Kalahari Research Articles

Paleohydrology of extraordinary floods along the Swakop River at the margin of the Namib Desert and their paleoclimate implications

The Swakop River is a major ephemeral river (drainage basin area about 30,000 km2) crossing the western Namib Desert. Its hydrology and limited water resources depend on storms and floods. Therefore, the hydrology and flow regime in the Swakop River basin determines the availability of water for human use. In this study we present a millennia-long record of extreme floods, using paleoflood hydrological methods and optically stimulated luminescence (OSL) ages. The record includes 44 large floods ranging in date from the late Pleistocene to the present. The oldest six to eight floods are dated from the late Pleistocene to the mid-Holocene (between 14,900 ± 1700 and 5100 ± 620 years ago), with calculated peak discharges of 550–1280 m3 s−1. Eighteen floods, eleven of which were between 1000 and 1600 m3 s−1, occurred between 740 ± 90 and 190 ± 10 years ago. Additional 17 later floods occurred between about AD 1850 and 1963, with peak discharges between 100 and 1000 m3 s−1. The historical record which partly parallels the latter period recorded 17 large floods during the period 1893–1963. Flood frequency analysis (FFA) of the combined systematically gaged record (1963–2003) and the paleoflood record since AD 1270 (740 ± 90 years, the most complete record), was applied using the maximum likelihood method. A two-component extreme value distribution (TCEV) estimates the 1% annual exceedance probability magnitude, using only the systematic gaged record at 520 m3 s−1. The combined paleoflood, historical, and gage records resulted in a much larger magnitudes for the 1% annual exceedance probability flood magnitude of 1320–1350 m3 s−1. The 0.1% annual exceedance probability magnitude is estimated at 770 m3 s−1 and 2100–2150 m3 s−1, respectively.The hydroclimatic interpretation of this paleoflood record is complex, due to the discontinuity of the record. During the late Holocene, our flood data show three intervals differing in their flood regime: (1) 1280 ± 80 to 740 ± 90 years BP, with one extraordinary flood (>200 m3 s−1) about every 180 years; (2) 740 ± 90 to 200 ± 45 14C years BP, with one large flood per 80 years; and (3) 200 ± 45 14C years BP to AD1963, with one large flood per 7 years. Interval 2 represents large floods, probably related to the transition from a drier climate to the colder and probably wetter climate of the Little Ice Age (LIA). The third period relates to the end of the LIA and to a wetter period of the 19th and early 20th centuries in which more rainfall in the Kalahari and Namib Deserts and many historical floods were documented.The presence of three distinct calcretes rich in calcified rhizoliths at one of the sites, two of which were dated by OSL to 13.2 ± 1.9 ka and 8.8 ± 1.0 ka, indicates, at least locally, higher moisture availability than in the current semiarid climate; the presence of denser vegetation can be associated with increased groundwater seepage and wetter climatic conditions.

Home Range, Habitat Selection and Activity Patterns of an Arid-Zone Population of Temminck's Ground Pangolins,Smutsia temminckii

All previous behavioural studies of Temminck's ground pangolins (Smutsia temminckii) have focused on populations in mesic regions. We examined home range size, activity periods, habitat selectivity and refuge site selection of 13 individuals over three years in the Kalahari Desert of South Africa, near the western edge of the species' range. Kernel home ranges of adults averaged 6.5 ± 5.9 km2, while juveniles had average home ranges of 6.1 ± 4.0 km2. Reliable prediction of 95% of the Kernel home range required 88 ± 67.7 tracking days. No significant habitat selectivity was observed. Earthen burrows were the most frequently used refuge type. The time at which activity commenced varied seasonally as well as among individuals, with an increase in diurnal activity during winter. Young pangolins also displayed more diurnal activity compared to adults. Individuals spent 5.7 ± 2.0 hours per 24-hour cycle outside of refuges, with no significant seasonal variation. Juvenile dispersal peaked during mid-summer, with individuals travelling up to 49 km from their natal areas. We estimate a breeding density of 0.16 individuals/km2 and a total density of 0.31 individuals/km2 for our study area. Our data suggest that activity patterns, movements and refuge selection is similar across the species’ southern African range, but that densities may be higher in the Kalahari compared to populations in more mesic eastern areas.

Home range, habitat selection and activity patterns of an arid-zone population of Temminck’s ground pangolins, Smutsia temminckii

All previous behavioural studies of Temminck’s ground pangolins (Smutsia temminckii) have focused on populations in mesic regions. We examined home range size, activity periods, habitat selectivity and refuge site selection of 13 individuals over three years in the Kalahari Desert of South Africa, near the western edge of the species’ range. Kernel home ranges of adults averaged 6.5 ± 5.9 km2, while juveniles had average home ranges of 6.1 ± 4.0 km2. Reliable prediction of 95% of the Kernel home range required 88 ± 67.7 tracking days. No significant habitat selectivity was observed. Earthen burrows were the most frequently used refuge type. The time at which activity commenced varied seasonally as well as among individuals, with an increase in diurnal activity during winter. Young pangolins also displayed more diurnal activity compared to adults. Individuals spent 5.7 ± 2.0 hours per 24–hour cycle outside of refuges, with no significant seasonal variation. Juvenile dispersal peaked during mid-summer, with individuals travelling up to 49 km from their natal areas. We estimate a breeding density of 0.16 individuals/km2 and a total density of 0.31 individuals/km2 for our study area. Our data suggest that activity patterns, movements and refuge selection is similar across the species’ southern African range, but that densities may be higher in the Kalahari compared to populations in more mesic eastern areas.

Estimating the sensitivity of regional dust sources to sea surface temperature patterns

AbstractExploring the impact of sea surface temperature (SST) anomaly patterns on local climate in major dust source regions helps clarify our understanding of variability in the global dust cycle. In contrast to previous work, this research focuses explicitly on the influence of SST anomalies on dust emissions and attempts to explain the mechanisms by which SST anomalies affect seasonal dust emissions. This study investigates the seasonal sensitivity of mineral aerosol emissions to SST anomaly patterns from the Bodele Depression, West Africa, Sahel, Kalahari Desert, Arabian Desert, and Lake Eyre basin. The global teleconnection operator, which relates regional climate responses to SST anomaly patterns, is estimated for relevant variables in an ensemble of the National Center for Atmospheric Research Community Atmosphere Model version 5 forced by randomly perturbed climatological SST fields. Variability in dust emissions from major dust sources is linked to tropical SST anomalies, particularly in the Indian and western Pacific Oceans. Teleconnections excited by remote SST anomalies typically impact dust emissions via changes in near‐surface wind speeds and friction velocity. However, SST‐driven impacts on the threshold friction velocity can be of the same order of magnitude as changes in the friction velocity, suggesting the impact of SST anomalies on precipitation and soil moisture is also significant. Identifying SST anomaly patterns as a component of internal variability in regional dust emissions helps characterize human influences on the dust cycle as well as improve predictions of climate, nutrient cycles, and human environments.

Documenting “Community” in the ≠khomani San Land Claim in South Africa

In this article I explore how documents created in support of ≠khomani San land claimants, located in the southern Kalahari Desert, represent a specific way of knowing that contributes to a socio‐legal construction of “community.” The documents that I use in this article have been authored by government organizations and NGOs, and compiled into a single repository of community information. By tracking the use of the term community throughout the repository, I demonstrate that the term is articulated through and across various fields of knowledge to achieve different social, political, and legal ends. This field of diverse motives, I argue, is neutralized and obscured through the standardized form of the documents themselves, contributing to a socio‐legal construction of community wherein notions of indigeneity are both exclusive and temporally fixed.

High fluoride and low calcium levels in drinking water is associated with low bone mass, reduced bone quality and fragility fractures in sheep

SummaryChronic environmental fluoride exposure under calcium stress causes fragility fractures due to osteoporosis and bone quality deterioration, at least in sheep. Proof of skeletal fluorosis, presenting without increased bone density, calls for a review of fracture incidence in areas with fluoridated groundwater, including an analysis of patients with low bone mass.IntroductionUnderstanding the skeletal effects of environmental fluoride exposure especially under calcium stress remains an unmet need of critical importance. Therefore, we studied the skeletal phenotype of sheep chronically exposed to highly fluoridated water in the Kalahari Desert, where livestock is known to present with fragility fractures.MethodsDorper ewes from two flocks in Namibia were studied. Chemical analyses of water, blood and urine were executed for both cohorts. Skeletal phenotyping comprised micro-computer tomography (μCT), histological, histomorphometric, biomechanical, quantitative backscattered electron imaging (qBEI) and energy-dispersive X-ray (EDX) analysis. Analysis was performed in direct comparison with undecalcified human iliac crest bone biopsies of patients with fluoride-induced osteopathy.ResultsThe fluoride content of water, blood and urine was significantly elevated in the Kalahari group compared to the control. Surprisingly, a significant decrease in both cortical and trabecular bones was found in sheep chronically exposed to fluoride. Furthermore, osteoid parameters and the degree and heterogeneity of mineralization were increased. The latter findings are reminiscent of those found in osteoporotic patients with treatment-induced fluorosis. Mechanical testing revealed a significant decrease in the bending strength, concurrent with the clinical observation of fragility fractures in sheep within an area of environmental fluoride exposure.ConclusionsOur data suggest that fluoride exposure with concomitant calcium deficit (i) may aggravate bone loss via reductions in mineralized trabecular and cortical bone mass and (ii) can cause fragility fractures and (iii) that the prevalence of skeletal fluorosis especially due to groundwater exposure should be reviewed in many areas of the world as low bone mass alone does not exclude fluorosis.

Spatial patterns of diurnal lightning activity in southern Africa during austral summer

In the present study we used harmonic analysis to investigate the spatial distribution of diurnal patterns of hourly lightning flash activity during the months of January and February from 1998 to 2013 in southern Africa. The data were obtained from the Tropical Rainfall Measuring Mission dataset collected through a lightning imaging sensor. The spatial distribution of lightning activity during the austral summer season was mostly concentrated over land, with the highest total lightning activity observed over the Congo and Zambezi river basins. The strength of the diurnal cycle was mainly determined by the presence of warm and cold ocean currents along the coastal areas, and the presence of the St. Helena high pressure cell, along with local level processes including land sea breeze convergence, local topography, and surface heating processes. The strength of the diurnal cycle was relatively weaker in the interior of the study area across the Kalahari Desert and Democratic Republic of Congo. The peak lightning activity across most of the study area occurred in the afternoon hours, while a nocturnal peak was observed in the case of the limited maritime activity in the Atlantic Ocean.

Exome capture from saliva produces high quality genomic and metagenomic data

BackgroundTargeted capture of genomic regions reduces sequencing cost while generating higher coverage by allowing biomedical researchers to focus on specific loci of interest, such as exons. Targeted capture also has the potential to facilitate the generation of genomic data from DNA collected via saliva or buccal cells. DNA samples derived from these cell types tend to have a lower human DNA yield, may be degraded from age and/or have contamination from bacteria or other ambient oral microbiota. However, thousands of samples have been previously collected from these cell types, and saliva collection has the advantage that it is a non-invasive and appropriate for a wide variety of research.ResultsWe demonstrate successful enrichment and sequencing of 15 South African KhoeSan exomes and 2 full genomes with samples initially derived from saliva. The expanded exome dataset enables us to characterize genetic diversity free from ascertainment bias for multiple KhoeSan populations, including new exome data from six HGDP Namibian San, revealing substantial population structure across the Kalahari Desert region. Additionally, we discover and independently verify thirty-one previously unknown KIR alleles using methods we developed to accurately map and call the highly polymorphic HLA and KIR loci from exome capture data. Finally, we show that exome capture of saliva-derived DNA yields sufficient non-human sequences to characterize oral microbial communities, including detection of bacteria linked to oral disease (e.g. Prevotella melaninogenica). For comparison, two samples were sequenced using standard full genome library preparation without exome capture and we found no systematic bias of metagenomic information between exome-captured and non-captured data.ConclusionsDNA from human saliva samples, collected and extracted using standard procedures, can be used to successfully sequence high quality human exomes, and metagenomic data can be derived from non-human reads. We find that individuals from the Kalahari carry a higher oral pathogenic microbial load than samples surveyed in the Human Microbiome Project. Additionally, rare variants present in the exomes suggest strong population structure across different KhoeSan populations.

Prey mortality profiles indicate that Early Pleistocene Homo at Olduvai was an ambush predator

The prime-adult-dominated mortality profile of large bovids in the 1.8 Ma FLK Zinj assemblage, Olduvai Gorge, Tanzania, was recently attributed to ambush hunting by early Homo (Bunn, H.T., Pickering, T.R. 2010. Quat. Res. 74, 395–404). We now investigate a logical follow-up question: is enough known about the causes and pervasiveness of prime-adult-dominated mortality profiles (defined as >70% prime adults) from modern ecosystems and from archaeological sites to warrant their attribution solely to hominin hunting? Besides hominin hunting, three methods of scavenging could have provided the large bovids butchered at FLK Zinj: first-access scavenging from non-predator-related accidents; late-access passive scavenging from lion (or other) kills; early-access aggressive scavenging from lion (or other) kills.We present new data on hunted prey from Hadza bow hunting (e.g., N = 50 impala; N = 18 greater kudu) near Lake Eyasi, Tanzania, and from San bow hunting (N = 13 gemsbok) in the Kalahari Desert, Botswana, documenting non-selective, living-structure profiles. We present new data on drowned wildebeest (N = 175) from Lake Masek, in the Serengeti, documenting many prime adults but also a significantly high percentage of old adults, unlike the profile at FLK Zinj. We also examine mortality profiles from modern African lions and from Old World Pleistocene archaeological sites, revealing that while prime-dominated profiles are present in some archaeological assemblages, particularly some Late Pleistocene European sites involving cervids, they are not documented from lion or other larger carnivore predation; moreover, living-structure profiles with prime adults representing ∼50–60% of prey are common, particularly in African archaeological assemblages involving bovids hunted by humans. Although taphonomic bias, prey socioecology, and season of death may all influence mortality profiles, prime-dominated profiles require careful evaluation. The prime-dominated profile at FLK Zinj is significantly different from profiles formed by the three scavenging methods, which likely indicates hunting by Early Pleistocene Homo.

The role of airborne dust in the growth of tree islands in the Okavango Delta, Botswana

The Okavango Delta, situated in the Kalahari Desert (Botswana), is host to extensive areas of seasonal swamp that are characterised by the presence of numerous tree-covered islands. Islands have been shown to play an important role in the landscape through the creation of habitat diversity, focusing of nutrients, and sequestration of salts. Islands are thought to grow through the subsurface precipitation of carbonate and silica, although recent work has suggested that other factors may be involved, notably airborne dust accumulation. In this study, we investigate the role of airborne dust in the maintenance and growth of tree islands in the seasonal swamps of the Okavango Delta. Chemical and grain size analyses indicate that whilst the channels and floodplains in the Okavango are dominated by well-sorted Kalahari sand that covers the entire region, material on the surface of islands is distinctly different. Island soils are enriched in Al2O3 and are characterised by higher proportions of poorly sorted, fine-grained material that we attribute to the addition of airborne dust. Large quantities of material that circulate in anticyclonic systems over southern Africa represent a potentially significant source of particulate sediment to the Okavango, whilst peat fires and the desiccation of the surrounding floodplains during the dry season are also considered to be important sources of local dust. The data suggest that varying proportions of Kalahari sand, dust, and chemical precipitate give rise to the range of compositions found on and within the islands of the Delta. Dust typically accounts for between 20 and 60% of material found on the surface of islands, whilst dust and chemical precipitate dominate the subsurface material. Islands thus appear to grow through a combination of ongoing surface and subsurface processes that result in considerable heterogeneity in soil composition. In both instances vegetation, especially trees, is the main driving force behind island development, not only causing the subsurface accumulation of CaCO3 and SiO2 in island soils, but also trapping airborne dust on the surface of islands. Our study suggests that dust fallout is an equally or possibly even more important contributor to the local topographic irregularities and thus habitat diversity in the Okavango Delta. Despite the potential importance of airborne material to the biogeochemistry and development of tree islands in wetland systems, our knowledge regarding these processes remains poor.

Adaptive thermoregulation during summer in two populations of an arid‐zone passerine

Heterothermy plays an important role in lowering the costs of thermoregulation in endotherms by reducing water and energy requirements. We tested predictions that birds in arid habitats should express fine-scale variation in their thermoregulatory patterns as a function of prevailing climatic conditions. We assessed effects of air temperature (Tair) and water vapor pressure deficit (D) on body temperature (Tb) in free-living White-browed Sparrow-Weavers (Plocepasser mahali) during summer in two arid habitats in the Kalahari Desert, South Africa, using data from a dry period at a hot, desert site (n=7 birds), and during a dry period (n=4 birds) and a wet period (n=5 birds) at a milder, semi-desert site. The desert birds maintained a significantly higher set-point Tb (41.5 degrees+/-0.2 degrees C, mean-SD) than semi-desert birds (40.2 degrees+/-0.2 degrees C). During the warmest part of day (12:00-18:00 hours), Tb increased significantly during periods of high Tair and/or high humidity, and mean and maximum Tb were up to 1.40 and 2.3 degrees C, respectively, above normal levels. However, as Tair increased, birds at the desert site maintained Tb at or below set-point levels for a greater proportion of the time than birds at the semi-desert site. Birds at the desert site also expressed a greater magnitude of daily heterothermy (heterothermy index, HI=2.4 degrees+/-0.3 degrees C, mean+/-SD) than birds at the semi-desert site: the latter population showed a greater magnitude of heterothermy during a dry period (HI=2.1 degrees+/-0.3 degrees C) than during a wet period (HI=1.6 degrees+/-0.2 degrees C). Birds continued foraging throughout the warmest part of the day, despite the fact that heat dissipation (percentage of time spent panting and wing-spreading) increased significantly with increasing Tair. Our findings reveal that populations can vary in their thermoregulatory responses in both space and time and suggest that small changes in Tair can have significant effects on thermoregulation in free-ranging desert birds, even when Tair<Tb. These data have important implications for assessing vulnerability of species to climate change, suggesting that sensitivity should be assessed at the population, rather than species, level.

Harpagoside: from Kalahari Desert to pharmacy shelf

Harpagoside is an iridoid glycoside that was first isolated from Harpagophytum procumbens (devil's claw, Pedaliaceae), a medicinal plant in which it is the major constituent of the iridoid pool. Both the pure compound and devil's claw extracts have potent anti-rheumatic, anti-inflammatory and analgesic effects. According to the European Pharmacopoeia commercial devil's claw products should contain at least 1.2% harpagoside. However, the compound has also been isolated from several other plant species and in vitro plant culture systems. Recent advances in knowledge of harpagoside distribution, biosynthesis/accumulation and pharmacology are summarized in this review. We also discuss the possible synergism and/or antagonism between major constituents in harpagoside-containing phytopharmaceutical products. Finally, future perspectives for its potential application are highlighted.

Phillip Vallentine Tobias (1925–2012)

Phillip Vallentine Tobias (1925–2012)

Anthro-tourism, documentary film and method

Abstract The lines between tourist and an anthropologist have become increasingly blurred. The idea of the Anthro-tourist is discussed in terms of a self-reflexive experience in the Kalahari Desert. A conceptual framework is developed through a case study of a reflexive video, I am, You Are? (2003). Auto-ethnographic reflections on personal encounters with the ≠Khomani Bushmen is offered as this author’s comparative experience in light of the commodification of indigenous cultures through tourism as well as the construction of the ‘self’ and ‘other’ relationships. Both tourists and anthropologists have a similar interest in the exotic. Anthropologists, however, aim to educate society through film and video rather than to advertise the exotic.

Impact of Prosopis invasion on a keystone tree species in the Kalahari Desert

Several Prosopis species were introduced into South Africa in the last century. Since then two species, Prosopis glandulosa var. torreyana and Prosopis velutina have invaded large parts of arid southern Africa. Here, we examine the extent to which increased mortality of Acacia erioloba, a keystone species in the Kalahari Desert, can be attributed to competition for water with Prosopis. We do this for A. erioloba and Prosopis sp. at invaded, as well as cleared sites through a determination of species abundance, canopy vitality, plant water stress and plant water source. Our stable isotope results show that in the riparian zone both A. erioloba and Prosopis are using the same water source. Our results also show that there is a 50 % increase in canopy dieback of A. erioloba in the invaded river plots relative to the cleared river plots. This dieback cannot be related to changes in rainfall and temperature as there were no adverse fluctuations (drought) in the weather in the 10 years preceding our study. We speculate that because A. erioloba is more water stressed in the invaded river plot this increase in mortality and dieback is related to plant moisture stress that is not related to climate but to competition for water with Prosopis. Our study gives strong support for the eradication of Prosopis from rivers in arid parts of Southern Africa.

Provenancing of silcrete raw materials indicates long-distance transport to Tsodilo Hills, Botswana, during the Middle Stone Age

Lithic artifacts from the African Middle Stone Age (MSA) offer an avenue to explore a range of human behaviors, including mobility, raw material acquisition, trade and exchange. However, to date, in southern Africa it has not been possible to provenance the locations from which commonly used stone materials were acquired prior to transport to archaeological sites. Here we present results of the first investigation to geochemically fingerprint silcrete, a material widely used for tool manufacture across the subcontinent. The study focuses on the provenancing of silcrete artifacts from the MSA of White Paintings Shelter (WPS), Tsodilo Hills, in the Kalahari Desert of northwest Botswana. Our results suggest that: (i) despite having access to local quartz and quartzite at Tsodilo Hills, MSA peoples chose to transport silcrete over 220 km to WPS from sites south of the Okavango Delta; (ii) these sites were preferred to silcrete sources much closer to Tsodilo Hills; (iii) the same source areas were repeatedly used for silcrete supply throughout the 3 m MSA sequence; (iv) during periods of colder, wetter climate, silcrete may have been sourced from unknown, more distant, sites. Our results offer a new provenancing approach for exploring prehistoric behavior at other sites where silcrete is present in the archaeological record.

Classification and mapping of the composition and structure of dry woodland and savanna in the eastern Okavango Delta

The dry woodland and savanna regions of the Okavango Delta form a transition zone between the Okavango Swamps and the Kalahari Desert and have been largely overlooked in terms of vegetation classification and mapping. This study focused on the species composition and height structure of this vegetation, with the aim of identifying vegetation classes and providing a vegetation map accompanied by quantitative data. Two hundred and fifty-six plots (50 m × 50 m) were sampled and species cover abundance, total cover and structural composition were recorded. The plots were classified using agglomerative, hierarchical cluster analysis using group means and Bray-Curtis similarity and groups described using indicator species analysis. In total, 23 woody species and 28 grass species were recorded. Acacia erioloba and Colophospermum mopane were the most common woody species, whilst Urochloa mossambicensis, Panicum maximum, Dactyloctenium gigantiumand Eragrostis lehmanniana were the most widespread grasses. Eleven vegetation types were identified, with the most widespread being Short mixed mopane woodland, Tall mopane woodland and Tall mixed mopane woodland, covering 288.73 km2 (28%), 209.14 km2 (20%) and 173.30 km2 (17%) of the area, respectively. Despite their extensive area, these three vegetation types were the least species-rich, whilst Palm thornveld, Short mixed broadleaf woodland and Open mixed Acacia woodland were the most taxonomically variable. By contrast, Closed mixed Acacia woodland and Closed Acacia–Combretum woodland had the most limited distribution, accounting for less than 1% of the mapped area each.Conservation implications: The dry woodland and savanna vegetation of the Okavango Delta comprises a much wider suite of plant communities than the Acacia-dominated and Mopane-dominated classifications often used. This classification provided a more detailed understanding of this vegetation and essential background information for monitoring, management and research.

Why Did the Meerkat Cross the Road? Flexible Adaptation of Phylogenetically-Old Behavioural Strategies to Modern-Day Threats

Risk-sensitive adaptive spatial organisation during group movement has been shown to efficiently minimise the risks associated with external ecological threats. Whether animals can draw on such behaviours when confronted with man-made threats is generally less clear. We studied road-crossing in a wild, but habituated, population of meerkats living in the Kalahari Desert, South Africa. We found that dominant females, the core member in meerkat social systems, led groups to the road significantly more often than subordinates, yet were consistently less likely to cross first. Our results suggest that a reshuffling occurs in progression order when meerkat groups reach the road. By employing a simple model of collective movement, we have shown that risk aversion alone may be sufficient to explain this reshuffling, but that the risk aversion of dominant females toward road crossing is significantly higher than that of subordinates. It seems that by not crossing first, dominant females avoid occupying the most risky, exposed locations, such as at the front of the group – a potential selfish strategy that also promotes the long-term stability and hence reproductive output of their family groups. We argue that our findings support the idea that animals can flexibly apply phylogenetically-old behavioural strategies to deal with emerging modern-day problems.

Sniffing out the stakes: hair-snares for wild cats in arid environments

Context Wild cats (Felis spp.) are difficult to monitor because of their cryptic lifestyle and usually low numbers. Hair-snaring is a promising non-invasive method being used increasingly to estimate mammal populations. Aims Our aim was to carry out pilot trials of a simple hair-snare designed to capture hair from wild cats in arid environments. Methods Roughened wooden stakes were set at multiple sites on the crests of sand dunes and in swales in western Queensland, Australia, and in mostly sandy habitats of the Namib and Kalahari Deserts, Namibia. In Australia, stakes were sprayed with cat urine, extracts of catnip or valerian herbs as lures, or left untreated; in Namibia, alternate stakes were sprayed with a food lure of tuna emulsion oil. The stakes were checked for hair, usually daily, for 2–14 days, and the surrounding ground was inspected for tracks. Remote cameras also were used at some sites to confirm the identity of visitors to stakes. Key results In Australia, feral cats (Felis catus) were attracted to, and left hairs on, stakes sprayed with cat urine six times more frequently than to unsprayed stakes irrespective of whether snares were on dune crests or in swales, and showed no response to catnip or valerian. Tracks and photos showed that cats, dingoes or wild dogs (Canis lupus ssp.) and foxes (Vulpes vulpes) also approached and sniffed the stakes. In Namibia, F. catus, F. lybica and F. nigripes left hair on stakes, with deposition rates two and a half-fold higher at stakes with the food lure than without it. At least five other species of predators visited the hair-snare sites. Conclusions Simple wooden stakes provide a cheap and simple method of snaring hairs from wild cats, especially if used in conjunction with appropriate lures. Our results broadly support previous work, and extend the utility of the method to different Felis spp. in arid habitats. Implications Further research is needed on snares to investigate the seasonal efficiency of different lures. If DNA also is to be extracted to identify individuals, more work is needed to confirm that snares yield hair of sufficient quality to allow this.

Caught in a sandstorm: an assessment of pressures on communal pastoral livelihoods in the Kalahari Desert of Botswana

Despite their importance to rural livelihoods, the economic and environmental sustainability of contemporary communal pastoral systems of the Kalahari is increasingly being put under scrutiny. Using data collected from a survey of randomly selected pastoral households from two districts of Ghanzi and Kgalagadi South, Botswana, this paper outlines the major constraints affecting contemporary extensive pastoral systems. Because of the prevailing semi-arid climate, recurrent drought outbreaks were cited as a common challenge in both study areas together with lack of fenced grazing areas. Stock theft was also highlighted as a challenge, even though it was more pronounced in Kgalagadi South. In Ghanzi area, the other important challenges included loss of livestock due to predation, while stray animals, stock theft and loss of livestock due to road accidents were equally important. Kgalagadi South pastoral households experienced serious shortage of drinking water for their livestock, followed by inadequate grazing land and limited access to distant markets. The preceding, together with several other less prominent challenges revealed in this study, exert pressure on pastoral livelihoods. There is need, therefore, to address these perceived challenges and strengthen resilience through effective policy reviews to secure rural livelihoods.