African Journal of Ecology最新文献

The African savannah elephant (Loxodonta Africana) migrate in response to limiting environmental factors in arid areas. Using global positioning systems (GPS) telemetry data, we determined: (i) the dominant vegetation types used by African savannah elephants and (ii) the differences in the area occupied by dominant vegetation types in Gonarezhou National Park (GNP) in Zimbabwe. Significant spatiotemporal differences (p < 0.05) detected in vegetation types utilised by the African savannah elephant, and in the area covered by vegetation types induced a determinate foraging pattern. Global positioning system telemetry is a smart conservation tool for surveillance of movement patterns of African savannah elephants in protected areas.

Cercopithecus monkeys are a species-rich genus generally considered arboreal frugivores with widespread distribution in sub-Saharan African forests. We studied a largely undocumented species threatened by habitat fragmentation, Cercopithecus denti, during 3 months in 2017 in a small forest fragment of Nyungwe National Park, Rwanda. C. denti's diet was composed of about 58% leaves and 18% fruits. They spent most of their time 10–20 m above ground in secondary forest and open areas. This first systematic study of C. denti shows capacity for a highly folivorous diet, supporting arguments that Cercopithecus have flexible diets, likely enabling persistence in forest fragments.

Wetland conversion threatens wetland specialists by reducing their core habitat. The sitatunga is a wetland specialist with declining populations. However, knowledge of sitatunga ecology and threats is limited, particularly outside protected areas. We examined sitatunga food sources, and habitat use in undisturbed Marshes and Marsh–Savannah transition blocks, and a Cultivated (disturbed) block in River Mayanja wetland, central Uganda. We recorded indirect indices and sightings of sitatunga along a 10 km transect in each block, and surveyed food sources in 34 plots along the transects. Our results indicate that the indices and sightings of Sitatunga had lower relative frequency in the Cultivated than in the Marshes and Marsh–Savannah transition blocks. Sitatunga feed on 39 plant species in 13 families and six growth forms; grasses, herbs, sedges, climbers, shrubs and water weeds. Cyperus papyrus, Echinochloa pyramidalis, Leersia hexandra accounted for 58% of sitatunga food sources. There were more individuals and species with Sitatunga feeding activity in the Marshes and Marsh–Savannah transition blocks than in the Cultivated block. Our results show that sitatunga habitat use and food sources are constrained in disturbed habitats while threats are intensified. To maintain wetland integrity and stability of sitatunga populations, stakeholders need to address wetland encroachment.

Elephants have been structuring woodlands along the Chobe Riverfront, changing them to shrublands. Along with the loss of woodland cover, impala populations seem to be increasing along the Chobe Riverfront. We tested the prediction that elephant-induced loss in woodland cover has increased preferred habitats for impalas along the Chobe Riverfront. We found that home range sizes of impala breeding herds did not differ among seasons at all spatial scales. Impala breeding herds were more selective at broader spatial scales than finer spatial scales in all seasons. Impala breeding herds selected shrublands more than the other habitats throughout the year. The Baikiaea woodland and the riparian woodland were the most avoided habitats, with mixed combretum shrublands and relationships between habitat selectivity and group size, inter-herd encounter and habitat fidelity. The results of our study suggest that impala breeding herds used elephant-transformed habitats throughout the year. Season did not influence habitat selectivity, suggesting that the preferred habitat had higher required resources relative to the other habitats throughout the year.

Over a period of 2 years, we noted that many large mammals in the Murchison Falls National Park, Uganda, remained fairly close to the road—rather than running away—as we drove past at a relatively slow speed, of about 20–25 kph. We consider that over recent years, many of these animals have become habituated to tourist vehicles passing nearby and we recorded the minimum distances at which nine common species remained at, or close to the road edge as we drove past. Many stayed still actually at the edge, while Oribis and Hartebbest sometimes remained on the road itself.

Habitat heterogeneity plays a vital ecological role in influencing community ecology dynamics. We evaluated the relationship between habitat heterogeneity and land-use cover with avian community structure in the human-dominated landscape of the Katavi-Rukwa ecosystem in Tanzania. We used the fixed-radius point count method to record birds in different habitats. We calculated the relative abundances and the Shannon-Wiener diversity index of bird guilds across habitats as well as the Normalised Difference Vegetation Index (NDVI) and estimated land-use cover of the study area from Landsat 8 images. We grouped birds into five major guilds: Insectivore, Granivore, Omnivore, Carnivore and Nectarivore. Among the guilds, Insectivores, Omnivores, Nectarivores and Carnivores were positively correlated with an increase in NDVI, while Granivores were negatively correlated with an increase in NDVI. Among the habitats, woodland had high species diversity whereas riverine had low species diversity. Our findings highlight the importance of habitat heterogeneity in biodiversity conservation in human-dominated landscapes, and we suggest implementing conservation in these landscapes.

Mt. Kasigau is the northeastern most of the Eastern Arc Mountains global hotspot and harbours some endemic and threatened species, but little is known about bird community changes along its elevational gradient. We assessed the relationship between bird biodiversity metrics, season, human disturbance, elevation and temperature using mist-netting data collected bi-annually over a 10-year period. Birds were sampled along the mountain's elevational gradient at four elevation levels (858, 1104, 1321 and 1547 m). Bird richness, diversity and evenness decreased with increasing altitude in both dry and wet seasons. Bird abundance declined with increasing elevation for the lower three elevation levels but peaked at the highest elevation. All diversity metrics were higher in the wet season compared to the dry season across all the years. Elevation had a greater effect on species assemblages than season, disturbance and temperature. Temperature had significant effects on abundance, diversity and richness, while disturbance had significant effects on diversity, evenness and richness. We conclude that bird assemblages in Mt. Kasigau are strongly shaped by elevational changes, while temperature and disturbance constitute important factors influencing bird conservation in the face of global warming. Our study highlights that elevation, disturbance and temperature influence bird assemblages along tropical elevational gradients.

Diadromous macrocrustaceans need connectivity between the ocean, estuary and river to complete their life cycle. Instream barriers in lower reaches of rivers threaten upstream migrations of diadromous macrocrustaceans. Varuna litterata migrate upstream after a spawning event out at sea. These migration events have been poorly documented. We documented the presence V. litterata and Macrobrachium spp. at a vertical slot fishway and a rock ramp on the Lower Thukela River Bulk Water Supply Scheme Weir, KwaZulu-Natal, South Africa, during 2021–2022. We found Macrobrachium spp. and V. litterata made use of the rock ramp. However, the vertical slot fishway did hinder the migration of V. litterata significantly, as found in other studies.

DNA metabarcoding requires reference libraries that link DNA sequences to species. Mitochondrial gene regions cytochrome c oxidase I (COI), 12S ribosomal RNA (12S rRNA), 16S ribosomal RNA (16S rRNA), cytochrome b (cyt b) and the hypervariable control region (D-loop) are routinely used in studies that measure genetic diversity in animal species. This study aimed to review the state of DNA reference libraries for small South African mammals as small mammals constitute a large portion of small and medium carnivore diet. Analyses of DNA records revealed that of 193 small mammal species in South Africa, only 141 have DNA sequences available for one or more of the mitochondrial genes examined. Cyt b had the highest species coverage, with 59.1% of South African species represented in the reference libraries. COI only has 33.7%, 12S rRNA has 23.8%, D-loop has 17.6%, and 16S rRNA has the lowest species coverage of 15%. This study supports the use of multiple gene regions when performing scat metabarcoding, particularly when wanting to determine the small mammal component of the diet. Additionally, it emphasises the need to build comprehensive DNA reference libraries linking sequences to taxonomically identified species.

Scientific exploration of the African continent, particularly during the 1700s and 1800s, was greatly supported by often unrecognised but essential contributions of native hunters, guides, translators, and cultural intermediaries. Their invaluable expertise in facilitating the integration of foreign naturalists into local communities, their capacity to share profound knowledge about the landscape, and their insights into the region's plant and animal life played a pivotal role in the success of numerous epic expeditions. Consequently, these foreign explorers managed to navigate extensive African rivers, venture into uncharted forests, and systematically record the abundant biotic and abiotic resources within untouched landscapes that had experienced minimal human interaction. Many of these unnamed local facilitators can be seen as uncelebrated ‘co-authors’ of many, if not all, the scientific discoveries made during the 1800s and early 1900s. Their unobtrusive existence, at times alluded to in the accounts of naturalists and explorers, acts as a form of ‘conciliation’ between the colonised and the colonisers. This conciliation was intended to promote scientific advancement despite the sombre legacy of colonialism and its deplorable transgressions and crimes (Ewans, 2017; Hickman, 2008; Karari, 2018). In the writings of naturalists from that era, the information provided by native individuals was not only considered fundamental and credible but also deserving of the highest scientific regard and admiration. One of the most renowned examples is the revelation of the Okapi (Okapia johnstoni), credited to the narratives conveyed by Mbuti Pygmies to the naturalist Sir Harry Johnston, which eventually led to the shipment of Okapi skins and skulls to the British Museum (Lankester, 1902). Using the words of Henry Stanley, Lankester (1902) noted that the ‘Warnbutti’ people, a Pygmy tribe, were acquainted with a creature similar to a donkey, which they called ‘Atti’. This term ‘Atti’ was a variant of the name ‘Okapi,’ as confirmed by Johnston from information provided by his native informants. In March 1900, Johnston first heard about the Okapi from the forest-dwelling natives who lived with him in Entebbe, Uganda. In early July, he arrived at the Semliki Forest in the Congo Free State. The first Belgian official to verify the accounts of the Okapi and assist in obtaining the coveted pelts was Lieutenant Rileura. The Okapi's extraordinary diet, primarily composed of leaves, elicited amazement.

In the early 1900s, the scientific approach differed from contemporary conventions, where methodological descriptions were notably less detailed. Nonetheless, if we were to narrate the discovery of the Okapi in a modern context, we would undoubtedly underscore that the Okapi's existence was validated through a meticulous process that involved direct interviews with local hunters belonging