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Habitat use and movements of plains zebra (Equus burchelli) in response to predation danger from lions

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Prey species must adapt their behavior to avoid predation. As a key prey item for lions (Panthera leo), plains zebras (Equus burchelli) were expected to respond to immediate threats posed by lions in their area. In addition, zebras were predicted to exhibit behavior tuned to reduce the potential for encounters with lions, by modifying their movement patterns in the times of day and habitats of greatest lion danger. We studied a population of approximately 600 plains zebra living in Ol Pejeta Conservancy, Kenya. We found that zebra abundance on or near a grassland patch was lower if lions had also been observed on that patch during the same day. Predation danger was highest in grassland habitat during the night, when lions were more active. Zebra sightings and global positioning system radio collar data indicated that zebras also reduced their use of grassland at night, instead using more woodland habitat. Zebras moved faster and took sharper turns in grassland at night. It is hypothesized that these more erratic movements assist zebras in avoiding detection or capture by lions. Copyright 2007, Oxford University Press.
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... Is it possible to reduce the risk of being bitten while still maintaining access to high-quality feeding sites on a regular basis? Insights on how horses could solve this dilemma emerge from how their close kin -zebras -adjust their behavior and activity patterns to simultaneously reduce the risks of being killed by lions without reducing feeding opportunities (Fischhoff et al., 2007). We know from studies on plains zebras (Equus quagga), that when a lion makes a kill, or when a zebra detects a lion in a particular habitat, the first response is often for the herd to abandon the area. ...
... For those remaining on the open plains, however, their movements change dramatically, becoming more protean, more unpredictable. At night on the plains, zebras move more quickly and turn more frequently and erratically than when grazing there during the daytime (Fischhoff et al., 2007). Like the zebras solving the lifedinner tradeoff (Dawkins and Krebs, 1979), might Shackleford horses adjust their temporal patterns of habitat use to avoid high fly densities without having to forgo feeding in particular regions of the island? ...
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The horses of Shackleford Banks, NC, United States are harassed by many species of biting flies. Apart from being a nuisance, their bites can lead to blood loss and transmit disease. As a result, these horses tend to avoid areas where fly abundances are high. Like other free-ranging horse populations, environmental factors such as low wind speeds and high temperatures increase fly loads per horse. Similarly, coat color matters since darker horses attract more flies than lighter ones, especially on hot sunny days. Many horse populations reduce per capita fly loads by living in large groups or by bunching tightly together. Shackleford horses do so, too, but also use wind speed differences among habitats to modulate fly numbers. By adopting a systematic pattern of moving between habitats such that they only visit a habitat when wind speed is high enough to keep fly harassment to a tolerable level, they can avoid being bitten while continuing to forage. Typically, they begin the day foraging on the salt marshes where fly abundance is inherently low and are lowered further by faint early morning breezes. Later in the morning, horses move to grassy patches (swales) when increasing wind speed reduces fly landings there to levels found on the marshes. Later still, when wind speeds peak, horses begin foraging among the sand dunes. At this point wind speeds are high enough so that horses using any habitat will be minimally harassed by flies, thus enabling them to freely choose where to feed based on which habitat meets particular dietary needs for protein, energy and nutrients on any particular day. Hence, Shackleford horses follow the breeze to solve a challenging dilemma of maintaining a high nutritional plane without succumbing to fly harassment. Other free-ranging horses populations appear to have a more limited “either-or” choice of “bite or be bitten,” thus limiting their decision-making options.
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The common dolphin (Delphinus sp.) is one of the most common cetaceans in Venezuela. This study aims to describe habitat use in the Mochima National Park, a protected area under high anthropogenic pressure. Opportunistic surveys were conducted following a pre-defined route from September 2009 to August 2010. Data such as the geographical position, group size, composition, behaviour were recorded at 5min intervals. A focal group-follow methodology was used. A grid of 500 × 500m was constructed and each cell was characterised by environmental features and a Coefficient of Area Use (CAU) was calculated. A logistic regression model was applied to identify factors that explain use pattern. Seventy opportunistic surveys were conducted during which 86 groups of dolphins were observed. Dolphins occupied an area of 36km 2 , but Tigrillo inlet and to the northeast of the Caracas Islands were the areas most used. The common dolphins exhibited differential use, using shallow inshore waters most intensively and with probability of occurrence decreasing with increasing water depth and distance to the coast. They spent most of their time in feeding (40%) and socialising (24%) activities. Feeding and travelling behaviours were observed throughout the area studied, whereas socialising and resting activities were mainly concentrated in Tigrillo inlet, the Manare peninsula and the Caracas islands. Behaviour was mostly determined by season, depth, distance to the coast, group size and group composition. Throughout the year, the Park provided areas for refuge, feeding, and resting. It is therefore imperative to promote management and conservation policies that prevent any negative impacts from the increasing tourism and fishing activities we observed.
... Instead, we saw encounters associated with areas of sparse hunting coverindicative of open grasslands where foraging herbivore herds congregate (Wilmshurst et al., 1999). As inferior hunting grounds for ambush predators, open areas are selected by ungulates when lions are nearby , although nocturnally, when lions can better exploit these areas, zebras have been shown to reduce their use of grasslands (Fischoff et al., 2007). ...
Article
Predation is a fundamental ecological process influencing the distribution and abundance of animal populations and underlying how prey species perceive risk. The predation process is composed of four sequential stages – search, encounter, attack and kill – each of which has been used to describe risk across the landscape. Here, we used direct observational data of free‐ranging, radio‐collared African lions in Serengeti National Park's western corridor to (1) investigate daily and seasonal predation stage probabilities and (2) using two analytical approaches, compare four mechanisms – prey distribution, intra‐specific competition, spatially anchored landscape features and predator hunting method – that potentially drive spatial predation stage patterns. Results showed that lions encountered potential prey at night significantly less than during diurnal or crepuscular periods. Nocturnal observations were predominantly during full‐moon phases, so if this lower nocturnal encounter rate was due to moon phase it may contribute to lions' typically poor full‐moon hunting success. Predation stage probabilities did not differ between seasons despite high variability in seasonal prey abundance. Spatially, lions encountered potential prey in prey‐rich, open areas near water and spatial range centres. Compared with available areas within seasonal ranges, lion attacks were more likely where prey abundance was high, and kill locations were associated with prey‐rich areas near water and range centres, collectively suggesting opportunistic hunting. However, compared with preceding predation stage locations, attacks occurred near range peripheries and kills where hunting cover was greater, suggesting ambush predation. Our results indicate substantial temporal and spatial variation across the different stages of the predation process. They also highlight first, that results can vary in important ways depending on how analyses are approached, and second, that understanding predator‐prey dynamics depends on analyses of the different stages of predation. This study used direct observational data of African lions in Serengeti National Park's western corridor to (1) investigate daily and seasonal predation stage probabilities and (2) compare, using two analytical approaches, four mechanisms ‐ prey distribution, intra‐specific competition, spatially anchored landscape features and predator hunting method ‐ that potentially drive spatial predation stage patterns. Results indicate substantial temporal and spatial variation across the different stages of the predation process, and highlight that results can vary in important ways depending on how analyses are approached, and that understanding predator‐prey dynamics depends on analyses of the different stages of predation.
... Les recherches conduites sur les zèbres des plaines se sont initialement focalisées sur leur organisation sociale (Klingel 1969b, Penzhorn 1984, Rubenstein 1986) et leur reproduction (Klingel 1969a, Smuts 1976b. Le comportement des zèbres des plaines a été documenté en 1974 par Klingel et de nombreux travaux de recherche sur ce sujet ont suivi : des études se sont par exemple intéressées au budget d'activité (Neuhaus and Ruckstuhl 2002), au leadership (Fischhoff et al. 2007a), à la sélection de l'habitat (Fischhoff et al. 2007b, Courbin et al. 2016, Makin et al. 2017, Patin 2018, Mandinyenya et al. 2020, aux comportements d'infanticide par les mâles (Pluháček and Bartoš 2000, Pluháček et al. 2006, Ransom and Kaczensky 2016, à la vigilance (Simpson et al. 2012, Schmitt et al. 2014, Creel et al. 2014, Barnier et al. 2016, Makin et al. 2017, Périquet et al. 2017) et à l'acquisition des ressources (Barnier et al. 2014, Creel et al. 2014, Périquet et al. 2017. Cependant, l'effet de la taille de groupe sur le comportement des zèbres des plaines a rarement été investigué (Schmitt et al. 2014, Périquet et al. 2017 (Smuts 1976a, Georgiadis et al. 2003, Grange et al. 2004, de Vos et al. 2020. ...
Thesis
Chez les espèces sociales, les coûts et bénéfices de la vie en groupe sont nombreux et dynamiques, et la balance entre ces derniers est un déterminant clé de la taille des groupes. La taille de groupe est un composant de la socialité qui peut avoir d’importants effets sur le comportement des individus, leurs paramètres démographiques et leur dynamique sociale (mouvements intergroupes des individus, associations entre groupes). Cependant, ces effets restent mal compris. Dans cette thèse, j’explore l’effet de la taille de groupe sur le comportement, la démographie et la dynamique sociale du zèbre des plaines Equus quagga dans les populations sauvages du Parc National de Hwange (HNP, Zimbabwe) et du Parc de Hluhluwe-iMfolozi (HiP, Afrique du Sud). Dans le premier chapitre, je montre qu’à HNP la taille de groupe a peu d’effet sur la vigilance individuelle et l’acquisition des ressources, et n’a pas d’effet significatif sur la survie des individus, ce qui suggère que les effets de dilution et de détection importent peu sur le plan comportemental et démographique dans cette population. Dans le second chapitre, je montre que la probabilité qu’il y ait un changement d’étalon au sein des harems augmente lorsque le nombre de femelles reproductrices dans les harems augmente à HNP, mais que ces changements d’étalon n’affectent pas la survie des poulains. Ainsi, si le comportement d’infanticide par les mâles existe chez le zèbre des plaines en milieu sauvage, il devrait être très rare et ne pas avoir d’impact important sur la survie des poulains à l’échelle de la population. Enfin, dans le troisième chapitre, je montre que le nombre de femelles reproductrices dans les harems n’a pas d’effet sur la probabilité des harems à être observés seuls ou avec d’autres harems. En revanche, les harems comprenant davantage de femelles reproductrices semblent être moins souvent observés avec des groupes de mâles célibataires (bien que des incertitudes demeurent). Cela suggère que les harems comprenant beaucoup de femelles reproductrices pourraient éviter de s’associer avec les mâles célibataires, et semblent mieux réussir à les éviter à HiP où la végétation est globalement plus fermée qu’à HNP. De ce fait, la probabilité qu’il y ait un changement d’étalon au sein des harems n’augmente pas avec le nombre de femelles reproductrices dans les harems à HiP. Globalement, cette thèse remet en question le fonctionnement de l'effet de dilution et souligne l'importance de considérer l'effet régulateur potentiel des dynamiques sociales sur les populations, à travers leur effet sur la distribution spatiale des groupes.
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Long-term continuous observations of hunting lions Panthera leo in the Kruger National Park were used to assess the variables affecting hunting success of male and female lions. Generalized linear models revealed that seven variables had significant independent influences on hunting success, with the most important being the prey species hunted. Three types of variables were recognized: (1) lion related, where type of hunt, wind orientation, and the number of adults hunting; (2) prey related, where prey species and herd size; (3) environment related, where moon brightness, and grass height were significant. The sex of the lions had no effect on the overall probability of hunting success. Five second-order interactions significantly influenced the probability of hunting success, with the most important being the interaction between sex and the type of prey. The only significant third-order interaction containing the variable sex, was the inter-relationship with prey species and shrub cover. After removing the over-riding bias of the prey species, greater resolution of the factors affecting success was revealed. The major difference was that group size influences hunting success and concomitantly prey selection, promoting selection for medium-sized ungulates like zebra Equus burchelli and wildebeest Connochaetes taurinus by females, and males mainly capturing buffalo Syncerus caffer. We conclude that in African ecosystems, the hunting success of male and female lions varies with a range of combinations of lion-, prey- and environment-related variables. We demonstrate the hunting ability of male lions, which has perhaps been understated in other studies.
Book
Preface; 1. The purpose of the book; 2. Survey of contents; 3. How to use the book; 4. Notation, terminology and conventions; 5. Acknowledgements; Part I. Introduction: Part II. Descriptive Methods: 2.1. Introduction; 2.2. Data display; 2.3. Simple summary quantities; 2.4. Modifications for axial data; Part III. Models: 3.1. Introduction; 3.2. Notation; trigonometric moments; 3.3. Probability distributions on the circle; Part IV. Analysis of a Single Sample of Data: 4.1. Introduction; 4.2. Exploratory analysis; 4.3. Testing a sample of unit vectors for uniformity; 4.4. Nonparametric methods for unimodal data; 4.5. Statistical analysis of a random sample of unit vectors from a von Mises distribution; 4.6. Statistical analysis of a random sample of unit vectors from a multimodal distribution; 4.7. Other topics; Part V. Analysis of Two or More Samples, and of Other Experimental Layouts: 5.1. Introduction; 5.2. Exploratory analysis; 5.3. Nonparametric methods for analysing two or more samples of unimodal data; 5.4. Analysis of two or more samples from von Mises distributions; 5.5. Analysis of data from more complicated experimental designs; Part VI. Correlation and Regression: 6.1. Introduction; 6.2. Linear-circular association and circular-linear association; 6.3. Circular-circular association; 6.4. Regression models for a circular response variable; Part VII. Analysis of Data with Temporal or Spatial Structure: 7.1. Introduction; 7.2. Analysis of temporal data; 7.3. Spatial analysis; Part VIII. Some Modern Statistical Techniques for Testing and Estimation: 8.1. Introduction; 8.2. Bootstrap methods for confidence intervals and hypothesis tests: general description; 8.3. Bootstrap methods for circular data: confidence regions for the mean direction; 8.4. Bootstrap methods for circular data: hypothesis tests for mean directions; 8.5. Randomisation, or permutation, tests; Appendix A. Tables; Appendix B. Data sets; References; Index.