Surviving at the extreme: Chimpanzee ranging is not restricted in a deforested human‐dominated landscape in Uganda

Abstract

Endangered wildlife increasingly inhabits human‐dominated landscapes outside protected areas. Large‐bodied mammals require large spaces, and their ranging may be especially impacted by landscape modifications including farming, road development and urbanisation. We studied the Wagaisa community of chimpanzees (Pan troglodytes) in Uganda, which inhabit a landscape characterised by high human population density, widespread deforestation, and rapid agricultural and infrastructural development. We aimed to assess whether this dynamic, fragmented environment constrains the chimpanzees’ ranging, and to identify critical habitat patches to aid their conservation. During March–May 2018, we assessed range use from locations of direct observations and indirect signs, corroborated by longer‐term behavioural monitoring of the chimpanzees (June 2018–December 2019). No evidence of limited ranging was found. The Wagaisa chimpanzees used an area measuring ≥ 43 km2 (100% MCP) and ranged extensively in the anthropogenic matrix. Most frequently used parts of the range (‘core habitat areas’) centred around small (5–20 acres), widely dispersed remnant forest patches and exotic eucalyptus plantations. Forty per cent of chimpanzee nests were constructed in eucalyptus trees, suggesting a behavioural adjustment to landscape changes. Actions to facilitate conservation of these ‘village chimpanzees’ and others surviving in transformed human‐dominated habitat need not conflict with the sustainable development of the region.

Recent genetic connectivity and clinal variation in chimpanzees

“…Chimpanzees have diverse and variable behavioural repertoires 64,65 that often vary among nearby communities 66 , they utilize learned techniques to harvest otherwise unobtainable foods 67 and their bevavioural diversity increases with environmental variability 68 . Indeed, chimpanzees living in arid habitats employ specialized behaviours to regulate the thermal exposure 8 and spontaneously innovate novel behaviours in response to increased environmental complexity arising from anthropogenic pressures [69][70][71] .…”

Chimpanzees (Pan troglodytes) adapt their nesting behavior after large‐scale forest clearance and community decline

“…have increased in Bulindi and chimpanzees are sometimes observed to nest in eucalyptus trees (Figure 5b). This corresponds to nesting behavior seen in nearby communities of chimpanzees in the Budongo–Bugoma corridor, which commonly use Eucalyptus plantations for nesting, representing a flexible response to this fast‐changing human‐modified environment (McCarthy et al, 2017; McLennan et al, 2021).…”

“…Since the 1990s, forest throughout the “Budongo–Bugoma corridor” was logged for timber and converted to farmland (McLennan & Hill, 2015; Twongyirwe et al, 2015), leaving only small patches of forest. Nevertheless, chimpanzees survive in this human‐dominated landscape, which covers about 1000 km 2 , using remnant forest fragments and agroforestry plantations amidst farmland and villages (McCarthy et al, 2017; McLennan et al, 2021; McLennan, 2008). A genetic census estimated a regional population of 260–320 chimpanzees in the Budongo–Bugoma corridor, in nine or more communities (McCarthy et al, 2015).…”

“…Between the Budongo and Bugoma Central Forest Reserves in western Uganda, chimpanzees inhabit a human‐modified landscape using small forest fragments among village homes, roads and agricultural land (McCarthy et al, 2015; McLennan & Asiimwe, 2016; McLennan et al, 2021; McLennan, 2008). Deforestation in this landscape, which is known as the “Budongo–Bugoma corridor,” has been extensive (i.e., most unprotected forest was logged and converted to other land uses since the 1990s; McLennan & Hill, 2015; Twongyirwe et al, 2015).…”

“…Therefore, this region is ideal for examining the effect of deforestation and general human disturbance on chimpanzee nesting patterns. In previous studies of nesting in the Budongo–Bugoma corridor, forest degradation and clearance were suggested to be the cause of a high frequency of chimpanzee nests in exotic trees (especially Eucalyptus sp., McCarthy et al, 2017; McLennan et al, 2021), as well as a high frequency of integrated nests (McCarthy et al, 2017; McLennan, 2018).…”