Density Of Large Mammals Research Articles

Effects of Community Participation in the Restoration of Rumuruti Forest in Laikipia County, Kenya

Reforestation is a concerted effort to discover forest formation, biodiversity, and ecosystem practices through tree planting. There is a drive by international organizations to reclaim about 150 million ha of degraded forests by 2030. The Rumuruti Forest is located in the Laikipia County of Kenya. It is a unique and biodiverse forest renowned for its high density of large mammals, including elephants, lions, leopards, and rhinoceroses. The forest is home to several rare species, such as the upright-horned antelope, the black-faced vervet monkey, and the yellow-necked spurfowl. Rumuruti Forest is an expansive 15,378-acre forest located in Laikipia County, Kenya. These benefits had been offset by rapid habitat loss and degradation despite concerted efforts by the Kenyan government to restore as well as maintain this resource. Besides, previous restoration attempts of Rumuruti forest had been ineffective, as indicated by the widespread withering of recently planted seedlings, resulting in a doubling of replanting operations. A descriptive research design was applied to describe the current state of variables that could be identified. The study's specific objective was to investigate the potential socio-economic benefits of Rumuruti forest restoration to community members. A descriptive research design was applied to describe the current state of variables that could be identified. Research took place in Rumuruti town, Laikipia County, Kenya. It is located 40 km due North of Nyahururu. The geographical coordinates of Rumuruti town are 0.25996°N, 36.53633°E, with a population of 31649 people. The target population for this study was 4,800 people. The sample size was 139 households. The study concluded that the community was considerably more eager to work with the government and NGOs to contribute to the restoration of the Rumuruti forest. The community desired to be more involved in the restoration operations, including tree planting, tendering, and protection. As a result, effective processes were put in place to maximize the potential to achieve optimal regeneration of the Rumuruti forest.

Dietary paleoecology of bison and horses on the mammoth steppe of eastern Beringia based on dental microwear and mesowear analyses

In contrast to the modern Arctic, high-latitude ecosystems of the Late Pleistocene supported a diverse range of large mammalian herbivores, including abundant bison (Bison priscus) and horses (Equus sp.). This ‘mammoth steppe’ biome has no extant analog and modern tundra vegetation is likely incapable of supporting such a high density of large mammals. Compared to modern Arctic ecosystems, higher diversity and biomass of Late Pleistocene large mammal populations may have been sustained by more nutritious forage and/or dietary niche partitioning. We used dental microwear texture analysis and dental mesowear analysis of bison and horses (Bison priscus, Equus sp.) to characterize diet and assess the degree to which dietary differences supported co-existence of these dominant and likely competing herbivores on the mammoth steppe. Additionally, we compared microwear and mesowear of Late Pleistocene specimens to modern Alaska bison (reintroduced Bison bison athabascae and introduced Bison bison bison) and published microwear and mesowear data for extant bovids and equids. Our results demonstrate that Late Pleistocene bison and horses had less abrasive diets than modern obligate grazers, suggesting that these “grazers” of the mammoth steppe likely incorporated more forbs in their diets than modern grazers. Furthermore, Late Pleistocene bison and horses ate foods with similar textures, indicating that dietary niche partitioning alone cannot explain their co-occurrence. However, taphonomic differences between bison and horse specimens indicate potential spatial or temporal niche partitioning during the Late Pleistocene.

Performance of spatial capture-recapture models with repurposed data: Assessing estimator robustness for retrospective applications.

Advancements in statistical ecology offer the opportunity to gain further inferences from existing data with minimal financial cost. Spatial capture-recapture (SCR) models extend traditional capture-recapture models to incorporate spatial position of capture and enable direct estimation of animal densities across a region of interest. The additional inferences provided are both ecologically interesting and valuable for decision making, which has resulted in traditional capture-recapture data being repurposed using SCR. Yet, many capture-recapture studies were not designed for SCR and the limitations of repurposing data from such studies are rarely assessed in practice. We used simulation to evaluate the robustness of SCR for retrospectively estimating large mammal densities over a variety of scenarios using repurposed capture-recapture data collected by an asymmetrical sampling grid and covering a broad spatial extent in a heterogenous landscape. We found performance of SCR models fit using repurposed data simulated from the existing grid was not robust, but instead bias and precision of density estimates varied considerably among simulations scenarios. For example, while the smallest relatives bias of density estimates was 3%, it ranged by 14 orders of magnitude among scenarios and was most strongly influenced by detection parameters. Our results caution against the casual repurposing of non-spatial capture-recapture data using SCR and demonstrate the importance of using simulation to assessing model performance during retrospective applications.

Conservation beyond protected areas: Using vertebrate species ranges and biodiversity importance scores to inform policy for an east African country in transition

AbstractConservation in eastern and southern Africa has historically centered on megafauna and protected areas (PAs), yet, in the face of rapid change, biodiversity outside of PAs is under threat. With policy changes underway in Kenya, we have performed an analysis that (a) quantifies how inclusive the current PA network is of the country's vertebrate diversity, and (b) identifies wildlife policy areas that need reform to achieve conservation targets. We found that species richness of mammals, birds, and amphibians is highest in areas of intermediate human pressures, whereas Kenya's current wildlife conservation policy focuses on land use (LU) types with the least human pressure. Percentage of range overlap for amphibians, mammals, and birds were all highest in rangelands followed by agricultural (cultivated) areas and then national PAs. Out of 1,535 terrestrial vertebrate species, 80 had no range overlap with national PAs. The current wildlife PA network adequately covers only 16% of amphibians, 45% of birds, and 41% of mammals. In addition, we used a biodiversity importance score which demonstrated the importance of rangelands and agricultural areas for biodiversity conservation. Finally, we observed that the distribution of current PAs, and the focus of Kenya's wildlife policy in general, is in areas of lowest human pressure, often with the highest large mammal densities. However, other biodiversity indicators ‐ such as bird and plant species richness ‐ show that areas under human‐dominated LU currently support substantial biodiversity. Overall, our analysis demonstrates that formal PAs and wildlife policy presently cover only a small fraction of national biodiversity, which resides mainly in human‐dominated landscapes that are undergoing rapid change. These findings echo global calls for a landscape‐based approach to conservation policy and practice that promotes the coexistence of people and wildlife within social‐ecological systems.

Heterogeneity of water physico-chemical characteristics in artificially pumped waterholes: do African herbivores drink at the same locations and does it lead to interference competition?

In many semi-arid savanna ecosystems, surface water is scarce and only found in artificially pumped waterholes at the end of the dry season, leading to high large mammal densities and competition. Further, the modification of the physico-chemical characteristics of the drinking water over the dry season (e.g. through faeces accumulation) could enhance competition. Indeed, elephants, considered as key-competitors, and other herbivores by aggregating near the trough where clear water arrives could compete for this resource. We studied the drinking locations of eight herbivore species around pumped waterholes in relation to these water characteristics in Hwange National Park, Zimbabwe. We identified differences of the physico-chemical characteristics of the water in different sections of pumped waterholes at the end of the dry season. Elephants drank the water in or close to the trough, whereas other species drank further in the waterhole, except roan and sable antelopes which were indifferent about where they drank. Interference competition with elephants for the access to water close to the trough was not detected for zebras and kudus. We discuss possible directions for future research to enhance our understanding of waterhole use by herbivores.

On the merits and feasibility of wildlife monitoring for conservation: a case study from Katavi National Park, Tanzania

Although long-term monitoring is viewed as an essential part of conserving wildlife populations, it is currently carried out in surprisingly few protected areas in Africa. Here, data from a 16-year vehicle transect monitoring programme in Katavi National Park, western Tanzania, are presented. These data provide information on large mammal densities, identify declines in populations of several large mammal species as based on encounter rates, support worrying trends observed in aerial census data and shed light on the effectiveness of recent changes in legal protection. Ground and aerial surveys confirmed that waterbuck, topi, warthog, lion and spotted hyaena populations are all in decline and that this should be a cause for concern. Counting animals by driving vehicle transects is relatively easy and inexpensive to carry out, and data here show that such counts have several pay-offs for conservation managers especially in identifying population declines; counts should be employed more often in East Africa and elsewhere.

Habitat availability, hunting or poaching: what affects distribution and density of large mammals in western Tanzanian woodlands?

AbstractGame reserves (GR) in Tanzania have been found to support similar or lower densities of large mammals compared with National parks (NP). But as these areas usually differ considerably not only in regard to management but also to environmental factors, we assessed the relative importance of vegetation cover, species‐specific habitat preferences and legal (trophy hunting) and illegal off‐take for observed differences in species‐specific densities. In the Katavi ecosystem, open habitats were characteristic elements of Katavi NP, while Rukwa GR was dominated by miombo forest. In an inter‐specific comparison, density differences were moderately correlated with preferences for open habitats, and with estimates of combined legal and illegal off‐take but not with one of these separately. In a multiple linear regression, open habitat preference was found to explain 39.6% of the density differences between the two protected areas. This analysis suggests that the broad‐scale pattern of most species’ distributions is governed by differing vegetation cover but that several species are overexploited by illegal (elephant, giraffe, buffalo, bush pig, warthog) or combined off‐take (hippopotamus, eland, waterbuck), thus emphasizing the need for quota readjustments and a more efficient anti‐poaching control.

ELEPHANTS AS AGENTS OF HABITAT CREATION FOR SMALL VERTEBRATES AT THE PATCH SCALE

Ecologists increasingly recognize the ability of certain species to influence ecological processes by engineering the physical environment, but efforts to develop a predictive understanding of this phenomenon are in their early stages. While many believe that the landscape-scale effects of ecosystem engineers will be to increase habitat diversity and therefore the abundance and richness of other species, few generalities exist about the effects of engineering at the scale of the engineered patch. According to one hypothesis, activities that increase structural habitat complexity within engineered patches will have positive effects on the abundance or diversity of other organisms. Here I show that, by damaging trees and increasing their structural complexity, browsing elephants create refuges used by a common arboreal lizard. Observational surveys and a lizard transplant experiment revealed that lizards preferentially occupy trees with real or simulated elephant damage. A second experiment showed that lizards vacate trees when elephant-engineered refuges are removed. Furthermore, local lizard densities increased with (and may be constrained by) local densities of elephant-damaged trees. This facilitative effect of elephants upon lizards via patch-scale habitat modification runs contrary to previously documented negative effects of the entire ungulate guild on lizards at the landscape scale, suggesting that net indirect effects of large herbivores comprise opposing trophic and engineering interactions operating at different spatial scales. Such powerful megaherbivore-initiated interactions suggest that anthropogenic changes in large-mammal densities will have important cascading consequences for ecological communities.

Human-Induced Changes in Large Herbivorous Mammal Density: The Consequences for Decomposers

Work on the impacts of herbivores on ecosystems has traditionally focused on aboveground effects, but a growing number of ecologists are beginning to consider how herbivores affect belowground organisms and processes. Human activity has caused considerable changes in densities of mammalian herbivores throughout the world, through the introduction of herbivores to new regions, the creation of conditions that promote high herbivore densities, and the reduction of their population sizes, sometimes to the point of extinction. These human influences on high mammal densities can have major effects on the decomposer subsystem. Whether these effects are positive or negative depends on the mechanisms involved: for example, whether the changes are in the quantity or quality of the decomposers' resources or in the pathway of vegetation succession. In turn, these belowground effects may influence aboveground biota by altering the supply of available nutrients from the soil. Changes in large mammal densities through human activity may represent an important, though frequently underappreciated, element of global change.

Human-induced changes in large herbivorous mammal density: the consequences for decomposers

Work on the impacts of herbivores on ecosystems has traditionally focused on aboveground effects, but a growing number of ecologists are beginning to consider how herbivores affect belowground organisms and processes. Human activity has caused considerable changes in densities of mammalian herbivores throughout the world, through the introduction of herbivores to new regions, the creation of conditions that promote high herbivore densities, and the reduction of their population sizes, sometimes to the point of extinction. These human influences on high mammal densities can have major effects on the decomposer subsystem. Whether these effects are positive or negative depends on the mechanisms involved: for example, whether the changes are in the quantity or quality of the decomposers' resources or in the pathway of vegetation succession. In turn, these belowground effects may influence aboveground biota by altering the supply of available nutrients from the soil. Changes in large mammal densities through human activity may represent an important, though frequently underappreciated, element of global change.

Human impact on wildlife populations within a protected Central African forest

AbstractThis paper addresses the effect of human activities on the density of large mammals in the Dzanga‐Ndoki National Park and the adjacent Dzanga‐Sangha Reserve in the Central African Republic.Between six and eight 20 km long permanent transects were walked on a monthly basis from January 1997 to August 1999 to assess large mammal populations as well as human intrusion. There were no obvious seasonal or monthly trends in elephant, gorilla or non‐human primate densities.Overall, it appears that human activities negatively influence the distribution of most of the large forest animals in Dzanga‐Sangha. Elephants in particular were significantly less common in areas used by humans, but also other species such as non‐human primates showed lower densities closer to the main road and the town of Bayanga. This study confirms the findings of previous studies that roads have a negative impact on wildlife populations.Results of this study stress the need for conservation of large uninterrupted forest blocks to maintain wildlife populations at normal levels. Simply creating roads, even within a protected Central African forest, is likely to have negative impacts on wildlife populations.

Water availability and its influence on the structure and dynamics of a savannah large mammal community

SummaryThe Amboseli ecosystem is in a semi‐arid savannah environment in which water availability is highly seasonal, a feature which has an important bearing on the structure and efficiency of the large mammal community.Data are presented to show that the seasonal movements, a wet season dispersal and dry season concentration of water‐dependent species (obligate drinkers) can be related to the seasonality of rainfall and water availability, but that similar patterns do not prevail in the water‐independent species.Evidence suggests that water availability is a crucial parameter in calculating the carrying capacity of a range, and that the duration of ephemeral supplies, which reflect rainfall seasonality, evapotranspiration, and soil water storage capacity, is equally important. A simplified model is presented which calculates the carrying capacity of water‐bound communities–taking into account these two limiting factors.There appears to be a physiological barrier to a heavy utilization of the low water content grasses beyond reach of the water‐dependent species, since most water‐independent species select high water content browse in order to maintain a positive water balance. Significantly, while the water‐independent community is almost exclusively composed of browsers, most water‐dependent species are grazers. The biomass density of large mammals beyond 15 km from water, a radius which encloses 99‐5% of the biomass of water‐dependent species, is extremely low compared to areas within 10 km of water.As a consequence of the physiological barrier to a heavy utilization of low water content forage in water‐deficient areas, the food chain efficiencies are appreciably lower than those with permanent water sources. Livestock development programmes have long appreciated this constraint and employed water development schemes to increase range‐carrying capacity.Seasonality in the movement patterns of Amboseli is compared to other large mammal communities and management implications are discussed.

The density and biomass of large mammals in Lake Nakuru National Park

SummaryOver the past 70 years, human activity has severely limited the diversity and movements of large mammals in the region of Lake Nakuru National Park, Kenya. Game counts were begun in April 1970 to assess the status of those species remaining. The density of large mammals per km2 was found to be 64.20±8.86 (mean ±S.D.) and the biomass density of the six major species in kg/km2 was 6298±801. The biomass was most heavily concentrated in the grassland‐woodland area south of the lake. Defassa water‐buck was the dominant species accounting for 76% of the biomass density. The probable reasons for their dominance are: (1) favourable habitat; (2) decreased competition; (3) reduced predation; (4) control of poaching; and (5) non‐migratory habits. Future management may ultimately depend on the relationship of waterbuck to the food resources available.