% hatched. Fledging success was 52% of eggs laid and 69% of eggs hatched. Chick mortality seemed to be caused mainly by falling from the nests and dying of starvation.     

A molecular genetic analysis of the communal nesting of the ostrich (Struthio camelus)

The ostrich breeding system is complex and unique; communal clutches are laid by several females, although only one female, the major female, and the resident territorial male provide parental care. More eggs are laid in the nest than can be incubated and the major female ejects surplus eggs from the incubated central clutch. Microsatellite markers were used to analyse the parentage of communal nests in Nairobi National Park. This revealed that major females contributed a disproportionate number of fertile eggs to the central, incubated clutch and that multiple paternity and maternity within a nest were common; 68.9% of all incubated eggs on a nest were not parented by both the resident territorial male and the major female of that nest. All the males fertilized eggs on the clutches of neighbouring males. Unexpectedly, every major female with her own nest was also simultaneously a minor female with incubated eggs on neighbouring clutches. The relatedness between females laying in the same nest was not significantly different from the population average and significantly less than that between chicks hatched from the same nest.     

THE BREEDING BIOLOGY OF THE GANNET SULA BASSANA ON THE BASS ROCK, SCOTLAND

The Bass colony is increasing—in 1962 there were 5,350–5,700 breeding pairs; 1,340–1,430 pairs of non-breeders with nests or sites (mainly pairs in their season before first breeding) and 2,000–2,500 “club” birds without nest or site. 15% of nests were occupied by both birds of a pair at the time of the count. Oldest males return to the colony in January, followed by experienced females, considerably later by young adult-plumaged birds, immature birds later still, and the few one year-olds that return usually not until May and June. Mid-cliff sites are the first to be re-colonized each year. Gannets usually breed in their fifth year and there is some evidence that females breed earlier than males. The characteristics of Gannet nests and sites are described. Nests function in raising the egg and young above the morass of the breeding colony, and reach a density of about 2.3 per square metre. Nests are demolished and their positions changed more often than might be suspected. The extremely strong social tendency which causes Gannets to establish their sites amongst or very close to existing breeders probably is the factor ensuring high density and this contributes to synchronization of laying. Egg laying is analysed. Experienced pairs forming an isolated group of 20 nests began laying later and showed less synchronization than two other groups of the same size but from the middle of a dense mass, probably due to the greater social stimulation experienced by the non-isolated groups. The date for first and median eggs was also earlier in larger than smaller groups in the same year. The effect of density as distinct from group size is also discussed. Early eggs are mainly laid on cliff or cliff-edge sites and in large nests. Different groups within the colony produced the median egg within 2–3 days of the end of April each year. In the fullest documented group the mean date was also constant from year to year and closely approached the median, implying a considerable degree of synchronization within the gannetry as a whole. Laying in the observation colony became progressively earlier in successive years, probably due to recovery from previous disturbance. Nevertheless, individual females tended to lay in a fixed position each year with relation to the mean for the group. Increasing age of the female causes earlier egg laying and heavier eggs for up to at least five years. It is suggested that the survival value of seasonally synchronized laying in the Gannet is maximum utilization of a seasonally dependable and abundant food supply for the production of young with the optimal chance of post-fledging survival. The spread of laying acts as an insurance against possible adverse conditions. There is a considerable reserve of unutilized breeding capability within the colony (adult non-breeders, a pre-maturity period longer than physiologically necessary for egg production, and a one-egg clutch when in fact two young can easily be reared). The mean of 393 Gannet eggs was 104.5 gm. (range 81–130). Eggs constitute about 3.4% of adult female weight and lose 9–13% in weight during incubation. Replacement laying of the invariable one-egg clutch takes 6–32 days. The mean incubation period was 43.6 days. Male incubation spells averaged 35.6 hours; female's 32.0 hours. Copulation ceases immediately after egg laying. During three seasons, 82% of eggs laid in the observation colony hatched. Inexperienced pairs hatched 62.6% of eggs laid; experienced pairs hatched 86%. Some of the processes of incubation and chick rearing depend on the maturation of innate abilities and not on experience Inexperienced breeders do not seem inferior to experienced ones in finding enough food for their young. Parental care of the new chick is described; the pterylosis of the chick is figured. A summarized account of plumage development is given. Food fish and chick feeding are described. The average frequency of feeds throughout a continuous two-day watch was 2.7 feeding bouts per chick per day. Adult fishing trips usually took 7–13 hours and the estimated fishing range is over 100 miles, and possibly up to 400 miles, from the breeding colony. Despite this, 15% of daylight hours are spent by the pair together at the nest in addition to the constant guarding of the chick by one or other. Gannet young have a very compressed growth period compared with boobies and fledge at 3,100–4,100 gm., after a steady growth uninterrupted by periods of starvation or arrested development after an average 90 days. 92.3% of all eggs which hatched in 500 nests in the observation colony during three years of the study gave fledged young. Excluding inexperienced birds, there was no difference in the fledging success of eggs laid at different dates in the breeding season, in accordance with the proved abund- ance of food. However, post-fledging survival is probably higher among young fledging at the peak period (first half of September) than later and the few relevant ringing returns tend to support this. Breeding success at the small colony at Bempton was less compared with groups from the Bass for the years 1961–3. Causes of chick loss before and during fledging are discussed. They are unimportant compared with the great mortality in the first year of life after fledging. The adaptive significance of black plumage in the juvenile Gannet probably lies in reduced attack-releasing qualities of such plumage on the male parent. The Gannet alone in the Sulidae produces young which leave the nest with large fat deposits, and which are not fed at all by the parents after fledging. This is possibly another result of adaptation to using a seasonally abundant food supply to the maximum. The present Gannet population increase is discussed in relation to cessation of human predation, the possible impetus given by a temporary but large increase in pelagic fish during the war, but also the overall steady downward trend in fishing returns since the early part of this century. One cannot explain the steady and considerable rise in Gannet numbers only in terms of increased food supply. The fact that, at a time of population expansion and obviously favourable conditions, Gannets are still far from utilizing their full recruiting powers, needs investigating further. It may be partly due to the relative slowness of evolutionary change in a long-lived species with slow population turn-over, if the Gannet has evolved its characteristics in response to an environment different from the present one.     

Effect of European wheat striate mosaic, acquired transovarially, on the biology of its planthopper vector Javesella pellucida

The proportion of infective nymphs of Javesella pellucida in the progenies of female vectors of European wheat striate mosaic (EWSM) disease ranged from 85 to 96%; 71% of these nymphs infected plants within one week of hatching. Inbreeding for one or two generations significantly decreased the viability of J. pellucida eggs, but EWSM had no effect on the viability of eggs laid by inbred or outbred vector lines. However, EWSM acquired transovarially usually increased the mortality of J. pellucida nymphs by 13 to 17%, although mortality was as high as 30% in some vector lines. EWSM, acquired transovarially for two generations, decreased the longevity of adult males and females of J. pellucida by 14%. Inbreeding for two generations resulted in 40% increase in the mortality of nymphs and more than 50% reduction in the longevity of adults.     

ASPECTS OF THE BREEDING BIOLOGY OF THE FIERYNECKED NIGHTJAR

Jackson H. D. 1985. Aspects of the breeding biology of the Fierynecked Nightjar. Ostrich 56: 263–276.

A marked population of nightjars in Zimbabwe was studied intensively for four breeding seasons. This paper covers certain aspects of the breeding biology of the Fierynecked Nightjar Caprimulgus pectoralis. The male shows strong site fidelity during the breeding season (September to December), singing, feeding and breeding within an area of about 5,8 ha. There is some evidence of site defence by the male. The female shows strong mate fidelity, resulting in a pair bond for life. Egg laying starts with full moon in September and is further stimulated by the next two full moon periods. The eggs are laid directly on dense leaf litter at a site overhung by foliage. The normal clutch is two eggs (12S % are one egg) laid on successive days during the afternoon. Incubation starts with the first egg and is by the male at night and the female by day. The incubation period is 18 days. The birds respond to undue disturbance by deserting the eggs and laying a replacement clutch. The chicks usually hatch on successive afternoons; they are mobile on the first day and will move to a parent if called. Both parents feed and brood the young during twilight and moonlight; the male broods them on dark nights and the female does so by day. The species is double-brooded when time permits, the female laying again once the first brood has reached independence; she may even lay a third clutch if the second one comes to grief. There is no evidence of adults transporting eggs or young.     

SOME NOTES ON THE CAPE GANNET,Morus capensis

Tarboton, W. R. 1978. Breeding of the Little Banded Goshawk. Ostrich 49:132-143.

The behaviour and vocalizations of a pair of Little Banded Goshawks Accipiter badius during part of their breeding cycle is described. Both sexes built the nest. Two eggs were laid three days apart. The first egg was incubated for 52% of the day, but this increased to 90% when the clutch was complete, of which the female's share was 86% and the male's 4%. The second egg hatched after 29 days, 18 h. The female did not hunt during the incubation or early nestling period and was fed by the male who brought her, on average, 7,0 food objects per day. Lizards formed 73% of the 91 identified prey objects, and small birds, 24%. The female and chick, when 16 days old, were killed by a predator on the nest at night.     

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

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

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

绿盲蝽成虫的产卵行为与习性

本文观察记录了绿盲蝽Apolygus lucorum(Meyer-Dür)雌性成虫的产卵行为,并研究了其产卵习性。结果发现,绿盲蝽卵主要产在植物组织中,单次产卵平均历时31.4 s;产卵主要在夜间进行,白天的产卵量仅占全天的6.6%。成虫交配后主要产可育卵,后期偶产不育卵;而未交配个体大部分能产不育卵。在25℃下,成虫从7日龄起开始产卵,16日龄前产卵量占总产卵量的48.9%;17～40日龄间产卵量约占40%。在棉株上,约65%卵分布在中部(第4到第7果枝),同时94.3%卵集中在叶柄、叶脉、蕾柄和铃柄上。     

Breeding behaviour and performance of the Knysna Warbler Bradypterus sylvaticus on the Cape Peninsula,South Africa

Three pairs of Knysna Warblers were monitored on the south-eastern slopes of Table Mountain during the 2000 breeding season. Males displayed alone on territories until the second half of August, when females arrived. Nest-building (8 days) and incubation (16 days) were undertaken entirely by the female, who was not fed on the nest by the male. Chick provisioning was done mainly by the male. Arachnids and terrestrial amphipods were the most common prey brought to chicks. The fledging period was 12 days. Modal clutch size was three eggs, and depredation rates of eggs and chicks were high. After losses, replacement clutches were laid on average 19 days later, after a new nest was built. A maximum of three clutches per pair was recorded. Of 18 eggs monitored, 28% hatched and 17% fledged, equating to a production of one fledgling per pair per year. Ten days after fledging, the entire family leaves the territory, males probably returning once young are independent. The main threats to the local populations are clearing of riparian undergrowth and management practices that impact the predators of rodents.     

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.     

Impact of a novel species of Nosema on the southwestern corn borer (Lepidoptera: Crambidae)

A study was undertaken to elucidate the impact of an undescribed Nosema sp. on the southwestern corn borer (SWCB; Diatraea grandiosella Dyar). The Nosema sp. (isolate 506) included in the study was isolated from an overwintering SWCB larva in Mississippi. It was highly infectious per os, with a median infective dose of 2.0 x 10(3) spores per larva. Even at the highest dosage tested (10(7) spores per larva), minimal mortality (< or = 3%) was observed in infected larvae, pupae, and adults reared in the laboratory on an artificial diet. However, infected pupae (0- and 7-d-old) were smaller, and the time to adult eclosion from pupation was slightly increased. Furthermore, the number of eggs produced by infected SWCB female moths substantially decreased (32%), and this effect was most pronounced on day 2, when the greatest number of eggs were oviposited by infected and noninfected moths. For eggs produced by infected females mated with infected males, hatch was slightly decreased by 16 and 15% for eggs laid on days 2 and 3, respectively. In addition, egg hatch was reduced in eggs oviposited by noninfected females mated with infected males on day 3. A low prevalence of infection (< 6%) was observed in the F1 generation originating from infected females mating with noninfected males, from noninfected females mating with infected males, and from infected females mating with infected males. Nosema 506 spores were observed in the proximity of reproductive tissues of infected female and male moths. Spores also were detected on the chorion surface and within eggs laid by infected females. Furthermore, 1-11% of larvae hatching from surface-sterilized eggs were infected by Nosema 506 indicating a transovarial mechanism of transmission.     

Reproductive biology and ecology of white‐winged trumpeters (Psophia leucoptera) and recommendations for the breeding of captive trumpeters

The reproductive biology and ecology of a wild population of white‐winged trumpeters (Psophia leucoptera) were studied in southeastern Peru from 1983 to 1987. Because little information is available about any of the trumpeter species and because trumpeters have proven difficult to breed in captivity, information relevant to breeding and management of captive trumpeters is reported in this paper. White‐winged trumpeters lived in territorial social groups that ranged in size from four to 13 individuals. A typical territorial group contained three adult males, two adult females, and several sexually immature offspring, but smaller temporary groups sometimes formed for the duration of the breeding season. Only the dominant female contributed eggs to the clutch, and all adult males in the group competed to obtain copulations with her. Eggs were laid in elevated nesting cavities and no nest was constructed. The average clutch size was three eggs and incubation was not begun until the final egg was laid. The dominant male and female shared most of the incubation duties, but subordinate males covered approximately 15% of the incubation shifts. Eggs hatched approximately 27 days after incubation was begun and chicks left the nesting cavity the day after they hatched. Chicks were completely dependent on older birds to feed them for their first 3 weeks and then gradually began to feed themselves more and more food. The subordinate adult males fed chicks the most food, the dominant male and female and older offspring fed chicks an intermediate amount, and the subordinate adult female fed chicks the least. Young chicks behaved aggressively toward each other but were separated by adults before they injured each other. If at least one chick from the clutch survived, trumpeters did not breed again until the beginning of the next breeding season the following year. Zoo Biol 19:65–84, 2000. © 2000 Wiley‐Liss, Inc.     

Reproductive behavior and spawning success of female Amblyglyphidodon leucogaster (Pisces: Pomacentridae) from the Red Sea

The reproductive behavior of female whitebelly damselfish, Amblyglyphidodon leucogaster, was investigated in the Gulf of Aqaba, Red Sea over two breeding seasons. Females were promiscuous, mating with 7–10 different males throughout the season. Females lay eggs in distinct batches, defined as the total number of eggs laid in a day. Generally females deposit a batch of eggs with one male (87.2%) and are capable of laying a new batch every other day. Egg batch size averaged 4009 eggs and females laid from 2 to 22 egg batches per season. The variation in spawning success was not correlated to body size. Females preferred to deposit eggs in nests that already contained early stage eggs (0–2 days old). Within a nest, females chose to lay eggs contiguous to the youngest egg batch, regardless if the nest contained either a single batch or multiple batches of different ages. Female within-nest spawning patterns appear to be a consequence of between nest preferences for nests with young eggs. It is proposed that the strong within-nest preference is a consequence of mate selection where females may use new egg batches as a visual cue as part of a copying style. Such a style may reduce the risk of predation and increase feeding opportunities, because less time is expended in mate selection, which would provide additional resources for egg production and ultimately increase female spawning success over the breeding season. This revised version was published online in July 2006 with corrections to the Cover Date.     

The breeding biology of the Scimitarbilled Woodhoopoe

Steyn, P. 1999. The breeding biology of the Scimitarbilled Woodhoopoe. Ostrich 70 (3&4): 173–178.

The breeding biology of the Scimitarbilled Woodhoopoe Rhinopomastus cyanomelas was studied at two sites in Zimbabwe over a 13-year period from 1964–1977. The pairs were resident, remained together throughout the year, and inspected their nest sites occasionally during the non-breeding season. The breeding season extended from August to December with a marked September/October peak. Eggs were laid at daily intervals. Clutch size averaged 2.9 (range 2–4). Incubation began either with the penultimate or last laid egg. During the 13–14 day incubation period the female left the nest only occasionally each day and was reliant on the male for food. This pattern continued for four days after the chicks hatch. Thereafter she started to forage and gradually increased her contribution to chick provisioning until she overtook that of the male. With one exception, he never fed the chicks directly and delivered the food to the female. The nestlings were brooded overnight for the first two weeks. The anti-predator response of the young included a malodorous brown exudation from the preen gland and unpleasant liquid excreta. The nestling period was 21–24 days and the young left the vicinity of the nest with their parents and did not return to roost in it. Twelve breeding cycles were monitored and 76% of eggs laid (n=37) produced fledged young. Second broods were raised in the same nest on two occasions after successful rearing of the first, presumably by the same pair, but the birds were not individually marked. There was no evidence of helpers at the nest.     

CLUTCH CHARACTERISTICS AND EGG DISCRIMINATIVE ABILITY OF THE AFRICAN VILLAGE WEAVERBIRD PLOCEUS CUCULLATUS

Over a three-year period, 917 eggs from 27 females were collected from a captive colony of African Village Weaverbirds Ploceus c. cucullatus. A study was made of egg-laying and incubation behaviour, clutch characteristics and egg recognition.
Fifteen yearling females laid their first clutches at a mean age of 348 days after hatching. The mean clutch-size was 2.26 in adults and 1.68 in yearlings. The mean clutch replacement interval was 6.6 days in adults and 7.4 days in yearlings with an absolute minimum of 4 days. Eggs were laid at intervals of from 24 to 26 hours beginning usually 2–3 hours after dawn.
The eggs laid by this species vary in ground colour and pattern of spotting between different females, but egg pigmentation is constant for each individual bird. The results of 322 egg-replacement tests showed that an individual female could recognise her own egg type and would eject from the nest eggs differing markedly from her own. The incidence of rejection was proportional the degree of difference between the eggs. The possible implications for parasitism by the Didric Cuckoo Chrysococcyx cuprius are discussed.     

The effect of artificial photoperiod on growth and reproduction in the land snail Cepaea nemoralis

Summary

Specimens of Cepaea nemoralis were raised from egg to adult in the laboratory for 15.5 months in two artificial photoperiods: short-day (LD 8:16) and long-day (LD 16:8). Over 20% of the snails in each photoperiod were functional adults by the end of the experiment and had fully developed male and female reproductive systems as determined both by dissection and by oviposition. A total of 925 eggs were laid by animals reared in a long-day photoperiod, whereas animals in a short-day photoperiod laid 677 eggs. Animals reared in a long-day photoperiod grew slightly faster (2.04 mg/day compared to 1.73 mg/day), began laying eggs about 18 days sooner, and suffered higher mortality (19% compared to 11%) than animals reared in a short-day photoperiod. These results clearly establish for C. nemoralis that gametogenesis and the development of a functional hermaphroditic reproductive system are neither prevented nor significantly retarded by exposing the animals to a short-day photoperiod for their entire pre-reproductive life.