Publications by authors named "Bram Van Moorter"

16 Publications

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Moving in the Anthropocene: Global reductions in terrestrial mammalian movements.

Authors:
Marlee A Tucker Katrin Böhning-Gaese William F Fagan John M Fryxell Bram Van Moorter Susan C Alberts Abdullahi H Ali Andrew M Allen Nina Attias Tal Avgar Hattie Bartlam-Brooks Buuveibaatar Bayarbaatar Jerrold L Belant Alessandra Bertassoni Dean Beyer Laura Bidner Floris M van Beest Stephen Blake Niels Blaum Chloe Bracis Danielle Brown P J Nico de Bruyn Francesca Cagnacci Justin M Calabrese Constança Camilo-Alves Simon Chamaillé-Jammes Andre Chiaradia Sarah C Davidson Todd Dennis Stephen DeStefano Duane Diefenbach Iain Douglas-Hamilton Julian Fennessy Claudia Fichtel Wolfgang Fiedler Christina Fischer Ilya Fischhoff Christen H Fleming Adam T Ford Susanne A Fritz Benedikt Gehr Jacob R Goheen Eliezer Gurarie Mark Hebblewhite Marco Heurich A J Mark Hewison Christian Hof Edward Hurme Lynne A Isbell René Janssen Florian Jeltsch Petra Kaczensky Adam Kane Peter M Kappeler Matthew Kauffman Roland Kays Duncan Kimuyu Flavia Koch Bart Kranstauber Scott LaPoint Peter Leimgruber John D C Linnell Pascual López-López A Catherine Markham Jenny Mattisson Emilia Patricia Medici Ugo Mellone Evelyn Merrill Guilherme de Miranda Mourão Ronaldo G Morato Nicolas Morellet Thomas A Morrison Samuel L Díaz-Muñoz Atle Mysterud Dejid Nandintsetseg Ran Nathan Aidin Niamir John Odden Robert B O'Hara Luiz Gustavo R Oliveira-Santos Kirk A Olson Bruce D Patterson Rogerio Cunha de Paula Luca Pedrotti Björn Reineking Martin Rimmler Tracey L Rogers Christer Moe Rolandsen Christopher S Rosenberry Daniel I Rubenstein Kamran Safi Sonia Saïd Nir Sapir Hall Sawyer Niels Martin Schmidt Nuria Selva Agnieszka Sergiel Enkhtuvshin Shiilegdamba João Paulo Silva Navinder Singh Erling J Solberg Orr Spiegel Olav Strand Siva Sundaresan Wiebke Ullmann Ulrich Voigt Jake Wall David Wattles Martin Wikelski Christopher C Wilmers John W Wilson George Wittemyer Filip Zięba Tomasz Zwijacz-Kozica Thomas Mueller

Science 2018 Jan;359(6374):466-469

Senckenberg Biodiversity and Climate Research Centre, Senckenberg Gesellschaft für Naturforschung, 60325 Frankfurt (Main), Germany.

Animal movement is fundamental for ecosystem functioning and species survival, yet the effects of the anthropogenic footprint on animal movements have not been estimated across species. Using a unique GPS-tracking database of 803 individuals across 57 species, we found that movements of mammals in areas with a comparatively high human footprint were on average one-half to one-third the extent of their movements in areas with a low human footprint. We attribute this reduction to behavioral changes of individual animals and to the exclusion of species with long-range movements from areas with higher human impact. Global loss of vagility alters a key ecological trait of animals that affects not only population persistence but also ecosystem processes such as predator-prey interactions, nutrient cycling, and disease transmission.
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http://dx.doi.org/10.1126/science.aam9712DOI Listing
January 2018

How many routes lead to migration? Comparison of methods to assess and characterize migratory movements.

J Anim Ecol 2016 Jan 1;85(1):54-68. Epub 2015 Dec 1.

Biodiversity and Molecular Ecology Department, Research and Innovation Centre, Fondazione Edmund Mach, Via Mach 1, 38010, San Michele all'Adige, TN, Italy.

Decreasing rate of migration in several species as a consequence of climate change and anthropic pressure, together with increasing evidence of space-use strategies intermediate between residency and complete migration, are very strong motivations to evaluate migration occurrence and features in animal populations. The main goal of this paper was to perform a relative comparison between methods for identifying and characterizing migration at the individual and population level on the basis of animal location data. We classified 104 yearly individual trajectories from five populations of three deer species as migratory or non-migratory, by means of three methods: seasonal home range overlap, spatio-temporal separation of seasonal clusters and the Net Squared Displacement (NSD) method. For migratory cases, we also measured timing and distance of migration and residence time on the summer range. Finally, we compared the classification in migration cases across methods and populations. All methods consistently identified migration at the population level, that is, they coherently distinguished between complete or almost complete migratory populations and partially migratory populations. However, in the latter case, methods coherently classified only about 50% of the single cases, that is they classified differently at the individual-animal level. We therefore infer that the comparison of methods may help point to 'less-stereotyped' cases in the residency-to-migration continuum. For cases consistently classified by all methods, no significant differences were found in migration distance, or residence time on summer ranges. Timing of migration estimated by NSD was earlier than by the other two methods, both for spring and autumn migrations. We suggest three steps to identify improper inferences from migration data and to enhance understanding of intermediate space-use strategies. We recommend (i) classifying migration behaviours using more than one method, (ii) performing sensitivity analysis on method parameters to identify the extent of the differences and (iii) investigating inconsistently classified cases as these may often be ecologically interesting (i.e. less-stereotyped migratory behaviours).
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http://dx.doi.org/10.1111/1365-2656.12449DOI Listing
January 2016

Memory Effects on Movement Behavior in Animal Foraging.

PLoS One 2015 19;10(8):e0136057. Epub 2015 Aug 19.

Environmental Laboratory, US Army Engineer Research and Development Center, Portland, Oregon, United States of America.

An individual's choices are shaped by its experience, a fundamental property of behavior important to understanding complex processes. Learning and memory are observed across many taxa and can drive behaviors, including foraging behavior. To explore the conditions under which memory provides an advantage, we present a continuous-space, continuous-time model of animal movement that incorporates learning and memory. Using simulation models, we evaluate the benefit memory provides across several types of landscapes with variable-quality resources and compare the memory model within a nested hierarchy of simpler models (behavioral switching and random walk). We find that memory almost always leads to improved foraging success, but that this effect is most marked in landscapes containing sparse, contiguous patches of high-value resources that regenerate relatively fast and are located in an otherwise devoid landscape. In these cases, there is a large payoff for finding a resource patch, due to size, value, or locational difficulty. While memory-informed search is difficult to differentiate from other factors using solely movement data, our results suggest that disproportionate spatial use of higher value areas, higher consumption rates, and consumption variability all point to memory influencing the movement direction of animals in certain ecosystems.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0136057PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4542208PMC
May 2016

Movement is the glue connecting home ranges and habitat selection.

J Anim Ecol 2016 Jan 30;85(1):21-31. Epub 2015 Jul 30.

Laboratoire de Biométrie et Biologie Evolutive, UMR 5558, CNRS, Université Lyon 1, 69622, Villeurbanne, France.

Animal space use has been studied by focusing either on geographic (e.g. home ranges, species' distribution) or on environmental (e.g. habitat use and selection) space. However, all patterns of space use emerge from individual movements, which are the primary means by which animals change their environment. Individuals increase their use of a given area by adjusting two key movement components: the duration of their visit and/or the frequency of revisits. Thus, in spatially heterogeneous environments, animals exploit known, high-quality resource areas by increasing their residence time (RT) in and/or decreasing their time to return (TtoR) to these areas. We expected that spatial variation in these two movement properties should lead to observed patterns of space use in both geographic and environmental spaces. We derived a set of nine predictions linking spatial distribution of movement properties to emerging space-use patterns. We predicted that, at a given scale, high variation in RT and TtoR among habitats leads to strong habitat selection and that long RT and short TtoR result in a small home range size. We tested these predictions using moose (Alces alces) GPS tracking data. We first modelled the relationship between landscape characteristics and movement properties. Then, we investigated how the spatial distribution of predicted movement properties (i.e. spatial autocorrelation, mean, and variance of RT and TtoR) influences home range size and hierarchical habitat selection. In landscapes with high spatial autocorrelation of RT and TtoR, a high variation in both RT and TtoR occurred in home ranges. As expected, home range location was highly selective in such landscapes (i.e. second-order habitat selection); RT was higher and TtoR lower within the selected home range than outside, and moose home ranges were small. Within home ranges, a higher variation in both RT and TtoR was associated with higher selectivity among habitat types (i.e. third-order habitat selection). Our findings show how patterns of geographic and environmental space use correspond to the two sides of a coin, linked by movement responses of individuals to environmental heterogeneity. By demonstrating the potential to assess the consequences of altering RT or TtoR (e.g. through human disturbance or climatic changes) on home range size and habitat selection, our work sets the basis for new theoretical and methodological advances in movement ecology.
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http://dx.doi.org/10.1111/1365-2656.12394DOI Listing
January 2016

Predicting the continuum between corridors and barriers to animal movements using Step Selection Functions and Randomized Shortest Paths.

J Anim Ecol 2016 Jan 6;85(1):32-42. Epub 2015 Aug 6.

Department of Animal and Human Biology, Sapienza University, Viale dell'Università 32, Rome, 00185, Italy.

The loss, fragmentation and degradation of habitat everywhere on Earth prompts increasing attention to identifying landscape features that support animal movement (corridors) or impedes it (barriers). Most algorithms used to predict corridors assume that animals move through preferred habitat either optimally (e.g. least cost path) or as random walkers (e.g. current models), but neither extreme is realistic. We propose that corridors and barriers are two sides of the same coin and that animals experience landscapes as spatiotemporally dynamic corridor-barrier continua connecting (separating) functional areas where individuals fulfil specific ecological processes. Based on this conceptual framework, we propose a novel methodological approach that uses high-resolution individual-based movement data to predict corridor-barrier continua with increased realism. Our approach consists of two innovations. First, we use step selection functions (SSF) to predict friction maps quantifying corridor-barrier continua for tactical steps between consecutive locations. Secondly, we introduce to movement ecology the randomized shortest path algorithm (RSP) which operates on friction maps to predict the corridor-barrier continuum for strategic movements between functional areas. By modulating the parameter Ѳ, which controls the trade-off between exploration and optimal exploitation of the environment, RSP bridges the gap between algorithms assuming optimal movements (when Ѳ approaches infinity, RSP is equivalent to LCP) or random walk (when Ѳ → 0, RSP → current models). Using this approach, we identify migration corridors for GPS-monitored wild reindeer (Rangifer t. tarandus) in Norway. We demonstrate that reindeer movement is best predicted by an intermediate value of Ѳ, indicative of a movement trade-off between optimization and exploration. Model calibration allows identification of a corridor-barrier continuum that closely fits empirical data and demonstrates that RSP outperforms models that assume either optimality or random walk. The proposed approach models the multiscale cognitive maps by which animals likely navigate real landscapes and generalizes the most common algorithms for identifying corridors. Because suboptimal, but non-random, movement strategies are likely widespread, our approach has the potential to predict more realistic corridor-barrier continua for a wide range of species.
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http://dx.doi.org/10.1111/1365-2656.12386DOI Listing
January 2016

REVIEW: Can habitat selection predict abundance?

J Anim Ecol 2016 Jan 16;85(1):11-20. Epub 2015 Mar 16.

Norwegian Institute for Nature Research (NINA), Trondheim, 7485, Norway.

Habitats have substantial influence on the distribution and abundance of animals. Animals' selective movement yields their habitat use. Animals generally are more abundant in habitats that are selected most strongly. Models of habitat selection can be used to distribute animals on the landscape or their distribution can be modelled based on data of habitat use, occupancy, intensity of use or counts of animals. When the population is at carrying capacity or in an ideal-free distribution, habitat selection and related metrics of habitat use can be used to estimate abundance. If the population is not at equilibrium, models have the flexibility to incorporate density into models of habitat selection; but abundance might be influenced by factors influencing fitness that are not directly related to habitat thereby compromising the use of habitat-based models for predicting population size. Scale and domain of the sampling frame, both in time and space, are crucial considerations limiting application of these models. Ultimately, identifying reliable models for predicting abundance from habitat data requires an understanding of the mechanisms underlying population regulation and limitation.
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http://dx.doi.org/10.1111/1365-2656.12359DOI Listing
January 2016

'You shall not pass!': quantifying barrier permeability and proximity avoidance by animals.

J Anim Ecol 2016 Jan 25;85(1):43-53. Epub 2014 Aug 25.

Institute of Biodiversity Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ, UK.

Impediments to animal movement are ubiquitous and vary widely in both scale and permeability. It is essential to understand how impediments alter ecological dynamics via their influence on animal behavioural strategies governing space use and, for anthropogenic features such as roads and fences, how to mitigate these effects to effectively manage species and landscapes. Here, we focused primarily on barriers to movement, which we define as features that cannot be circumnavigated but may be crossed. Responses to barriers will be influenced by the movement capabilities of the animal, its proximity to the barriers, and habitat preference. We developed a mechanistic modelling framework for simultaneously quantifying the permeability and proximity effects of barriers on habitat preference and movement. We used simulations based on our model to demonstrate how parameters on movement, habitat preference and barrier permeability can be estimated statistically. We then applied the model to a case study of road effects on wild mountain reindeer summer movements. This framework provided unbiased and precise parameter estimates across a range of strengths of preferences and barrier permeabilities. The quality of permeability estimates, however, was correlated with the number of times the barrier is crossed and the number of locations in proximity to barriers. In the case study we found that reindeer avoided areas near roads and that roads are semi-permeable barriers to movement. There was strong avoidance of roads extending up to c. 1 km for four of five animals, and having to cross roads reduced the probability of movement by 68·6% (range 3·5-99·5%). Human infrastructure has embedded within it the idea of networks: nodes connected by linear features such as roads, rail tracks, pipelines, fences and cables, many of which divide the landscape and limit animal movement. The unintended but potentially profound consequences of infrastructure on animals remain poorly understood. The rigorous framework for simultaneously quantifying movement, habitat preference and barrier permeability developed here begins to address this knowledge gap.
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http://dx.doi.org/10.1111/1365-2656.12275DOI Listing
January 2016

Selecting habitat to survive: the impact of road density on survival in a large carnivore.

PLoS One 2013 10;8(7):e65493. Epub 2013 Jul 10.

Fort Lauderdale Research and Education Center, University of Florida, Fort Lauderdale, Florida, United States of America.

Habitat selection studies generally assume that animals select habitat and food resources at multiple scales to maximise their fitness. However, animals sometimes prefer habitats of apparently low quality, especially when considering the costs associated with spatially heterogeneous human disturbance. We used spatial variation in human disturbance, and its consequences on lynx survival, a direct fitness component, to test the Hierarchical Habitat Selection hypothesis from a population of Eurasian lynx Lynx lynx in southern Norway. Data from 46 lynx monitored with telemetry indicated that a high proportion of forest strongly reduced the risk of mortality from legal hunting at the home range scale, while increasing road density strongly increased such risk at the finer scale within the home range. We found hierarchical effects of the impact of human disturbance, with a higher road density at a large scale reinforcing its negative impact at a fine scale. Conversely, we demonstrated that lynx shifted their habitat selection to avoid areas with the highest road densities within their home ranges, thus supporting a compensatory mechanism at fine scale enabling lynx to mitigate the impact of large-scale disturbance. Human impact, positively associated with high road accessibility, was thus a stronger driver of lynx space use at a finer scale, with home range characteristics nevertheless constraining habitat selection. Our study demonstrates the truly hierarchical nature of habitat selection, which aims at maximising fitness by selecting against limiting factors at multiple spatial scales, and indicates that scale-specific heterogeneity of the environment is driving individual spatial behaviour, by means of trade-offs across spatial scales.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0065493PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3707854PMC
March 2014

Understanding scales of movement: animals ride waves and ripples of environmental change.

J Anim Ecol 2013 Jul 15;82(4):770-80. Epub 2013 Feb 15.

Centre for Conservation Biology, Department of Biology, Norwegian University of Science and Technology (NTNU), NO-7491, Trondheim, Norway; Terrestrial Department, Norwegian Institute for Nature Research (NINA), NO-7485, Trondheim, Norway.

Animal movements are the primary behavioural adaptation to spatiotemporal heterogeneity in resource availability. Depending on their spatiotemporal scale, movements have been categorized into distinct functional groups (e.g. foraging movements, dispersal, migration), and have been studied using different methodologies. We suggest striving towards the development of a coherent framework based on the ultimate function of all movement types, which is to increase individual fitness through an optimal exploitation of resources varying in space and time. We developed a novel approach to simultaneously study movements at different spatiotemporal scales based on the following proposed theory: the length and frequency of animal movements are determined by the interaction between temporal autocorrelation in resource availability and spatial autocorrelation in changes in resource availability. We hypothesized that for each time interval the spatiotemporal scales of moose Alces alces movements correspond to the spatiotemporal scales of variation in the gains derived from resource exploitation when taking into account the costs of movements (represented by their proxies, forage availability NDVI and snow depth respectively). The scales of change in NDVI and snow were quantified using wave theory, and were related to the scale of moose movement using linear mixed models. In support of the proposed theory we found that frequent, smaller scale movements were triggered by fast, small-scale ripples of changes, whereas infrequent, larger scale movements matched slow, large-scale waves of change in resource availability. Similarly, moose inhabiting ranges characterized by larger scale waves of change in the onset of spring migrated longer distances. We showed that the scales of movements are driven by the scales of changes in the net profitability of trophic resources. Our approach can be extended to include drivers of movements other than trophic resources (e.g. population density, density of related individuals, predation risk) and may facilitate the assessment of the impact of environmental changes on community dynamics and conservation.
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http://dx.doi.org/10.1111/1365-2656.12045DOI Listing
July 2013

Reciprocal modulation of internal and external factors determines individual movements.

J Anim Ecol 2013 Mar 5;82(2):290-300. Epub 2012 Oct 5.

Université de Lyon, F-69000, Lyon, Université Lyon 1, CNRS, UMR5558, Laboratoire de Biométrie et Biologie Evolutive, F-69622, Villeurbanne, France; Department of Ecology and Natural Resource Management, Norwegian University of Life Science, P.O. Box 5003, NO-1432, Ås, Norway; Office National de la Chasse et de la Faune Sauvage, CNERA PAD, Equipe ours, Impasse de la Chapelle, 31800, Villeneuve de Rivière, France; Centre for African Ecology, School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Wits 2050, South Africa.

Movement is fundamental to individual and population dynamics, as it allows individuals to meet their basic requirements. Although movement patterns reflect interactions between internal and external factors, only few studies have examined the effects of these factors on movement simultaneously, and they generally focused on particular biological contexts (e.g. dispersal, foraging). However, the relative importance of these factors in driving individual routine movements might reflect a species' potential flexibility to cope with landscape changes and therefore buffer their potential impact on fitness. We used data from GPS collars on Scandinavian brown bears to investigate the relative role of these factors, as well as an additional factor (period of the year) on routine movements at two spatial scales (hourly and daily relocations). As expected, internal factors played a major role in driving movement, compared to external factors at both scales, but its relative importance was greater at a finer scale. In particular, the interaction between reproductive status and period of the year was one of the most influential variables, females being constrained by the movement capacity of their cubs in the first periods of the year. The effect of human disturbance on movement was also greater for females with cubs than for lone females. This study showed how reciprocal modulation of internal and external factors is shaping space use of brown bears. We stress that these factors should be studied simultaneously to avoid the risk of obtaining context-dependent inferences. Moreover, the study of their relative contribution is also highly relevant in the context of multiple-use landscapes, as human activities generally affect the landscape more than they affect the internal states of an individual. Species or individuals with important internal constraints should be less responsive to changes in their environment as they have less freedom from internal constraints and should thus be more sensitive to human alteration of the landscape, as shown for females with cubs in this study.
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http://dx.doi.org/10.1111/j.1365-2656.2012.02038.xDOI Listing
March 2013

A migratory northern ungulate in the pursuit of spring: jumping or surfing the green wave?

Am Nat 2012 Oct 23;180(4):407-24. Epub 2012 Aug 23.

Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, NO-1432 Aas, Norway.

The forage-maturation hypothesis (FMH) states that herbivores migrate along a phenological gradient of plant development in order to maximize energy intake. Despite strong support for the FMH, the actual relationship between plant phenology and ungulate movement has remained enigmatic. We linked plant phenology (MODIS-normalized difference vegetation index [NDVI] data) and space use of 167 migratory and 78 resident red deer (Cervus elaphus), using a space-time-time matrix of "springness," defined as the instantaneous rate of green-up. Consistent with the FMH, migrants experienced substantially greater access to early plant phenology than did residents. Deer were also more likely to migrate in areas where migration led to greater gains in springness. Rather than "surfing the green wave" during migration, migratory red deer moved rapidly from the winter to the summer range, thereby "jumping the green wave." However, migrants and, to a lesser degree, residents did track phenological green-up through parts of the growing season by making smaller-scale adjustments in habitat use. Despite pronounced differences in their life histories, we found only marginal differences between male and female red deer in this study. Those differences that we did detect pointed toward additional constraints on female space-use tactics, such as those posed by calving and caring for dependent offspring. We conclude that whereas in some systems migration itself is a way to surf the green wave, in others it may simply be a means to reconnect with phenological spring at the summer range. In the light of ubiquitous anthropogenic environmental change, understanding the relationship between the green wave and ungulate space use has important consequences for the management and conservation of migratory ungulates and the phenomenon of migration itself.
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http://dx.doi.org/10.1086/667590DOI Listing
October 2012

Habitat quality influences population distribution, individual space use and functional responses in habitat selection by a large herbivore.

Oecologia 2012 Jan 16;168(1):231-43. Epub 2011 Jul 16.

Centre for Conservation Biology, Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway.

Identifying factors shaping variation in resource selection is central for our understanding of the behaviour and distribution of animals. We examined summer habitat selection and space use by 108 Global Positioning System (GPS)-collared moose in Norway in relation to sex, reproductive status, habitat quality, and availability. Moose selected habitat types based on a combination of forage quality and availability of suitable habitat types. Selection of protective cover was strongest for reproducing females, likely reflecting the need to protect young. Males showed strong selection for habitat types with high quality forage, possibly due to higher energy requirements. Selection for preferred habitat types providing food and cover was a positive function of their availability within home ranges (i.e. not proportional use) indicating functional response in habitat selection. This relationship was not found for unproductive habitat types. Moreover, home ranges with high cover of unproductive habitat types were larger, and smaller home ranges contained higher proportions of the most preferred habitat type. The distribution of moose within the study area was partly related to the distribution of different habitat types. Our study shows how distribution and availability of habitat types providing cover and high-quality food shape ungulate habitat selection and space use.
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http://dx.doi.org/10.1007/s00442-011-2072-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3254876PMC
January 2012

A model-driven approach to quantify migration patterns: individual, regional and yearly differences.

J Anim Ecol 2011 Mar 25;80(2):466-76. Epub 2010 Nov 25.

Department of Wildlife, Fish and Environmental Sciences, Swedish University of Agricultural Sciences, SE-90183 Umeå, Sweden.

1. Animal migration has long intrigued scientists and wildlife managers alike, yet migratory species face increasing challenges because of habitat fragmentation, climate change and over-exploitation. Central to the understanding migratory species is the objective discrimination between migratory and nonmigratory individuals in a given population, quantifying the timing, duration and distance of migration and the ability to predict migratory movements. 2. Here, we propose a uniform statistical framework to (i) separate migration from other movement behaviours, (ii) quantify migration parameters without the need for arbitrary cut-off criteria and (iii) test predictability across individuals, time and space. 3. We first validated our novel approach by simulating data based on established theoretical movement patterns. We then formulated the expected shapes of squared displacement patterns as nonlinear models for a suite of movement behaviours to test the ability of our method to distinguish between migratory movement and other movement types. 4. We then tested our approached empirically using 108 wild Global Positioning System (GPS)-collared moose Alces alces in Scandinavia as a study system because they exhibit a wide range of movement behaviours, including resident, migrating and dispersing individuals, within the same population. Applying our approach showed that 87% and 67% of our Swedish and Norwegian subpopulations, respectively, can be classified as migratory. 5. Using nonlinear mixed effects models for all migratory individuals we showed that the distance, timing and duration of migration differed between the sexes and between years, with additional individual differences accounting for a large part of the variation in the distance of migration but not in the timing or duration. Overall, the model explained most of the variation (92%) and also had high predictive power for the same individuals over time (69%) as well as between study populations (74%). 6. The high predictive ability of the approach suggests that it can help increase our understanding of the drivers of migration and could provide key quantitative information for understanding and managing a broad range of migratory species.
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http://dx.doi.org/10.1111/j.1365-2656.2010.01776.xDOI Listing
March 2011

Habitat-performance relationships: finding the right metric at a given spatial scale.

Philos Trans R Soc Lond B Biol Sci 2010 Jul;365(1550):2255-65

Unité Mixte de Recherche CNRS-Université Lyon 1 N degrees 5558 Biométrie et Biologie Evolutive, Bâtiment Gregor Mendel, 43 boulevard du 11 novembre 1918, 69622 Villeurbanne Cedex, France.

The field of habitat ecology has been muddled by imprecise terminology regarding what constitutes habitat, and how importance is measured through use, selection, avoidance and other bio-statistical terminology. Added to the confusion is the idea that habitat is scale-specific. Despite these conceptual difficulties, ecologists have made advances in understanding 'how habitats are important to animals', and data from animal-borne global positioning system (GPS) units have the potential to help this clarification. Here, we propose a new conceptual framework to connect habitats with measures of animal performance itself--towards assessing habitat-performance relationship (HPR). Long-term studies will be needed to estimate consequences of habitat selection for animal performance. GPS data from wildlife can provide new approaches for studying useful correlates of performance that we review. Recent examples include merging traditional resource selection studies with information about resources used at different critical life-history events (e.g. nesting, calving, migration), uncovering habitats that facilitate movement or foraging and, ultimately, comparing resources used through different life-history strategies with those resulting in death. By integrating data from GPS receivers with other animal-borne technologies and combining those data with additional life-history information, we believe understanding the drivers of HPRs will inform animal ecology and improve conservation.
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http://dx.doi.org/10.1098/rstb.2010.0085DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2894964PMC
July 2010

Lost in space? Searching for directions in the spatial modelling of individuals, populations and species ranges.

Biol Lett 2010 Oct 19;6(5):575-8. Epub 2010 May 19.

Department of Life Sciences, Imperial College London, Ascot SL5 7PY, UK.

The workshop 'Spatial models in animal ecology, management and conservation' held at Silwood Park (UK), 9-11 March 2010, aimed to synthesize recent progress in modelling the spatial dynamics of individuals, populations and species ranges and to provide directions for research. It brought together marine and terrestrial researchers working on spatial models at different levels of organization, using empirical as well as theory-driven approaches. Different approaches, temporal and spatial scales, and practical constraints predominate at different levels of organization and in different environments. However, there are theoretical concepts and specific methods that can fruitfully be transferred across levels and systems, including: habitat suitability characterization, movement rules, and ways of estimating uncertainty.
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http://dx.doi.org/10.1098/rsbl.2010.0338DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3226956PMC
October 2010

Maternal and individual effects in selection of bed sites and their consequences for fawn survival at different spatial scales.

Oecologia 2009 Mar 17;159(3):669-78. Epub 2008 Dec 17.

Unité Mixte de Recherche no. 5558, Biométrie et Biologie Evolutive, Bâtiment 711, Université Claude Bernard Lyon 1, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne Cedex, France.

We examined the relationship between survival of roe deer (Capreolus capreolus) fawns at Trois Fontaines, Champagne-Ardennes, France, and factors related to bed-site selection (predator avoidance and thermoregulation) and maternal food resources (forage availability in the maternal home range). Previous studies have demonstrated that at small scales, the young of large herbivores select bed sites independently from their mothers, although this selection takes place within the limits of their mother's home range. Fawn survival was influenced largely by the availability of good bed sites within the maternal home range, not by the fawn's selection of bed sites; however, selection for thermal cover when selecting bed sites positively influenced survival of young fawns. Typical features of a good home range included close proximity to habitat edges, which is related to forage accessibility for roe deer. The availability of bed sites changed as fawns aged, probably due to an increased mobility of the fawn or a different use of the home range by the mother; sites offering high concealment and thermal protection became less available in favor of areas with higher forage accessibility. Despite the minor influence of bed-site selection on survival, roe deer fawns strongly selected their bed sites according to several environmental factors linked to predator avoidance and thermoregulation. Fawns selected for sites providing concealment, light penetration, and avoided signs of wild boar (Sus scrofa) activity. Avoidance of sites with high light penetration by young fawns positively affected their survival, confirming a negative effect on thermoregulation due to reduced thermal cover. Selection for light penetration by older fawns was less clear. We discuss these results in the context of cross-generational effects in habitat selection across multiple scales, and the potential influence of the 'ghost of predation past'.
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http://dx.doi.org/10.1007/s00442-008-1245-1DOI Listing
March 2009