Seasonal changes in the birdlife of a pen-urban grassland community
TL;DR: Nuttall et al. as discussed by the authors investigated the seasonal changes in the birdlife of a pen-urban grassland community and investigated possible reasons for any changes in avifauna and found that the influence of rainfall on food availability and vegetation is considered important in determining the structure of this avian community.
Abstract: Summary Nuttall, R.J. 1993. Seasonal changes in the birdlife of a pen-urban grassland community. Ostrich 64: 1–7. Visits to a grassland habitat near Pietermaritzburg, Natal, South Africa were undertaken over a period of ten months (March-December) to document changes in avifauna, and to investigate possible reasons for any changes. A total of 72 bird species was recorded. Monthly species totals showed considerable fluctuation, with species diversity highest in spring-early summer (n=53) and lowest in winter (n=14). Terrestrial insectivores were the best represented fin terms of number of species) during the course of the study. The influence of rainfall on food availability and on vegetation is considered important in determining the structure of this avian community. Observations of the assumption (and loss) of nuptial plumage in euplectines showed that Longtailed Widows Euplectes progne developed breeding plumage earliest, and retained it for the longest period of time. Both Whitewinged E. albonotatus a...
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TL;DR: For at least five months after two controlled and one accidental fire at the Barberspan Nature Reserve in South Africa, birds in an area larger than that burned were affected as mentioned in this paper.
Abstract: Considering the frequent nature of fires and resultant drastic change in habitat following fire, research on the effects of fire on birds in the grasslands of South Africa is surprisingly scarce. For at least five months after burns we followed the changes in bird species composition, species richness and densities of two controlled burns and one accidental fire at the Barberspan Nature Reserve in grasslands that had not been burned or grazed in 10 years. Compared with the control areas, species richness and densities increased in the burned areas immediately following the burns, with more species and birds recruited to the burned areas than were lost. Immediate post-burn opportunists tended to be larger species, and the biomass increase mirrored the increases in species richness and densities in burned areas. Avian species richness, densities and biomass tended to return to the initial conditions after a number of months. Although the bird communities from two controlled-burns differed before the burns, they converged to a characteristic immediate post-burn composition. Five months after the burns however, the bird communities reflected a pre-burn composition. Indications were that birds in an area larger than that burned were affected. Mosaic burning, with shifting large and small patches, should be considered on a landscape scale. Ostrich 2007, 78(3): 591–608
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Cites background or result from "Seasonal changes in the birdlife of..."
...Nuttall (1993) also noted similar responses to fire of Crowned Lapwings and Black-headed Herons....
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...The studies reviewed by Parr and Chown (2003), dealing with birds in grasslands, were mainly from the high grasslands of the Drakensberg (Nuttall 1993, Malan 1998, Jansen et al. 1999, Muchai 2001)....
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...Some avian studies, however, are relevant to the central grasslands, as they share many of the same bird species (Dean 1987, Nuttall 1993, Malan 1998, Jansen et al. 1999, Mills 2004), and comparisons would be interesting....
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...…the findings of other studies, although not all are directly comparable, most dealing with findings on other continents and other types of habitat (Nuttall 1993, van’t Hul et al. 1997, Johnson 1997, Reynolds and Krausman 1998, Davis et al. 2000, Herrando et al. 2002 , Pons et al. 2003, Mills…...
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...Nuttall (1993) also found insectivores associated with recently burnt grasslands in KwaZulu-Natal....
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TL;DR: Yellow Bishops have rounder wings than other weaver species, possibly because their larger size affects flight aerodynamics, and the longer duration of primary moult of the Yellow Bishop may be related to food.
Abstract: The grassland biome in South Africa has a summer rainfall and Southern Red Bishops Euplectes orix , Fan-tailed Widows E. axillaris , White-winged Widow E. albonotatus , Red-collared Widow E. ardens and Long-tailed Widow E. progne breed from October or November to March. Primary moult starts in late March or early April. The widows with long tails (Long-tailed and Red-collared Widows) have moult durations of two months, while the widows with shorter tails (White-winged and Fan-tailed Widows) had moult durations of 1.5–1.7 months. Moult ends in late May or early June. Long-tailed Widows have rounder wings than other weaver species, possibly because their larger size affects flight aerodynamics. In the winter rainfall region, Southern Red Bishops and Yellow Bishops E. capensis start breeding after the winter rains, from August–November, and moult starts in early December. Primary moult duration in Yellow Bishops is relatively long, at 3.4 months. Yellow Bishops grow individual primary feathers at an average rate of 21.3 days per feather, while the other species moult primaries more quickly: White-winged Widow 8.1 days, Fan-tailed Widow 11.3 days, and Red-collared Widow 14.4 days. The number of primaries growing simultaneously is similar in the different species. The longer duration of primary moult of the Yellow Bishop may be related to food. Ostrich 2006, 77(3&4): 142–152
12 citations
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...exhibited breeding plumage for the shortest periods (Nuttall 1993)....
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TL;DR: The fact that Palaearctic migrants arrive in the northern tropical savannah of Africa during the dry season suggests potential competition for food with African species, which appears not to compete for available resources with closely related species of African birds.
Abstract: SUMMARY
The fact that Palaearctic migrants arrive in the northern tropical savannah of Africa during the dry season suggests potential competition for food with African species. Moreover, in the southern tropical savannah African species breed during the rainy seasons, when Palaearctic migrants are present.
In the equatorial area of Serengeti, East Africa, an index of the food supply for insectivorous birds was obtained from 3 years of light-trap measurements and sweep net samples. Adults of Lepidoptera, Coleoptera, Orthoptera and Isoptera are sparse in the dry season but become locally abundant after the first rainstorms that mark its close. They are apparently blown by converging winds ahead of the inter-tropical front and settle to lay eggs where rain has fallen. These early storms therefore produce localized superabundances of food. In the ensuing rainy seasons insect abundance remains high.
African insectivorous birds breed during the wet period, reaching a peak two months after the insect increase. It is suggested that this lag is due to the need to recover body condition, build up reserves for eggs, develop gonads and wait for vegetation and insect larvae to develop. In the samples available, breeding records of above-ground nesters peaked in the first rains, while ground-nesters peaked in the second (main) rains. Predators bred towards the end of the rains, when there is an abundance of fledglings and small mammals. Thus the food supply could act as the ultimate factor determining the timing of the breeding season in this area.
Palaearctic migrants arrive in the Serengeti 4–10 weeks ahead of the main rain front. However, most species are only found where rain has fallen recently. When conditions dry up they move on to other wet areas. Thus they overlap with African species only where there is a superabundance of insects. When the rains become widespread Palaearctic migrants disperse into their usual habitats, and therefore appear not to compete for available resources with closely related species of African birds. The situation in West Africa, where residents and migrants overlap throughout the dry season, cannot be explained in the same terms.
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