David Lehmann

• Dr.
• University of Stirling

Understanding primate dietary plasticity provides insights into trait evolution and resilience to environmental change. Here, we investigate the feeding ecology of mandrills ( Mandrillus sphinx ), a species that forms groups of close to 1000 individuals, which presumably impacts feeding ecology by creating exceptionally high feeding competition. Ma...

The present work reports on new records of the flat-headed or Cameroon cusimanse (Crossarchus platycephalus) obtained from camera trap surveys carried out between 2021 and 2023 in central and northwestern Gabon. These records—in the form of high-definition videos—extend the southern limit of the species' known range by 172 km, as well as provide ad...

Efforts to preserve, protect and restore ecosystems are hindered by long delays between data collection and analysis. Threats to ecosystems can go undetected for years or decades as a result. Real‐time data can help solve this issue but significant technical barriers exist. For example, automated camera traps are widely used for ecosystem monitorin...

Modeling fire spread as an infection process is intuitive: An ignition lights a patch of fuel, which infects its neighbor, and so on. Infection models produce nonlinear thresholds, whereby fire spreads only when fuel connectivity and infection probability are sufficiently high. These thresholds are fundamental both to managing fire and to theoretic...

Efforts to preserve, protect, and restore ecosystems are hindered by long delays between data collection and analysis. Threats to ecosystems can go undetected for years or decades as a result. Real-time data can help solve this issue but significant technical barriers exist. For example, automated camera traps are widely used for ecosystem monitori...

Ecological data are collected over vast geographic areas using digital sensors such as camera traps and bioacoustic recorders. Camera traps have become the standard method for surveying many terrestrial mammals and birds, but camera trap arrays often generate millions of images that are time‐consuming to label. This causes significant latency betwe...

Global change is expected to increase savanna woody encroachment as well as fire spreading into forest. Forest–savanna ecotones are the frontier of these processes and can thus either mitigate or enhance the effects of global change. However, the ecology of the forest–savanna ecotone is poorly understood. In this study, we determined whether a dist...

Fruit decline threatens forest elephants Large mammal herbivores in African tropical forests are major consumers of fruit, and many tree species rely on these consumers for dispersal of their seeds. Bush et al. monitored fruit production over three decades in a protected national park in Gabon, showing an 80% decline across the 73 plant species mon...

Ecological data are increasingly collected over vast geographic areas using arrays of digital sensors. Camera trap arrays have become the ‘gold standard’ method for surveying many terrestrial mammals and birds, but these arrays often generate millions of images that are challenging to process. This causes significant latency between data collection...

Ungulates are famous for large-scale movements in response to local and regional changes in plant productivity. However, it is poorly understood how non-migratory ungulates respond towards shortages in plant availability. In the arid Kunene Region of Namibia, we studied the variation of home ranges and habitat use of gemsbok during a period of seve...

Background The humid tropical forests of Central Africa influence weather worldwide and play a major role in the global carbon cycle. However, they are also an ecological anomaly, with evergreen forests dominating the western equatorial region despite less than 2,000 mm total annual rainfall. Meteorological data for Central Africa are notoriously s...

Forest edges that border savanna are dynamic features of tropical landscapes. Although the role of fire in determining edge dynamics has been relatively well explored, the role of mega-herbivores, specifically elephants, has not received as much attention. We investigated the role of forest elephants in shaping forest edges of the forest–savanna mo...

Background. The humid tropical forests of Central Africa influence weather worldwide and play a major role in the global carbon cycle. However they are also an ecological anomaly, with evergreen forests dominating the western equatorial region despite less than 2000mm total annual rainfall. Meteorological data for Central Africa are notoriously spa...

Forest-savanna mosaics are maintained by fire-mediated positive feedbacks; whereby forest is fire suppressive and savanna is fire promoting. Forest-savanna transitions therefore represent the interface of opposing fire regimes. Within the transition there is a threshold point at which tree canopy cover becomes sufficiently dense to shade out grasse...

Aquatic and terrestrial ecosystems are linked by fluxes of carbon and nutrients in riparian areas. Processes that alter these fluxes may therefore change the diet and composition of consumer communities. We used stable carbon isotope (δ¹³C) analyses to test whether the increased abundance of aquatic prey observed in a previous study led to a dietar...

The killing of large numbers of migratory bats at wind turbines is a pressing conservation problem. Even though avoidance and mitigation measures could benefit from a better knowledge of the species' migratory habits, we lack basic information about what habitats and corridors bats use during migration. We studied the isotopic niche dimensions of t...

In food web studies, hydrogen stable isotope ratios (δ ² H) are increasingly used as endogenous markers to quantify the relative importance of allochthonous input of organic material into aquatic ecosystems. Yet, it is unclear if differences in δ ² H values between aquatic and terrestrial food webs translate into corresponding differences of δ ² H...

Ungulates often adjust their diet when food availability varies over time. However, it is poorly understood when and to what extent individuals change their diet and, if they do so, if all individuals of a population occupy distinct or similar dietary niches. In the arid Namibian Kunene Region, we studied temporal variations of individual niches in...

Desert ungulates live in adverse ecosystems that are particularly sensitive to degradation and global climate change. Here, we asked how two ungulate species with contrasting feeding habits, grazing gemsbok (Oryx g. gazella) and browsing springbok (Antidorcas marsupialis), respond to an increase in food availability during a pronounced rain period....