461 research outputs found

    Identifying Birds' Collision Risk with Wind Turbines Using a Multidimensional Utilization Distribution Method

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    Renewable energy plays a key role in reducing greenhouse gas emissions. However, the expansion of wind farms has raised concerns about risks for bird collisions. We tested different methods used to understand whether birds' flight occurs over wind turbines and found kernel density estimators outperform other methods. Previous studies using kernel utilization distribution (KUD) have considered only the 2 horizontal dimensions (2D). However, if altitude is ignored, an unrealistic depiction of the situation may result because birds move in 3 dimensions (3D). We quantified the 3D space use of the Griffon vulture (Gyps fulvus) in El Estrecho natural park in Tarifa (southern Spain, on the northern shore of the Strait of Gibraltar) during 2012-2013, and, for the first time, their risk of collision with wind turbines in an area in the south of Spain. The 2D KUD showed a substantial overlap of the birds' flight paths with the wind turbines in the study area, whereas the 3D kernel estimate did not show such overlap. Our aim was to develop a new approach using 3D kernel estimation to understand the space use of soaring birds; these are killed by collision with wind turbines more often than any other bird types in southern Spain. We determined the probability of bird collision with an obstacle within its range. Other potential application areas include airfields, plane flight paths, and tall buildings. (c) 2020 The Authors. Wildlife Society Bulletin published by Wiley Periodicals, Inc. on behalf of The Wildlife Society.Peer reviewe

    Simulating detection-censored movement records for home range analysis planning

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    Home range estimation is an important analytical method in applied spatial ecology, yet best practices for addressing the effects of spatial variation in detection probability on home range estimates remain elusive. We introduce the R package “DiagnoseHR,” simulation tools for assessing how variation in detection probability arising from landscape, animal behavior, and methodological processes affects home range inference. We demonstrate the utility of simulation methods for home range analysis planning by comparing bias arising from three home range estimation methods under multiple detection scenarios. We simulated correlated random walks in three landscapes that varied in detection probability and constructed home ranges from locations filtered through a range of sampling protocols. Home range estimates were less biased by reduced detection probability when sampling effort was increased, but the effects of sampling day distribution were minimal. Like others, we found that kernel density estimates were the least affected by variation in detection probability, while minimum convex polygons were most affected. Our results illustrate the value of quantifying uncertainty in home range estimates and suggest that field biologists working in environments with low detection may wish to weight sample-size greater than concerns about temporal autocorrelation when designing sampling protocols

    EDITORIAL: Stuck in motion? Reconnecting questions and tools in movement ecology

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    In this editorial for the Special Feature, I firstly briefly review the major milestones in tool development for movement ecology research, from the first mark–recapture techniques to the current techniques allowing users to collect high-frequency movement data and high-resolution environmental data, as well as the methods for statistical and mathematical analyses. I then briefly describe the methods covered in the Special Feature and conclude with a brief outlook on ongoing and future developments

    Space Use And Habitat Selection By Bobcats In Southeastern Kentucky

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    Population estimation and trend analyses are critically important for sustainable harvest and management of many species. The bobcat (Lynx rufus) plays important ecological and economic roles in Kentucky as a furbearer and mesopredator. I conducted a study of the bobcat in southeastern Kentucky as a twenty year follow-up to research conducted in the same study area. I radio-collared five (4F, 1M) bobcats and assessed space and habitat use patterns. Mean annual minimum convex polygon (MCP) home range size for all bobcats was 14.7 km2 (n = 5, SE = 3.9 km2), and 22.2 km2 (n = 5, SE = 7.5 km2) using the adaptive kernel (AK) method. Mean female annual home range size was 17.4 km2 (MCP, n = 4, SE = 3.9 km2) and 27.4 km2 (AK, n = 4, SE = 7.5). Mean female-female home range overlap was 29.1% (MCP, n = 6, SE= 8.7), and female-male overlap was 17.1% (MCP, n = 4, SE = 7.0). Mean female-female core area overlap was 10.5% (MCP, n = 6, SE = 10.5), and female-male 12.1% (MCP, n = 4, SE = 12.1). Bobcats (all bobcats pooled) used forest in proportion to availability at the study area spatial scale, used open habitat more than expected, but avoided active mines (P \u3c 0.001). Movement rate (x = 0.12 km/hr) of a single GPS-collared male bobcat was lower during midday than during the morning, late afternoon, or nighttime periods. Also, more locations were recorded in forested habitat than expect based on habitat available within the home range, which contradicts the trend seen in the VHF data analysis, possibly indicating VHF data were not reliable in assessing habitat selection

    Potential path volume (PPV) : a geometric estimator for space use in 3D

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    UrĆĄka DemĆĄar is supported by a Leverhulme Trust Research Project Grant (RPG-2018-258).Background: Many animals move in three dimensions and many animal tracking studies collect the data on their movement in three physical dimensions. However, there is a lack of approaches that consider the vertical dimension when estimating animal space use, which is problematic, as this can lead to mistakes in quantification of spatial differentiation, level of interaction between individuals or species, and the use of resources at different vertical levels. Methods: This paper introduces a new geometric estimator for space use in 3D, the Potential Path Volume (PPV). The concept is based on time geography and generalises the accessibility measure, the Potential Path Area (PPA) into three dimensions. We derive the PPV mathematically and present an algorithm for their calculation. Results: We demonstrate the use of the PPV in a case study using an open data set of 3D bird tracking data. We also calculate the size of the PPV to see how this corresponds to trip type (specifically, we calculate PPV sizes for departure/return foraging trips from/to a colony) and evaluate the effect of the temporal sampling on the PPV size. PPV sizes increase with the increased temporal resolution, but we do not see the expected pattern than return PPV should be smaller than departure PPV. We further discuss the problem of different speeds in vertical and horizontal directions that are typical for animal movement and to address this rescale the PPV with the ratio of the two speeds. Conclusions: The PPV method represents a new tool for space use analysis in movement ecology where object movement occurs in three dimensions, and one which can be extended to numerous different application areas.Publisher PDFPeer reviewe

    Travel Routes and Spatial Abilities in Wild Chacma Baboons (Papio ursinus)

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    The primary objective of this research was to give insight into the spatial cognitive abilities of chacma baboons (Papio ursinus) and to address the question whether chacma baboons internally represent spatial information of large-scale space in the form of a so-called topological map or a Euclidean map. Navigating the environment using a topological map envisions that animals acquire, remember and integrate a set of interconnected pathways or route segments that are linked by frequently used landmarks or nodes, at which animals make travel decisions. When animals navigate using a Euclidean map, animals encode information in the form of true angles and distances in order to compute novel routes or shortcuts to reach out of view goals. Although findings of repeatedly used travel routes are generally considered evidence that animals possess topological-based spatial awareness, it is not necessarily evidence that they navigate (solely) using a topological map or lack complete Euclidean spatial representation. Therefore, three predictions from the hypothesised use of a topological map and Euclidean map were tested to distinguish between them. It was investigated whether there was a difference in travel linearity between the core area and the periphery of the home range, whether travel goals were approached from all directions or from one (or a few) distinct directions using the same approach routes and lastly, whether there was a difference between the initial leaving direction from a travel goal and the general direction towards the next goal. Data were collected during a 19-month period (04/2007-11/2008) at Lajuma research centre in the Soutpansberg (Limpopo Province, South Africa). A group of baboons were followed from their morning sleeping site to their evening sleeping site for 234 days, during which location records, behavioural data and important resource data were recorded. A statistical procedure termed the change-point test (CPT) was employed to identify locations at which baboons started orienting towards a goal and baboons showed goal-directed travel towards identified travel goals. Subsequently, hotspot analysis was employed to delineate clusters of such change-points, termed ‘decision hotspots’. Decision hotspots coincided with highly valuable resources, towards which baboons showed significantly faster travel. It thus seemed that they ‘knew’ when they were nearing their goals and adapted their speed accordingly. Decision hotspots were also located at navigational landmarks that delineated a network of repeatedly used travel routes characteristic of a topological map. Therewith, this method reveals an important utility to the study of decision-making by allowing a range of sites to be selected for detailed observations, which were previously limited to sleeping sites or ‘stop’ sites, which would be impossible if the decision hotspots had not been previously identified. Furthermore, baboons travelled as efficiently in the periphery as in the core area of their home range, which was suggested to be more consistent with Euclidean spatial awareness. However, comparatively low travel linearity throughout the home range revealed it is more likely that the baboons accumulated a similar knowledge of the periphery as of the core area, which allowed them to navigate with a similar efficiently through both areas. The mountainous terrain at the study site provided ample prominent landmarks to aid the baboons in navigation and allowed baboons to initiate navigation to a travel goal with the same direction as when they reached that goal. Baboons did not approach travel goals from all directions, but instead they approached their goals from the same direction(s). In conclusion, the findings of this research are more consistent with the use of a topological spatial representation of large scale space, where landmarks aid baboons to navigate efficiently through large scale space. A review of the literature shows that until date, evidence for the existence of Euclidean spatial representation in both animals and humans is extremely limited and often unconvincing. It is likely that a high level of experimental control is necessary to unambiguously demonstrate the existence of Euclidean spatial awareness in the future

    Factors modulating home range and resource use: a case study with Canarian houbara bustards

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    ABSTRACT: The home range of an animal is determined by its ecological requirements, and these may vary depending on many intrinsic and extrinsic factors, which are ultimately driven by food resources. Investigating the effects of these factors, and specifically how individuals use food resources within their home ranges is essential to understand the ecology and dynamics of animal populations, and to establish conservation measures in the case of endangered species. Here, we investigate these questions in the Canarian houbara bustard, an endangered subspecies of African houbara endemic to the Canary Islands.We are grateful to A. RodrĂ­guez, T. DĂ­az-Valera and F. Corujo for their collaboration during the fieldwork, E. Arrondo for helping with the AcceleRater software, and A. Perona for his help and tips about the “rhr package”, M. A. Cabrera for managing capture permits and for his support during the project, F. Crespo, M. Armas, A. Ibarguren and M. Gil for their assistance during the preparation of the project, the guards of the Cabildo of Lanzarote, Timanfaya National Park and La Graciosa, including TRAGSA personnel, the veterinarian C. M. SuĂĄrez, and all authorities of the Government of the Canary Islands for their collaboration. We also thank J. M. Poveda and F. SuĂĄrez of GRAFCAN for providing images and ortophotos of the islands. Two anonymous reviewers and the associate editor provided useful comments that helped to improve our manuscript. This study was funded by Red ElĂ©ctrica de España (REE) through a contract with Agencia Estatal Consejo Superior de Investigaciones CientĂ­ficas (CSIC)

    Factors modulating home range and resource use: a case study with Canarian houbara bustards

    Get PDF
    ABSTRACT: The home range of an animal is determined by its ecological requirements, and these may vary depending on many intrinsic and extrinsic factors, which are ultimately driven by food resources. Investigating the effects of these factors, and specifically how individuals use food resources within their home ranges is essential to understand the ecology and dynamics of animal populations, and to establish conservation measures in the case of endangered species. Here, we investigate these questions in the Canarian houbara bustard, an endangered subspecies of African houbara endemic to the Canary Islands.We are grateful to A. RodrĂ­guez, T. DĂ­az-Valera and F. Corujo for their collaboration during the fieldwork, E. Arrondo for helping with the AcceleRater software, and A. Perona for his help and tips about the “rhr package”, M. A. Cabrera for managing capture permits and for his support during the project, F. Crespo, M. Armas, A. Ibarguren and M. Gil for their assistance during the preparation of the project, the guards of the Cabildo of Lanzarote, Timanfaya National Park and La Graciosa, including TRAGSA personnel, the veterinarian C. M. SuĂĄrez, and all authorities of the Government of the Canary Islands for their collaboration. We also thank J. M. Poveda and F. SuĂĄrez of GRAFCAN for providing images and ortophotos of the islands. Two anonymous reviewers and the associate editor provided useful comments that helped to improve our manuscript. This study was funded by Red ElĂ©ctrica de España (REE) through a contract with Agencia Estatal Consejo Superior de Investigaciones CientĂ­ficas (CSIC)
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