Suchergebnisse

Intro -- Contents -- Preface -- Chapter 1 -- The Role of Cassava Production in Improving Food Security in the Delta State of Nigeria -- Abstract -- 1. Introduction -- 1.1. An Overview of Global Cassava Production -- 1.2. Problem Statement -- 1.3. Objective of the Study -- 2. Literature Review -- 2.1. Cassava Production in Nigeria -- 2.2. Cassava Production in Delta State of Nigeria -- 2.3. Contribution of Agriculture to Nigerian Economy -- 3. Food Security -- 3.1. Global Food Security -- 3.2. Food Security Situation in Nigeria -- 3.3. Government Interventions and Strategies to Curb Food Insecurity in Nigeria -- 4. Materials and Methods -- 4.1. Study Area -- 4.2. Sources of Data -- 4.3. Data Analysis -- 5. Results and Discussion -- 5.1. Socioeconomic Characteristics -- 5.2. Determinants of Factors Influencing Cassava Production in the Study Area -- 6. Value Chain Concept in Agriculture -- 6.1. Cassava Value Chain in Nigeria -- Conclusion -- Suggestions -- References -- Chapter 2 -- An Assessment of Rural Women's Use of Information and Communication Technologies for Food Security Information in the Niger Delta, Nigeria -- Abstract -- Introduction -- Materials and Methods -- Results and Discussion -- Personal and Socio-Economic Characteristics of the Respondents -- Rural Women's Use of ICTs for Food Security Information -- Personal and Socio-Economic Characteristics Influencing Rural Women's Use of ICTs -- Perceived Constraints to Rural Women's Use of ICTs for Food Security Information -- Conclusion -- References -- Chapter 3 -- Women Food-Crop Entrepreneurs in Southwestern Cameroon: Challenges to Promoting National Food Security -- Abstract -- Introduction -- Food Security in Cameroon and the Sub-Region -- Contextualizing Women and Food Security -- Framing the Study

For many cryptic mammal species, limited distributional data restrict the scope or effectiveness of conservation actions, particularly in relation to habitat protection and/or management. The critically endangered Leadbeater's possum illustrates this, with wet forests throughout its range impacted by logging and bushfire. The possum's habitat has been subject to major disturbance and degradation over recent decades; however, the cryptic behaviour of the species has meant population trajectories have been difficult to monitor. Since 2012, surveys for the possum have been greatly expanded, predominantly based around camera trapping. This paper examines outcomes following a decade of targeted camera trapping for this high-profile threatened species. There have been 1143 camera trapping detections of Leadbeater's possum since 2012, representing 57% of all detections over this period. For comparison, there were just 274 detections of the species over a comparable period during the preceding decade using all other survey techniques. The substantial increase in records reflects greater survey effort, but also the effectiveness of baited camera traps at detecting this cryptic mammal. As a consequence, we have greatly improved understanding of the species' distribution within its core range following major bushfire in 2009. These detection data have informed some aspects of forest management, including the establishment of small logging exclusion areas. Other applications of camera traps have included directing them at dens, providing a non-invasive means of monitoring translocated individuals and reproductive success. Several important caveats regarding camera trapping surveys are discussed, particularly that detection/non-detection data may be insensitive at detecting population declines for communally-denning species such as Leadbeater's possum, where abundance may change more readily than occupancy. A risk accompanying the proliferation of camera trapping is over-reliance on rapid, one-off camera surveys that fail to provide the in-depth insights on demography and population dynamics required to inform effective management of threatened species. This case study highlights the importance of robust survey and monitoring data to inform species conservation planning and management. The results also demonstrate that camera trapping can be as effective and efficient in determining occupancy for some arboreal mammals as it is for terrestrial species, where it is more commonly applied.

Context Invasive species are a leading cause of extinctions, yet predicting their ecological impacts poses a formidable challenge for conservation biologists. When native predators are naïve to invaders, they may lack appropriate behaviours to deal with the invader. In northern Australia, the invasion of the highly toxic cane toad (Rhinella marina) has caused serious population declines of reptilian and mammalian predators that are ill equipped to deal with toad toxins. Cane toads recently invaded the Kimberley region of Western Australia, where they potentially threaten several species of small dasyurid predators. Aims We investigated whether red-cheeked dunnarts (Sminthopsis virginiae) attack cane toads, and if so, whether individuals subsequently learn to avoid toads as prey. Methods We quantified feeding and learning behaviours in toad-naïve red-cheeked dunnarts from the north Kimberley in Western Australia. Key results All toad-naïve dunnarts attacked toads during their first encounter. Most dunnarts bit the toad on the snout, killed it by biting the cranium, and consumed the toad snout-first, thereby initially avoiding the toad's parotoid glands. Most dunnarts partially consumed toads before discarding them, and only one animal showed visible signs of toad poisoning. All dunnarts rapidly learnt to avoid toads as prey after one or two encounters. Predators rejected toads as prey for the duration of the study (22 days), suggesting long-term retention of the knowledge that toads are noxious. Conclusions Our results show that red-cheeked dunnarts rapidly learn to avoid cane toads as prey. Implications Our study was limited by small sample sizes, but our results suggest that small dasyurids can adapt to the cane toad invasion via taste aversion learning.

Context Among amphibians and reptiles, traditional methods of capture–mark–recapture (CMR) have relied on artificial marking techniques (in particular, toe clipping), which has raised concerns because it may impact climbing ability, survival, and behaviour. A potential alternative involves the exploitation of natural biometric identifiers that are already present, including scale configuration or colour patterns. These natural markers can be applied in photo-based CMR, which has several advantages over artificial markers, including reduced costs, the reduction of harm or stress, and the potential for public participation in conservation and research. Aim Our aim was to test the feasibility of applying citizen science in the manual visual identification of the endangered Monaro grassland earless dragon (Tympanocryptis osbornei) using dorsal pattern as a natural marker. Methods We collected photographs of dorsal patterns of wild T. osbornei individuals using a smartphone device under field conditions. We subsequently recruited participants anonymously from the public using social media to complete an online survey, in which they were asked to correctly match these field-captured images of individuals from small image pools, mimicking the process of detecting recapture events. Key results Participants were able to successfully detect recapture events from small image pools based solely on a comparison of dorsal patterns. High consensus was reached on all matches included in the online survey, with the majority vote among participants representing the correct matching of individuals on all occasions. Conclusion Our results indicate that there is sufficient intra-specific variability and temporal stability in dorsal patterning for it to be used as a reliable natural marker for identifying T. osbornei at the individual level. Implications Our findings suggest that photo-CMR could be applied to other agamids with similar dorsal patterns, making it a potentially valuable tool and an alternative to artificial marking for monitoring wild populations of Australian lizards in the future.

We examined the impact of habitat degradation (removal of surface rocks) on an
endangered snake species (Hoplocephalus bungaroides,
Elapidae) at 23 sites in south-eastern Australia, by quantifying the impact of
rock removal on (i) the availability of suitable shelter-sites for the snakes
and their major prey species (the velvet gecko,
Oedura lesueurii), and (ii) the numbers of snakes and
geckos. Our survey showed that both the snakes and the geckos prefer rocks
lying on other rocks, rather than on soil, and select rocks of particular
sizes. The rocks removed by bush-rock collectors overlap considerably in size
(diameter and thickness) and substrate (rock on rock) with those used by
broad-headed snakes and velvet geckos. Multivariate path analysis suggests
that population densities of broad-headed snakes (as measured by capture
rates) may be determined primarily by gecko numbers, which in turn depend upon
availability of suitable rocks. In some sites, rock numbers were substantially
reduced by anthropogenic disturbance. Thus, our survey data suggest that
bush-rock removal has contributed to the endangerment of
H. bungaroides.

Context Understanding the temporal and spatial scales at which wildlife move is vital for conservation and management. This is especially important for semi-aquatic species that make frequent inter-wetland movements to fulfil life-history requirements. Aims We aimed to investigate the drivers of movement and space-use of the imperilled spotted turtle (Clemmys guttata), a seasonal wetland specialist, in three large, isolated wetland complexes in Virginia, USA. Methods We used VHF radio-transmitters to radio-locate adult and juvenile turtles, and estimated movement and space-use during their active and aestivation seasons (March–August). We then used generalised linear mixed models to examine how movement and space-use varied, based on intrinsic turtle characteristics and extrinsic wetland and climatic factors. Key results We show that, on average, individual spotted turtles used five wetlands per year (range 3–13), and that their inter-wetland movement and movement distance varied seasonally in accordance with wetland availability and breeding phenology. Spotted turtle movement and space-use was influenced by the arrangement and size of the wetland complexes, with turtles moving further and occupying larger home-ranges as size and distance between wetlands increased. Inter-wetland movement was not influenced by intrinsic turtle effects but larger adult turtles moved further, used more wetlands, and had larger home-ranges than smaller turtles. Conclusions Turtle responses to variation in season and wetland configuration highlight the need for complex and dynamic landscapes required to sustain this species. Implications This study has important conservation implications showing that spotted turtles rely on a large number of diverse wetlands, as well as upland habitat, to fulfil their resource needs – and that these habitat associations vary seasonally. Results from our study can aid the understanding of spatial and temporal variation in patch characteristics (e.g. quality and extent) and inter-patch movement by organisms, which is critical for the conservation and management of semi-aquatic species and other organisms that occupy patchy habitat complexes.

Abstract
In urban bushland, the installation of nest boxes is widely used to compensate for the loss of natural tree hollows. However, current nest box designs may not provide thermal refuges for wildlife during summer heatwaves, particularly if internal temperatures exceed the upper critical temperatures of wildlife. We investigated whether the addition of roofing insulation to nest boxes deployed for sugar gliders (Petaurus breviceps) and squirrel gliders (Petaurus norfolcensis) in urban bushland would reduce internal nest box temperatures during summer heatwaves. We measured temperatures of 44 insulated and 47 uninsulated nest boxes during one of the hottest summers on record (2018–2019) in the Lake Macquarie region of NSW, Australia, a period during which several prolonged heatwaves occurred. Over the 90-day study, maximum temperatures were, on average, 3.1°C lower in insulated boxes than in uninsulated boxes. The addition of insulation significantly lowered nest box temperatures regardless of aspect (north or south facing) or day of measurement. Temperatures exceeded the upper critical temperature (35.1°C) of gliders more frequently in uninsulated nest boxes (28% of days) than in insulated nest boxes (8% days). Although the addition of insulation to nest boxes lowered their internal temperatures, during heatwaves spanning 23 days, nest box temperatures exceeded the upper critical temperatures of gliders on 58% and 23% of days in uninsulated and insulated nest boxes respectively. These findings underscore the importance of retaining natural hollows in urban bushland to provide thermally suitable refuges for wildlife during extreme heat events.

Context Small population sizes and no possibility of metapopulation rescue put narrowly distributed endemic species under elevated risk of extinction from anthropogenic change. Desert spring wetlands host many endemic species that require aquatic habitat and are isolated by the surrounding xeric terrestrial habitat. Aims We sought to model the occupancy dynamics of the Dixie Valley toad (Anaxyrus williamsi), a recently described species endemic to a small desert spring wetland complex in Nevada, USA. Methods We divided the species' range into 20 m × 20 m cells and surveyed for Dixie Valley toads at 60 cells during six primary periods from 2018 to 2021, following an occupancy study design. We analysed our survey data by using a multi-state dynamic occupancy model to estimate the probability of adult occurrence, colonisation, site survival, and larval occurrence and the relationship of each to environmental covariates. Key results The detection probabilities of adult and larval toads were affected by survey length and time of day. Adult Dixie Valley toads were widely distributed, with detections in 75% of surveyed cells at some point during the 3-year study, whereas larvae were observed only in 20% of cells during the study. Dixie Valley toad larvae were more likely to occur in cells far from spring heads with a high coverage of surface water, low emergent vegetation cover, and water temperatures between 20°C and 28°C. Adult toads were more likely to occur in cells with a greater coverage of surface water and water depth >10 cm. Cells with more emergent vegetation cover and surface water were more likely to be colonised by adult toads. Conclusions Our results showed that Dixie Valley toads are highly dependent on surface water in both spring and autumn. Adults and larvae require different environmental conditions, with larvae occurring farther from spring heads and in fewer cells. Implications Disturbances to the hydrology of the desert spring wetlands in Dixie Valley could threaten the persistence of this narrowly distributed toad.

Context Accurate monitoring data on species presence and distribution are crucial for effective conservation management. Environmental DNA (eDNA)-based techniques, in which species are detected from trace amounts of DNA found throughout the environment, are promising tools that may complement traditional monitoring methods and improve detection. However, imperfect detection is a feature of all survey methods that should be properly assessed so that the probability of detecting a target species' DNA at a site where it is present (i.e. the sensitivity of the method) can be determined. The spot-tailed quoll (Dasyurus maculatus), a carnivorous marsupial found in eastern Australia, is a difficult species to detect as it is rare and has large home ranges, often in remote and difficult to access habitat. Aims In this study, we aimed to evaluate the feasibility of using eDNA soil analysis as a viable alternative or complement to traditional monitoring techniques for detecting spot-tailed quoll. Methods We developed a species-specific assay and validated it using synthetic oligos, tissue samples and soil collected from a captive quoll enclosure. We then assessed the assay on natural environment soil samples taken from the Snowy River region from communal quoll defecation sites (latrines) and from broader quoll habitat. We used amplification success data to model the concentration of quoll DNA in soil from different site types and calculate the sensitivity of our assay. Key results Sensitivity was highest at latrine sites, but decreased sharply when sampling just 1 m away. In non-latrine habitat, the positive amplification rate was too low to allow for meaningful statistical analyses, suggesting that a prohibitively large number of samples would need to be analysed for detection probabilities to be adequate for routine monitoring programs. Conclusions Overall, we found that low sensitivity was driven by the low concentration of spot-tailed quoll DNA at many of the surveyed sites. Implications Given that quoll latrines can usually be identified from the accumulation of scats, and scats themselves can be sampled for DNA, we suggest that eDNA analysis of soil is unlikely to offer improvements over current spot-tailed quoll monitoring methods.

Context Australia has been a battleground of invasive versus native species for ~200 years. Two of the most impactful invasive species to Australian animal communities are the toxic cane toad (Rhinella marina) and the predatory feral cat (Felis catus). Australia's native fauna is evolutionarily naïve to both invaders because neither's taxonomic group is native to the continent. Both invaders have had severe effects on Australian native animal communities including species extinctions, extirpations, and severe population declines, but until now their effects have generally been thought to be independent of one another. Aims We aimed to determine the impacts of invasive cane toads on monitor lizards and feral cats by estimating changes in relative abundance before and after the toad invasion. Methods We studied toad impacts at three sites in the Kimberley region of northern Australia. We used two methods for estimating relative abundance: camera traps and track station data. Data included greater than 4000 trap days and included 7 years over an 11-year period. Key results As expected, invading cane toads rapidly decimated populations of two species of monitor lizards (97–99% declines), including the top-order predatory Varanus panoptes. Unexpectedly, this loss was associated with a >10-fold mean increase in detection rates of cats by 5 years after the loss of V. panoptes, reflecting relative increases of 3.3–8.7 individual cats per site. Conclusions Although some unknown factor may have caused an increase in cats, their similar trophic position and niche to V. panoptes suggests that toads facilitated cats by effectively removing the lizards from the animal community. This interaction likely reflects one type of invasional meltdown, whereby a non-native species (cane toad) facilitated any aspect of another's (feral cat) invasion (e.g. survival, reproduction, resource acquisition), but the latter has no detected influence on the former (+/0 interaction). Implications Because both invaders cause declines in animal populations and are difficult to control, the potentially synergistic tandem of cane toads and feral cats could have chronic, irreversible effects on animal communities.

Context Free-roaming dogs are ubiquitous worldwide and pose a threat to wildlife. An understanding of the roaming behaviour of dogs is useful for developing effective management strategies. Aims We aimed to assess the activity ranges and patterns of free-roaming dogs in a rural Cambodian village. An adjacent wildlife sanctuary protects populations of threatened species that may be negatively impacted by dogs. Methods We used rudimentary hand-made GPS collars to track village dogs and quantify their movements. Activity ranges were calculated for male and female dogs, and the mean distances travelled at night and during the day were determined. Additionally, forays outside of the activity range were characterised. Key results We estimated a mean activity range of 178 ± 190 ha and found that dogs typically travelled longer distances at night. Females had significantly smaller activity ranges, as well as covering shorter distances per day. Foray behaviour was variable, with some dogs entering the wildlife sanctuary regularly and others not at all. Conclusions Free-roaming Cambodian dog activity overlapped with native mammals in the study site, posing a risk of predation, resource exclusion, harassment and competition of Cambodian species. Implications The data suggest that although dogs generally spend the majority of their time within the village, there is significant risk to wildlife. Actions are required to mitigate threats to native wildlife, in particular threatened species such as Eld's Deer.

Context Wildlife is ubiquitous in urban environments, resulting in frequent interactions with humans and human infrastructure. The result of these interactions is often negative, in the form of road injury, orphaning of dependent young or eviction from natural home ranges. Wildlife rehabilitation programmes are devised to counter these negative interactions. However, the success of current management strategies is rarely assessed. Aims We aimed to determine whether short-term survival of juvenile hand-reared common brushtail possums (Trichosurus vulpecula) released in the wild was a function of (1) intrinsic factors such as sex, individual personality and level of human habituation, and (2) extrinsic factors such as release practice (soft vs hard-release) or location (urban vs rural). We also evaluated the relationship between habituation to humans and time spent in care by possums, if presence of conspecifics during the rehabilitation process influenced the development of individual personality, and if this differed in hand-raised animals compared with wild individuals. Methods We radio-tracked and monitored 20 hand-reared juvenile possums (10 females and 10 males) for up to 40 days after release in the wild. Key results Eight possums (40%) survived until the end of the study, nine possums (45%) were killed by foxes or had to be returned into care and three possums (15%) had unknown fates (i.e. lost VHF signal). We found that more exploratory individuals and those less human-habituated were more likely to be successful in the wild in both rural and urban areas, whether or not they were hard or soft released. Conclusions Our results suggest that personality is a key criterion to consider when evaluating the success of rehabilitation programmes. Behavioural traits of hand-reared brushtail possums differed significantly from those of wild individuals, showing that captive conditions can affect the development of personality. Hand-reared possums that spent more time in care were also more likely to display highly human-habituated behaviours. Implications By demonstrating which factors influence success of hand-reared wildlife after release in the wild, our results help in evaluating current rearing and release practices, and improve the evidence base for developing best practice wildlife rehabilitation guidelines.