Spatial processes decouple management from objectives in a heterogeneous landscape: predator control as a case study

Abstract

Predator control is often implemented with the intent of disrupting top-down regulation in sensitive prey populations. However, ambiguity surrounding the efficacy of predator management, as well as the strength of top-down effects of predators in general, is often exacerbated by the spatially implicit analytical approaches used in assessing data with explicit spatial structure. Here, we highlight the importance of considering spatial context in the case of a predator control study in south-central Utah. We assessed the spatial match between aerial removal risk in coyotes (Canis latrans) and mule deer (Odocoileus hemionus) resource selection during parturition using a spatially explicit, multi-level Bayesian model. With our model, we were able to evaluate spatial congruence between management action (i.e., coyote removal) and objective (i.e., parturient deer site selection) at two distinct scales: the level of the management unit and the individual coyote removal. In the case of the former, our results indicated substantial spatial heterogeneity in expected congruence between removal risk and parturient deer site selection across large areas, and is a reflection of logistical constraints acting on the management strategy and differences in space use between the two species. At the level of the individual removal, we demonstrated that the potential management benefits of a removed coyote were highly variable across all individuals removed and in many cases, spatially distinct from parturient deer resource selection. Our methods and results provide a means of evaluating where we might anticipate an impact of predator control, while emphasizing the need to weight individual removals based on spatial proximity to management objectives in any assessment of large-scale predator control. Although we highlight the importance of spatial context in assessments of predator control strategy, we believe our methods are readily generalizable in any management or large-scale experimental framework where spatial context is likely an important driver of outcomes.

Location‐specific factors influence patterns and effects of subsistence sea otter harvest in Southeast Alaska

“…The difference between stock and subregional patterns of harvest and population effects highlights the challenge of detecting impacts of localized perturbations at larger spatial scales. As seen in the range of environmental gradients across Hawaiian monk seal (Monachus schauinslandi) populations (Schmelzer 2000, Baker et al 2007) and predatory control of coyotes (Canis latrans; Mahoney et al 2018), a clear understanding of the demographic impacts and context of a given perturbation is best achieved by monitoring dynamics at the appropriate spatial scale. For species which have high site fidelity and small home ranges, localized disturbances can have outsized effects possibly leading to genetic bottlenecking, as seen in sea otters (Larson et al 2002(Larson et al , 2012 and wolves (Moura et al 2014).…”

“…As predator populations continue to recover worldwide, ecologists, conservation biologists, managers, and other stakeholders are likely to face new questions regarding the management of these species (Silliman et al 2018). In preparation for, or in response to, recovering predator populations, it will be important to re-examine the spatial context of current management frameworks and their ability to effectively manage spatially heterogeneous populations (Mahoney et al 2018). Our analyses showed that spatial scale, proximity to human settlements, and status and trends of the local population are all important considerations when evaluating the effects of harvest on SEAK sea otter populations.…”

“…Therefore, effective management of populations requires information about population status and dynamics at spatial scales relevant to the species in question. For populations that are hunted for subsistence, harvest data can provide local-scale information that can be used to evaluate population status, management actions, and harvest sustainability (Shaffer et al 2017, Mahoney et al 2018). Furthermore, subsistence harvest data can inform our understanding of population dynamics and highlight spatially dependent factors that may influence the population and hunting itself (van Vliet et al 2010).…”

The intrepid urban coyote: a comparison of bold and exploratory behavior in coyotes from urban and rural environments

“…We conducted our work at a rural area (central Utah, USA) and an urban area (Denver, Colorado, USA) and details of each area can be found in Mahoney et al . 35 and Poessel et al . 36 .…”

Restricted‐area culls and red fox abundance: Are effects a matter of time and place?

“…Fundamentally, the effectiveness of predator control depends on clear objectives and adequately intensive removal effort (Reynolds & Tapper, ; Salo et al, ). In addition, predator control must adequately match the ecological requirements of the respective target species (i.e., account for predator and prey biology) in both space and time to produce the desired conservation outcome (Conner & Morris, ; Lennox et al, ; Mahoney et al, ). In practice, however, the effectiveness of predator control may be limited by constraints such as the available person hours, the limits imposed by hunting legislation and/or the variation in property rights (access for control operations) across an area of interest, leading to potentially insufficient and spatially uncoordinated actions.…”