The distribution and biology of nomadic birds in the Karoo, South Africa

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Dryland nomadic bird species, as a proportion (shrubland and grassland) on open plains. Most nomadic of all bird species in a biome in southern Africa, are highest bird species in the Karoo are granivorous. Perennial desert in the arid grassland and arid and semi-arid Karoo in South grasses are important components of the habitat and diet Africa.Nomadic birds, ofwhich themost widespread species of small nomadic granivores, and also provide nest sites is the greybacked finchlark Eremopterix verticalis (Smith), and nest material. Nomadic birds can breed throughout the are most frequently observed in the north-central and north year, without a clearly defined 'season' in both the Succulent western Nama Karoo. The species richness of nomadic and Nama Karoo. Average clutch sizes do not differ species is inversely correlated with species richness of all significantly between resident and all nomadic species in the bird species in the Karoo. Since the distribution of nomadic arid and semi-arid Karoo. Nomadism is an evolutionary birds is in areas where rainfall is patchy, low (<250mm per stable strategy for individual species only when extremes year) and aseasonal, this supports the idea that fewer species in environmental conditions are frequent enough, and are able to cope with resources that are patchy in time and unpredictable enough, to maintain movements to high space, and that there has been selection for nomadism in resource patches or to maintain dispersal away from low the species that are able to use patchy environments. Species resource patches. If high rainfall years are too regular or richness and abundance of nomadic birds is negatively infrequent, or peaks in fluctuations of resources in the correlated with rainfall amount but positively correlated environment too low, or rainfall patches are randomly with the coefficient of variation of the rainfall and with distributed, nomadism would not be maintained as part of rainfall in autumn. The frequency of nomadic birds is the individual behaviour pattern is inversely correlated with altitude range. Keywords: Granivorous birds, arid, semi-arid, Karoo, avian biogeography, larks, southern Africa.

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Journal of Biogeography

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Journal Article
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Dean 1997 Nomadic Birds of Karoo.pdf 918.39 KB

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