Wildlife Movement Research Articles

Connecting models to movements: testing connectivity model predictions against empirical migration and dispersal data

Connectivity has become a top conservation priority in response to landscape fragmentation. Many methods have been developed to identify areas of the landscape with high potential connectivity for wildlife movement. However, each makes different assumptions that may produce different predictions, and few comparative tests against empirical movement data are available. We compared predictive performance of the most-used connectivity models, cost-distance and circuit theory models. We hypothesized that cost-distance would better predict elk migration paths, while circuit theory would better predict wolverine dispersal paths, due to alignment of the methods’ assumptions with the movement ecology of each process. We used each model to predict elk migration paths and wolverine dispersal paths in the Greater Yellowstone Ecosystem, then used telemetry data collected from actual movements to assess predictive performance. Methods for validating connectivity models against empirical data have not been standardized, thus we applied and compared four alternative methods. Our findings generally supported our hypotheses. Circuit theory models consistently predicted wolverine dispersal paths better than cost-distance, though cost-distance models predicted elk migration paths only slightly better than circuit theory. In most cases, our four validation methods supported similar conclusions, but provided complementary perspectives. We reiterate suggestions that alignment of connectivity model assumptions with focal species movement ecology is an important consideration when selecting a modeling approach for conservation practice. Additional comparative tests are needed to better understand how relative model performance may vary across species, movement processes, and landscapes, and what this means for effective connectivity conservation.

A movement-driven approach to quantifying grizzly bear (Ursus arctos) near-road movement patterns in west-central Alberta, Canada

Advances in GPS telemetry and remote sensing technologies provide researchers with abundant data that can be used to investigate detailed questions about wildlife behavior. Existing methods for linking wildlife movement to remotely sensed landscape data generally rely on the application of subjectively derived distance thresholds to represent proximity (i.e., near or far) relative to disturbance, thereby possibly limiting the scope of research questions and insight gained. We develop an alternative method based on semivariogram modeling that quantifies consistency in movement parameters as a function of distance to disturbance features. Our approach uses movement data to identify spatially explicit scales of wildlife response to linear features. We illustrate the benefit of movement-driven approaches for generating hypotheses about wildlife movement with grizzly bear (Ursus arctos) movement data. We concentrate specifically on building hypotheses to explain how seasonal mortality is linked to near road movements. The movement-driven method demonstrated consistency in step length (i.e., spatial scales of response) ranging from 35m–90m from roads, depending on age, sex, and season. Given this pattern, our data suggest a minimum vegetation buffer of 90m to serve as screening cover along roadsides to improve survival in this ecosystem. More broadly, our generalizable method can identify definitive spatial scales of response around human disturbance features in any wildlife system, thereby providing managers with movement-driven insight to reduce impacts on wildlife in multi-use landscapes.

基于物种运动路径识别的动物通道选址——以武深高速为例

PDF HTML阅读 XML下载 导出引用 引用提醒 基于物种运动路径识别的动物通道选址——以武深高速为例 DOI: 10.5846/stxb201505120971 作者: 作者单位: 广东省生物资源应用研究所,广东省生物资源应用研究所,广东省环境科学研究院,广东省野生动物救护中心,广东省生物资源应用研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金资助项目（31572257）；广州市海珠区科技和信息化局资助项目（2013-cg-03，2014-cg-17） Location design of wildlife corridors based on animal movement path identification: a case study of the Wuhan-Shenzhen Highway Author: Affiliation: Guangdong Institute of Applied Biological Resources,Guangdong Institute of Applied Biological Resources,Guangdong Academy of Environmental Science,,Guangdong Institute of Applied Biological Resources Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:动物通道是缓解高速公路对其周边野生动物生境隔离的有效措施，通道的位置是影响其使用效率的关键因素，然而现有研究对通道的选址却甚少涉及。以武深高速为例，推荐一种基于物种运动路径识别的通道选址方法，选取影响动物生境选择的环境因子构建评价体系，借助GIS手段对公路周边野生动物生境适宜性进行分析，在此基础上借鉴水文分析原理快速准确地刻画出物种在生境中的潜在活动路径，从而确定了5处高速公路上建设动物通道的理想位置。结果表明，该方法能定量地反映出生境的质量格局对于物种运动的影响，准确定位出物种运动受到阻碍的关键区域，在景观层次上，提出的通道位置能有效地缓解栖息地破碎化造成的生态压力；研究不但能弥补目前研究的不足，同时亦为道路网设计、城市生态规划等相关领域研究提供科学参考。 Abstract:Highways are an important landscape type and have brought significant economic benefits to communities. However, highway construction may adversely affect wildlife survival through habitat fragmentation, degradation, loss, and reduced connectivity. This can then lead to declines in wildlife populations and to the loss of biodiversity. Wildlife corridors are thought to be an efficient way to mitigate the isolation and fragmentation of habitat caused by highway construction and can provide safety avenues for wildlife movement between habitat patches, which facilitates gene dispersal and interflow. However, there has been little research on wildlife corridor design in China, compared to the western, developed countries. Most previous studies have focused on theoretical discussions on the types, size, design principles, and procedures for corridor construction, but the location, which is the key factor affecting corridor use by wildlife, has rarely been discussed. We propose a new method, based on animal movement path identification, for wildlife corridor design, and have undertaken a case study of the Wuhan-Shenzhen Highway. Based on previous studies and wildlife resources of the study area, six indicators, which have been shown to significantly affect wildlife habitat selection, were chosen for our habitat suitability model. We used the model and GIS to assess the suitability of wildlife habitat around the highway and then identified the potential movement path of wildlife by using hydrologic analysis. According to that, five ideal locations were suggested by overlaying the movement paths on the highway, and landscape pattern indices were used to evaluate the efficiency of the proposed corridor location at the landscape level. Our proposed method could quantitatively reflect the ecological relationship between habitat characteristics and wildlife movement, and the critical areas used by wildlife to cross the highway could be precisely identified. Hence, the proposed corridor location could improve wildlife movement connectivity among spatially separated habitats and effectively alleviate the ecological pressure of habitat fragmentation caused by highway construction. Our proposed method could reduce the influence of subjective factors in the decision-making process, and make it possible to acquire and analyze a large amount of environmental data rapidly by using GIS and Analytic Hierarchy Process (AHP). Moreover, by analyzing the landscape patterns of suitable habitats, we could effectively assess the ecological function of the proposed corridor, which was often overlooked in previous studies. Thus, our study could fill a gap in wildlife corridor design, and provide insights for further research related areas, such as urban ecological planning and road network design. 参考文献 相似文献 引证文献

A Field-Based Time Geography for Wildlife Movement Analysis

GIScience 2016 Short Paper Proceedings A Field-Based Time Geography for Wildlife Movement Analysis J. A. Long 1 School of Geography and Geosciences, University of St Andrews, Irvine Building, North Street, St Andrews, Fife, UK KY169AL Email: jed.long@st-andrews.ac.uk Abstract Field-based time geography is proposed as a new, specialized model for estimating wildlife utilization distributions (UDs) and home ranges. Field-based time geography represents the combining of classical time geography with least-cost path analysis. Here the derivation of field-based time geography is emphasized, paying particular attention to how it can be implemented in wildlife analysis. An example showing caribou movement in northern British Columbia is used to demonstrate field-based time geography and compare it with the Brownian bridge model, a popular method for delineating wildlife UDs. The results show how field-time geography is able to better represent the structure and barriers of the landscape, and provide alternative insights into wildlife space use. The entire process is implemented in R, making it attractive to movement ecologists. 1. Introduction One of the fundamental pieces of spatial information used in the study of wildlife movement is the home range. A home range is broadly defined as the area an animal uses in its normal day-to-day activities (Burt, 1943). From a GIScience perspective, a home range is a polygon, and thus represents this area discretely. Recognizing that animals typically do not use their home ranges evenly, alternatively a utilization distribution (UD) can be estimated, which represents the home range as a two dimensional probability density surface, where the values indicate the probability of observing the animal at different locations within (and outwith) the home range (Worton, 1989). Typically, a UD is represented as a raster grid after selecting an appropriate spatial resolution. After creating a UD it is common to estimate the home range simply as a % volume contour of the UD (most commonly the 95% volume contour). Many methods have been proposed for estimating UDs and home ranges and there is little consensus on which is best. Historically, kernel density estimation (Worton, 1989) has been the preferred approach, however in recent years Brownian bridges (Horne et al., 2007) have become increasingly popular. Time geographic methods have also been proposed as powerful alternatives for delineating home ranges (Long and Nelson, 2012) and UDs (Downs et al., 2011). However, one limitation that is present in all currently available home range and UD methods is the assumption that wildlife move within a homogeneous arena. That is, the underlying environment has no influence on the model used to calculate the home range and UD. By failing to consider how the underlying landscape characteristics (e.g., topography, structure, land cover) contribute to the formation of home ranges and UDs, current approaches fail to adequately capture how a heterogeneous environment contributes to observed movement patterns. In many cases, the natural environment constrains the area potentially visited by an animal, and thus home ranges and UDs are incorrectly estimated. To address this limitation, this paper proposes field-based time geography as a new tool for estimating wildlife UDs. Field-based time geography was originally proposed by Miller and Bridwell (2009) in the study of transportation, and thus focused on applications on a spatial network. Here, the conceptual framework outlined by Miller and Bridwell (2009) is extended to the study of wildlife movement in a two-dimensional field. In this context, field based time

多国籍の大学生に対する野生動物問題に関する授業の実践と効果

Learning about environmental problems that include human-wildlife conflict with international students could provide great opportunities for students to improve their understanding of the theme from a global perspective and to train themselves to potentially become global leaders in this field. The author conducted a study to understand the effects of a course entitled “Facilitating Nature Conservation in Our Society,” taught in English at Chiba University, Japan. Every class included lectures and group discussions. The author taught this course for one semester (i.e., a total of 15 classes) in which 12 students―7 from Japan, 2 from the US, and one each from Australia, Finland, and Thailand―attended. The contents included understanding the relationship between human society and the natural environment, the value of biodiversity, human-wildlife issues in Japan, and efforts to live in harmony with wildlife all over the world. Throughout the course, students were required to submit reports after each class. These reports, submitted by the 12 students, were reviewed to understand what students learned from the class and group discussions with other students from various countries. The author subjectively analyzed some reports and revealed that students 1) learned about similarities and differences of environmental issues all over the world, and 2) acquired communication skills such as how to reach a consensus with people from different cultural backgrounds. For example, an American student and a Finnish student felt the characteristics of wildlife issues in Japan were somewhat different from their countries. They addressed that interventions well used in their countries (i.e., the US and Finland) such as participatory monitoring of wildlife movement around cities and hunting could potentially mitigate the issues in Japan. Japanese students learned about the importance of actively stating their opinions in English in the group discussions and workshops in order to promote mutual understanding.

Landscape feature-based permeability models relate to puma occurrence

Habitat fragmentation in human-dominated landscapes is seen as a major threat to biodiversity persistence. Nearly all corridor conservation plans designed to restore habitat connectivity are based on modeled data, and are rarely tested with empirical field data. Here we describe landscape permeability models derived from an estimated linear relationship between specific landscape features related to human land use (e.g. traffic volume, housing density) and bird and mesocarnivore detection levels from empirical field studies. We compare these model estimates with existing occurrence data for pumas (Puma concolor), a generalist predator commonly used as a focal species for connectivity analysis, in the Santa Cruz Mountains. Our results show that pumas were observed to readily use moderately disturbed habitats, and rarely were detected in the most heavily disturbed areas. This comparison of a more generic connectivity model estimate with animal field observations shows that while generic models can be useful for corridor designs in highly disturbed environments they may be less useful in moderately impacted rural to semi-natural landscapes, where more detailed studies of species behavior may be required to delineate functional corridors. Mapping the level of landscape permeability that surrounds the built environment, as measured by distance to roads and housing density, offers a spatially explicit way to identify areas important wildlife movement. This approach provides a tool to help managers and land-use planners prioritize habitat corridors for biodiversity conservation across fragmented landscapes.

Integrated adaptive design for wildlife movement under climate change

Climate change is anticipated to alter both wildlife movement and distributions. Despite mounting evidence that wildlife‐crossing infrastructure offers a reliable, physical solution to the linked problems of wildlife road mortality and habitat fragmentation, pervasive barriers – from economic to governance structures – prevent the widespread introduction of an infrastructure network. To overcome these barriers, and to cope with the challenges posed by climate change, we argue that proactive, anticipatory planning and evidence‐based, integrated highway‐impact mitigation strategies are needed. Specifically, wildlife‐crossing infrastructure should emphasize an integrated and adaptive approach to constructing innovative, modular, and potentially moveable structures that can be transferred from one location to another as monitoring of habitats and wildlife needs indicate. Continued investment in fixed, static structures, which are typically based on engineering standards designed for traffic loads rather than wildlife movement, may prove ineffectual as habitats change in composition and location, potentially leading to associated changes in the locations of wildlife–vehicle collisions.

Mapping areas of spatial-temporal overlap from wildlife tracking data.

BackgroundThe study of inter-individual interactions (often termed spatial-temporal interactions, or dynamic interactions) from remote tracking data has focused primarily on identifying the presence of such interactions. New datasets and methods offer opportunity to answer more nuanced questions, such as where on the landscape interactions occur. In this paper, we provide a new approach for mapping areas of spatial-temporal overlap in wildlife from remote tracking data. The method, termed the joint potential path area (jPPA) builds from the time-geographic movement model, originally proposed for studying human movement patterns.ResultsThe jPPA approach can be used to delineate sub-areas of the home range where inter-individual interaction was possible. Maps of jPPA regions can be integrated with existing geographic data to explore landscape conditions and habitat associated with spatial temporal-interactions in wildlife. We apply the jPPA approach to simulated biased correlated random walks to demonstrate the method under known conditions. The jPPA method is then applied to three dyads, consisting of fine resolution (15 minute sampling interval) GPS tracking data of white-tailed deer (Odocoileus virginianus) collected in Oklahoma, USA. Our results demonstrate the ability of the jPPA to identify and map jPPA sub-areas of the home range. We show how jPPA maps can be used to identify habitat differences (using percent tree canopy cover as a habitat indicator) between areas of spatial-temporal overlap and the overall home range in each of the three deer dyads.ConclusionsThe value of the jPPA approach within current wildlife habitat analysis workflows is highlighted along with its simple and straightforward implementation and interpretation. Given the current emphasis on remote tracking in wildlife movement and habitat research, new approaches capable of leveraging both the spatial and temporal information content contained within these data are warranted. We make code (in the statistical software R) for implementing the jPPA approach openly available for other researchers.Electronic supplementary materialThe online version of this article (doi:10.1186/s40462-015-0064-3) contains supplementary material, which is available to authorized users.

A wildlife movement approach to optimally locate wildlife crossing structures

Transportation networks negatively impact wildlife populations by limiting the physical movement of the individual animal. In extreme cases road presence can lead to collisions between vehicles and animals, resulting in direct mortality if an animal attempts to cross the road. Crossing structures are one commonly used method for reducing wildlife–vehicle collisions. However, limited funding often reduces the amount of structures that may be constructed in practice. Therefore, areas that have the highest probability for animal interactions with roads should be targeted for locating new structures to provide the best possible outcome. This research uses a probabilistic time-geographic strategy coupled with a site selection phase handled by a classical optimization model to site wildlife crossing structures. To achieve optimal site selection, crossing locations are first identified where wildlife frequently cross roads, and then a maximum covering location problem is applied to these areas as demand nodes. The objective is to cover the largest area having the highest probability of interaction given a finite number of crossing structures available to be located. Coverage is defined in terms of fencing distance associated with a particular structure. The approach was demonstrated using Florida panther telemetry data identifying potential crossing structures across two counties in south Florida. The maximal covering location problem (MCLP) was solved for four coverage distances using radio telemetry tracking data, which captured frequent contact with roads. The results identify that the most effective coverage distance is 2000 m, which incrementally covers more total animal–road interaction probability than that of lower fencing distances in the case of the Florida panther. The results illustrate how this new time-geographic approach, combined with location modeling, measures animal–road interactions probabilistically for finding the optimum placement of wildlife crossing structures.

An Unexpected Journey: Greater Prairie-chicken Travels Nearly 4000 km after Translocation to Iowa

Abstract After translocation a female greater prairie-chicken (Tympanuchus cupido pinnatus) traveled over 3988 km between 5 April 2013 and 20 June 2014. The bird traveled a mean distance of 21.5 km per day during the spring (median distance per day 22.2 km; range 0–115 km per day) moving through portions of four states. Nine other marked birds traveled a mean distance of 336 km and a mean distance per day of 7.5 km during the spring (median distance per day 4.6 km; range 0–92 km per day). This is the first record of movements of this magnitude by a greater prairie-chicken. This report highlights the use of recent advances in satellite/GPS telemetry methods for advancing our knowledge of wildlife movements.

Faunal diversity in a semi-evergreen forest of Bornadi-Khalingduar Complex of Assam, India

The Bornadi-Khalingduar Complex under the Manas Tiger Reserve, Assam is known to be an important area for wildlife movement to and from India and Bhutan. The contiguous landscape encompassing the two neighbouring countries provides a good habitat for diversity of wildlife and also as an important corridor area. We carried out an opportunistic camera-trapping exercise to document the faunal diversity in the area. A month-long exercise photo-captured a total of 19 species belonging to 12 families, including the Leopard, Wild Dog, Leopard Cat, Binturong, Elephant, Sambar, Barking Deer and various birds. These findings of the study reveal the importance, threats and potential of the area and recommendations have been made to secure this corridor for continuous animal movement. Anthropogenic disturbance is a major deterrent to undisturbed animal movement in this area with resultant forest fragmentation and degradation. This indicates the need for effective conservation strategies in order to maintain the remnants of this corridor complex.

Evaluating the functionality of expert-assessed wildlife corridors with genetic data from roe deer

Traffic infrastructure such as fenced motorways may reduce functional connectivity by impeding the movement of wildlife and thus reduce gene flow across landscapes. This may result in increased genetic differentiation, eventually leading to decreasing genetic diversity in wildlife populations owing to genetic drift. Landscape managers and conservation agencies apply a range of measures to mitigate such adverse effects in intensively managed landscapes. Efficient measures to facilitate landscape permeability for wildlife include expert-assessed wildlife corridors. However, whether wildlife corridors are used as such and whether they fulfill their purpose remains largely unknown. Here, we evaluated whether the expert-based categorization of wildlife corridors into functional, impaired and interrupted held true in the Swiss Plateau by testing the landscape's permeability using genetic assessments. We identified the spatial genetic structure of roe deer (Capreolus capreolus) and tested, whether the estimated gene flow supported the expert categorization of wildlife corridors. Among the four study regions (ca. 300–2600km2), pairwise genetic differentiation was rather low (FST ranging between 0.008 and 0.0264). However, wildlife corridors identified as intact on the basis of expert evaluation showed higher gene flow between populations of roe deer (mean FST=0.008) than corridors classified as impaired or interrupted (mean FST=0.022). Thus, expert judgement on the functionality of wildlife corridors could be generally confirmed by our genetic assessment on the permeability of landscapes for roe deer. This shows that genetic methods may constitute a useful set of tools to identify the state of management measures and to prioritize action plans for maintaining functional wildlife corridors across landscapes.

Is there a single best estimator? Selection of home range estimators using area-under-the-curve.

BackgroundGlobal positioning system (GPS) technology for monitoring home range and movements of wildlife has resulted in prohibitively large sample sizes of locations for traditional estimators of home range. We used area-under-the-curve to explore the fit of 8 estimators of home range to data collected with both GPS and concurrent very high frequency (VHF) technology on a terrestrial mammal, the Florida panther Puma concolor coryi, to evaluate recently developed and traditional estimators.ResultsArea-under-the-curve was the highest for Florida panthers equipped with Global Positioning System (GPS) technology compared to VHF technology. For our study animal, estimators of home range that incorporated a temporal component to estimation performed better than traditional first- and second-generation estimators.ConclusionsComparisons of fit of home range contours with locations collected would suggest that use of VHF technology is not as accurate as GPS technology to estimate size of home range for large mammals. Estimators of home range collected with GPS technology performed better than those estimated with VHF technology regardless of estimator used. Furthermore, estimators that incorporate a temporal component (third-generation estimators) appeared to be the most reliable regardless of whether kernel-based or Brownian bridge-based algorithms were used and in comparison to first- and second-generation estimators. We defined third-generation estimators of home range as any estimator that incorporates time, space, animal-specific parameters, and habitat. Such estimators would include movement-based kernel density, Brownian bridge movement models, and dynamic Brownian bridge movement models among others that have yet to be evaluated.Electronic supplementary materialThe online version of this article (doi:10.1186/s40462-015-0039-4) contains supplementary material, which is available to authorized users.

Impacts of Windfarm Development Activities on Rocky Plateaus - Discussions on Chalkewadi plateau, Dist. Satara, Maharashtra

Rocky plateaus are ecologically very important as they harbor special diversity and are part of catchments of major rivers of Maharashtra. Detailed studies on the components and fragility of rocky plateau ecosystems are sparse. Recently, the instances of these plateaus being subjected to various land use changes without detailed assessments, have affected the balance of the complex ecosystem and the services offered by them. Windfarm development is one major activity on the rocky plateaus for which little data is available on ecosystem level impacts. Results of the present study describe the Chalkewadi plateau complex, Satara district and impacts on the plateau surface brought about by the development of a high-density windfarm. Broad observations were made on the changing land use, microhabitats and associated vegetation. Manual analysis of Google Earth images of the plateau was done to understand the nature and scale of the ground-level disturbance. Results show that even though the actual area under windmill establishment is relatively smaller compared to the total plateau area, its environmental footprint is relatively large. The network of temporary and permanent roads, created to erect and operate the windfarm, has dissected the habitat and corridors of wildlife movement. An increase in road kill incidences was observed. Roads have also initiated erosional features all along the plateau surface. Disturbance due to windfarms is widespread on the plateau with the only exception being in the Reserve Forest area and disconnected smaller plateaus. Our results complement conclusions from other studies regarding negative impacts of windfarms on birds and reptiles. Thus overall impact of windfarms, in terms of habitat destruction is significant and should be studied in depth before establishment of wind farms. Establishment of windfarms on ecologically sensitive areas should be avoided as far as possible. However, we recommend good ecological management practices that could reduce the impacts, if wind farm establishment is inevitable. The recommendations can be applied to other plateaus in Sahyadri where windfarms are already in place

Disentangling the drivers of change in Common Teal migration phenology over 50 years: land use vs. climate change effects

A large body of research has accumulated on the impact of climate change on wildlife movements and distributions, especially for migratory birds. We used large ringing datasets for the Common Teal (Anas crecca) from the Camargue, southern France, to compare historic (from 1956–1975) spatiotemporal patterns of teal recovery with those seen in modern (2002–2012) years and assess whether the migration phenology of these ringed birds and their use of the Camargue as winter quarters has changed. Because teal are short-distance migrants (i.e., they breed in northern Europe and winter north of the Sahara), they would be predicted to delay their autumn migration in response to climate change. Conversely, ring recoveries showed that teal are now arriving much earlier: a stable 80 % of the recoveries were made locally in the Camargue each week between mid-November and late January in the modern dataset, whereas this percentage was only 53 % on average in the older data, and the proportion of recoveries made locally in the Camargue gradually increased through the autumn and winter until late January. This suggests that Camargue habitats have changed markedly and become more attractive to teal compared to other potential wintering areas, consistent with known changes in local habitat management practices and improvements in the body condition of the birds. Despite the fact that global climate change will likely be one of the main drivers of wildlife distribution over the long term and at large spatial scales, local habitat management should not be overlooked, as it can increase habitat attractivity to migratory birds.

A time geographic approach for delineating areas of sustained wildlife use

Geographic information systems (GIS) are widely used for mapping wildlife movement patterns, and observed wildlife locations are surrogates for inferring on wildlife movement and habitat selection. We present a new approach to mapping areas where wildlife exhibit sustained use, which we term slow movement areas (SMAs). Nested within the habitat selection concepts of home range and core areas, SMAs are an additional approach to identifying areas important for wildlife. Our method for delineating SMAs is demonstrated on a grizzly bear (Ursus arctos) case study examining road density. Our results showed that subadult females had significantly higher road densities within SMAs than in their potential path area home ranges. The lowest road density was found in the SMAs of adult male grizzly bears. Given increased mortality risks associated with roads, female encampment near roads may have negative conservation implications. The methods presented in this manuscript compliment recent developments to identify movement suspension and intensively exploited areas defined from wildlife telemetry data. SMA delineation is sensitive to missing data and best applied to telemetry data collected with a consistent resolution.

Quantifying Spatial-temporal Interactions from Wildlife Tracking Data: Issues of Space, Time, and Statistical Significance

New tracking technologies are allowing researchers to study wildlife movements at unprecedented spatial and temporal resolutions. Researchers now routinely deploy tracking sensors on multiple individual animals simultaneously, offering new opportunities to study the spatial-temporal interactions (often termed dynamic interaction) in the movements of these animals. The objective of this paper is to examine the statistical properties of a suite of currently available methods aimed at measuring spatial-temporal interactions and the ability of each method to characterize and capture different patterns of spatial-temporal interaction encountered in practice. Specifically, this paper examines issues relating to the spatial arrangement of interactions across a study area, temporal patterns in interactions over a tracking period, and the effectiveness of different statistical testing procedures used to identify significant spatial-temporal interaction. Simulations using biased correlated random walks are used to emulate different patterns of spatial-temporal interaction encountered in empirical data. The results demonstrate the challenges of statistical testing of interaction patterns with several methods having high rates of type I and/or type II error. More problematic is that, in practice, spatial-temporal interactions exhibit underlying spatial and/or temporal patterns, for example with key watering holes revisited daily, which can cause problems for statistics that use permutation tests from the original data to test for significance. The need to consider statistical significance in the context of biological significance, which relates to quantifying the spatial locations and temporal patterns of interaction events and types of interactions, is emphasized. Methods that can be adapted to facilitate spatial and temporally ‘local’ analysis are advantageous with high resolution tracking data currently being collected. An R package–wildlifeDI–provides the computational tools for performing the analysis described herein and is made openly available to other researchers.

A Pneumatic Net Gun Method for Capture of Great Egrets (Ardea alba)

Many techniques to evaluate survival and movement of wildlife rely on the capture and instrumentation of individuals. However, effective capture techniques for Great Egrets (Ardea alba) outside the breeding season remain elusive, particularly a method to attain robust sample sizes to investigate several aspects of biology. A handheld pneumatic net gun method was developed and successfully captured 97 Great Egrets in 121 trap days. No direct mortalities or substantial injuries occurred. The handheld pneumatic net gun was more cost-effective than commercially available or similar devices, and could prove useful for sensitive species where injury or mortality must be minimized or where the use of explosive devices is restricted.

The carriage of antibiotic resistance by enteric bacteria from imported tokay geckos (Gekko gecko) destined for the pet trade

The emergence of antibiotic-resistant bacteria is a growing public health concern and has serious implications for both human and veterinary medicine. The nature of the global economy encourages the movement of humans, livestock, produce, and wildlife, as well as their potentially antibiotic-resistant bacteria, across international borders. Humans and livestock can be reservoirs for antibiotic-resistant bacteria; however, little is known about the prevalence of antibiotic-resistant bacteria harbored by wildlife and, to our knowledge, limited data has been reported for wild-caught reptiles that were specifically collected for the pet trade. In the current study, we examined the antibiotic resistance of lactose-positive Enterobacteriaceae isolates from wild-caught Tokay geckos (Gekko gecko) imported from Indonesia for use in the pet trade. In addition, we proposed that the conditions under which wild animals are captured, transported, and handled might affect the shedding or fecal prevalence of antibiotic resistance. In particular we were interested in the effects of density; to address this, we experimentally modified densities of geckos after import and documented changes in antibiotic resistance patterns. The commensal enteric bacteria from Tokay geckos (G. gecko) imported for the pet trade displayed resistance against some antibiotics including: ampicillin, amoxicillin/clavulanic acid, cefoxitin, chloramphenicol, kanamycin and tetracycline. There was no significant difference in the prevalence of antibiotic-resistant bacteria after experimentally mimicking potentially stressful transportation conditions reptiles experience prior to purchase. There were, however, some interesting trends observed when comparing Tokay geckos housed individually and those housed in groups. Understanding the prevalence of antibiotic resistant commensal enteric flora from common pet reptiles is paramount because of the potential for humans exposed to these animals to acquire antibiotic-resistant bacteria and the potential for released pets to disseminate these bacteria to native wildlife.

Using Artificial Passageways to Facilitate the Movement of Wildlife on Namibian Farmland

Wildlife-proof fencing is increasing in extent as a result of the growing wildlife industry on private lands in southern Africa. In environments where such fences hinder the movements of free-ranging wildlife, the provision of artificial passageways can restore connectivity for some species. We tested the use of 49 discarded car tyres as wildlife passageways along the border of a Namibian wildlife farm. Tyres were installed into a wildlife-proof fence to reduce regular warthog (Phacochoerus africanus) damage to the fence and to provide connectivity and dispersal opportunities for selected indigenous wildlife species between adjacent farmland properties. The total cost for all 49 tyre installations was USD 252, which is significantly cheaper than daily fence patrols and maintenance. In addition, one tyre was monitored specifically for large carnivore activity with a motion-triggered camera trap (n = 96 trap days between August and December 2010). Eleven mammalian species used the tyre as a passageway and both cheetahs (Acinonyx jubatus) and leopards (Panthera pardus) made regular and repeated use of the tyre. Nine independent recordings of cheetahs, representing seven individuals, were made. One leopard was photographed four times. The suitability of discarded tyres as cost-effective artificial wildlife passageways for a range of mammalian species is stressed.