Abstract
BackgroundWhere apex predators move on the landscape influences ecosystem structure and function and is therefore key to effective landscape-level management and species-specific conservation. However the factors underlying predator distribution patterns within functional ecosystems are poorly understood. Predator movement should be sensitive to the spatial patterns of inter-specific competitors, spatial variation in prey density, and landscape attributes that increase individual prey vulnerability. We investigated the relative role of these fundamental factors on seasonal resource utilization by a globally endangered apex carnivore, the African lion (Panthera leo) in Tanzania’s Serengeti National Park. Lion space use was represented by novel landscape-level, modified utilization distributions (termed “localized density distributions”) created from telemetry relocations of individual lions from multiple neighbouring prides. Spatial patterns of inter-specific competitors were similarly determined from telemetry re-locations of spotted hyenas (Crocuta crocuta), this system’s primary competitor for lions; prey distribution was derived from 18 months of detailed census data; and remote sensing data was used to represent relevant habitat attributes.ResultsLion space use was consistently influenced by landscape attributes that increase individual prey vulnerability to predation. Wet season activity, when available prey were scarce, was concentrated near embankments, which provide ambush opportunities, and dry season activity, when available prey were abundant, near remaining water sources where prey occurrence is predictable. Lion space use patterns were positively associated with areas of high prey biomass, but only in the prey abundant dry season. Finally, at the broad scale of this analysis, lion and hyena space use was positively correlated in the comparatively prey-rich dry season and unrelated in the wet season, suggesting lion movement was unconstrained by the spatial patterns of their main inter-specific competitors.ConclusionsThe availability of potential prey and vulnerability of that prey to predation both motivate lion movement decisions, with their relative importance apparently mediated by overall prey abundance. With practical and theoretical implications, these results suggest that while top carnivores are consistently cognizant of how landscape features influence individual prey vulnerability, they also adopt a flexible approach to range use by adjusting spatial behaviour according to fluctuations in local prey abundance.Electronic supplementary materialThe online version of this article (doi:10.1186/s40462-016-0082-9) contains supplementary material, which is available to authorized users.
Highlights
Where apex predators move on the landscape influences ecosystem structure and function and is key to effective landscape-level management and species-specific conservation
The Corridor is composed of a sparse woodland-grassland mosaic interspersed with patches of dense woodland [28]. This is a transitory zone for the wildebeest migration as it moves in a sweeping arc from the Serengeti Plains to the North, with the influx of migrating animals arriving in the Corridor at the onset of the dry season (June – July) and typically passing through prior to commencement of the wet season [30]
In the dry season, localized lion density was concentrated in areas of the landscape that were heavily used by hyenas (Table 4)
Summary
Where apex predators move on the landscape influences ecosystem structure and function and is key to effective landscape-level management and species-specific conservation. The distribution and abundance of top predators on the landscape can exert profound influence on the distribution and abundance of their prey [1,2,3] This in turn can impact predator-prey population dynamics [4, 5] as well as ecosystem structure as mediated by trophic cascades [6, 7]. The mechanism governing predator distribution is more elusive, with space use either dictated by areas of the landscape where prey are abundant or spatial locations where individual prey capture is more efficient [12]
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