Long‐term persistence of wildlife populations in a pastoral area

Facilitating coexistence between people and wildlife is a major conservation challenge in East Africa. Some conservation models aim to balance the needs of people and wildlife, but the effectiveness of these models is rarely assessed. Using a case‐study approach, we assessed the ecological performance of a pastoral area in northern Tanzania (Manyara Ranch) and established a long‐term wildlife population monitoring program (carried out intermittently from 2003 to 2008 and regularly from 2011 to 2019) embedded in a distance sampling framework. By comparing density estimates of the road transect‐based long‐term monitoring to estimates derived from systematically distributed transects, we found that the bias associated with nonrandom placement of transects was nonsignificant. Overall, cattle and sheep and goat reached the greatest densities and several wildlife species occurred at densities similar (zebra, wildebeest, waterbuck, Kirk's dik‐dik) or possibly even greater (giraffe, eland, lesser kudu, Grant's gazelle, Thomson's gazelle) than in adjacent national parks in the same ecosystem. Generalized linear mixed models suggested that most wildlife species (8 out of 14) reached greatest densities during the dry season, that wildlife population densities either remained constant or increased over the 17‐year period, and that herbivorous livestock species remained constant, while domestic dog population decreased over time. Cross‐species correlations did not provide evidence for interference competition between grazing or mixed livestock species and wildlife species but indicate possible negative relationships between domestic dog and warthog populations. Overall, wildlife and livestock populations in Manyara Ranch appear to coexist over the 17‐year span. Most likely, this is facilitated by existing connectivity to adjacent protected areas, effective anti‐poaching efforts, spatio‐temporal grazing restrictions, favorable environmental conditions of the ranch, and spatial heterogeneity of surface water and habitats. This long‐term case study illustrates the potential of rangelands to simultaneously support wildlife conservation and human livelihood goals if livestock grazing is restricted in space, time, and numbers.     

Antipredator behaviour of African ungulates around human settlements

As human populations grow and come into more frequent contact with wildlife, it is important to understand how anthropogenic disturbance alters wildlife behaviour. Using fine‐scale spatial analyses, we examined how proximity to human settlements affects antipredator responses of ungulates. We studied seven common ungulate species (Kirk's dik‐dik, Thomson's gazelle, impala, common warthog, common wildebeest, common zebra and Masai giraffe) in the Tarangire–Manyara ecosystem in northern Tanzania. In zebra and giraffe, flight responses to humans were significantly more likely when closer to settlements; however, there was a weak relationship between flight responses and distance to settlement in all other species. While there was largely a weak relationship between proximity to human settlements, the distribution of settlements in the landscape appears to affect wildlife behaviour, suggesting that animals perceive and respond to spatial variation in risk exerted by humans.     

Human impact on wildlife populations within a protected Central African forest

This 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.     

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.     

Locating elephant corridors between Saadani National Park and the Wami‐Mbiki Wildlife Management Area,Tanzania

Although more than 40% of Tanzania mainland is managed for nature conservation, protected areas are increasingly becoming isolated because of rapid habitat degradation in the matrix in between. Knowledge on corridors connecting the protected areas is urgently needed. We assessed the area between Saadani National Park and Wami‐Mbiki Wildlife Management Area, combining interviews about wildlife occurrences from 20 villages in the area with least‐cost landscape modelling with African elephants (Loxodonta africana) as the focal species. The interviews suggested that, in contrast to earlier assumptions, migration of elephants or the presence of one or more independent elephant populations still exists in the unprotected area between Saadani and Wami‐Mbiki. A combination of the interview results and multiple least‐cost models showed three corridors in the area. The corridor along the Wami river is the most important one, the area between Miono and Mandera was identified as an impeding zone. Management decisions on the wildlife corridors to be protected will require further in‐depth research in the three specified corridor zones. Apart from providing insights into elephant movement ecology, the approach may be useful for localizing corridors elsewhere in eastern Africa.     

Using citizen‐based survey data to determine densities of large mammals: a case study from Mana Pools National Park,Zimbabwe

Since 1993, members of the national wildlife society have undertaken annual surveys of large mammals in the Zambezi alluvial woodlands of Mana Pools National Park, Zimbabwe. Data are collected along 36 systematically‐arranged transects. We provide the first thorough assessment of the data from any survey within this long‐term project. The transect data from 2011 were analysed with DISTANCE software to assess if the data were suitable for determining the densities of large mammals using distance sampling techniques. Successful application of distance sampling depended on observers using printed, large‐scale, georeferenced satellite images onto which they mapped the location of animal groups detected. The assumptions of the distance sampling were well met and thus the 2011 survey provided reliable estimates of the densities of nine species of common large mammals on the Zambezi alluvium during the late dry season. Estimated density in this dry‐season concentration area varied from 3.6 km^?2 for kudu, to 204 km^?2 for impala. The precision of the estimates ranged from a coefficient of variation of 7.9% for elephant, to 25.5% for buffalo. For elephant, warthog and baboon, the morning and afternoon densities differed significantly.     

An empirical evaluation of the African elephant as a focal species for connectivity planning in East Africa

Aim Large, charismatic and wide‐ranging animals are often employed as focal species for prioritizing landscape linkages in threatened ecosystems (i.e. ‘connectivity conservation’), but there have been few efforts to assess empirically whether focal species co‐occur with other species of conservation interest within potential linkages. We evaluated whether the African elephant (Loxodonta africana), a world‐recognized flagship species, would serve as an appropriate focal species for other large mammals in a potential linkage between two major protected area complexes. Location A 15,400 km² area between the Ruaha and Selous ecosystems in central Tanzania, East Africa. Methods We used walking transects to assess habitat, human activity and co‐occurrence of elephants and 48 other large mammal species (> 1 kg) at 63 sites using animal sign and direct sightings. We repeated a subset of transects to estimate species detectability using occupancy modelling. We used logistic regression and AIC model selection to characterize patterns of elephant occurrence and assessed correlation of elephant presence with richness of large mammals and subgroups. We considered other possible focal species, compared habitat‐based linear regression models of large mammal richness and used circuit theory to examine potential connectivity spatially. Results Elephants were detected in many locations across the potential linkage. Elephant presence was highly positively correlated with the richness of large mammals, as well as ungulates, carnivores, large carnivores and species > 45 kg in body mass (‘megafauna’). Outside of protected areas, both mammal richness and elephant presence were negatively correlated with human population density and distance from water. Only one other potential focal species was more strongly correlated with species richness than elephants, but detectability was highest for elephants. Main conclusions Although African elephants have dispersal abilities that exceed most other terrestrial mammals, conserving elephant movement corridors may effectively preserve habitat and potential landscape linkages for other large mammal species among Tanzanian reserves.     

Performance of individual species as indicators for large mammal species richness in Northern Tanzania

In order to prioritize areas for biodiversity conservation, conservation practitioners frequently employ a single species whose distribution is statistically related to overall species richness. However, the performance of single mammal species in terms of (1) their strength, (2) spatial and (3) temporal variability for predicting large mammal species richness has rarely been assessed. Drawing upon data from multiple vehicle-based surveys in four study sites with varying conservation management approaches in the Tarangire–Manyara ecosystem, we assessed the performance of thirteen candidate indicator species. Overall, we found that the association strength between the distribution of single large mammal species and overall large mammal species richness varied (1) considerably across four management units within the same ecosystem, (2) between seasons and (3) years. In contrast to a study carried out in central Tanzania, elephants performed poorly as an indicator of large mammal species richness. Applying our findings to conservation planning, we suggest that information on zebra and wildebeest distribution should be used for delineating corridors for large mammals between protected areas in this ecosystem. The distribution of these two species had a high correlation with overall large mammal species richness, and these correlations were relatively constant throughout time and space. More generally, our study suggests that the performance of indicator species (1) should be assessed across multiple seasons because snapshot surveys may provide biased estimates of indicator performance, (2), cannot necessarily be extrapolated to other ecosystems and (3) should be supplemented by ecological or functional considerations.     

Environmental factors affecting the distribution of African elephants in the Kasigau wildlife corridor,SE Kenya

The African elephant, Loxodonta africana, is under threat from habitat loss, poaching and human–elephant conflict. To mitigate for impact of habitat loss and reduce conflict, connectivity between elephant habitats can be improved through the protection of corridor areas. This study looks at elephant distribution and movement patterns within the Kasigau Wildlife Corridor (KWC) within the Tsavo Conservation Area in South‐east Kenya. Elephant presence data were obtained from observations by rangers during routine patrols across KWC, and were analysed in MaxEnt. The environmental factors predicting elephant distribution and density were tested, as well as the relationship between elephant maximum entropy and the presence and abundance of other wildlife. Seasonal variations in temperature and precipitation, plus presence of waterholes were found to play significant roles in elephant distribution across KWC. Higher elephant densities were not found to correlate with lower densities of other wildlife species; indeed, during the dry seasons, elephant presence was associated with greater wild herbivore densities. Besides illustrating the importance of the KWC for elephant conservation in the Tsavo ecosystem, both as a key corridor and habitat, this study also hopes to highlight the untapped utility of routine ranger patrol data, and encourage the use of such presence‐only data for deducing important knowledge for conservation of biodiversity.     

Response of native ungulates to drought in semi‐arid Kenyan rangeland

The distribution and abundance of native ungulates were measured on commercially managed, semi‐arid rangeland in central Kenya over a 3‐year period that encompassed severe drought and above‐average rainfall. Native ungulate biomass density averaged 5282 kg km^?2 over the study and was dominated by elephant (Loxodonta africana), impala (Aepyceros melampus) and dik‐dik (Madoqua kirkii). Biomass density of domestic cattle (Bos taurus) averaged 2280 kg km^?2 during the study. Responses of native ungulates to severe drought were variable. Impala densities were similar to or greater than densities for similar habitat in protected areas, and varied from 12 to 16 km^?2 during and following the drought to 24–29 km^?2 following above‐average rainfall. Dik‐dik densities were also greater than densities reported for protected areas and were surprisingly stable throughout the study despite the wide annual fluctuations in rainfall. Elephant migrated out of the region during drought but were present at high densities (2.9–5.2 km^?2) during wet seasons, consistent with telemetry studies emphasizing the importance of Acacia bushland habitat on commercial rangelands for the migratory portion of the Laikipia–Samburu elephant population. Results show that substantial densities of native browsing and mixed‐feeding ungulates can occur on rangeland managed for commercial beef production and suggest that the capacity for ungulates to move over large spatial scales (>100 km²) and to shift distributions in response to locally variable thunderstorms may be important for sustaining these populations.     

The migration of zebra and wildebeest between Tarangire National Park and Simanjiro Plains, northern Tanzania, in 1972 and recent trends

In 1972, four aerial censuses were carried out to assess the annual migration of zebra and wildebeest between Tarangire National Park and Simanjiro Plains. About 6000 zebra and 10,000 wildebeest were in the Plains in the middle of the rainy season, in April. During the dry season in August the animals were concentrated in the Park. The migration from the Park to the Plains started at beginning of the rains, in November/December. Recent censuses by Tanzania Wildlife Conservation Monitoring (TWCM, 1991, 1995) indicate that an estimated 23,000 zebra and 11,000 wildebeest migrate into the Park from Simanjiro and other wet season areas. Encroaching cultivation is a threat to the migration corridors and sustainability of the ecosystem . Providing benefits from wildlife to communities around the park would safeguard the future of the wildlife.     

Fire frequency drives habitat selection by a diverse herbivore guild impacting top–down control of plant communities in an African savanna

In areas with diverse herbivore communities such as African savannas, the frequency of disturbance by fire may alter the top–down role of different herbivore species on plant community dynamics. In a seven year experiment in the Kruger National Park, South Africa, we examined the habitat use of nine common herbivore species across annually burned, triennially burned and unburned areas. We also used two types of exclosures (plus open access controls) to examine the impacts of different herbivores on plant community dynamics across fire disturbance regimes. Full exclosures excluded all herbivores > 0.5 kg (e.g. elephant, zebra, impala) while partial exclosures allowed access only to animals with shoulder heights ≤ 0.85 m (e.g. impala, steenbok). Annual burns attracted a diverse suite of herbivores, and exclusion of larger herbivores (e.g. elephant, zebra, wildebeest) increased plant abundance. When smaller species, mainly impala, were also excluded there were declines in plant diversity, likely mediated by a decline in open space available for colonization of uncommon plant species. Unburned areas attracted the least diverse suite of herbivores, dominated by impala. Here, herbivore exclusion, especially of impala, led to strong declines in plant richness and diversity. With no fire disturbance, herbivore exclusion led to competitive exclusion via increases in plant dominance and light limitation. In contrast, on triennial burns, herbivore exclusion had no effect on plant richness or diversity, potentially due to relatively little open space for colonization across exclosure treatments but also little competitive exclusion due to the intermediate fire disturbance. Further, the diverse suite of grazers and browsers on triennial burns may have had a compensating effect of on the diversity of grasses and forbs. Ultimately, our work shows that differential disturbance regimes can result in differential consumer pressure across a landscape and result in heterogeneous patterns in top–down control of community dynamics.     

Population size estimation of an Asian elephant population in eastern Cambodia through non-invasive mark-recapture sampling

The Asian elephant is a flagship species for conservation in tropical Asia, but reliable population estimates are available only from a few populations. This is because the species can be elusive and occurs at low densities in dense habitat over a large part of its range. Phnom Prich Wildlife Sanctuary in the Eastern Plains, Cambodia, which is part of one of the largest protected area complexes in South-East Asia, is one such habitat that had not been systematically censused for elephants. We, therefore, used fecal-DNA based capture-mark-recapture sampling to estimate the population size for establishing a monitoring baseline. Five sampling sessions targeted all areas in and adjacent to Phnom Prich Wildlife Sanctuary believed to be used by elephants. Fresh dung was collected as the source of DNA and genotyping was carried out based on nine microsatellite loci. The 224 samples collected yielded 78 unique genotypes. Using model averaging of closed population capture-mark-recapture models, the elephant population in Phnom Prich Wildlife Sanctuary was estimated to number 136 ± 18 (SE) individuals. Our results suggest that eastern Cambodia supports a regionally important Asian elephant population.     

The influence of trap density and sampling duration on the detection of small mammal species richness

Assessing species richness of small mammal communities is an important research objective for many live-trapping studies designed to assess or monitor biological diversity. We tested the effectiveness and efficiency of various trap densities for determining estimates and counts of small mammal species richness. Trapping was conducted in grassland habitats in northeastern Kansas during spring and fall of 2002 and 2003. Estimates and counts of species richness were higher at increased trap densities. This effect appeared to be primarily due to the higher number of individuals sampled at higher trap densities. At least 3 nights duration was needed to produce a stable estimate of species richness for the range of trap densities tested (9–144 trap stations/ha). Higher trap densities generally reached stable richness estimates in fewer nights than low density trapping arrangements. Given that counts and estimates of species richness were influenced by trap density and sampling duration, it is critical that these parameters are selected to most effectively meet research objectives.     

The use of teak (Tectona grandis) plantations by large mammals in the Kilombero Valley, southern Tanzania

The establishment of plantations is impacting the large mammal populations of the Kilombero Valley, Tanzania. Animal spoors were used as a proxy for activity to determine the influence of teak stand age on mammals. Habitat variables were compared between different aged stands to investigate the relationship between mammal activity and vegetation characteristics. Vegetation surveys found plantation composition to differ with age; with young stands characterized by slender teak trees, limited leaf litter, abundant grass layer and substantial bare ground. Older plantations contained a high leaf litter layer and dead wood, low grass abundance and minimal bare ground. Spoor transects revealed that mammal species number decreased as the teak matured. Of those vegetation variables tested, grass and bare ground abundance explained significantly the variation in species number and in individual species' habitat use between differently aged stands; therefore this habitat use was influenced by the foraging value of the plantation. This study showed that several species (some of which warrant conservation attention, such as elephant) use plantations <6 years old to a greater extent than plantations >6 years. Thus, there is a need for conservation measures, such as wildlife corridors and staggered teak planting to be continued, allowing large mammal movements in the valley.     

Model highlights likely long‐term influences of mesobrowsers versus those of elephants on woodland dynamics

The potential long‐term influences of mesobrowsers versus those of savannah elephants on woodland dynamics have not been explored. This may be a critical omission especially in southern African savannahs, where efforts to preserve existing woodlands are typically directed at elephant management. We describe a simple browse–browser model, parameterized from an extensive review of the literature and our own data, including quantitative assessment of impala impact, from the study site, iMfolozi Park, South Africa. As there is a paucity of species‐specific demographic data on savannah woody species, we modelled, in a novel approach, functional groups of plant species typical of Acacia woodlands. Outputs suggest that over the long term (100 years), low‐to‐moderate densities of impala will have a similar impact on woodland structure, in terms of density of adult trees, as low‐to‐moderate densities of elephant. Further, the outputs highlight the apparently strong synergistic effect impala and elephant impacts combined have on woodland dynamics, suggesting that reduction or removal of either impala or elephant will radically reduce long‐term destruction of savannah woodlands. Recorded changes in adult tree numbers in iMfolozi broadly supported the model's outputs.     

Participatory wildlife surveys in communal lands: a case study from Simanjiro,Tanzania

It is widely accepted that protected areas alone are not sufficient to conserve wildlife populations particularly for migratory or wide‐ranging species. In this study, we assess the population density of migratory species in the Tarangire–Simanjiro Ecosystem by conducting a ground census using DISTANCE sampling. We focus on the Simanjiro Plains which are used as a dispersal area by wildebeest (Connochaetes taurinus) and zebra (Equus burchellii). We demonstrate that DISTANCE sampling can provide precise estimates of population density and is an affordable method for monitoring wildlife populations over time. We stress the importance of involving local communities in monitoring programmes across landscapes that incorporate communal lands as well as protected areas.     

Censusing large mammals in Kibale National Park: evaluation of the intensity of sampling required to determine change

Monitoring programmes are essential for management of large mammal populations because they can detect population change. It is vital that we have the means to evaluate the effectiveness of protected areas. Kibale National Park is a stronghold for large mammal conservation in Uganda. Past wildlife surveys in Kibale focused on specific taxa or areas, but our large mammal survey covered the entire protected area and we evaluated the intensity of sampling required to determine population change. Using line transect sampling, we found that the distribution of large mammals was nonrandom and related to habitat‐type. However, confidence intervals of population estimates revealed that much more intensive sampling was required to detect changes in population density at a time scale reasonable for management. For many species, populations would have to decline by 40–60% for this method to detect population change. Post‐stratification decreased confidence intervals of density estimates slightly, increasing our ability to detect change. However, confidence intervals of estimates were still too large to detect a meaningful population change on a time scale that would allow management to take action. Most incidences of illegal activity were about 5 km from the park boundary; however, animal densities were not lower in this area.     

Optimising sampling methods for small mammal communities in Neotropical rainforests

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Measuring species diversity while counting large mammals: comparison of methods using species-accumulation curves

With a growing need for wildlife conservation and management in the communal lands of Africa, comprehensive ecological monitoring tools need to be developed and evaluated. While wildlife census methods are often compared in terms of precision and accuracy to estimate the population size of various target species, little attention has been paid to the measure of species diversity in mammal communities. A combined measure of abundance and community composition is, however, a crucial source of information in determining conservation priorities and to evaluate the ecosystem responses to management activities. In this study, we present five census methods of large to medium‐sized mammals and compare their efficacy in measuring species diversity. A species accumulation curve analysis is used with a predictive model to estimate the local species richness, the level of completeness of our censuses as well as the effort required to carry out a census. Advantages and limits of each method are discussed through comparison of their respective measure of species richness and their species accumulation rate. Results illustrate a large difference between methods in the ability for species detection, with censuses completed by bicycle offering the best option within the context of a unprotected area.