Michel Goulard

Testing Global Positioning System Performance for Wildlife Monitoring Using Mobile Collars and Known Reference Points

Abstract To determine the spatial resolution of Global Positioning System (GPS) receiver data, rigorous testing is essential. We tested performance of the Lotek 3300 GPS collar for medium-sized mammals (Lotek Engineering, Inc., Newmarket, ON, Canada). To mimic real wildlife monitoring situations, we performed both static (stationary receiver) and mobile tests, placing the receiver collar on a dog. We compared fix locations of the mobile receiver with the actual trajectory described by a portable Trimble high-precision GPS. We determined performance in relation to habitat type and leaf cover. Location error was habitat-dependent, with the best results in open habitat and much poorer ones in forest, particularly coniferous-dominated forest. For both static and mobile tests, location accuracy was higher when the number of satellites contacted was high and when the residual positional dilution of precision (PDOP) value was low. However, location error was highly variable, even for a given PDOP value and a given number of satellites contacted. Finally, mobile collars performed less well than their static counterparts, presumably because of frequent changes of GPS position and orientation.

Contrasting spatial and temporal responses of bird communities to landscape changes

Quantifying the impact of land-use changes on biodiversity is a major challenge in conservation ecology. Static spatial relationships between bird communities and agricultural landscapes have been extensively studied. Yet, their ability to mirror the effects of temporal land-use dynamics remains to be demonstrated. Here, we test whether such space-for-time substitution approaches are relevant for explaining temporal variations in farmland bird communities. We surveyed 256 bird communities in an agricultural landscape in southwest France at the same locations in 1982 and 2007, and quantified the same seven landscape descriptors for each period. We compared the effects of spatial and temporal landscape changes over this 25-year period on bird species distributions and three community-level metrics: species richness and two community indices reflecting birds’ specialisation regarding local vegetation structure (local CSI) and landscape composition (landscape CSI). Landscape heterogeneity decreased between 1982 and 2007 and crop area increased sharply at the expense of grassland as a result of agricultural intensification. We found that the correlations between temporal changes in bird distributions or community metrics and landscape components were less consistent than their spatial relationships in each year. This result advocates caution when using a space-for-time substitution approach to assess the effects of landscape changes on biodiversity. Additionally, community metrics showed contrasted responses to landscape changes. Species richness and local CSI for each period were negatively related to the area of crops and positively related to landscape heterogeneity. Conversely, the landscape CSI was positively related to the area of crop and negatively to landscape heterogeneity. To understand the ecological processes linked to changes in farm landscapes, our study underlines the need to develop long-term studies with bird and habitat data collected during several periods, and particularly to consider multiple community indices in monitoring change.

Seasonal and daily walking activity patterns of free-ranging adult red deer (Cervus elaphus) at the individual level

We studied the walking activity over the year of free-ranging adult red deer (Cervus elaphus) in a mountainous area with the aim of describing the dynamics of movement patterns at the individual level. We monitored the distance walked by two males and two females fitted with global positioning system collars to test the hypothesis that deer adopt behaviours to reduce costs of locomotion. We predicted that both sexes would travel less in winter when disadvantageous environmental conditions occurred. We also predicted that the males would (1) reduce their movement soon after the rut due to very high energy expenditure during the breeding season and (2) travel less than the females due to their larger body mass. As we expected, minimum walking activity occurred after the rut from November to February for the males and in late February for the females. The walking activity of males peaked during the rut whereas that of females decreased. But compared to males, females moved more both during winter and daylight hours. Although our study stems from just four individuals, these results and the methodology used can be inspirational for red deer research as well as for ungulate research in general.

Short- and long-term repeatability of docility in the roe deer: sex and age matter

Behavioural consistency is a key assumption when evaluating how between-individual differences in behaviour influence life history tactics. Hence, understanding how and why variation in behavioural repeatability occurs is crucial. While analyses of behavioural repeatability are common, few studies of wild populations have investigated variation in repeatability in relation to individual status (e.g. sex, age, condition) and over different timescales. Here, we aimed to fill this gap by assessing within-population variation in the repeatability of docility, as assessed by the individuals response to human handling, in a free-ranging population of European roe deer, Capreolus capreolus. Docility was an equally repeatable behaviour at both short- and long-term timescales, suggesting that this behavioural trait is stable across time. Repeatability did not differ markedly between age and sex categories but tended to be higher in juvenile males than in juvenile females. Finally, contrary to expectation, individual variation in the repeatability of docility was not correlated with individual body mass. Further studies are required to assess the life history consequences of the individual variation in docility we report here.

Investigations on distribution patterns in soil: basic and relative distributions of roots, channels and cracks

Abstract Krebs, M., Kretzschmar, A., Babel, U., Chadoeuf, J. and Goulard, M., 1994. Investigations on distribution patterns in soil: basic and relative distributions of roots, channels and cracks. In: A.J. Ringrose-Voase and G.S. Humphreys (Editors), Soil Micromorphology: Studies in Management and Genesis. Proc. IX Int. Working Meeting on Soil Micromorphology, Townsville, Australia, July 1992. Developments in Soil Science 22, Elsevier, Amsterdam, pp. 437–449.

Detection of Flavescence dorée Grapevine Disease Using Unmanned Aerial Vehicle (UAV) Multispectral Imagery

Flavescence doree is a grapevine disease affecting European vineyards which has severe economic consequences and containing its spread is therefore considered as a major challenge for viticulture. Flavescence doree is subject to mandatory pest control including removal of the infected vines and, in this context, automatic detection of Flavescence doree symptomatic vines by unmanned aerial vehicle (UAV) remote sensing could constitute a key diagnosis instrument for growers. The objective of this paper is to evaluate the feasibility of discriminating the Flavescence doree symptoms in red and white cultivars from healthy vine vegetation using UAV multispectral imagery. Exhaustive ground truth data and UAV multispectral imagery (visible and near-infrared domain) have been acquired in September 2015 over four selected vineyards in Southwest France. Spectral signatures of healthy and symptomatic plants were studied with a set of 20 variables computed from the UAV images (spectral bands, vegetation indices and biophysical parameters) using univariate and multivariate classification approaches. Best results were achieved with red cultivars (both using univariate and multivariate approaches). For white cultivars, results were not satisfactory either for the univariate or the multivariate. Nevertheless, external accuracy assessment show that despite problems of Flavescence doree and healthy pixel misclassification, an operational Flavescence doree mapping technique using UAV-based imagery can still be proposed.

Using Spatial Statistics Tools on Remote-Sensing Data to Identify Fire Regime Linked with Savanna Vegetation Degradation

Fire is acknowledged to be a factor for explaining the disturbance of vegetation dynamics interacting with other environmental factors. In this study, the authors want to clarify the importance and the role of fire on the dynamics of savanna vegetation. The study area is the Marovoay watershed located on the north-west coast of Madagascar. In this site, burning herbaceous cover is the main practice in the extensive grazing system. They analyzed the relationship between two indicators, one related to vegetation activity changes and one about fire regime that results from a combination of fire frequency and seasonality. All indicators were measured between 2000 and 2007 using a time series of MODIS images. In this work, the authors implemented two approaches of spatial analysis. The first one analyzes the spatial structure of the residuals of a per-pixel non-spatial GLM model. In the second approach, a spatial GLM model is directly computed. In both approaches, the authors proposed two levels of stratification for the study area according to the spatial variations of the relationship established between vegetation activity changes and fire regime. The use of spatial statistical tools produces parsimonious models which they found to be consistent with expert knowledge. The authors demonstrated that a statistical analysis based on spatial GLM is able either to stratify an area when non ancillary data on land use exist or to validate an existing stratification.

Random Boolean Functions: Non-Parametric Estimation of the Intensity. Application to Soil Surface Roughness

A non-parametric estimation method is proposed for the intensity of the Poisson process associated to a Boolean random function. The case studied is that of marks being half-spheres as primary functions, these half-spheres lying on a given horizontal plane. The proposed method is derived from the method presented in Gyorfi, Hardle, Sarda et Vieu [1989] for the case of time series. An application in soil science is presented.

About predictions in spatial autoregressive models: optimal and almost optimal strategies

ABSTRACT About predictions in spatial autoregressive models: optimal and almost optimal strategies. Spatial Economic Analysis. This paper addresses the problem of prediction in the spatial autoregressive (SAR) model for areal data, which is classically used in spatial econometrics. With kriging theory, prediction using the best linear unbiased predictors (BLUPs) is at the heart of the geostatistical literature. From a methodological point of view, we explore the limits of the extension of BLUP formulas in the context of SAR models for out-of-sample prediction simultaneously at several sites. We propose a more tractable ‘almost best’ alternative and clarify the relationship between the BLUP and a proper expectation–maximization (EM) algorithm predictor. From an empirical perspective, we present data-based simulations to compare the efficiency of classical formulas with the best and almost best predictions.

Predators, food and social context shape the types of vigilance exhibited by kangaroos

Vigilance in prey species can serve many purposes, including predator detection and monitoring other group members, and is generally thought to impose a cost due to reduced food intake. However, previous studies have shown that herbivores are able to reduce the foraging cost of vigilance by chewing their food during vigilance bouts (‘vigilance with chewing’, as compared to ‘vigilance without chewing’). How predation risk, food availability and competition affect both the functions and the foraging costs of vigilance remains an open question. We studied female eastern grey kangaroos, Macropus giganteus, during winter and summer, when available food supplies were poor and rich, respectively, to investigate how group size, distance to cover, proximity between foragers and food patch quality affected decisions of foraging female kangaroos to exhibit antipredator or social vigilance, distinguishing vigilance with and without chewing. The use of antipredator vigilance was mainly driven by the perception of predation risk, and antipredator vigilance without chewing decreased with increased group size whereas antipredator vigilance with chewing increased nonlinearly with group size in winter. Distance to cover affected both forms of antipredator vigilance in summer only but there was no effect of nearest-neighbour distance. Social vigilance was affected positively by group size, and distance between foragers affected social vigilance without chewing positively, particularly in winter, and social vigilance with chewing negatively. Finally, patch quality increased the use of social vigilance with chewing in both seasons and decreased the use of antipredator vigilance with chewing in winter. This study provides new information on how animals make decisions about the functions and foraging costs of vigilance and allows a better understanding of how social foragers respond to an ever-changing environment.