The Role of Forest Elephants in Shaping Tropical Forest–Savanna Coexistence

Abstract

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 forestsavanna mosaic in Lopé National Park, Gabon. Using forty camera traps, we collected 1.2 million images between May 2016 and June 2017. These images were classified by over 10,000 volunteers

Climatic and Resource Determinants of Forest Elephant Movements

“…Below we discuss the implications of the links between resource availability, climate and individual identity on elephant movement behavior. The spatiotemporal heterogeneity in fruit availability observed here confirms previous research demonstrating significant seasonal and spatial variation in the Central African tropics (Chapman et al, 1999(Chapman et al, , 2005Morgan, 2009;Cardoso et al, 2019). The high abundance of fruit in the dry season in Wonga Wongué is particularly noteworthy as it is often assumed that fruit abundance is highest in the wet season in Central Africa, although a similar pattern was observed in Loango National Park (Morgan, 2009) and a recent synthesis of long-term phenological studies showed marked intersite variation in seasonal fruiting (Adamescu et al, 2018).…”

“…Understanding the spatiotemporal availability of resources and elephants responses to changes in their availability represents an important step in identifying drivers of humanwildlife conflict and designing effective solutions. Our observed changes in diet composition and movement behavior in response to fruit and water availability are consistent with more frequent crop raiding (e.g., Buij et al, 2007) and use of edge habitats (Cardoso et al, 2019) in the dry season. Elephants tend to be attracted to agricultural fields with fruiting trees (Ngama et al, 2019), which could be compounded when fruits are seasonally scarce in the forest.…”

“…Consistent with this, Central African forests demonstrate distinct fruiting fluctuations, linked with both annual and seasonal patterns (Tutin et al, 1993;White, 1994a;Takenoshita et al, 2008;Adamescu et al, 2018). Peak fruit production consistently falls within the wettest months of the year across geographic locations, particularly for fleshy fruits (Frankie et al, 1974;Chapman et al, 1999Chapman et al, , 2005van Schaik et al, 2003), at least in the forest interior (Cardoso et al, 2019). Studies of other frugivores (e.g., primates) have highlighted that the spatial distribution and temporal periodicity of flowering and fruiting often drive their ranging behavior and habitat use (Heithaus et al, 1975;Wallace, 2006), and that frugivores can show marked seasonal dietary shifts by switching to alternative diets when particular energy resources are scarce (Wallace, 2005(Wallace, , 2006.…”

“…The African forest elephant (Loxodonta cyclotis) is a wideranging megaherbivore and keystone species for Afrotropical rainforests that influences the composition and structure of the ecosystem through movement and browsing (Turkalo and Fay, 2001;Blake, 2002;Poulsen et al, 2018;Cardoso et al, 2019). Forest elephants can move over 2800 km annually with average home ranges of ∼700 km 2 (Mills et al, 2018).…”

High performance machine learning models can fully automate labeling of camera trap images for ecological analyses

“…Individual studies also used different field protocols for camera deployment but all were focused on detecting terrestrial forest mammals, with cameras installed on trees approximately 30 -40 cm above ground level. The exception to this was data from (14) who installed cameras at a height of approximately 1 m for the primary purpose of detecting forest elephants Loxodonta cyclotis. Camera trap configuration was set to be highly sensitive in some cases and images were often captured in a series of rapid, short bursts (e.g.…”