African Journal of Ecology最新文献

Little is known about the diversity and ecology of mesocarnivores in the Mpem and Djim National Parks in central Cameroon. Therefore, we undertook a rapid assessment using camera traps from September 2021 to December 2021. The main objective of our study was to collect data on the diversity, abundance and relative frequency of mesocarnivores per habitat type and their activity period using camera traps with a distance sampling method. In 1700 trap nights, we recorded 53 events of seven mesocarnivores, all belonging to the family of Viveridae, Herpesdidae and Felidae which yield 3.12 mesocarnivores per 100 days. The black-legged mongoose (Bdeogale nigripes, Pucheran, 1855) exhibited the highest capture rate (CR, 0.88). The long-nosed mongoose (Xenogale naso, Winton, 1901) was found in all habitats class and was the more active mesocarnivore. The Shannon-Weaver diversity index (H) showed a high diversity of species in the community with high diversity in the near primary forest. We obtained a lower dominance of one species over the other, a lower richness and a more even distribution of species between habitats. Our results suggest a possible spatio-temporal niche partitioning between the species recorded, with blotched genet (Genetta maculata, Gray, 1830), showing no clear peak of activity. However, the rarefaction curve indicates that the effort expended was insufficient, suggesting that additional sampling is required to obtain a reasonable estimate of species richness within our community. The activity patterns of the recorded mesocarnivores were generally similar to those reported elsewhere but suggest some behavioural flexibility. Although all these species are listed as Least Concern by the IUCN, the low number of recorded events may indicate that mesocarnivores may be threatened in this area if effective conservation strategies are not implemented.

The savannah ecosystem is influenced by seasonal fires that shape the landscape, with different fire intensities. The objective of this study is to assess the trend in fire intensity and the influence of the vegetation types. A linear regression model was employed to analyse the trend in fire intensity over the years. The results demonstrate a linear positive evolution of mean fire intensity over the years, with the highest fire intensity observed during the months of November to January. Woodland, shrub savannah and grassland areas exhibited high fire intensity, whereas wetland areas and forests displayed low fire intensity. Overall, remote sensing techniques can facilitate the monitoring of fire events, specifically fire intensity, in the savannah regions of West Africa, thereby aiding in the implementation of appropriate fire management plans.

Pangolins have generated great interest in recent years, largely due to the unprecedented scale of trafficking the species experiences. Detailed knowledge of pangolin distribution in West Africa is lacking, but many local extinctions are suspected. The last documented sighting of a giant pangolin in Senegal was in Niokolo-Koba National Park (NKNP) and dates back to 1999. Following a large camera-trap survey carried out in NKNP in 2023, we present photographic evidence that giant pangolins are still present in the park. Such rediscoveries not only underscore the importance of systematic biodiversity inventories, but also the critical value of West Africa's large protected areas.

Spotted hyaenas live in unusually large social groups for a carnivore. Since, all else equal, the ‘infertility trap’ (a negative relationship between fertility and the number of females in a group) limits social group sizes to ~5 reproductive females in mammals, hyaena must, like other very social species, have found a way to mitigate the stresses involved in order to do so. From a comparative analysis of data from 19 well-studied Crocuta crocuta populations, I show (1) that the distribution of hyaena clan sizes is multimodal, with a fractal scaling ratio close to 3 and a base unit of 12–15 individuals (3–5 reproductive females), (2) that fertility is a negative function of number of females in the group and (3) that there is a trade-off between the benefits of having more males in the group and the costs incurred by having more females. Although females do buffer themselves against the infertility trap by forming matrilineal alliances (thereby creating a primate-like multilevel structure), males seem to play an important role, such that, in areas with a low density of males, clan sizes are much smaller.

When our dart guns failed in Morocco, we devised an artisanal pressurised air launcher to replace them. The effective shooting range was between 12 and 20 m, which made it possible to capture wild Barbary macaques (Macaca sylvanus), from groups that would not allow for a closer approach or enter any trap. To assess the effect of that method of capture, we monitored the groups on foot before and after the captures. We looked for evidence of a change in risk perception after the captures. We did not uncover any such evidence in the step lengths, turning angles, home range area, frequency of rest while on the ground or frequency of social interactions. We conclude that for the study animals, being captured with our artisanal dart launcher, had a similar effect to being darted with a professional gun, and we intend this note as an inspiration to other field operators finding themselves in a similar predicament.

In many African countries, anthropogenic pressure and poor governance have led to the degradation of wildlife corridors, which are important for the long-term viability of wildlife populations. Yet the nature of such degradation is poorly understood, hindering our ability to reverse these trends. We studied a deteriorating wildlife corridor between Katavi and Mahale National Parks in western Tanzania. Using satellite imagery, we found that the corridor still contains large areas of natural vegetation, diverse terrain and numerous water sources. There has nonetheless been increasing encroachment of the corridor by people between 1990 and 2017, exemplified by a 9% reduction in the area covered by miombo woodlands and a fourfold increase in the area covered by settlements and agricultural land. We used three additional methods to assess deterioration over the last three decades: elephants' movement routes, peoples' perception of animal populations and incidents of human–wildlife conflicts. Elephants were primarily found only in the parts of the corridor adjacent to the two national parks. Tracking of elephant spoor revealed a much-diminished corridor use, suggesting that seemingly ‘healthy’ habitat within a wildlife corridor will not necessarily predict the presence of elephants or perhaps of other species. Other factors particularly the increasing presence of humans in the area are possibly more important for predicting elephant use of a corridor. Interviews with local residents and conservation experts suggested that, although use by some animal species has declined, many ungulates were still seen in the corridor and neighbouring villages, some of which were associated with human–wildlife conflict. All villages around the corridor were affected by the human–wildlife conflict; this comprised crop damage, livestock injury or killing and attacks on humans. We conclude that corridors could be restored if people were restricted from settling, but this would require governments to enact policies that balance the conservation of Natural Capital with survival of human populations; the latter may involve internal migration in response to growing population pressures.

Despite global conservation efforts, elasmobranchs still face increased fishing pressure due to high demand for their products. Although certain species have been afforded international and local protection, the high value of their products in international markets incentivises the trade of protected species covertly within marketed fish products. To address the problem, we amplified fragments of the cytochrome oxidase subunit I gene (approximately 595 base pairs) from 164 elasmobranch fins collected from fish markets in Tanzania to test whether protected species and those of conservation concern are among these specimens. Similarly, we conducted 130 in-depth key informant interviews with stakeholders involved in the elasmobranch-fin trade to gather diverse perspectives on the factors perpetuating the trade. Our findings revealed fifteen elasmobranch species, with requiem sharks (Carcharhinidae) and wedgefishes (Rhinidae) accounting for 44.1% and 33.8% of the fins, respectively. Alarmingly, over 70% of the traded fins originated from threatened elasmobranchs, with 36.8% sourced from critically endangered species. Unexpectedly, almost 9% of the traded fins were sourced from two nationally protected species, Carcharhinus longimanus and Alopias pelagicus, highlighting the existence of regulatory gaps that require immediate attention. Similarly, 91.2% of traded fins were sourced from CITES-listed species, emphasising the severity of the problem. The interviews highlighted technological challenges in tracking the trade, limited awareness of trade impacts on elasmobranch sustainability, scarce surveillance resources, inadequate training to identify routes and offenders and lack of public support as the main factors perpetuating the trade. Addressing these issues necessitates a total ban on elasmobranch-fin trade, coupled with increased funding for enforcement agencies, providing specialised training for law enforcement personnel, launching public awareness campaigns and promoting community-based monitoring and collaboration with international organisations. By doing so, Tanzania can effectively safeguard the sustainability of threatened elasmobranchs and advance global conservation efforts for these fishes.

Sub-Saharan freshwater biodiversity is impacted by changes in land use and climate change. To evaluate the relationship between physico-chemical variables and macroinvertebrate community assemblages in Kakamega and the East Usambara Mountains forests, we explored benthic macroinvertebrate community structure in relation to physico-chemical conditions of the water along an anthropogenic stress gradient. Sampling was done in six selected streams during the rainy and dry seasons between April 2017 and November 2019. At Kakamega, 367 macroinvertebrate individuals were identified belonging to 22 families, while at Usambara, 456 individuals belonging to 25 families were identified. Spearman's correlation revealed significant interactions in species diversity, evenness, and richness between macroinvertebrates and several physico-chemical parameters (pH, conductivity, total dissolved substances, salinity and temperature). At Usambara, species richness, evenness and diversity was significantly negatively correlated with conductivity, tds, salinity, temperature and pH. We demonstrated that macroinvertebrate indices can be used as a quick evaluation tool of water quality in response to stream systems in the region as well as help in pointing out early warnings to help mitigate and reduce threats to stream biodiversity from anthropogenic activities.

This study investigates the response of large mammal populations to human-induced modifications in the Omo-Shasha-Oluwa Forest Reserves landscape. The impact of habitat alterations on species diversity and distribution remains poorly understood in this region. Over four seasons from May 2017 to April 2019, 52 sites were surveyed, revealing the presence of 12 large mammal species across six families. Maxwell's duiker exhibited the highest overall occupancy (0.897 ± 0.062), while the Forest elephant had the lowest (0.115 ± 0.043). Forest buffalo experienced the greatest increase in site occupancy (0.290 ± 0.076 to 0.358 ± 0.098), whereas the Mona monkey saw the most significant decrease (0.713 to 0.651). The study employed single-species, multi-season occupancy modelling, predicting colonisation and extinction events solely for the civet (ϒ = 0.347 ± 0.154; ε = 0.041 ± 0.031) and Red river hog (ϒ = 0.158 ± 0.098; ε = 0.098 ± 0.059). The likelihood of Civet cat and Red river hog colonisation increased with distance from the nearest settlement. These findings enhance our understanding of habitat characteristics influencing large mammal distribution, offering valuable insights for the conservation of these species in forest landscapes.

Human land use can have lasting impacts on landscape characteristic, yet there remains a lack of information on how former land use affects plant communities in protected African grasslands. In this study, we investigated how land uses prior to the creation of Kitulo National Park, Tanzania, shaped the presence and abundance of the native shrub, Helichrysum species. We evaluated both plant species composition and soil properties across the park by dividing our sample into three different zones of historical land use based on participatory mapping. We divided the park into three former land uses: (1) livestock grazed and cultivated; (2) grazed only and (3) wild grazing with limited human impact. We observed that former grazed cultivated land use had five times higher Helichrysum abundance than former ‘wild’ land use. Soil pH, magnesium and phosphorus levels varied significantly across zones of historical land use but not between sites with and without Helichrysum species. Helichrysum splendidum was more abundant in soils with low soil phosphorus and magnesium concentrations. Our study demonstrates that historic grazing and cropping land uses through changes in soil nutrient properties can explain current Helichrysum species spread in protected areas. As such, conservation management plans would benefit from integrating mapping of former land uses to target interventions for problematic encroaching shrubs.