Two x-ray methods have been developed for determining the crystallinity of cellulose using a Geiger counter spectrometer. The two methods were applied to six native cotton varieties, to a cross-bred variety, and to two cottons chemically modified with ethylamine. The x-ray scattering curves for each of the nine samples were compared with those from a highly crystalline sample, a cotton hydrolyzed in HCl, and an amorphous cotton sample to provide a relative measure of crystallinity, or crystalline index. With fully corrected data the average crystalline index of the six cotton varieties was found to be 68.3 and 78.7% by the correlation and by integral methods, respectively. The crystalline indices of the remaining samples determined by the correlation and by the integral methods are, respectively, cross-bred cotton (S×P), 54.3 and 77.2%; cotton treated with anhydrous ethylamine, 29.7 and 50.9%; and cotton treated with 75% aqueous ethylamine, 28.3 and 50.3%.

Use of vultures is an important component of traditional medicine, particularly in South Africa and there is evidence to suggest that traditional use is at least partly responsible for the rapid decline of vulture populations in this country. Until very recently, little information on the extent of the trade in animal parts, particularly vultures, for traditional medicine was available. The secretive and illegal nature of vulture use makes it extremely difficult to obtain reliable data on amounts and turnovers of species traded, which is essential to assess potential impacts on species populations. Research confirms that vultures are used in the traditional medicine industry for a range of purposes, but are believed to be most effective for providing clairvoyant powers, foresight and increased intelligence. The main drivers of demand for these uses are betting and gambling, for improved business success, and intelligence in school children. Vulture is also prescribed by traditional healers for various ailments, including headaches. It is estimated that 160 vultures are sold per annum in eastern South Africa, with some 59,000 consumption events of vulture pieces. The total annual value of sales of vultures to end consumers in eastern South Africa (excluding the costs of vultures as input costs) is estimated at R1,2 million ($US 120k). Various species of vulture are used for traditional medicine; there is no distinct species preference. Vultures traded in the eastern South African markets are harvested by vulture hunters from a range of formally protected and unprotected natural areas in KwaZulu-Natal, Eastern Cape, Lesotho and southern Mozambique. They are killed using shotguns, poisons or traps. Poisoning is the most destructive and widely used method of harvesting as large numbers of vultures are usually killed in one poisoning event. An estimated 1,250 vulture traders, hunters and traditional healers in eastern South Africa are involved in the vulture trade. With small vulture populations and poor breeding success, the current trade in vultures is not sustainable at the present harvest levels. The implication for people using or trading in vultures is that the benefits currently enjoyed will not be available in 15 to 30 years time.

Summary1. The habitat requirements of various species have been evaluated by statistical models. However, recent studies have shown that models are often not transferable between regions, limiting their applicability and ability to inform management decisions. One possible cause is that models tend to reflect dominant landscape features, which vary between regions. Transferability, and thus applicability, may be increased by developing models from multiple regions. 2. We addressed this via a case study of two vulture species (white-backed and lappet-faced vultures, Gyps africanus and Aegypius tracheliotos) from six biogeographically different regions across southern Africa. Logistic models, developed using an information-theoretic approach, were used to predict nest occurrence based on explanatory variables derived from a Geographic Information System (GIS), the usual method for species with large ranges. Variables reflected key requirements at different spatial scales: food availability, human disturbance and nesting trees. We developed models using data from single and multiple regions, and tested the cross-regional transferability. We also collected field data to asses the adequacy of the GIS variables. 3. There was a significant negative correlation between specificity and regional generality, multiregion models tending to be more consistently transferable than single-region models but having a weaker fit within the regions where they were developed. Multi-region models of nesting habitat were more structurally similar to each other than single-region models. GIS variables adequately represented the landscape but with differing adequacy between regions. There were no observed fitness benefits to the observed site selection. 4. Synthesis and applications. Models of species distribution are not transferable between regions, and use of models to inform management decisions in regions other than that used for model development should be undertaken with caution. Models are often built using GIS predictors only broadly related to the landscape properties of interest and the adequacy of such proxies can vary between regions, leading to models that emphasize dominant landscape features. Models developed from multiple regions partially overcome this problem by identifying predictors that apply across many regions and are more transferable. However, this increased generality trades off against reduced specificity. Models should be constructed with consideration to their intended use.

No abstract

The Blue Swallow (Hirundo atrocaerulea) is a threatened intra-African migrant with breeding populations in three geographically disjunct regions. We analysed stable hydrogen, nitrogen and carbon isotope ratios in feather keratin to determine whether these vary among breeding populations, and whether feathers can be used to infer migratory connections between breeding and non-breeding areas. Blue Swallows from the three major breeding populations differed significantly in terms of their feather δD but not in terms of feather δ 13 C. We also analysed feathers from seven individuals caught in the non-breeding range on the shores of Lake Victoria in Uganda. A discriminant function analysis assigned four of these birds to the South Africa / Swaziland breeding population and two to the Malawi / Tanzania breeding population (p > 0.997), with the remaining individual not being unambiguously assigned. Our results reveal that migratory connections in this threatened species can be inferred from feather stable isotope analysis, and that there is overlap in the wintering ranges of at least two of the three major breeding populations.