Inferring parturition and neonate survival from movement patterns of female ungulates: a case study using woodland caribou

Analyses of animal movement data have primarily focused on understanding patterns of space use and the behavioural processes driving them. Here, we analyzed animal movement data to infer components of individual fitness, specifically parturition and neonate survival. We predicted that parturition and neonate loss events could be identified by sudden and marked changes in female movement patterns. Using GPS radio‐telemetry data from female woodland caribou (Rangifer tarandus caribou), we developed and tested two novel movement‐based methods for inferring parturition and neonate survival. The first method estimated movement thresholds indicative of parturition and neonate loss from population‐level data then applied these thresholds in a moving‐window analysis on individual time‐series data. The second method used an individual‐based approach that discriminated among three a priori models representing the movement patterns of non‐parturient females, females with surviving offspring, and females losing offspring. The models assumed that step lengths (the distance between successive GPS locations) were exponentially distributed and that abrupt changes in the scale parameter of the exponential distribution were indicative of parturition and offspring loss. Both methods predicted parturition with near certainty (>97% accuracy) and produced appropriate predictions of parturition dates. Prediction of neonate survival was affected by data quality for both methods; however, when using high quality data (i.e., with few missing GPS locations), the individual‐based method performed better, predicting neonate survival status with an accuracy rate of 87%. Understanding ungulate population dynamics often requires estimates of parturition and neonate survival rates. With GPS radio‐collars increasingly being used in research and management of ungulates, our movement‐based methods represent a viable approach for estimating rates of both parameters.     

A dynamic theory of coordination of discrete movement

The concepts of pattern dynamics and their adaptation through behavioral information, developed in the context of rhythmic movement coordination, are generalized to describe discrete movements of single components and the coordination of multiple components in discrete movement. In a first step we consider only one spatial component and study the temporal order inherent in discrete movement in terms of stable, reproducible space-time relationships. The coordination of discrete movement is captured in terms of relative timing. Using an exactly solvable nonlinear oscillator as a mathematical model, we show how the timing properties of discrete movement can be described by these pattern dynamics and discuss the relation of the pattern variables to observable end-effector movement. By coupling several such component dynamics in a fashion analogous to models of rhythmic movement coordination we capture the coordination of discrete movements of two components. We find the tendency to synchronize the component movements as the discrete analogon of in-phase locking and study its breakdown when the components become too different in their dynamic properties. The concept of temporal stability leads to the prediction that remote compensatory responses occur such as the restore synchronization when one component is perturbed. This prediction can be used to test the theory. We find that the discrete analogon to antiphase locking in rhythmic movement is a tendency to move sequentially, a finding that can also be subjected to empirical test.     

Fragmenting citizenship: dynamics of cooperation and conflict in France's immigrant rights movement

This paper examines the contradictory relational dynamics of immigrant rights movement through a close examination of the French case during the 1990s. Through this movement, we find a network made up of different groups of immigrants and well-established rights organizations. As the movement intensified over the months, powerful cleavages developed between groups of undocumented immigrants (e.g. families, single men, etc.) and between certain immigrants and rights organizations. The same discursive and political structures that precipitated the cooperation of these diverse actors were also responsible for planting seeds of conflict by presenting different groups of migrants with unequal opportunities and placing resource-rich associations in a powerful position in the network. The paper concludes by discussing how the theory developed here can be ‘extended’ to analyse the relational dynamics found in similar social movements in other countries (e.g. USA).     

Modeling activity patterns of wildlife using time‐series analysis

The study of wildlife activity patterns is an effective approach to understanding fundamental ecological and evolutionary processes. However, traditional statistical approaches used to conduct quantitative analysis have thus far had limited success in revealing underlying mechanisms driving activity patterns. Here, we combine wavelet analysis, a type of frequency‐based time‐series analysis, with high‐resolution activity data from accelerometers embedded in GPS collars to explore the effects of internal states (e.g., pregnancy) and external factors (e.g., seasonal dynamics of resources and weather) on activity patterns of the endangered giant panda (Ailuropoda melanoleuca). Giant pandas exhibited higher frequency cycles during the winter when resources (e.g., water and forage) were relatively poor, as well as during spring, which includes the giant panda's mating season. During the summer and autumn when resources were abundant, pandas exhibited a regular activity pattern with activity peaks every 24 hr. A pregnant individual showed distinct differences in her activity pattern from other giant pandas for several months following parturition. These results indicate that animals adjust activity cycles to adapt to seasonal variation of the resources and unique physiological periods. Wavelet coherency analysis also verified the synchronization of giant panda activity level with air temperature and solar radiation at the 24‐hr band. Our study also shows that wavelet analysis is an effective tool for analyzing high‐resolution activity pattern data and its relationship to internal and external states, an approach that has the potential to inform wildlife conservation and management across species.     

Living in the branches: population dynamics and ecological processes in dendritic networks

Spatial structure regulates and modifies processes at several levels of ecological organization (e.g. individual/genetic, population and community) and is thus a key component of complex systems, where knowledge at a small scale can be insufficient for understanding system behaviour at a larger scale. Recent syntheses outline potential applications of network theory to ecological systems, but do not address the implications of physical structure for network dynamics. There is a specific need to examine how dendritic habitat structure, such as that found in stream, hedgerow and cave networks, influences ecological processes. Although dendritic networks are one type of ecological network, they are distinguished by two fundamental characteristics: (1) both the branches and the nodes serve as habitat, and (2) the specific spatial arrangement and hierarchical organization of these elements interacts with a species' movement behaviour to alter patterns of population distribution and abundance, and community interactions. Here, we summarize existing theory relating to ecological dynamics in dendritic networks, review empirical studies examining the population- and community-level consequences of these networks, and suggest future research integrating spatial pattern and processes in dendritic systems.     

Herbivory and patch dynamics on rocky reefs in temperate Australasia: The roles of fish and sea urchins

Sea urchins are widely considered to be the major grazers in temperate subtidal systems, with herbivorous fish being browsers of minor importance. This paper reviews spatial and temporal patterns in these herbivores on rocky reels in temperate Australasia, with the aim of assessing their relative impacts on patch structure and dynamics. Herbivorous fishes are widespread and make up a significant numerical component the reel fish fauna. Sea urchins are also abundant, but not all geographic locations support actively grazing species. Both fish and sea urchins exhibit distinct patterns of distribution among depth strata. Within depth strata, all herbivores are restricted to (sea urchins) or forage preferentially in (fish) particular habitat patches, causing a mosaic of different feeding activities. These patches are either related to specific features of the habitat (e.g. Kelp patches, topography) or behavioural interactions. Foraging by sea urchins and demersal-nesting damselfishes is intense and persistent, whereas in the kelp-feeding fish Odax cyanomelas, foraging reaches greatest intensity at predictable locations during a few months of every year. Many fish and sea urchins consume some algae in preference to others. However, feeding preferences may determine the nature of the impact only in fishes. For sea urchins, preference may occasionally determine the order in which algae are consumed, but at high densities they consume all available macroalgae. Impacts of both types of herbivore on the abundance of algae have been recorded. Some sea urchins (e.g. Evechinus chloroticus, Centrostephanus rodgersii) appear to severely modify biogenic habitat structure by maintaining ‘barrens’ (areas devoid of macroalgae) over long periods. In contrast to this, the effects of fishes may be more transitory (e.g. seasonal impact of Odax cyanomelas on brown algae) or occur at smaller spatial scales (e.g. nest sites maintained by male Parma victoriae) Herbivorous and other fishes appear to respond to spatial patterns in algal distributions, rallier than having it major impact upon them. The relative effects of fish and sea urchins on the long-term dynamics of kelp forests are unknown, hut temporal patterns in herbivore abundance and behaviour, and algal demography arc urgent targets for research.     

Birthplace‐dependent dispersal: are directions of natal dispersal determined a priori?

Sib–sib or, more generally, family resemblance for dispersal seems a widespread characteristic of vertebrates, and the birthplace has the potential to shape the dynamics and features of animal populations. Dispersal studies have often stressed the fundamental link between the fate of dispersers and population dynamics, but few have focused on the dispersal directions of individuals, despite the profound implications that this may have on population distribution, structure, dynamics and viability. We investigated the directions followed by 72 radio‐tagged dispersers (43 males and 29 females from 14 nest sites) in an eagle owl Bubo bubo population, and assessed their a) inter‐individual distances during dispersal and b) age at dispersal departure. For siblings, as well as potential‐siblings (i.e. individuals born in the same nest in different years), the birthplace influenced inter‐individual distances and dispersal directions, i.e. dispersers from the same nest moved to similar locations during the study; moreover, in each year, individuals from the same birthplace moved across the same areas in a short time period. Finally, siblings and potential‐siblings born in the same nest in different years started dispersal at similar ages. Based on the movement patterns of dispersers we discuss: a) the potential implications of the birthplace‐dependent dispersal on the ideal free distribution theory, as well as in terms of kin competition, inbreeding avoidance and population dynamics; and, more generally, b) the effect of the temporal features of the natal dispersal on the concept of habitat suitability vs density of individuals developed by the ideal free distribution theory.     

Larval dispersal and movement patterns of coral reef fishes,and implications for marine reserve network design

Well‐designed and effectively managed networks of marine reserves can be effective tools for both fisheries management and biodiversity conservation. Connectivity, the demographic linking of local populations through the dispersal of individuals as larvae, juveniles or adults, is a key ecological factor to consider in marine reserve design, since it has important implications for the persistence of metapopulations and their recovery from disturbance. For marine reserves to protect biodiversity and enhance populations of species in fished areas, they must be able to sustain focal species (particularly fishery species) within their boundaries, and be spaced such that they can function as mutually replenishing networks whilst providing recruitment subsidies to fished areas. Thus the configuration (size, spacing and location) of individual reserves within a network should be informed by larval dispersal and movement patterns of the species for which protection is required. In the past, empirical data regarding larval dispersal and movement patterns of adults and juveniles of many tropical marine species have been unavailable or inaccessible to practitioners responsible for marine reserve design. Recent empirical studies using new technologies have also provided fresh insights into movement patterns of many species and redefined our understanding of connectivity among populations through larval dispersal. Our review of movement patterns of 34 families (210 species) of coral reef fishes demonstrates that movement patterns (home ranges, ontogenetic shifts and spawning migrations) vary among and within species, and are influenced by a range of factors (e.g. size, sex, behaviour, density, habitat characteristics, season, tide and time of day). Some species move <0.1–0.5 km (e.g. damselfishes, butterflyfishes and angelfishes), <0.5–3 km (e.g. most parrotfishes, goatfishes and surgeonfishes) or 3–10 km (e.g. large parrotfishes and wrasses), while others move tens to hundreds (e.g. some groupers, emperors, snappers and jacks) or thousands of kilometres (e.g. some sharks and tuna). Larval dispersal distances tend to be <5–15 km, and self‐recruitment is common. Synthesising this information allows us, for the first time, to provide species, specific advice on the size, spacing and location of marine reserves in tropical marine ecosystems to maximise benefits for conservation and fisheries management for a range of taxa. We recommend that: (i) marine reserves should be more than twice the size of the home range of focal species (in all directions), thus marine reserves of various sizes will be required depending on which species require protection, how far they move, and if other effective protection is in place outside reserves; (ii) reserve spacing should be <15 km, with smaller reserves spaced more closely; and (iii) marine reserves should include habitats that are critical to the life history of focal species (e.g. home ranges, nursery grounds, migration corridors and spawning aggregations), and be located to accommodate movement patterns among these. We also provide practical advice for practitioners on how to use this information to design, evaluate and monitor the effectiveness of marine reserve networks within broader ecological, socioeconomic and management contexts.     

The influence of landscape and environmental factors on ranavirus epidemiology in a California amphibian assemblage

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Predicting food‐web structure with metacommunity models

Synthesis Metacommunity theory aims to elucidate the relative influence of local and regional‐scale processes in generating diversity patterns across the landscape. Metacommunity research has focused largely on assemblages of competing organisms within a single trophic level. Here, we test the ability of metacommunity models to predict the network structure of the aquatic food web found in the leaves of the northern pitcher plant Sarracenia purpurea. The species‐sorting and patch‐dynamics models most accurately reproduced nine food web properties, suggesting that local‐scale interactions play an important role in structuring Sarracenia food webs. Our approach can be applied to any well‐resolved food web for which data are available from multiple locations. The metacommunity framework explores the relative influence of local and regional‐scale processes in generating diversity patterns across the landscape. Metacommunity models and empirical studies have focused mostly on assemblages of competing organisms within a single trophic level. Studies of multi‐trophic metacommunities are predominantly restricted to simplified trophic motifs and rarely consider entire food webs. We tested the ability of the patch‐dynamics, species‐sorting, mass‐effects, and neutral metacommunity models, as well as three hybrid models, to reproduce empirical patterns of food web structure and composition in the complex aquatic food web found in the northern pitcher plant Sarracenia purpurea. We used empirical data to determine regional species pools and estimate dispersal probabilities, simulated local food‐web dynamics, dispersed species from regional pools into local food webs at rates based on the assumptions of each metacommunity model, and tested their relative fits to empirical data on food‐web structure. The species‐sorting and patch‐dynamics models most accurately reproduced nine food web properties, suggesting that local‐scale interactions were important in structuring Sarracenia food webs. However, differences in dispersal abilities were also important in models that accurately reproduced empirical food web properties. Although the models were tested using pitcher‐plant food webs, the approach we have developed can be applied to any well‐resolved food web for which data are available from multiple locations.     

Scaling marine fish movement behavior from individuals to populations

Understanding how, where, and when animals move is a central problem in marine ecology and conservation. Key to improving our knowledge about what drives animal movement is the rising deployment of telemetry devices on a range of free‐roaming species. An increasingly popular way of gaining meaningful inference from an animal's recorded movements is the application of hidden Markov models (HMMs), which allow for the identification of latent behavioral states in the movement paths of individuals. However, the use of HMMs to explore the population‐level consequences of movement is often limited by model complexity and insufficient sample sizes. Here, we introduce an alternative approach to current practices and provide evidence of how the inclusion of prior information in model structure can simplify the application of HMMs to multiple animal movement paths with two clear benefits: (a) consistent state allocation and (b) increases in effective sample size. To demonstrate the utility of our approach, we apply HMMs and adapted HMMs to over 100 multivariate movement paths consisting of conditionally dependent daily horizontal and vertical movements in two species of demersal fish: Atlantic cod (Gadus morhua; n = 46) and European plaice (Pleuronectes platessa; n = 61). We identify latent states corresponding to two main underlying behaviors: resident and migrating. As our analysis considers a relatively large sample size and states are allocated consistently, we use collective model output to investigate state‐dependent spatiotemporal trends at the individual and population levels. In particular, we show how both species shift their movement behaviors on a seasonal basis and demonstrate population space use patterns that are consistent with previous individual‐level studies. Tagging studies are increasingly being used to inform stock assessment models, spatial management strategies, and monitoring of marine fish populations. Our approach provides a promising way of adding value to tagging studies because inferences about movement behavior can be gained from a larger proportion of datasets, making tagging studies more relevant to management and more cost‐effective.     

Anthropogenic disturbance in a changing environment: modelling lifetime reproductive success to predict the consequences of multiple stressors on a migratory population

Animals make behavioural and reproductive decisions that maximise their lifetime reproductive success, and thus their fitness, in light of periodic and stochastic variability of the environment. Modelling the variation of an individual's energy levels formalises this tradeoff and helps to quantify the population‐level consequences of stressors (e.g. disturbance from human activities and environmental change) that can affect behaviour or physiology. In this study, we develop a dynamic state variable model for the spatially explicit behaviour, physiology and reproduction of a female, long‐lived, migratory marine vertebrate. The model can be used to investigate the spatio‐temporal patterns of behaviour and reproduction that allow an individual to maximise its overall reproductive output. We parametrised the model for eastern North Pacific blue whales Balaenoptera musculus, and used it to predict the effects of changing environmental conditions and increasing human disturbance on the population's vital rates. In baseline conditions, the model output had high fidelity to observed energy dynamics, movement patterns and reproductive strategies. Simulated scenarios suggested that environmental changes could have severe consequences on the population's vital rates, but that individuals could tolerate high levels of anthropogenic disturbance. However, this ability depended on where, when and how often disturbance occurred. In scenarios with both environmental change and anthropogenic disturbance, synergistic interactions caused stronger effects than in isolation. In general, larger body size offered a buffer against stochasticity and disturbance, and, consequently, we predicted juveniles to be more susceptible to disturbance. We also predicted that females prioritise their own survival at the expense of the current reproductive attempt, presumably the result of their long lifespan. Our approach provides a general framework to make predictions of the cumulative and synergistic effects of human disturbance and climate change on migratory populations, which can inform effective management and conservation efforts.     

Scaling down from species to individuals: a flower–visitation network between individual honeybees and thistle plants

Studies of ecological networks usually focus upon interaction patterns among species. However, linkage among species is mediated by their constituting individuals. Thus, every linked species pair in a network encapsulates a new network of interacting individuals. Very few studies outside the sociology of larger animals have investigated networks at the level of the individual. Here, we analyse the structure of a flower–visitation network of individual thistles Cirsium arvense and honeybees Apis mellifera in a small meadow patch in Denmark. We marked and numbered 62 honeybees and 32 thistle stems and monitored all floral visits. The constructed bipartite network of individual plants and bees had a high connectance and low nestedness, but it was not significantly modular. Frequency distributions of number of links per species (i.e. linkage level) had their best fit to a truncated power law, and interactions were asymmetrical. Unipartite networks of either plants or bees had exceedingly short average path length and high clustering. Linkage level of plants increased with their number of flower heads and height of inflorescence (floral display parameters). Overall, the individual network of honeybees and thistles was denser linked than what is known from species pollination networks. Characteristics of both plants (e.g. floral display) and animals (e.g. foraging behaviour) are likely to generate this intra–specific, inter–individual link pattern. Such features of individual–individual networks may scale up and become important drivers of the structure and dynamics of species–species networks.     

Social structure and indirect genetic effects: genetics of social behaviour

The social environment modulates gene expression, physiology, behaviour and patterns of inheritance. For more than 50 years, this concept has been investigated using approaches that include partitioning the social component out of behavioural heritability estimates, studying maternal effects on offspring, and analysing dominance hierarchies. Recent advances have formalized this ‘social environment effect’ by providing a more nuanced approach to the study of social influences on behaviour while recognizing evolutionary implications. Yet, in most of these formulations, the dynamics of social interactions are not accounted for. Also, the reciprocity between individual behaviour and group‐level interactions has been largely ignored. Consistent with evolutionary theory, the principles of social interaction are conserved across a broad range of taxa. While noting parallels in diverse organisms, this review uses Drosophila melanogaster as a case study to revisit what is known about social interaction paradigms. We highlight the benefits of integrating the history and pattern of interactions among individuals for dissecting molecular mechanisms that underlie social modulation of behaviour.     

Dealing with Uncertainty in Spatially Explicit Population Models

It has been argued that spatially explicit population models (SEPMs) cannot provide reliable guidance for conservation biology because of the difficulty of obtaining direct estimates for their demographic and dispersal parameters and because of error propagation. We argue that appropriate model calibration procedures can access additional sources of information, compensating the lack of direct parameter estimates. Our objective is to show how model calibration using population-level data can facilitate the construction of SEPMs that produce reliable predictions for conservation even when direct parameter estimates are inadequate. We constructed a spatially explicit and individual-based population model for the dynamics of brown bears (Ursus arctos) after a reintroduction program in Austria. To calibrate the model we developed a procedure that compared the simulated population dynamics with distinct features of the known population dynamics (=patterns). This procedure detected model parameterizations that did not reproduce the known dynamics. Global sensitivity analysis of the uncalibrated model revealed high uncertainty in most model predictions due to large parameter uncertainties (coefficients of variation CV 0.8). However, the calibrated model yielded predictions with considerably reduced uncertainty (CV 0.2). A pattern or a combination of various patterns that embed information on the entire model dynamics can reduce the uncertainty in model predictions, and the application of different patterns with high information content yields the same model predictions. In contrast, a pattern that does not embed information on the entire population dynamics (e.g., bear observations taken from sub-areas of the study area) does not reduce uncertainty in model predictions. Because population-level data for defining (multiple) patterns are often available, our approach could be applied widely.     

Subsocial spiders in space and time: A fine scale approach to the dynamics of dispersal

Less than 0.2% of all spider species live in close associations with conspecifics. Among these, subsocial spiders show characteristics of both solitary spiders (e.g., individuals disperse for breeding) and social spiders (e.g., prolonged cooperative behaviours at least prior to independent reproduction). Dispersing individuals build small webs, usually with one inhabitant, whereas colonies are large webs with plant debris and harbouring multiple females. We studied the spatiotemporal dynamics of dispersal in the subsocial spider Anelosimus baeza. We followed the occupancy of all colonies and dispersal webs over the breeding season by mapping the number and sex of spiders with respect to their location in three dimensions. We studied the settlement patterns of new webs and fluctuation in web occupancy through movement between occupied and abandoned webs of colonies and dispersal webs. The occupancy of webs was highly dynamic with changes occurring at small time scales. The similarity in the patterns of web occupancy by females among dispersal webs was partially explained by their spatial and their temporal proximity. Our results suggest that dispersal webs may be used by spiders as a temporary refuge by both sexes during the breeding season. Patterns described here suggest new approaches to dispersal studies in group living spiders.     

Viscoelasticity of living materials: mechanics and chemistry of muscle as an active macromolecular system

At the molecular and cellular level, mechanics and chemistry are two aspects of the same macromolecular system. We present a bottom-up approach to such systems based on Kramers' diffusion theory of chemical reactions, the theory of polymer dynamics, and the recently developed models for molecular motors. Using muscle as an example, we develop a viscoelastic theory of muscle in terms of an simple equation for single motor protein movement. Both A.V. Hill's contractile component and A.F. Huxley's equation of sliding-filament motion are shown to be special cases of the general viscoelastic theory of the active material. Some disparity between the mechanical and the chemical views of cross-bridges and motor proteins are noted, and a duality between force and energy in discrete states and transitions of macromolecular systems is discussed.     

Winter Movement Dynamics of Black Brant

ABSTRACT Although North American geese are managed based on their breeding distributions, the dynamics of those breeding populations may be affected by events that occur during the winter. Birth rates of capital breeding geese may be influenced by wintering conditions, mortality may be influenced by timing of migration and wintering distribution, and immigration and emigration among breeding populations may depend on winter movement and timing of pair formation. We examined factors affecting movements of black brant (Branta bernicla nigricans) among their primary wintering sites in Mexico and southern California, USA, (Mar 1998-Mar 2000) using capture-recapture models. Although brant exhibited high probability (>0.85) of monthly and annual fidelity to the wintering sites we sampled, we observed movements among all wintering sites. Movement probabilities both within and among winters were negatively related to distance between sites. We observed a higher probability both of southward movement between winters (Mar to Dec) and northward movement between months within winters. Between-winter movements were probably most strongly affected by spatial and temporal variation in habitat quality as we saw movement patterns consistent with contrasting environmental conditions (e.g., La Niña and El Niño southern oscillation cycles). Month-to-month movements were related to migration patterns and may also have been affected by differences in habitat conditions among sites. Patterns of winter movements indicate that a network of wintering sites may be necessary for effective conservation of brant.     

Time geography and wildlife home range delineation

We introduce a new technique for delineating animal home ranges that is relatively simple and intuitive: the potential path area (PPA) home range. PPA home ranges are based on existing theory from time geography, where an animal's movement is constrained by known locations in space–time (i.e., n telemetry points) and a measure of mobility (e.g., maximum velocity). Using the formulation we provide, PPA home ranges can be easily implemented in a Geographic Information System (GIS). The advantage of the PPA home range is the explicit consideration of temporal limitations on animal movement. In discussion, we identify the PPA home range as a stand-alone measure of animal home range or as a way to augment existing home range techniques. Future developments are highlighted in the context of the usefulness of time geography for wildlife movement analysis. To facilitate the adoption of this technique we provide a tool for implementing this method. © 2011 The Wildlife Society.