Patrick Duncan

• Retired at French National Centre for Scientific Research

Current theory predicts that plains zebra ( Equus quagga ) populations should be resource‐limited. Long‐term, detailed work in the Hwange ecosystem (Zimbabwe) on zebras and all their major predators provides empirical data to test this on a population that has been at a low density for at least 2 decades and is largely naturally regulated. Informat...

Simple Summary Parasites tend to be unevenly distributed among hosts, with most hosts in a population carrying few parasites and most of the parasites found in a few heavily infected individuals. This property, known as aggregation or overdispersion, is important to the diagnosis of parasite infections in groups of animals and their management. Ana...

Social dynamics can play a major role in shaping the population ecology and evolutionary trajectory of a species. This is, for instance, the case in species known to experience infanticide when a dominant male is replaced by another. Infanticide by males has been observed in many taxa, mostly in species that breed year-round and in which a few male...

A large part of the diversity of longevity and actuarial senescence (i.e., the progressive decline of survival probabilities with age) across vertebrates can be related to body size, phylogeny, and the species’ position on the slow-fast continuum of life histories. However, differences in mortality patterns between ecologically similar species, suc...

Prey face a trade‐off between acquiring food and avoiding predation, but food availability, and therefore its effect, is rarely measured in field studies investigating non‐lethal effects of predation. The main aim of this study was to investigate the role of the presence of predators in the functional adjustments of feeding parameters with patch qu...

Group living is assumed to benefit prey by reducing predation risk due to dilution and detection effects. This increased safety could be exchanged against a reduced individual vigilance leading to increased foraging and fitness until costs of intra‐group competition offset this benefit. However, very few studies have been able to directly test the...

When prey are time limited in their access to food, any trade-off involving time should ultimately affect their intake rate. In many herbivores, males and females experience different ecological pressures affecting their survival and reproduction because of differences in morphology, physiology and energy/nutrient requirements. If males and females...

When prey are time limited in their access to food, any trade-off involving time should ultimately affect their intake rate. In many herbivores, males and females experience different ecological pressures affecting their survival and reproduction because of differences in morphology, physiology and energy/nutrient requirements. If males and females...

We test whether the intensity of tooth wear influences the strength of actuarial senescence across species of large herbivores. We collected from the literature data on tooth wear in the wild (measured as the slope of the regression of log-transformed M1 crown height on age), longevity (measured as the age at which 90% of individuals are dead) and...

In natural ecosystems, ungulate densities show strong temporal variations. The ecological processes driving these fluctuations are complex: food limitation and predation are both important and can interact. Survival rates are central to this debate, but data are sparse for tropical ecosystems. Here, we estimate age- and sex-specific survival rates...

The predictive adaptive response (PAR) hypothesis proposes that animals adjust their physiology and developmental trajectory during early life in anticipation of their future environments. Accordingly, when environmental conditions in early life match environmental conditions during adulthood, individual fitness should be greater. Here, we test thi...

Predators influence prey populations not only through predation itself, but also indirectly through prompting changes in prey behaviour. The behavioural adjustments of prey to predation risk may carry nutritional costs, but this has seldom been studied in the wild in large mammals. Here, we studied the effects of an ambush predator, the African lio...

The social organization of giraffes (Giraffa camelopardalis) imposes a high-cost reproductive strategy on bulls, which adopt a 'roving male' tactic. Our observations on wild giraffes confirm that bulls indeed have unsynchronized rut-like periods, not unlike another tropical megaherbivore, the elephant, but on a much shorter timescale. We found prof...

L’intérêt social, économique et écologique du cheval pour la valorisation des territoires ; Cournon (France) - (2013-10-04 - 2013-10-04) / Conférence

There is increasing evidence that environmental conditions experienced early in life can markedly affect an organism's life history, but the pathways by which early environment influences adult phenotype are poorly known. We used long-term data from two roe deer (Capreolus capreolus) populations (Chizé and Trois-Fontaines, France) to investigate th...

The giraffe ( Giraffa camelopardalis ) is usually described as an exclusive browser, feeding only on shrubs and trees, preferrably between 2 and 5 m above ground (Lamprey, 1963; McNaughton & Georgiadis, 1986; Ciofolo & Le Pendu, 2002). Although browsing seems to be an easier form of feeding for giraffes in terms of accessibility and vigilance (Youn...

In an agricultural context promoting the development of sustainable grazing systems, horses – whose numbers are increasing in Europe – have a significant role to play. However, compared to ruminants, the lack of data on how horses exploit pastures makes it difficult to propose management recommendations, despite evidence that grass can cover their...

Vigilance allows individuals to escape from predators, but it also reduces time for other activities which determine fitness, in particular resource acquisition. The principles determining how prey trade time between the detection of predators and food acquisition are not fully understood, particularly in herbivores because of many potential confou...

Horses, whose numbers are growing in France and Europe, are set to play an increasing role in preserving the biodiversity of pasture land. This resume sums up available data and information regarding the impact of equine pasture land, and emphasizes its specificities and advantages. Horses have an innate capacity to ingest rough forage, which means...

Indices of diet quality are useful tools for research on the ecology, behaviour and the management of wildlife. The quality of diets is an essential driver of the performance of individuals, which in turn drives the dynamics of populations. Dietary nitrogen (DN) is a good index of diet quality in some herbivores, and faecal nitrogen (FN) has proved...

Horses, whose numbers are growing in France and Europe, are set to play an increasing role in preserving the biodiversity of pasture land. This résumé sums up available data and information regarding the impact of equine pasture land, and emphasizes its specificities and advantages. Horses have an innate capacity to ingest rough forage, which means...

In most previous studies of habitat selection, the use of a given habitat type is assumed to be directly proportional to its availability. However, the use and (or) the selection of a given habitat may be conditional on the availability of that habitat. We aim here to (i)identify the environmental variables involved in habitat selection, (ii)identi...

The spatial heterogeneity of grasslands determines the abundance and quality of food resources for grazing animals. As plants mature, they increase in mass, which allows greater instantaneous intake rates, but the cell wall concentrations increase too, reducing diet quality. In ruminants, daily intake rates are often constrained by the time needed...

This chapter explores the management objectives and the different approaches to wildlife management of large ungulates in France. A detailed analysis is done about the species present, their numerical status and the distribution of the different ungulates that occur. Management systems are described (legislative and administrative structures) with...

Density‐dependence is a key concept in population dynamics. Here, we review how body mass and demographic parameters vary with population density in large herbivores. The demographic parameters we consider are age‐ and sex‐specific reproduction, survival and dispersal. As population density increases, the body mass of large herbivores typically dec...

Dans un contexte agricole favorable au développement de systèmes herbagers durables, les équidés ont un rôle majeur à jouer dans l’entretien de l’espace et la préservation de la biodiversité prairiale. Les effectifs de chevaux augmentent fortement en France comme dans le reste de l’Europe. Pourtant la filière équine est confrontée à un manque de ré...

In an agricultural context promoting the development of sustainable grazing systems, horses have a significant role to play in the management of grasslands and their biodiversity. While the number of horses has been increasing in France and in Europe, the lack of data on how horses exploit pastures makes it difficult to propose management recommend...

The Golden mole, Chrysochloris stuhlmanni fosteri, occurs in the west of Kenya, on Mount Elgon and the Cherangani Hills, while the mole-shrews, Surdisorex pollulus and 5. norae occur on Mount Kenya and the Aberdare Mountains respectively (Fig. 1). These species were trapped and their stomach contents recorded over two months. Some ecological simila...

The numbers of horses grazing at pasture are increasing in developed countries, so a proper understanding of their feeding selectivity and of the tactics they use for extracting nutrients from swards is essential for the management of horses and grasslands. Resource acquisition in herbivores can be optimised through the modulation of their intake a...

Les tempêtes qui ont frappé la France en décembre 1999 nous ont donné une opportunité sans précédent de quantifier l'impact de perturbations climatiques majeures sur les populations de vertébrés.

We investigated density dependence on the demographic parameters of a population of Camargue horses (Equus caballus), individually monitored and unmanaged for eight years. We also analysed the contributions of individual demographic parameters to changes in the population growth rates. The decrease in resources caused a loss of body condition. Adul...

The functional response, that is the relationship between the food intake rate of a forager and the availability of food items, has been subject to numerous investigations in ruminants. In horses however, the functional response has been poorly studied despite of the importance of grazed forage in horse nutrition and the increasing role of horses i...

We describe food selection by roe deer (Capreolus capreolus) in relation to the food quality of the plants available (the concentrations of fibres, sugars, crude protein, and of phenolics and terpenes). Seven tame roe deer feeding in an oak-beech woodland edge used the majority (80-94%) of the plant species available: they were therefore generalist...

Ce projet avait pour objectif d'évaluer l'impact des tempêtes de décembre 1999 sur la dynamique des populations de chevreuils à court et à moyen terme, de comprendre les processus écologiques qui régissent ces populations, de coupler des modèles de dynamique des plantes et de dynamique des grands herbivores pour la prévision à long terme, et d'affi...

Food intake is a key biological process in animals, as it determines the energy and nutrients available for the physiological and behavioural processes. In herbivores, the abundance, structure and quality of plant resources are known to influence intake strongly. In ruminants, as the forage quality declines, digestibility and total intake decline....

Bone marrow dry weight expressed as a percentage of its fresh weight was found to be a good indication of its fat content in wildebeest, kongoni, and buffalo. The calculated regression equations were similar enough to suggest a more general formula for the larger ruminants. Bone marrow fat is mobilized after the kidney fat and hence is a better mea...

The relationship between individual performance and nonrandom use of habitat is fundamental to ecology; however, empirical tests of this relationship remain limited, especially for higher orders of selection like that of the home range. We quantified the association between lifetime reproductive success (LRS) and variables describing lifetime home...

Management of grazed grasslands for production and/or conservation objectives requires a thorough understanding of the choices of feeding sites by herbivores, and of the biological processes involved. Most models of the feeding strategies of herbivores are based on the principle that optimising the intake of energy (or some nutrient) is the primary...

abstractText"> Management of large wild herbivores sometimes includes action on the availability of resources and/or on the abundance of Management of large wild herbivores sometimes includes action on the availability of resources and/or on the abundance of predators, but the management of most populations of these animals is limited to the choice...

Arkins, especially as the abstract raises interesting issues, such as: • a major methodological,problem—that,positive reinforce-

High‐density populations of large herbivores are now widespread. Wildlife managers commonly attempt to control large herbivores through hunting to meet specific management objectives, considering population density as the minimal key source of information. Here, we review the problems of censusing populations of large herbivores and describe an alt...

African ungulate populations appear to be limited principally by their food resources. Within ungulate communities, plains zebras coexist with grazing bovids of similar body size, but rarely are the dominant species. Given the highly effective nutritional strategy of the equids and the resistance of zebras to drought, this is unexpected and suggest...

Animals in seasonal environments are affected by climate in very different ways depending on season and part of the climatic effects operates indirectly through the plants. Vegetation conditions in spring and summer are regarded as decisive for the reproductive success and the offspring's condition of large herbivores, but objective ways to determi...

POSTER • Size of horns in bovids has important and diverse biological implications and researchers have been trying to understand which factors determine this trait (Jorgenson et al., 1998; Giacometti et al., 2002) • In addition to factors, such as genotype, population density, habitat quality or climatology, anthropic actions like trophy hunting m...

Data on 22 radio-collared adult female roe deer Capreolus capreolus in the Chizé forest were used to test whether their home-range size was influenced by resource availability and reproductive status. As roe deer females are income breeders and invest heavily in each reproductive attempt, they should be limited by energetic constraints. Thus it was...

The primary goal of foraging herbivores is to maximise the net rate of intake of digestible energy (or of a limiting nutrient). However, foraging strategies of herbivores are also sensitive to other selective forces (e.g. predation, parasites), which may modify their choice of feeding patches. Horses feed in spatially complex swards, and allocate t...

1. Temporal and spatial variation can strongly affect life-history traits, but few studies to date have quantified the importance of the interplay between temporal and spatial components of population dynamics. 2. We analysed spatiotemporal variation in early survival of roe deer fawns over 15 years (1985–99) in an intensively monitored population...

New Caledonia has an exceptionally diverse and unique flora, and there is growing concern about the impacts of introduced wild rusa deer on native forests. The diets of free-ranging rusa deer from two native forest sites were studied using rumen content analysis. Samples (n = 61) from a sclerophyll forest site consisted principally of graminoids (6...

The populations of the ecologically dominant ungulates in the Serengeti ecosystem (zebra, wildebeest and buffalo) have shown markedly different trends since the 1960s: the two ruminants both irrupted after the elimination of rinderpest in 1960, while the zebras have remained stable. The ruminants are resource limited (though parts of the buffalo po...

Abstract Hurricanes profoundly modify the structure of forests, affecting the habitat quality of forest dwelling ungulates. For browsers in European forests the effects are expected to be positive in the short-term due to increased availability of browse, but the data to test this prediction are rarely available. In this study, data on home ranges...

Recent findings suggest that herbivores select feeding sites of intermediate biomass in order to maximise their digestible nutrient intake as the result of the trade-off between forage quality and quantity ('forage maturation hypothesis'). We propose a reformulation of this hypothesis which recognises this trade-off, but also underlines that constr...

It is well established that the dynamics of mammalian populations vary in time, in relation to density and weather, and often in interaction with phenotypic differences (sex, age and social status). Habitat quality has recently been identified as another significant source of individual variability in vital rates of deer, including roe deer where s...

We analyzed spatial variations in movements and survival in a roe deer (Capreolus capreolus) population (Chizé, western France) by using recent developments of multistate capture–mark–recapture modeling in order to estimate transition and survival probabilities of individuals living in three habitats of contrasting quality. Irrespective of both pop...

Although extreme weather events—such as hurricanes—cause obvious changes in landscape and tree cover, the impact of such events on population dynamics of ungulates has not yet been measured accurately. We report a first quantification of the demographic consequences on roe deer (Capreolus capreolus) of the strongest hurricane (Lothar) that France h...

Rusa Deer Cervus timorensis russa was introduced to New Caledonia in 1870 from Java, and has colonized the main island of Grande Terre, where it is found in virtually all the terrestrial biotopes. Despite its abundance and its socio-economic importance for New Caledonians, little is known about the diets of the wild deer populations living in conta...

The functional response, i.e. the quantity of food consumed per unit of time as a function of food availability, is a central process in foraging ecology. The application of this concept to foraging by mammalian herbivores has led to major insights into the process of resource acquisition, but it has so far been little used to understand foraging i...

The functional responses of roe deer were examined using 11 plant species. A technique to discriminate between encounter‐ and handling‐limited processes was used, and it can be concluded that the functional response applicable to patch browsing by roe deer is governed not by the rate of encounter but by the rate of oral processing. The large differ...

Body mass is a key determinant of fitness components in many organisms, and adult mass varies considerably among individuals within populations. These variations have several causes, involve temporal and spatial factors, and are not yet well understood. We use long-term data from 20 roe deer cohorts (1977-96) in a 2600 ha study area (Chizé, western...

We used a data set of ungulate censuses from 31 natural ecosystems from East and Southern Africa to test two hypotheses: (1) megaherbivores should dominate ungulate communities in ecosystems with high rainfall and low soil nutrient status because of their ability to survive on poor quality food resources, and (2) the abundance of megaherbivores aff...

We studied the diurnal and nocturnal habitat use of wintering dabbling ducks (Anas spp.) in two protected areas of an internationally important winter quarter in western France. The waterbodies of the reserves are heavily used by ducks during daylight hours, and 3–55% of these birds used the reserves at night: >50% of shoveler (A. clypeata), 20% of...

Equids are generalist herbivores that co‐exist with bovids of similar body size in many ecosystems. There are two major hypotheses to explain their co‐existence, but few comparative data are available to test them. The first postulates that the very different functioning of their digestive tracts leads to fundamentally different patterns of use of...

Most important day-roosts for wintering ducks are protected, but the useof such sites as foraging habitats by Anatidae has received little attention. Westudied the foraging activity of wintering mallard (Anasplatyrhynchos) and teal (A. crecca) at fourprotected areas of the Marshes of Rochefort, western France. These species aregenerally nocturnal f...

Cet article présente de façon synthétique et critique les apports de la session 5 du Congrès Européen des Herbages 2002 (La Rochelle, 27-30 mai) --- Les stratégies de conservation des milieux présentées en session plénière se distinguent par la place qui est consacrée à l’homme et à ses pratiques agricoles. Corrélativement, l’espace est soit celui...

Diverses études qui ont été conduites ces dernières années apportent un éclairage nouveau au problème des dégâts forestiers causés par le chevreuil. Dans le cas des plantations, il a pu être montré que l'abroutissement est déterminé par la qualité nutritionnelle des pousses mais l'apport alimentaire de celles-ci reste malgré tout très faible en reg...

A major assumption in most models of foraging is that feeding and vigilance are mutually exclusive. A recent experimental study challenged this hypothesis and demonstrated that birds are able to detect predators while pecking seeds on the ground (head-down vigilance). Experimental obstruction of head-down vigilance makes birds increase head-up vigi...