Investigation of the effect of poaching on African elephant (Loxodonta africana) group size and composition in Ruaha National Park, Tanzania

Monitoring the impacts of poaching on wildlife is crucial to the management of ecosystems and wildlife populations. Previous studies have shown that poaching can affect the demography, reproduction and behavior of wildlife. For African elephants (Loxodonta africana), poaching has been shown to affect population numbers, structure, breeding system, behavior and activity patterns. This study investigated whether there were significant differences in group size and composition of African elephants in Ruaha National Park, Tanzania between areas of high- and low poaching levels, based on the 2013 whole-ecosystem aerial census, which we used as a proxy for poaching pressure. Elephant group size and composition were recorded along 417.6 km of monthly transects from May to November 2016, and again from May to November 2017. Comparison of cow/calf group sizes revealed that the group sizes were larger in areas with low poaching pressure. The dependent-to-adult female ratio was higher in areas with low poaching pressure, while the proportion of adult females was higher in areas with high poaching pressure. The proportions of cow/calf and mixed group types were higher in areas with low poaching pressure. A higher proportion of bull groups were seen in areas with high poaching pressure, which could be evidence of a risk response strategy. Therefore, poaching has significantly shaped grouping patterns, composition and has caused reproductive suppression in Ruaha elephants. We recommend a genetic study of this elephant population to establish the degree of relatedness among families to understand the extent of social structure breakdown caused by social stress due to high poaching pressure in the past years

Age structure as an indicator of poaching pressure: insights from rapid assessments of elephant populations across space and time

Detecting and monitoring illegal harvesting pressure on wild populations is challenging due to the cryptic nature of poaching activities. Although change in population age structure has been suggested as an indicator of harvesting pressure, few studies have tested its validity when based on short-term field surveys. Using data from rapid demographic assessment surveys carried out in 2009 at six sites in Tanzania, we examined whether African elephant populations experiencing contrasting levels of poaching pressure showed significant differences in their age structure, operational sex ratio (i.e. adult males to adult females), dependent individual to adult female ratio at the group level, and proportion of tuskless individuals. We also compared similar metrics between the population sampled in Ruaha National Park in 2009 and again in 2015 following a suspected increase in poaching. Elephant populations experiencing medium and high levels of poaching in 2009 were characterised by fewer calves and old individuals, a reduced number of adult males relative to adult females, and a lower ratio of calves to adult females within groups. We also found a higher proportion of tuskless individuals in poached populations (>6%). Changes in age structure in the Ruaha population between 2009 and 15 were similar to those observed across sites in 2009. Our findings are consistent with previous work documenting how the loss of older individuals – targeted for their larger tusks – decreases recruitment and survival of elephant calves. Illegal killing for ivory is a huge threat to the survival of African elephants. In this context, the present study contributes towards validating the use of age structure as an indicator of poaching pressure in elephant populations, but also in other wildlife populations where illegal offtake is targeted at specific age classes

Camera trapping and spatially explicit capture-recapture for the monitoring and conservation management of lions: Insights from a globally important population in Tanzania

Accurate and precise estimates of population status are required to inform and evaluate conservation management and policy interventions. Although the lion (Panthera leo) is a charismatic species receiving increased conservation attention, robust status estimates are lacking for most populations. While for many large carnivores population density is often estimated through spatially explicit capture–recapture (SECR) applied to camera trap data, the lack of pelage patterns in lions has limited the application of this technique to the species. Here, we present one of the first applications of this methodology to lion, in Tanzania's Ruaha-Rungwa landscape, a stronghold for the species for which no empirical estimates of status are available. We deployed four camera trap grids across habitat and land management types, and we identified individual lions through whisker spots, scars and marks, and multiple additional features. Double-blind identification revealed low inter-observer variation in photo identification (92% agreement), due to the use of xenon-flash cameras and consistent framing and angles of photographs. Lion occurred at highest densities in a prey-rich area of Ruaha National Park (6.12 ± SE 0.94 per 100 km2), and at relatively high densities (4.06 ± SE 1.03 per 100 km2) in a community-managed area of similar riparian-grassland habitat. Miombo woodland in both photographic and trophy hunting areas sustained intermediate lion densities (1.75 ± SE 0.62 and 2.25 ± SE 0.52 per 100 km2, respectively). These are the first spatially explicit density estimates for lion in Tanzania, including the first for a trophy hunting and a community-managed area, and also provide some of the first insights into lion status in understudied miombo habitats. We discuss in detail the methodology employed, the potential for scaling-up over larger areas, and its limitations. We suggest that the method can be an important tool for lion monitoring and explore the implications of our findings for lion management

Anthropogenic risk increases night-time activities and associations in African elephants (Loxodonta africana) in the Ruaha-Rungwa ecosystem, Tanzania

Elephants face diverse threats from human activities and use temporal and social strategies to reduce human-induced mortality risk. We used data from camera trap surveys in 2018–2019 (n= 1625 independent detection events from 11,751 sampling days) to investigate elephant responses to anthropogenic risk in the Ruaha-Rungwa ecosystem, Tanzania. The study was conducted in one low- risk and three high- risk sites using 26–40 paired camera trap stations per site. Risk influenced the active pe-riods, use of roads and water sources, social associations and behaviour of elephants. Elephants demonstrated significantly more night-time and reduced daytime activ-ity in the high- risk sites relative to the low- risk site. This higher night-time activity in the high- risk sites was observed for both males and females, though it was more pronounced for cow–calf groups than lone males. Foraging events and use of water sources were more frequent at night in the high- risk sites. Elephants used roads as movement routes in the low- risk site but avoided roads in the high- risk sites. Males were significantly more likely to associate with other males and cow–calf groups in the high- risk sites. Fewer occurrences of relaxed behaviours were observed in the high- risk sites compared to the low- risk site. We discuss the potential implications of our findings for elephant survival and reproduction.Output Status: Forthcoming/Available Onlin

Leopard population density varies across habitats and management strategies in a mixed-use Tanzanian landscape

With large carnivores undergoing widespread range contractions across Africa, effective monitoring across mixed-use landscapes should be considered a priority to identify at-risk populations and prioritise conservation actions. We provide the first comparison of leopard population density within different components of a mixed-use landscape in Tanzania, via spatially explicit capture-recapture (SECR) modelling of camera trap data from the Ruaha-Rungwa landscape in 2018 and 2019. Population density was highest in highly-productive Acacia-Commiphora habitat in the core tourist area of Ruaha National Park (6.81 ± 1.24 leopards per 100 km2). The next highest density (4.23 ± 1.02 per 100 km2) was estimated in similar habitat in a neighbouring community-managed area (Idodi-Pawaga MBOMIPA WMA). Lowest densities were estimated in miombo (Brachystegia-Jubelnardia) woodland habitat, both in a trophy hunting area (Rungwa Game Reserve; 3.36 ± 1.09 per 100 km2) and inside the National Park (3.23 ± 1.25 per 100 km2). Population density was highly correlated with prey abundance, suggesting that variation in leopard density may be primarily driven by availability of prey, which likely varies with habitat types and anthropogenic impacts. Anthropogenic mortality may also have a direct influence on leopard in more impacted areas, but further research is required to investigate this. Our findings show that a hunting area with significant protection investment supports a leopard density comparable to similar habitat in a photographic tourism area. We also provide evidence that community-managed areas have the potential to effectively conserve large carnivore populations at relatively high densities, but may be vulnerable to edge effects