Spatial heterogeneity facilitates carnivore coexistence

Abstract

Competitively dominant carnivore species can limit the population sizes and alter the behavior of inferior competitors. Established mechanisms that enable carnivore coexistence include spatial and temporal avoidance of dominant predator species by subordinates, and dietary niche separation. However, spatial heterogeneity across landscapes could provide inferior competitors with refuges in the form of areas with lower competitor density and/or locations that provide concealment from competitors. Here, we combine temporally overlapping telemetry data from dominant lions (Panthera leo) and subordinate African wild dogs (Lycaon pictus) with high-resolution remote sensing in an integrated step selection analysis to investigate how fine-scaled landscape heterogeneity might facilitate carnivore coexistence in South Africa's Hluhluwe-iMfolozi Park, where both predators occur at exceptionally high densities. We ask whether the primary lion-avoidance strategy of wild dogs is spatial avoidance of lions or areas frequented by lions, or if wild dogs selectively use landscape features to avoid detection by lions. Within this framework, we also test whether wild dogs rely on proactive or reactive responses to lion risk. In contrast to previous studies finding strong spatial avoidance of lions by wild dogs, we found that the primary wild dog lion-avoidance strategy was to select landscape features that aid in avoidance of lion detection. This habitat selection was routinely used by wild dogs, and especially when in areas and during times of high lion-encounter risk, suggesting a proactive response to lion risk. Our findings suggest that spatial landscape heterogeneity could represent an alternative mechanism for carnivore coexistence, especially as evershrinking carnivore ranges force inferior competitors into increased contact with dominant species.

Cats and dogs: A mesopredator navigating risk and reward provisioned by an apex predator

“…For example, the range at which a source of risk or reward is directly perceivable should dictate the scale at which direct responses occur—for difficult to perceive sources of risk and reward, memory and learning may allow an animal to use indirect assessments to respond at greater scales than would be possible with direct assessments. Despite combining two potentially different scales of assessment (i.e., direct vs. indirect), our first analysis was consistent with contemporary methods of evaluating risk‐avoiding and reward‐seeking tactics (Davies et al, 2021 ). Importantly, we compared the results of this analysis with direct inferences drawn from analyses in the following two assessments.…”

“…Despite likely occurring at a greater scale, we were still not able to capture the direct perception of coyotes toward kills made by mountain lions. In a recent study where direct and indirect responses were framed as “reactive” and “proactive,” respectively, African wild dogs ( Lycaon pictus ) avoided the risk of predation from African lions ( Panthera leo ) using indirect rather than direct responses to risk when both were compared within iSSF analyses (Davies et al, 2021 ). As is indicated by the framing of direct responses as “reactive”, direct responses are perhaps more likely to occur at finer spatiotemporal scales than indirect responses.…”

“…Based on our movement rate analysis (aforementioned), ten hours encompassed the period in which pre-and post-encounter behavior was likely to change. We paired each observed step with 10 available steps (Davies et al, 2021;Northrup et al, 2013;Prokopenko et al, 2017;Thurfjell et al, 2014) sampled from distributions of step lengths and turning angles, with step lengths generated separately for preand post-encounter groups to preserve existing differences in movement behavior. We sampled turning angles in radians for available steps from a uniform distribution ranging fromπ to π, and sampled step lengths from gamma distributions parameterized from the ob- as "open" because they were not tall enough to conceal an averagesized coyote (Hinton & Chamberlain, 2014;Hinton et al, 2019).…”

Carnivore coexistence facilitated by spatial and dietary partitioning and fine‐scale behavioural avoidance in a semi‐arid ecosystem

“…Spatial heterogeneity in the landscape may also play a key role in facilitating carnivore coexistence through the availability of different habitats and other physical features, as well as uneven resource distribution (Chesson, 2000; Stein et al., 2014) which can provide vital refuges for subordinate species to reduce encounters with dominant carnivores (Davies et al., 2021; Durant, 1998). Our results indicated that spatial avoidance was slightly higher in the fynbos biome compared to the karoo which is likely due to the landscape heterogeneity which provides more refugia (e.g.…”

Landscapes shaped from the top down: predicting cascading predator effects on spatial biogeochemistry

“…Ecosystems are complex and spatially heterogeneous, and spatial heterogeneity can have decided consequences for ecosystem functioning (Hunter and Price 1992, Turner and Chapin 2005, Chapin et al 2011). The degree of heterogeneity at the landscape scale can influence community dynamics (Hastings 1977, Turner and Gardner 2015), species coexistence (Davies et al 2021) and resilience to environmental change (van Nes and Scheffer 2005). Much effort, especially, has been devoted to characterizing how landscape‐scale spatial heterogeneity impacts wildlife population persistence and community dynamics (Hutchings et al 2000), with the goal of understanding how habitat should be protected to best support species of conservation concern (Lovett et al 2005).…”