Factors affecting the densities of nectarivores in protea roupeuae woodland
TL;DR: Male sugarbirds show site tenacity while localized movements have been observed in individual sugarbirds, and factors influencing bird densities, including Protea flowering period, dump-size and the effect of fire are factors influencingBird densities.
Abstract: Summary De Swardt, D.H. 1993. Factors affecting the densities of nectarivores in Protea roupelliae woodland. Ostrich 64:172-177. Between December 1986 and December 1992, 812 birds were captured at eleven selected Protea roupelliae sites at Lydenburg in the eastern Transvaal, South Africa. In this sample were 638 nectarivores, of which high densities of Gurney's Sugarbird Promerops gurneyi (41,3%) and Malachite Sunbird Nectarinia famosa (27,7%) were captured. Mean densities of 4,6 Gurney's Sugarbirds ha−1 and 3,5 Malachite Sunbirds ha−1,746) were recorded. No significant correlation was found between the clump-sizes and the number of birds although higher densities were recorded at some of the smaller sites. Protea flowering period, dump-size and the effect of fire are factors influencing bird densities. Male sugarbirds show site tenacity while localized movements have been observed in individual sugarbirds.
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TL;DR: The 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.
Abstract: 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
79 citations
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...The assumption that it is bird pollinated has been based solely on floral traits and observations of frequent visits by nectarivorous birds, namely malachite sunbirds (Nectarinia famosa) and Gurney’s sugarbirds (Promerops gurneyi) (De Swardt 1993)....
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...Although Gurney’s Sugarbirds carried large Protea pollen loads and have previously been implicated in the pollination of P. roupelliae (De Swardt 1993), they were unimportant pollinators at Mt Gilboa due to their low abundance....
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TL;DR: A conceptual framework is developed that could be used as a basis for understanding fire effects on aggregate network properties to inform fire management strategies buffering plant–pollinator networks against secondary species extinctions.
Abstract: Summary
Increased incidence of landscape fire and pollinator declines with co-extinctions of dependent plant species are both globally significant. Fire can alter species distributions, but its effects on plant–pollinator interactions are poorly understood so its present and future role in coupled plant–pollinator declines cannot be assessed.
We develop a conceptual model of fire effects on plant–pollinator interactions. We review the empirical literature in the context of this model to identify important knowledge gaps regarding the processes underlying these effects and the phenotypic traits of flowering plants and pollinators mediating these effects. Fire generates, and plant–pollinator interactions respond to, heterogeneity at multiple spatial scales. There is evidence of local-scale fire effects on these interactions, but landscape-scale effects are poorly understood. Nest location and floral resource utilization primarily mediate pollinator survival during and after fire. Voltinism and mobility traits are potentially important, but poorly studied. Plant traits mediating flowering responses to fire include growth form, phenology and potentially bud location, seasonal changes in bud exposure and response to bud damage.
Synthesis and applications. We suggest management actions and an agenda for future research to fill knowledge gaps currently inhibiting predictions of fire effects on plant–pollinator interactions. Fire regimes promoting floral diversity at local scales provide a surrogate means of managing pollinators and pollination while empirical research continues. Above-ground nesting, univoltine pollinators may be particularly vulnerable under expected fire regime changes. Improved knowledge of traits mediating the exploitation of landscape heterogeneity could be used to enhance the persistence of these species. Ultimately, our conceptual framework could be used as a basis for understanding fire effects on aggregate network properties to inform fire management strategies buffering plant–pollinator networks against secondary species extinctions.
58 citations
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...This has not been investigated in pollinators, but both pollinator nesting substrate and floral resources are known to vary with fire history (De Swardt 1993; Potts et al. 2003a, b, 2005; Moretti et al. 2009; Chalmandrier et al. 2013; Rodr ıguez & Kouki 2015), and pollinators use other landcover…...
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TL;DR: In this article, the effects of fire on Fynbos fauna are investigated and the response of bird communities to long-term fire-induced vegetation changes using space-for-time substitution.
Abstract: Global changes are influencing fire regimes in many parts of the world. In the Fynbos plant diversity hotspot (Cape Floristic Region, South Africa), fire frequency has increased in protected areas where the mean fire interval went from 12–19 to 6–9 years between 1970 and 2000. Fire is one of the main drivers of plant diversity in the Cape Floristic Region. Too frequent fires threaten the persistence of slow-maturing plant species, and such insights have led to the adoption of fire management principles based on plant responses. The effects of fire on Fynbos fauna are much more poorly understood, and have not generally been considered in depth in Fynbos conservation policies, planning or management. We assessed the response of bird communities to long-term fire-induced vegetation changes using space-for-time substitution. We studied bird communities, vegetation structure and plant functional composition in 84 Fynbos plots burnt between two and 18 years before. Ten of the 14 bird species analysed showed a significant change in their abundance with time since fire. We observed a significant species turnover along the post-fire succession due to changes both in vegetation structure and plant functional composition, with a characteristic shift from non-Fynbos specialists and granivorous species to Fynbos specialists and nectarivorous species. If current trends of increasing fire frequency continue, Fynbos endemic birds such as nectarivores may become vulnerable. Conservation management should thus aim more carefully to maintain mosaics of Fynbos patches of different ages. Future research needs to estimate the proportion of vegetation of different ages and patch sizes needed to support dependent fauna, particularly endemics.
40 citations
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...Moreover, most studies focus on short-term responses of the avifauna to fire (e.g. Fraser, 1989; De Swardt, 1993), neglecting longer-term responses (Watson et al., 2012) essential for effective fire management (Driscoll et al., 2010)....
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TL;DR: In this article, the impact of fire on nectar-feeding birds in fire-prone regions of the world has been studied, and the results are surprising given the large number of birds that have fire-stimulated flowering.
Abstract: Nectar-feeding birds are important pollinators in fire-prone regions of the world, but the impact of fires on these bird communities has seldom been studied. Nectar-feeding bird communities were censused during peak flowering, before and after fire in the Cape fynbos of South Africa. The abundance and species richness of nectar-feeding birds decreased at all sites. In a controlled experiment, two common bird-pollinated plants, which flower profusely after a fire, were presented in floral arrays in burnt and unburnt vegetation. Birds visited flowers only in the unburnt areas. The results are surprising given the large number of bird-pollinated plants that have fire-stimulated flowering.
34 citations
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...Taken together, these observations suggest that bird-pollinated plants flowering in a post-fire landscape might suffer severe pollinator limitation (Fraser 1989; De Swardt 1993; Pauw 2004)....
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TL;DR: In this article, a set of ten land types, defined by combinations of classes of geology, altitude and rainfall, were sampled in the afforestable part of the Maclear district, Eastern Cape Province.
Abstract: Large-scale afforestation with pines is taking place in montane grasslands of South Africa. Many species dependent on the grass sward will be eliminated from the planted areas. Land should be maintained as conservation areas to ensure the long-term survival of the wildlife within the afforestable region. Ten land types, defined by combinations of classes of geology, altitude and rainfall, were sampled in the afforestable part of the Maclear district, Eastern Cape Province. Areas of five land types are required in a network of conservation areas to protect all the montane-endemic grasshopper, butterfly and bird species recorded. The addition of a sixth land type to this set of five would protect 93·8% of all the taxa considered. Regions within which conservation areas should be situated are indicated at the district scale.
23 citations
References
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TL;DR: A review of research on fire in South Africa can be found in this article, where the authors discuss the effects of fire on various aspects of South African biodiversity, such as vegetation structure and dynamics, forage production and quality, and water yield.
Abstract: 1 Characteristics of South African Biomes.- 2 Fire Regimes in the Biomes of South Africa.- 3 Man's Historical and Traditional Use of Fire in Southern Africa.- 4 An Historical Review of Research on Fire in South Africa.- 5 Fire in Fynbos.- 6 Fire in Grassland.- 7 Fire in Savanna.- 8 Fire in Forest.- 9 Fire Behaviour.- 10 Effects of Fire on Vegetation Structure and Dynamics.- 11 The Effect of Fire on Forage Production and Quality.- 12 Effects of Fire Regime on Faunal Composition and Dynamics.- 13 The Responses and Survival of Organisms in Fire-Prone Environments.- 14 The Effect of Fire on Soil and Microclimate.- 15 The Effect of Fire on Water Yield.- 16 The Use of Fire as a Management Tool.- Concluding Remarks. Fire Research - a Perspective for the Future.- References.- Index of Plants and Animals (Scientific).- Index of Plants and Animals (Common).
426 citations
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01 Jan 1984
TL;DR: Fires in fynbos are frequent, spectacular and alarming as discussed by the authors, and they often cause considerable economic loss, as when 21 houses were lost in the Betty's Bay fire of 1970.
Abstract: Fires in fynbos are frequent, spectacular and alarming. They often cause considerable economic loss, as when 21 houses were lost in the Betty’s Bay fire of 1970. Great fires, such as those in the region between Swellendam and Port Elizabeth in 1869, are cardinal in the history of land management in the zone and the lessons from them are embedded in the manager’s lore. To the biologist the consequences of fire often seem disastrous. It is hard for an observer to imagine that the blackened waste to be seen after a fynbos fire is merely a stage in the cycle of regeneration and development of such rich and attractive communities.
205 citations
TL;DR: The flowering phenology of Erica and proteaceous plants and the abundance of nectarivorous birds were monitored in Mountain Fynbos in the Jonkershoek State Forest, South Africa, and statistical analyses confirmed that the distribution of Promerops cafer is primarily correlated with the Plenty of protea flowers, and that of Nectarinia violacea with Erica flowers.
Abstract: The flowering phenology of Erica and proteaceous plants and the abundance of nectarivorous birds were monitored in Mountain Fynbos in the Jonkershoek State Forest, South Africa. Species tended to flower for short periods in summer at high altitudes, or for longer periods in autumn and winter at low altitudes. Three avian species apparently tracked the flowers occurring at low altitudes during winter and, when present, at high altitudes during summer. Statistical analyses confirmed that the distribution of Promerops cafer is primarily correlated with the abundance of protea flowers, and that of Nectarinia violacea with Erica flowers. The evolution of an unusually high ratio of putative avian pollinators to ornithophilous plant species in Mountain Fynbos is discussed.
62 citations
42 citations
TL;DR: In this paper, the short-term responses of birds to fire in old Mountain Fynbos vegetation near Stellenbosch, Cape Province, South Africa were observed from six weeks before until one year after a fire.
Abstract: Summary FRASER, M. W. 1989. Short-term responses of birds to fire in old Mountain Fynbos. Ostrich: 60:172-182. Observations of birds were made from six weeks before until one year after a fire in 28-year-old Mountain Fynbos vegetation near Stellenbosch, Cape Province, South Africa. No fire attendance by birds was observed, in contrast to observations made at fires in other southern African vegetation types. Bird species composition in the study site as a whole was virtually unchanged after the fire. With the exception of the density of nectarivorous birds (which decreased), variation in the bird densities of study plots in six vegetation structural formations was considered to be as much seasonal as fire-related.
24 citations