Opportunistic breeding by the redbilled quelea in eastern kenya
TL;DR: Thompson et al. as discussed by the authors described the demography and breeding patterns of the Redbilled Quelea in eastern Kenya with respect to abnormally high rainfall in Tsavo-East National Park during late 1984 and early 1985.
Abstract: Summary Thompson, J.J. 1993. Opportunistic breeding by the Redbilled Quelea in eastern Kenya. Ostrich 64: 32–37. The demography and breeding patterns of the Redbilled Quelea in eastern Kenya are described with respect to abnormally high rainfall in Tsavo-East National Park during late 1984 and early 1985. The prolonged breeding that occurred, together with the early sexual maturation of young queleas and their entry into the breeding population, underlined the opportunistic nature of quelea migration and breeding strategies. Opportunism may be considered to be the most adaptive breeding strategy for queleas generally, but may be more conspicuous in East Africa than in some other parts of Africa because of more complex rainfall patterns.
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TL;DR: The large differences in timing and duration of moult in this study only support the short-distance ‘rainfall-migration’ model for Red-billed Queleas in southern Africa.
Abstract: The onset and duration of primary moult were investigated for adult Red-billed Queleas (Quelea quelea) in southern Africa. The duration of moult was shortest in Namibia (75 days), intermediate in Botswana (83 days) and longest in Gauteng Province (101 days) and the Eastern Cape (124 days), South Africa. The timing of the onset of moult was similar in Namibia and Botswana (21 and 31 May respectively), but considerably earlier in the Eastern Cape and Gauteng Province (6 and 23 April respectively). Completion of primary moult was well synchronised, ending in August in all sub-regions. Production of feather mass was uniform and speed of moult was controlled by the rate of growth of individual primaries. When moult was faster, fewer feathers grew simultaneously, possibly to reduce the aerodynamic effect of the wing-gap. Red-billed Queleas are thought to migrate relative to the movement of rain fronts, allowing possible multiple breeding events in one season. In southern Africa, Queleas are present throughout their range all year, and a proportion of the population moves short distances in apparently random directions. The large differences in timing and duration of moult in this study only support the short-distance ‘rainfall-migration’ model.
13 citations
Cites background or result from "Opportunistic breeding by the redbi..."
...Thompson (1993) suggested thatQueleas follow anopportunistic pattern of movements and breeding, rather than a fixedmigratory pattern....
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...Thompson (1993) foundQuelea remaining in one area in Kenya to breed for a second time after prolonged rainfall, in contrast to the prediction of the ‘rainfall-migration model’....
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TL;DR: Proposed methods for estimating the hatching dates of free-flying juvenile Red-billed Queleas, Quelea quelea, and hence establishing their likely geographical origins and patterns of post-natal dispersal are evaluated.
Abstract: This paper evaluates potential methods for estimating the hatching dates of free-flying juvenile Red-billed Queleas, Quelea quelea, and hence establishing their likely geographical origins and patterns of post-natal dispersal. Based on studies of captive juveniles, the progress of the post-juvenile moult can discriminate up to three differently aged cohorts of young in the same population. Bill colour can help to differentiate very young birds from older ones before post-juvenile moult begins. Skull pneumatization is not useful for precise ageing; it proceeds significantly more slowly in moles than females and may not be complete by one year of age. Iris colour remains to be properly evaluated as an ageing criterion. Collections from the Okavango region of northwestern Botswana indicated that juvenile Red-billed Queleas started to arrive there as the local breeding season began. Such birds could only have originated outside Botswana in colonies established in regions of earlier rainfall, probably in those...
9 citations
Cites background from "Opportunistic breeding by the redbi..."
...intermedia), the post-juvenile primary moult may be interrupted to enable the birds to make a precocious breeding attempt before they are one year old (Thompson 1993)....
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...Very rarely (recorded only in eastern African Q. q. intermedia), the post-juvenile primary moult may be interrupted to enable the birds to make a precocious breeding attempt before they are one year old (Thompson 1993)....
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01 Jan 1983
TL;DR: This work gives a systematic species-by-species account of points including the number of flight feathers, the sequence, season and rate of moult, its relationship to breeding and migration, and the extent of the post-juvenile moult.
Abstract: This work falls into two parts. The first section gives a short general summary of the plumage of birds, its structure, arrangement and functions and briefly reviews the various types of moult patterns which are found and the ways of recording them. The second part gives a systematic species-by-species account of points including the number of flight feathers, the sequence, season and rate of moult, its relationship to breeding and migration, and the extent of the post-juvenile moult. In addition, scatter diagrams of primary moult score plotted against date are given for some species.
529 citations
TL;DR: The results are used to support the view that in this quelea the actual clutch-size produced on any occasion is the largest the female can produce before becoming too enfeebled, and clutch- size appears to be determined phenotypically downward from a maximum which is indirectly under genetic control.
Abstract: SUMMARY
Changes in the fat and flight muscle protein reserves of adult Red-billed Queleas Quelea quelea were followed in two colonies in Tanzania and Botswana. At the start of a breeding attempt the protein reserves were higher that at any other time of the year, particularly in females which had heavier flight muscles (non-fat dry weight) than did the (larger) males at that time. The pre-breeding increase in the labile component of the muscle protein (the actual protein reserve) is calculated at 80% for females, but only 14% for males. The fat reserve was only increased slightly at the beginning of the breeding attempt.
In both sexes, though for different reasons, the protein and fat reserves fell rapidly during the first few days of the attempt, in some individuals to dangerously low levels. During the incubation period there was rapid recovery while the situation during the rearing period appeared to vary between colonies.
It is proposed that the proximate control of breeding is provided by the individual's own body condition, and particularly the state of its protein reserves. No environmental releasers are required for the birds to breed at the appropriate time of the year.
Individual females producing two, three and four egg clutches differed in the rate at which their reserves fell during egg formation. The results are used to support the view that in this quelea the actual clutch-size produced on any occasion is the largest the female can produce before becoming too enfeebled. Thus, clutch-size appears to be determined phenotypically downward from a maximum which is indirectly under genetic control.
388 citations
TL;DR: Red-billed Queleas migrate, at the beginning of the wet season, away from their dry-season concentration areas and towards areas where rain started several weeks earlier, and the adaptive value of this “itinerant breeding” is discussed.
Abstract: SUMMARY
Red-billed Queleas migrate, at the beginning of the wet season, away from their dry-season concentration areas and towards areas where rain started several weeks earlier. Considerable fat deposits are accumulated for this “early-rains migration”.
The direction taken by the migrants, the distance they must fly, and the timing of the movement are dependent upon the timing of the rains and the way the rain-front moves.
On the return “breeding migration” individuals in breeding condition stop to breed (in large aggregations) wherever they find conditions suitable for the founding of colonies. The location of the colonies can vary greatly from year to year.
The migrations performed by several populations, in different parts of Africa, are predicted on the basis of general rainfall patterns, and the predictions tested against the facts available.
There is evidence that individual females are able to produce a succession of broods in the same breeding season, at colonies which may be very far apart, and probably with different mates. The adaptive value of this “itinerant breeding” is discussed.
Many other bird species, which breed at a particular phase of the wet-season/dry-season cycle, are expected to perform similar “itinerant breeding”.
109 citations
01 Jan 1980
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96 citations
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