Late Dry Season Research Articles

The giant that makes do with little: small and easy‐to‐leave home ranges found in the giant root‐rat

AbstractMammalian space‐use patterns are largely determined by the resources utilized as well as by given habitat characteristics, as can be illustrated by rodents displaying predominantly subterranean activity. These rodents are largely limited in their use of space by their burrow systems. This results in smaller home ranges than is usual for rodents of a similar size. However, there is little information regarding how stable these home ranges are over time. We studied space use in the giant root‐rat,Tachyoryctes macrocephalus, a large fossorial rodent endemic to the Bale Mountains of southern Ethiopia where it is the principal prey of the Ethiopian wolfCanis simensis. We radio‐tracked 22 root‐rats during a period of 36 days in the early dry season and 17 of them once again during a period of 37 days in the late dry season. The root‐rats occupied very small (around 100 m2) home ranges which were often tightly packed, especially on a wetland shore that was a part of the study locality, but displayed little overlap. Almost 30% of the radio‐collared root‐rats of either sex dispersed (80–428 m from their original home range) during the 5 months of the study, mostly in a period between the early and late dry season characterized by a decreasing food supply and the soil becoming dry and hard. Individuals who did not disperse during this time usually shifted their home range. Root‐rats living on the wetland shore, which were the largest and therefore likely competitively strongest individuals, shifted their home ranges into the wetland, likely for the purpose of increasing their food supply.

Seasonal selection of key resources by cattle in a mixed savannah-wetland ecosystem increases the potential for conflict with lions

In Africa's pastoral conservation landscapes, apex predators frequently kill livestock. Retaliatory persecution such as poisoning threatens predators, but also non-target biota. Several factors influence conflict severity, including livestock husbandry, overlap in seasonal habitat use, and the degree to which livestock perceive and are able to respond to a landscape of fear. We investigated these factors by GPS-tracking 42 Tswana beef cattle (Bos taurus) from 29 herds in 2017 and six lions (Panthera leo) from different prides (May 2016–Dec. 2017) in the northern Okavango Delta, Botswana, where cattle depredation significantly impacts the livelihoods of rural agro-pastoralists. Cattle exhibited seasonal habitat selection patterns similar to wild ungulates in the region. They preferred woodland habitats, with more digestible grasses, during the wet season. During the dry season, they preferred wetland habitats with reliable forage and water availability. Cattle also preferred areas close to human settlements, but the necessity to forage in wetlands during the dry season exposed them to significant depredation risk, especially >4 km from settlements. Lions killed most cattle in wetlands during the late dry season but the intensity of recent lion presence (previous 14 days) only had a weak negative effect on cattle habitat selection patterns. Cattle used rangelands according to nutritional requirements, irrelevant of the associated predation risk, suggesting that socio-ecologically acceptable conflict solutions cannot rely on the exclusion of livestock from seasonal wetlands. Curbing depredation by lions will best be achieved by a combination of resource- and predation-cognisant seasonal herding strategies with adequate livestock protection. Understanding the ecological constraints that intensify conflict is pertinent to any livestock production landscape with predator presence. It is also a central prerequisite for future land use planning and devolution of legal, controlled resource access rights through policy. Coexistence strategies must account for the strong reliance of people, their livestock, and wildlife on shared key resources. This is particularly important in large trans-frontier conservation areas where the successful merging of biodiversity conservation and rural development is a strategic goal. Omission will foster resentment and resistance to coexistence with apex predators, particularly if livestock productivity and human livelihoods are negatively affected.

Small to modest impact of social group on the gut microbiome of wild Costa Rican capuchins in a seasonal forest.

The horizontal transmission of pathogenic and beneficial microbes has implications for health and development of socially living animals. Social group is repeatedly implicated as an important predictor of gut microbiome structure among primates, with individuals in neighboring social groups exhibiting distinct microbiomes. Here we examine whether group membership is a predictor of gut microbiome structure and diversity across three groups of white-faced capuchins (Cebus capucinus imitator) inhabiting a seasonal Costa Rican forest. We collected 62 fecal samples from 18 adult females during four sampling bouts. Sampling bouts spanned the dry-to-wet-to-dry seasonal transitions. To investigate gut microbial composition, we sequenced the V4 region of the 16S rRNA gene. We used the DADA2 pipeline to assign amplicon sequence variants and the RDP database to classify taxa. Our findings are: 1) gut microbiomes of capuchins clustered by social group in the late dry season, but this pattern was less evident in other sampling bouts; 2) social group was a significant variable in a PERMANOVA test of beta diversity, but it accounted for less variation than season; 3) social group was not an important predictor of abundance for the ten most abundant microbial taxa in capuchins; 4) when examining log2-fold abundances of microbes between social groups, there were significant differences in some pairwise comparisons. While this is suggestive of group-wide differences, individual variation may have a strong impact and should be assessed in future studies. Overall, we found a minor impact of social group membership on the gut microbiota of wild white-faced capuchins. Future research including home range overlap and resource use, as well as fine-scale investigation of individual variation, will further elucidate patterns of socially structured microbes.

Studies on parasitic contamination of soil and local drinking water sources, Doma Local Government Area, Nasarawa State, Nigeria

Water is essential to all living things on earth, however if contaminated, can be injurious to human health when consumed. This study evaluates the parasitic contamination of potable water sources and surrounding soil in Doma Local Government Area of Nasarawa State. Forty-eight soil and water samples from different sources (wells, streams and boreholes) were collected from March to July 2017. Water samples were analyzed using the Calcium carbonate (CaCO 3 ) floatation method while a modified Baermann Technique was used to microscopically examine soil samples for the parasitic presences. 32 water samples were parasitized including 2 protozoans ( Entamoeba histolytica , and Giardia lamblia) 3 nematodes ( Trichuris trichiura , Ascaris lumbricoides and hookworm), and Fasciola hepatica a trematode. The nematodes were most contaminated 19(59.38%) while trematodes were least 1(3.13%). The most contamination was in stream water sources for late dry and early wet season (69.23% and 94.74%) while the boreholes had no contamination for both seasons. Prevalence of parasites in relation to water sources showed a high significant difference ( p = 0.0000001), while there was no significant difference in relation to late dry and early rainy seasons ( p = 0.1258). Geohelminths was highest around the boreholes 15(35.71%) but least in the streams 13(30.95%). However, there was no significant difference ( p = 0.6221) in the prevalence rate of geohelminths in relation to sources of water. Result indicated a high rate of parasitic contamination of soil and drinking water sources in the study=area. Hence there is need for advocacy and enlightenment on the importance of proper drinking water treatment. Keywords: Geohelminths; parasitic contamination; water

Seasonal Abundance of the Harvester Termite, Hodotermes mossambicus (Hagen) (Isoptera: Hodotermitidae), and Its Impact on Vegetation in a Semi-Arid Grassland in Zimbabwe

The size of harvester termite Hodotermes mossambicus (Hagen) (Isoptera: Hodotermitidae) populations on the clay-rich red-soils of semi-arid grasslands in southwestern Zimbabwe in any particular dry season was found to be strongly influenced by the annual rainfall received the preceding rainy season. The size of the termite population of the antecedent dry season also had an important influence. Populations were found to build up over successive dry years and crashed following a season of substantially above average rainfall to fall further after the next rainy season which was also above average. Termite populations and foraging activity also fluctuated considerably within seasons. There was an increase as the dry season progressed but foraging fell dramatically at the end of the season and remained at low levels throughout the summer months. Foraging was confined to degraded patches in the red-soil veld mosaic in the early dry season with expansion into the other grass communities occurring in the late dry season. Fluctuations in harvester termite populations had a marked effect on the extent of the foraging area and hence on the amounts of grass cover remaining in the degraded, ecotone and sound veld communities of the red-soil mosaic at the end of the dry season. Termite foraging activities serve to maintain the grass sward in a vigorous condition by preventing excessive accumulation of dead foliage on ungrazed sites and they had an important influence on the botanical changes which occurred within each grass community of the mosaic. The main effect was to favour those grass species such as Heteropogon contortus and Themeda triandra, that are intolerant of excessive top-hamper (standing dead grass) and litter accumulation.

Rapid response of habitat structure and above-ground carbon storage to altered fire regimes in tropical savanna

Abstract. Fire regimes across the globe have been altered through changes in land use, land management, and climate conditions. Understanding how these modified fire regimes impact vegetation structure and dynamics is essential for informed biodiversity conservation and carbon management in savanna ecosystems. We used a fire experiment at the Territory Wildlife Park (TWP), northern Australia, to investigate the consequences of altered fire regimes for vertical habitat structure and above-ground carbon storage. We mapped vegetation three-dimensional (3-D) structure in high spatial resolution with airborne lidar across 18 replicated 1 ha plots of varying fire frequency and season treatments. We used lidar-derived canopy height and cover metrics to extrapolate field-based measures of woody biomass to the full extent of the experimental site (R2=0.82, RMSE = 7.35 t C ha−1) and analysed differences in above-ground carbon storage and canopy structure among treatments. Woody canopy cover and biomass were highest in the absence of fire (76 % and 39.8 t C ha−1) and lowest in plots burnt late in the dry season on a biennial basis (42 % and 18.2 t C ha−1). Woody canopy vertical profiles differed among all six fire treatments, with the greatest divergence in height classes <5 m. The magnitude of fire effects on vegetation structure varied along the environmental gradient underpinning the experiment, with less reduction in biomass in plots with deeper soils. Our results highlight the large extent to which fire management can shape woody structural patterns in savanna landscapes, even over time frames as short as a decade. The structural profile changes shown here, and the quantification of carbon reduction under late dry season burning, have important implications for habitat conservation, carbon sequestration, and emission reduction initiatives in the region.

Tree recruitment dynamics in fire‐prone eucalypt savanna

AbstractSavanna sites are idealized as exhibiting a demographic “bottleneck” physiognomy comprising a lower stratum of abundant resprouting persistent “juveniles” (albeit of indeterminate age), a mid‐stratum comprising relatively few released “saplings,” and a canopy‐layer cohort of “adults.” The magnitude and frequency of disturbance is considered to influence the critical transition from juvenile into adult phases. Under fire‐prone Australian savanna conditions, an extensive suite of both observational and manipulative studies have explored the responses of tree recruitment to fire disturbances. These studies oftentimes have produced seemingly highly disparate responses, particularly with respect to the differential responses of relatively fast‐growing eucalypts versus non‐eucalypts under different fire regime, and overstory competition, conditions. This study contrasts the responses of tree recruitment height classes to (1) the effects of total canopy removal from severe Cyclone Monica in 2006 over a subsequent 10‐yr period, (2) with observations from long‐term monitoring sites under relatively stable overstory conditions at Litchfield National Park over a six‐year period, (3) under ambient, frequent fire occurrence (mean > 0.5 fires/yr) at both locales including relatively severe late dry season fires. Recruitment at both study sites was represented mostly by resprouting, clonally reproducing juvenile trees <2 m tall, around half of which died over respective assessment periods. At post‐cyclone assessment plots, there was substantial release of eucalypts, including within the first five years, into the >5 m height class, with negligible corresponding release of non‐eucalypts. At Litchfield plots, there was negligible release of both eucalypts and non‐eucalypts. In discussion, we contrast these results with findings from relevant regional studies. We contend that collective disparate observations feasibly can be reconciled as reflecting significant interactions between fire regime characteristics and variable site overstory competition effects, such that the rate of recruitment of fast‐growing savanna eucalypt individuals into the midstory is relatively independent of the fire regime, but is significantly regulated by resource competition interactions especially with the overstory, whereas recruitment of non‐eucalypts is relatively independent of overstory competitive effects, but is suppressed under fire regimes dominated by frequent, especially severe fires.

Delivering effective savanna fire management for defined biodiversity conservation outcomes: an Arnhem Land case study

Given the recent history of frequent and extensive late dry season wildfire in Australia’s fire-prone northern savannas, regional conservation-based fire management programs typically aim to mitigate wildfire through the use of strategic prescribed burning during the cooler early dry season. However, it remains unclear as to the extent such environmental management concerns are being addressed by these renewed fire management efforts. This study documents changes in fire regime in the western Arnhem Land region of northern Australia associated with the implementation of active fire management since 2006. Over a 12-year period, the regional fire regime has transitioned from late dry season, wildfire-dominated to being characterised by a majority of fires occurring as small early dry season prescribed burns. Although overall area burnt has not significantly decreased, most ecological threshold metrics have improved, with the exception of those describing the maintenance of longer-unburnt habitat. Challenges involved with defining, delivering, monitoring and evaluating heterogeneity targets are discussed.

Studies on the prevalence of fascioliasis among ruminant animals in northern Bauchi state, north-eastern Nigeria

A study of prevalence of ruminant fascioliasis was undertaken from May 2017 to April 2018. A set of 7640 stool and 7640 bile samples were collected from slaughtered cattles, sheeps and goats in seven local abattoirs located within the seven Local Government Areas making up northern Bauchi state. The Sample collection was demarcated into four sections of three months each corresponding into four local seasons. 1910 samples were collected from the beginning to the end of each of the four local seasons. Direct postmortem investigation to detect adult Fasciola spp. was employed. Stool samples were analyzed using formol-etha concentration technique. ANOVA (Analysis of variance) was conducted to examine the prevalence of fascioliasis in six communities of northern Bauchi state. The prevalence of infection was statistically different on different localities. The highest infection rates from the seven sampling sites was Jama'are (48.5%) followed by Zaki (46.9%) p = 0.05. Specie specific prevalence of fascioliasis between the host species was statistically different. Cattles were more infected than sheep and goat. Prevalence of fascioliasis on gender was statistically different, with bulls showing a higher prevalence rate and female sheep and goat recorded higher prevalence. Prevalence of fascioliasis based on estimated ages of animals sampled was statistically significant, animals above 5 years had higher prevalence of 64.5% followed by animals below the age of 1 with 41.3% (p = 0.05). Prevalence of fascioliasis among sampled ruminants based on seasonal variations was statistically significant. Higher prevalence percentages were observed during the early and late rainy season (47.2% and 58.4%) compared to early and late dry seasons (36.2% and 20.1%) p = 0.05. The study, therefore, recommends regular meat inspection alongside public awareness campaigns.

The Great Barrier Reef: A source of CO2 to the atmosphere

The Great Barrier Reef (GBR) is the largest contiguous coral reef system in the world. Carbonate chemistry studies and flux quantification within the GBR have largely focused on reef calcification and dissolution, with relatively little work on shelf-scale CO2 dynamics. In this manuscript, we describe the shelf-scale seasonal variability in inorganic carbon and air-sea CO2 fluxes over the main seasons (wet summer, early dry and late dry seasons) in the GBR.Our large-scale dataset reveals that despite spatial-temporal variations, the GBR as a whole is a net source of CO2 to the atmosphere, with calculated air–sea fluxes varying between −6.19 and 12.17 mmol m−2 d−1 (average ± standard error: 1.44 ± 0.15 mmol m−2 d−1), with the strongest release of CO2 occurring during the wet season. The release of CO2 to the atmosphere is likely controlled by mixing of Coral Sea surface water, typically oversaturated in CO2, with the warm shelf waters of the GBR. This leads to oversaturation of the GBR system relative to the atmosphere and a consequent net CO2 release.

Evaluation of parasitic contamination of local potable water sources in Doma Local Government Area of Nasarawa State, Nigeria

The health and well-being of individuals in a nation absolutely depends on the quality of water available for consumption. Therefore, this study evaluated parasitic contaminants of drinking water sources in Doma Local Government Area of Nasarawa State, Nigeria. A total of 48 water samples were collected from different sources (boreholes, wells and streams) from March to July 2017. The water samples were analyzed using the Calcium Carbonate (CaCO3) floatation method and the samples were examined microscopically for the presences of parasites. A total of 32 (66.67%) water samples were parasitized by a trematode (Fasciola hepatica), two protozoans (Entamoeba histolytica, and Giardia lamblia) and three nematodes (Trichuris trichiuria, Ascaris lumbricoides and Hookworm). The nematode group had the highest contamination rate 19 (59.38%) followed by the protozoan group 12 (37.50%) while trematode was the least with 1(3.13%). The stream source was the most contaminated in late dry and early wet seasons having 69.23% and 94.74% respectively, followed by wells which had 30.77% and 5.26% in late dry and early wet seasons respectively while boreholes had 0% contamination in both seasons. Therefore, prevalence of parasites in relation to sources of water showed a very high significant association (X2= 49.741, df = 2, P < 0.0001), while there was no significant association with seasons (X2 = 2.3438, df = 1, P = 0.1258).Result indicated high rate of parasitic contamination of drinking water sources in the study area. Hence, the need for advocacy and enlightenment of the inhabitants of the area on the importance of proper treatment of potable water.Key words: Parasites, potable water sources, seasons

Genetic and nongenetic factors affecting on-farm performance of peri-urban dairy cattle in west Africa

Population growth and urbanization lead to an increasing demand for milk in sub-Saharan Africa, but the production potential of the 65.9 million dairy cows in the region is far from being fully exploited to meet this demand. With the aim to support decision-making for breeding and management of dairy cattle in commercial farms, we performed a comparative study of daily milk offtake, chemical composition of milk, prevalence of metabolic disorders, and body weight development of local and crossbred cattle genotypes in peri-urban commercial farms in Ouagadougou, Burkina Faso. We used data that were collected during regular visits of 7 farms in peri-urban areas of the city over a 16-mo period. Animals belonged to 3 breed groups (123 local zebu, 49 Sahelian crossbred, and 42 European crossbred cows). We applied a mixed model approach to evaluate the genetic and seasonal effects on daily milk offtake, milk composition, and body weight. Nonlinear growth models were fitted to model the body weight development according to genotype, season, and reproductive status of cows. The milk fat-to-milk protein ratio was used to determine the prevalence of ketosis and acidosis. Daily milk offtake from crossbred cows was 3.1- to 4.3-fold higher than from local zebu cows; furthermore, crossbred cows had a higher body weight and maturity rate than local zebu cows. In contrast, no genotype differences were found in milk fat and milk protein percentage and prevalence of ketosis and acidosis. Additionally, seasonal effects suggested that higher production performances could be realized through improved management of dairy cows, particularly in the late dry and rainy season. Improved feeding management could also reduce the risk of metabolic disorders. In summary, production performances of crossbred dairy cows in peri-urban production systems in Burkina Faso are higher as compared with local zebu cows. However, environmental effects suggest that further studies are needed to systematically assess genotype by environment interactions to guide the development of sustainable breeding and management programs for dairy cattle in Burkina Faso.

Notes on ecology of wild goffin’s cockatoo in the late dry season with emphasis on feeding ecology

Experimental work on captive Goffin’s cockatoos (Cacatua goffiniana) has highlighted the remarkable cognitive abilities of this species. However, little is known about its behavior in the natural habitat on the Tanimbar Archipelago in Indonesia. In order to fully understand the evolutionary roots leading to cognitively advanced skills, such as multi-step problem solving or flexible tool use and manufacture, it is crucial to study the ecological challenges faced by the respective species in the wild. The three-month expedition presented here aimed at gaining first insights into the cockatoos’ feeding ecology and breeding behavior. We could confirm previous predictions that Goffin’s cockatoos are opportunistic foragers and consume a variety of resources (seeds, fruit, inflorescence, roots). Their breeding season may be estimated to start between June and early July and they face potential predation from ground and aerial predators. Additionally, the observational data provide indications that Goffin’s cockatoos are extractive foragers, which together with relying on multiple food sources might be considered a prerequisite of tool use.

Attributing the hydrological impact of different land use types and their long-term dynamics through combining parsimonious hydrological modelling, alteration analysis and PLSR analysis

Understanding the relationship between hydrological processes and environmental changes is important for improved water management. The Geba catchment in Ethiopia, forming the headwaters of Tekeze-Atbara basin, was known for its severe land degradation before the recent success in integrated watershed management. This study analyses the hydrological response attributed to land management change using an integrated approach composed of (i) simulating the hydrological response of Land Use/Cover (LULC) changes; (ii) assessing the alteration of streamflow using Alteration of Hydrological Indicators (IHA); and (iii) quantifying the contribution of individual LULC types to the hydrology using Partial Least Square Regression model (PLSR).The results show that the expansion of agricultural and grazing land at the expense of natural vegetation has increased the surface runoff 77% and decreased dry season flow by 30% in the 1990s compared to 1970s. However, natural vegetation started to recover from the late 1990s and dry season flows increased by 16%, while surface runoff declined by 19%. More pronounced changes of the streamflow were noticed at sub-catchment level, mainly associated with the uneven spatial distribution of land degradation and rehabilitation. However, the rate of increase of low-flow halted in the 2010s, most probably due to an increase of water withdrawals for irrigation. Fluctuations in hydrological alteration parameters are in agreement with the observed LULC change. The PLSR analysis demonstrates that most LULC types showed a strong association with all hydrological components.These findings demonstrate that changing water conditions are attributed to the observed LULC change dynamics. The combined analysis of rainfall-runoff modelling, alteration indicators and PLSR is able to assess the impact of environmental change on the hydrology of complex catchments. The IHA tool is robust to assess the magnitude of streamflow alterations obtained from the hydrological model while the PLSR method is useful to zoom into which LULC is responsible for this alteration.

Phenological study of populations of Cnidoscolus quercifolius in the Western Seridó, Paraiba state, Brazil

Abstract The phenological patterns of two populations of Cnidoscolus quercifolius were evaluated in the western Seridó region of Paraiba state, Brazil, from March 2009 to February 2011, with data collected monthly. The evaluations have addressed the quantitative method of analysis that represents the activity indices for both populations growing seasons (fall and sprout) and reproductive (flowering and fruiting), and also studied the intensity index Borchert, who evaluated the flow leaves. The stages were evaluated with respect to variations in rainfall, water potential of plant and quantum efficiency of photosystem II. The bud in the two populations occurred in the late dry season and transition into the rainy season, with peak leafing in January and November 2010 and was negatively correlated with rainfall (rs = -0.54 p &lt;0.05). Leaf fall showed the peak phase in October 2009 and 2010, showing a direct relationship with water potential and photosynthetic quantum efficiency. The flowering and fruiting had greater synchrony in the seasonal rainy period, fruit set was positively correlated with precipitation values during the study period (rs = 0.56 p &lt;0.05). The phenological events of C. quercifolius show marked seasonality in relation to precipitation, water potential and the quantum efficiency of photosystem II.

The legacy of colonial fire management policies on traditional livelihoods and ecological sustainability in savannas: Impacts, consequences, new directions

Land occupation and management systems have defined fire regimes and landscapes for millennia. The savanna biome is responsible for 86% of all fire events, contributes to 10% of the total carbon emissions annually and is home to 10% of the human population. European colonization has been associated with the implementation of fire suppression policies in many tropical savanna regions, markedly disrupting traditional fire management practices and transforming ecosystems. In this paper we assess savanna burning approaches from pre-colonial to contemporary eras in three regions: northern Australia, southern Africa and Brazil. In these regions, fire suppression policies have led to (i) conflicts between government authorities and local communities; (ii) frequent late dry season wildfires and/or (iii) woody encroachment. Such consequences are facilitating changes to fire management policies, including recognition and incorporation of traditional ecological knowledge in contemporary community-based adaptive savanna fire management. Such programs include implementation of prescribed early dry season fires and, in some regions, generating income opportunities for rural and traditional communities through the reduction of late dry season wildfires and associated greenhouse gas emissions. We present a brief history of fire management policies in these three important savanna regions, and identify ongoing challenges for implementation of culturally and ecologically sustainable fire management policies.

Fire regime effects on annual grass seeds as food for threatened grass-finch

BackgroundThe Gouldian finch (Erythrura gouldiae, Gould 1844) is a threatened grass finch (Estrildidae) endemic to the tropical savannas of northern Australia. Current fire regimes, consisting of frequent and extensive fire across these savanna grasslands, affect the type and availability of grass seed for granivores. Gouldian finches are particularly affected as they feed exclusively on grass seed and, unlike other finches, do not supplement their own or their hatchlings’ diet with other protein sources. Annual Sorghum spp. provides the main source of seed to Gouldian finches throughout the monsoonal dry season and concurrent breeding season, making it a critical resource throughout breeding habitat. This study examined the effects of fire regimes, including fire frequency, time since the last fire, seasonality of fire on plant density, seed production, and overall seed abundance of the annual grass Sorghum stipoideum (Ewart & White) C.A. Gardn. & C.E. Hubb. Monitoring of S. stipoideum took place across Gouldian finch breeding habitat over three consecutive years and these measures were used in conjunction with local fire history at these sites to test for effects of fire attributes on Sorghum spp. seed ecology.ResultsWe found that seasonality of fire had the greatest impact on S. stipoideum plant density and overall seed abundance, with early dry season fires resulting in 25% higher plant and seed density compared to late dry season fires. Seed production per plant peaked at three years post fire but then declined. There was no significant influence of fire frequency in the analysis.ConclusionsAlthough fire effects were detected, these were muted within current fire regimes experienced in the region, and it is unlikely that appreciable impacts would occur on S. stipoideum seed availability to Gouldian finches while breeding. However, reduced seed density resulting from repeated high intensity fires could lead to exacerbation of food shortages postulated for Gouldian finches in the late dry season, as seeds naturally become scarce at the soil surface where finches forage. Early dry season fires maximize Sorghum spp. seed abundance. These findings support the implementation of low intensity early dry season burning to promote optimal food and breeding resources for threatened finches.

Seasonal fire management by traditional cattle ranchers prevents the spread of wildfire in the Brazilian Cerrado.

The use of fire by cattle ranchers is a major source of conflict between conservationists and local communities in tropical savannas. We evaluate the role of traditional pastoral management in wildfire prevention in two protected areas within the Brazilian savanna. Fine-grain field data from transect walks and interviews were combined with geospatial data at landscape scale to compare fire regimes in community-managed areas with those in government-managed areas. Local pastoral management creates seasonal mosaic patterns of burnings performed for productive activities and for deliberate landscape management, i.e. to protect fire-sensitive vegetation and avoid wildfires. Whereas government-managed areas were affected by large biennial late dry season wildfires, community-managed areas with a regular fire regime suffered less damage. These systems are under threat and poorly understood by researchers and environmental managers. In order to improve fire management in tropical savannas, greater understanding of pastoral management practices and their spatiotemporal dimensions is required.

Tropical summer induces DNA fragmentation in boar spermatozoa: implications for evaluating seasonal infertility.

Summer infertility continues to undermine pig productivity, costing the pig industry millions in annual losses. The boar's inefficient capacity to sweat, non-pendulous scrotum and the extensive use of European breeds in tropical conditions, can make the boar particularly vulnerable to the effects of heat stress; however, the link between summer heat stress and boar sperm DNA damage has not yet been demonstrated. Semen from five Large White boars was collected and evaluated during the early dry, late dry and peak wet seasons to determine the effect of seasonal heat stress on the quality and DNA integrity of boar spermatozoa. DNA damage in spermatozoa during the peak wet was 16-fold greater than during the early dry and nearly 9-fold greater than during the late dry season. Sperm concentration was 1.6-fold lower in the peak wet than early dry whereas no difference was found across several motility parameters as determined by computer-assisted sperm analysis. These results demonstrate that tropical summer (peak wet season) induces DNA damage and reduces concentration without depressing motility in boar spermatozoa, suggesting that traditional methods of evaluating sperm motility may not detect inherently compromised spermatozoa. Boar management strategies (such as antioxidant supplementation) need to be developed to specifically mitigate this problem.

Elephant-induced landscape heterogeneity change around artificial waterholes in a protected savanna woodland ecosystem

In protected areas, establishment of artificial waterholes has been hypothesised to result in increased elephant (Loxodonta africana) densities around these waterholes which would in turn result in changes in landscape heterogeneity. To test this hypothesis this study first tested the relationship between waterhole distribution from remotely sensed waterholes and elephant density in Hwange National Park (HNP), Zimbabwe. The study tested using the coefficient of variation of the Normalised Difference Vegetation Index (NDVI CoV) the short-term effects of varying elephant densities on vegetation heterogeneity change at the landscape scale. This study also tested the relation between artificial waterholes and surrounding landscape configuration and composition change and in addition assessed the potential influence of spatial variability in rainfall on landscape configuration and composition dynamics. Results indicate that elephant density increases in response to the increase in concentration of late dry season waterholes. Results indicate that there is no relationship between elephant density and vegetation heterogeneity change at the seasonal scale (short-term). This could be attributable to differences in sensitivity and response of different vegetation types to elephant browsing even the variable foraging preferences of elephants at the landscape scale regardless of elephant occupation. Findings of this study imply that in the long term, maintenance of artificial waterholes results in a decrease in woody vegetation structural heterogeneity through conversion of woodlands to coppiced bushland in areas with high artificial waterhole density. Findings of this study also show that landscape heterogeneity change is not significantly related to the existing north-east to south-west gradient of decreasing rainfall in HNP.