Bush Encroachment and Large Carnivore Predation Success in African Landscapes:A Review

Bush encroachment is a habitat change phenomenon that threatens savanna and grassland ecosystems worldwide. In Africa, large carnivores in bush encroached landscapes must adjust to increasing woody plant cover and biomass, which could affect predation success at multiple stages through complex and context-dependent pathways. We highlight, interpret, and compare studies that assessed how bush encroachment or related habitat parameters affect the predation stages of large African carnivores. Bush encroachment may directly or indirectly affect predation success in various ways, including by: (1) altering habitat structure, which may affect hunting efficiency and prey accessibility; (2) changing prey abundance/distribution, with smaller species and browsers being potentially favoured; (3) influencing interference competition within the carnivore guild. For habitat or dietary specialists, and subordinate predators that are vulnerable to both top-down and bottom-up ecosystem effects, these alterations may be detrimental and eventually incur population fitness costs. As the threat of bush encroachment continues, future studies are required to assess indirect effects on competitive interactions within the large African carnivore guild to ensure that conservation efforts are focused. Additionally, to better understand the effects of bush encroachment across Africa, further research is necessary in affected areas as overall little attention has been devoted to the topic

Path-planning strategies for ambush avoidance

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2005.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (p. 71-72).This thesis examines a variety of ambush games in which one player must navigate between an origin and a destination, and the other player seeks to intercept and ambush him. These games include single-stage games, in which all decisions are made at the outset of the game, and multi-stage games, in which the second player may choose his ambush locations based on real-time updates of the first player's position. For both types of ambush games, methods are presented for efficiently computing the optimal mixed strategies for the first player to navigate between the origin and destination, so as to minimize the probability of being ambushed. The results are applicable to a wide range of real-life situations, including the routing of VIPs and convoys through hostile areas.by Farmey A. Joseph.S.M

Error-avoidance theory: sniper employment for military and civilian law enforcement

Sniper operations are high risk, high reward missions with unique traits and distinctive capabilities often resulting in great success or punishing failure. Within nearly all conceptions of sniper operations there is a perceived difference between civilian and military sniper engagements. This thesis presents an error-avoidance theory for guiding successful sniper operations across both domains. Inside sniper operations there are two critical errors that need to be avoided. These errors are defined as Type 1 and Type 2 errors. Type 1 errors are those that result in the death of an innocent individual. Type 2 errors occur when the targeted individual escapes the situation and the mission objective is not met, and thus the threat or potential threat remains active. Naturally, the goal is to avoid both errors. However, the rules of engagement established for any mission must, by necessity, privilege the avoidance of one error type over the other. The evaluation of three critical variablesoperational environment, political and social context, and the stakes or risk in the situationshould prioritize which error to avoid. This thesis thereby establishes a theoretical framework that can be universally employed to establish rules of engagement by all those who use the sniper tactic, for both civilian and military operations.http://archive.org/details/erroravoidanceor1094539001Major, United States ArmyApproved for public release; distribution is unlimited

The behavioural ecology and predator-prey interactions of leopards (Panthera pardus) and chacma baboons (Papio ursinus) in an Afromontane environment

The interactions between predators and prey have long been considered to play an important role in behaviour, physiology, and evolution. Both predators and prey can influence one another’s spatial and temporal patterns in activity and space use. To understand such dynamic processes, one must simultaneously assess the behavioural ecology of both predator and prey within the same environment. Such analyses have been rare in primatology. With the aid of behavioural, telemetry, and environmental data collected between the years 2012 and 2017, a combination of methods including home range analyses, resource selection functions, activity pattern analyses and spatial regression models were used to independently test hypotheses relating to space use and activity patterns in chacma baboons (Papio ursinus) and their main predator, the leopard (Panthera pardus) within the western Soutpansberg Mountains, South Africa. Collectively, the results allowed me to test hypotheses about how baboons spatially and behaviourally respond to the threat posed by predation. The utilisation of spatial-temporal data deriving from two sympatric species provides not only a detailed assessment on how such animals independently use their environment yet is a novel approach for understanding the complex dynamics of predator-prey interactions. My results showed that leopards established home ranges in topographically complex and highly vegetated areas while avoiding humans and also preferentially used areas of dense vegetation. Leopards were also less active in these areas, preferentially resting in areas of cover and away from human activity. Although primarily crepuscular, leopards shifted their behaviour when in proximity to humans with an increase in nocturnal activity, with day length and weather also influencing their activity scheduling. Despite the presence of leopards on the landscape, baboons primarily avoided areas that were perceived to be risky from the threat imposed by other baboon groups rather than leopards. In contrast, the probability of encountering leopards had the biggest influence on spatial variation in vigilance. In confirmation of previous studies, risk effects exceeded the importance of food availability in determining range use, although baboons selected areas of greater food availability during winter when food was shortest suggesting that they trade off an increase in risk for foraging opportunities at these times. Despite clear seasonal constraints on behaviour in winter, however, the baboons did not appear to compensate with increased nocturnal activity at these times. This study highlights the value of integrating information on both predators and prey into studies of primate-predator interactions and suggests potential avenues for future research

Predictors of Puma Occupancy Indicate Prey Vulnerability is More Important Than Prey Availability in a Highly Fragmented Landscape

Habitat fragmentation represents the single greatest conservation challenge of the 21st century. This problem is particularly acute for large, obligate carnivores like pumas Puma concolor which have persisted in North and South America in the face of habitat fragmentation and other anthropogenic disturbances. Shrinking habitat and reduced connectivity mean that mapping habitat is increasingly important for species conservation in multiple-use landscapes. Previous work suggests that pumas occupy habitats where sufficient stalking cover and preferred prey are present, yet the intersection of these factors has rarely been assessed. Here we used data from 68 299 camera trap nights collected from 181 sites throughout the San Francisco Bay Area over a four-year period to identify key predictors of habitat occupancy for pumas and their primary prey (mule deer Odocoileus hemionus). Our goal was to determine whether pumas occupy habitats based on relative measures of prey availability (detection frequency), or ease of predation (density of stalking cover) and whether these predictors changed between seasons. Our results indicated that pumas primarily occupied forested habitats and did not choose habitats with abundant deer. Instead, pumas preferentially occupy habitats that facilitate their stalk and ambush hunting strategy, rather than higher prey densities, per se. The best occupancy models for mule deer indicated the importance of roads and shrub cover. However, even the best deer models performed poorly compared to the puma models, likely due to the ubiquity of mule deer in the region. Although prey density is a widely accepted correlate of habitat quality for many carnivores, our results suggest that structural elements of habitat may be a more important variable in predicting habitat use by large stalk and ambush predators like pumas, which has important implications for conservation success

Outrun or Outmaneuver: Predator–Prey Interactions as a Model System for Integrating Biomechanical Studies in a Broader Ecological and Evolutionary Context

Behavioral studies performed in natural habitats provide a context for the development of hypotheses and the design of experiments relevant both to biomechanics and to evolution. In particular, predator–prey interactions are a model system for integrative study because success or failure of predation has a direct effect on fitness and drives the evolution of specialized performance in both predator and prey. Although all predators share the goal of capturing prey, and all prey share the goal of survival, the behavior of predators and prey are diverse in nature. This article presents studies of some predator–prey interactions sharing common predation strategies that reveal general principles governing the behaviors of predator and prey, even in distantly related taxa. Studies of predator–prey interactions also reveal that maximal performance observed in a laboratory setting is not necessarily the performance that determines fitness. Thus, considering locomotion in the context of predation ecology can aid in evolutionarily relevant experimental design. Classification by strategy reveals that displaying unpredictable trajectories is a relevant anti-predator behavior in response to multiple predation strategies. A predator’s perception and pursuit of prey can be affected indirectly by divergent locomotion of similar animals that share an ecosystem. Variation in speed and direction of locomotion that directly increases the unpredictability of a prey’s trajectory can be increased through genetic mutation that affects locomotor patterns, musculoskeletal changes that affect maneuverability, and physical interactions between an animal and the environment. By considering the interconnectedness of ecology, physical constraints, and the evolutionary history of behavior, studies in biomechanics can be designed to inform each of these fields.Organismic and Evolutionary Biolog

Prey capture behaviour by pygmy bluetongue lizards with simulated grazing

Published version made available in accordance with the Publishers policy. This article is under an embargo for a period of three years from the date of publication

Coping with spatial heterogeneity and temporal variability in resources and risks: Adaptive movement behaviour by a large grazing herbivore.

Movement is a key mean for mobile species to cope with heterogeneous environments. While in herbivorous mammals large-scale migration has been widely investigated, finescale movement responses to local variations in resources and predation risk remain much less studied, especially in savannah environments. We developed a novel approach based on complementary movement metrics (residence time, frequency of visits and regularity of visits) to relate movement patterns of a savannah grazer, the blue wildebeest Connochaetes taurinus , to fine-scale variations in food availability, predation risk and water availability in the Kruger National Park, South Africa. Wildebeests spent more time in grazing lawns where the grass is of higher quality but shorter than in seep zones, where the grass is of lower quality but more abundant. Although the daily distances moved were longer during the wet season compared to the dry season, the daily net displacement was lower, and the residence time higher, indicating a more frequent occurrence of area-concentred searching. In contrast, during the late dry season the foraging sessions were more fragmented and wildebeests moved more frequently between foraging areas. Surprisingly, predation risk appeared to be the second factor, after water availability, influencing movement during the dry season, when resources are limiting and thus expected to influence movement more. Our approach, using complementary analyses of different movement metrics, provided an integrated view of changes in individual movement with varying environmental conditions and predation risk. It makes it possible to highlight the adaptive behavioral decisions made by wildebeest to cope with unpredictable environmental variations and provides insights for population conservation