ABSTRACT

In September 2024 and 2025, Biosphere Expeditions’ citizen scientists supported research activities conducted by Lilongwe Wildlife Trust (LWT) in Vwaza Marsh Wildlife Reserve (VMWR) for the fifth and sixth year running since 2018 (excluding COVID years 2020 and 2021) This combined 2024/2025 report presents comparative 2024/2025 data, as well as across all six expeditions, to examine ecological changes in VMWR.

Data collected during the annual Biosphere Expeditions projects in VMWR have been invaluable in monitoring biodiversity and megafauna population levels. Elephant populations appear to be stable and not consuming cultivated crops. Hippo populations have dramatically declined over the past six years and the reasons for this decline should be investigated and management strategies developed in partnership with Nyika-Vwaza Co-Management Trust (NVCMT). The expedition so far has been limited to one or more groups during the dry season. It is recommended to replicate the expedition work during other seasons, potentially bi-annually, to assess seasonality of these results. Group-specific results were:

Elephant herd sightings and dung sampling: Across Malawi, conflict between humans and elephants Loxodonta africana - when elephants leave protected areas and enter community- or farm-land - has become an increasing threat to human livelihoods. This in turn is a threat to elephants, which are at risk of retaliatory attacks when they forage on crops. In 2021, a fence was erected along the southern and eastern boundaries of Vwaza Marsh Wildlife Reserve (VMWR) in an attempt to keep the elephants inside the reserve. In 2025 citizen scientists recorded 323 elephants in 38 sightings (four solo males and 34 herds) inside VMWR. This was low compared to most previous years apart from 2023. However, the decline over time was not statistically significant. Citizen scientists also added one new elephant ID to the LWT elephant database and updated three existing IDs. 146 dung boli samples were also collected and their seed content analysed to assess which plant species elephants feed on and whether crops are being consumed. No evidence of crop consumption was found, despite recent reports of elephants leaving the park. This was consistent with previous years. 

Hippo transects: Hippopotamus amphibius teeth are a source of ivory, making this species susceptible to poaching. Within VMWR, Lake Kazuni and the southern section of the Rukuru River are the only permanent water sources and therefore primary areas for hippos. Monitoring them is essential and Biosphere Expeditions’ annual monitoring is the only effort of this kind. The expedition completed six transects along the northern lakeside, which resulted in 502 hippos being counted. The largest single transect count was 114. The hippo population trend in VMWR has statistically significantly decreased over time, with peaks in 2018 and 2019 and the lowest counts in 2024. There was a population increase from 2024 to 2025. However, this was still much lower than 2018 and 2019 levels. The reasons for this decline are as yet unknown.

Camera trapping: Camera traps are a non-invasive way to monitor biodiversity and detect elusive and shy species, which may not be otherwise detected. 14 camera traps were deployed by the expedition along the two main roads within the reserve (the main track and northern track), as well as six at sites of animal activity, such as mammal paths, along the lakeside and airstrip. Over 264 camera trap nights, the cameras recorded 2835 animal photos of 24 species with hippos recorded the most (972 photos over 95 captures). Other noteworthy species included leopard Panthera pardus, serval Leptailurus serval and side-striped jackal Lupulella adusta. Results were consistent with previous years, and the number of species captured over the expeditions did not differ significantly. 

Bird transects: Birds are an excellent indicator of overall ecosystem health, particularly aquatic birds. VMWR has sporadically monitored bird diversity in the past, but records have not been updated recently so this activity was added to update records. The expedition conducted four bird transects along the northern section of the lakeside and recorded 42 species over 85 sightings. 

Night transects: Nocturnal mammals are elusive and difficult to monitor. To complement the camera trapping study and make biodiversity assessments more robust, the expedition conducted four evening/early morning driving transects around the southern area of VMWR, recording any nocturnal mammals spotted along with opportunistic sightings of other taxa. This resulted in 19 species recorded across 89 sightings, including African civet Civettictis Civetta and bushy-tailed mongoose Bdeogale crassicauda.

iNaturalist: iNaturalist is a digital citizen science platform to upload evidence-based wildlife observations. iNaturalist has been used across expeditions in VWMR enabling species diversity comparisons across years. In 2025, citizen scientists recorded 171 observations of 109 species. Birds were the most recorded taxa followed by mammals. Since 2022, birds have remained the taxa with the highest number of records. Observations and number of species peaked in 2022 at 389 and 154, respectively, with 2025 seeing the second highest numbers for each of these categories.