Taking individual heterogeneity in mortality risks into account in demographic studies of wild animal populations: development and use of statistical models.

The Cormarck-Jolly-Seber model incorporating frailty implemented in WinBUGS, using the 9000 kittiwake’s dataset monitorized during 22 years, showed that the convergence is very low over computational view. We developed different kind of multistate model, considering independence/dependence between random effect of breeding and survival probability. The last part of the work was dedicated to model selection with Bayesian framework

On the distribution of proportions and ratios as indicators of ungulate body condition

In the wildlife literature various studies have shown that the amount of fat around the kidneys is often a good indicator of body condition and health of ungulate species ([1],[2]). Wildlife biologies often measure the weights of fat around the kidneys and the kidneys themselves (without fat), comparing these two quantities and transforming them into a ratio or a proportion as surrogates of body condition of dead animals. Later, they use these indices as response variables to model the e®ect of covariates or treatments, such as age group and season of the year, on body condition. The more commonly used models are ANOVA-type. Most debate has been concentrated on whether or not to use a simple ANOVA model of ratios or proportions with ¯xed e®ects, or an ANCOVA model using fat weight as response variable, and the kidneys weight as a covariate ([3]). Results have taken by surprise some biologists because using one or another model with both response variables could lead to very di®erent results for what it considered the most important e®ects. In this manuscript we attempt to highlight the main di®erences and the distributional properties of these response variables, ratio and proportion

Sobre a distribuição de proporções e razões como indicadores da condição dos ungulados

Desde 1955 um procedimento comum para estudar a condi¸c˜ao corporal em ungulados, depois de mortos, consiste em pesar o rim com e sem a sua gordura associada. Calcula-se depois a raz˜ao entre o peso da gordura do rim e o peso do rim sem gordura, ou a propor¸c˜ao de gordura do rim relativamente ao total do peso do rim mais gordura. Os investigadores encontram discrepˆancias na an´alise estat´ıstica quando a vari´avel resposta ´e expressa como uma raz˜ao (R) ou quando ´e expressa como propor¸c˜ao (P). Apesar do nosso trabalho ser motivado pela necessidade de avaliar a sa´ude nos ungulados, o problema ´e muito comum noutras ´areas, al´em das Ciˆencias Medicas e da Vida. Dependendo do dom´ınio destas vari´aveis, verifica-se que as propriedades de R e P s˜ao bastante diferentes. Assim, ´e natural que em muitas situa¸c˜oes a sua variabilidade possa n˜ao ser igualmente explicada pelos mesmos efeitos ou covari´aveis (isto ´e, sexo, idade, esta¸c˜ao do ano), quando se usa o teste de ANOVA ou outros testes similares, apesar da sua robustez quando se parte dos mesmos pressupostos. Em muitas aplica¸c˜oes estas quantidades s˜ao usadas indiferentemente, sem se tomar aten¸c˜ao aos seus inconvenientes ou limita¸c˜oes. Apresentamos a nossa metodologia analisando dados de popula¸c˜oes de veados, e estudamos as distribui¸c˜oes de R e P, sob alguns pressupostos simplificadores

A half a century of measuring ungulate body condition using indices: is it time for a change?

From a literature review of five wildlife ecology journals since 1937, we document how using indices to monitor ungulate body condition is common practice, with the kidney fat index (KFI = weight of fat around the kidneys/weight of kidneys without fat × 100) as the favoured tool (82% of studies). In this context, we highlight the problems of using indices when underlying statistical assumptions are not met (isometry, parallel slopes between treatments). We show, with real and simulated data for two cervids with contrasting fat storage strategies, how results from analysis of variance of KFI values differ from analysis of covariance (ANCOVA) of raw data. We conclude that the KFI is affected by the restrictions typically associated with derived index values, and as a consequence, statistical analysis of the KFI could generate spurious results leading to erroneous interpretations concerning variation in body condition of ungulate populations. Thus, we recommend analysing fat weight as an untransformed variable in ANCOVA (kidney weight as covariate) to describe body condition variation in ungulates

What Courses Do I Need to Teach in Order to Address Food Insecurity in Sub Saharan Africa? A Delphi Study

Sub Saharan Africa is a region that has been struggling with food insecurity for decades. Though the percentage of undernourished people in the region has decreased over the last 25 years, the actual number of undernourished people increased by more than forty million. Combatting food insecurity in the region requires an arsenal of skills, knowledge, and abilities across a broad range of disciplines. One way to target food insecurity is through education and capacity building. The purpose of this study was to identify the courses and topics that should be included in a food security (FS) graduate certificate focused on Sub Saharan Africa. Identification of the topics and courses came from faculty and professionals working in the FS field in Sub Saharan Africa. A three-round Delphi technique was conducted to accomplish the purpose of the study with a total of 63 experts. Of the original 101 topics that the expert panel proposed in Round One, 80 reached the level of agreement. Researchers grouped the topics into 28 courses. The final result of the study was 24 courses that reached the level of agreement for determining the main topics and courses that should be included in a graduate certificate focused on FS for Sub Saharan Africa

The effect of data analysis strategies in density estimation of mountain ungulates using distance sampling

Distance sampling is being extensively used to estimate the abundance of animal populations. Nevertheless, the great variety of ways in which data can be analyzed may limit comparisons due to the lack of standardization of such protocols. In this study, the influence of analytical procedures for distance sampling data on density estimates and their precision was assessed. We have used data from 21 surveys of mountain ungulates in the Iberian Peninsula, France and the Italian Alps. Data from such surveys were analyzed with the program Distance 6.0. Our analyses show that estimated density can be higher for higher levels of data truncation. We also confirm that the estimates tend to be more precise when data are analyzed without binning and without truncating. We found no evidence of size biased sampling as group size and distances were uncorrelated in most of our surveys. Despite distance sampling being a fairly robust methodology, it can be sensitive to some data analysis strategies

Policy design for the Anthropocene

This is the author accepted manuscript. The final version is available from Nature Research via the DOI in this recordToday, more than ever, ‘Spaceship Earth’ is an apt metaphor as we chart the boundaries for a safe planet1. Social scientists both analyse why society courts disaster by approaching or even overstepping these boundaries and try to design suitable policies to avoid these perils. Because the threats of transgressing planetary boundaries are global, long-run, uncertain and interconnected, they must be analysed together to avoid conflicts and take advantage of synergies. To obtain policies that are effective at both international and local levels requires careful analysis of the underlying mechanisms across scientific disciplines and approaches, and must take politics into account. In this Perspective, we examine the complexities of designing policies that can keep Earth within the biophysical limits favourable to human life.Stockholm Resilience CentreBECC - Biodiversity and Ecosystem services in a Changing ClimateMistra Carbon Exi