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Mortality of animals on roads is a critical threat to many wildlife populations and is poised to increase strongly because of ongoing and planned road construction. If these new roads cannot be avoided, effective mitigation measures will be necessary to stop biodiversity decline. Fencing along roads effectively reduces roadkill and is often used in combination with wildlife passages. Because fencing the entire road is not always possible due to financial constraints, high-frequency roadkill areas are often identified to inform the placement of fencing. We devised an adaptive fence-implementation plan to prioritize road sections for fencing. In this framework, areas along roads of high, moderate, and low levels of animal mortality (respectively, roadkill hotspots, warmspots, and coldspots) are identified at multiple scales (i.e., in circles of different diameters [200-2000 m] in which mortality frequency is measured). Fence deployment is based on the relationship between the amount of fencing being added to the road, starting with the strongest roadkill hotspots, and potential reduction in road mortality (displayed in mortality-reduction graphs). We applied our approach to empirical and simulated spatial patterns of wildlife-vehicle collisions. The scale used for analysis affected the number and spatial extent of roadkill hot-, warm-, and coldspots. At fine scales (e.g., 200 m), more hotspots were identified than at coarse scales (e.g., 2000 m), but combined the fine-scale hotspots covered less road and less fencing was needed to reduce road mortality. However, many short fences may be less effective in practice due to a fence-end effect (i.e., animals moving around the fence more easily), resulting in a trade-off between few long and many short fences, which we call the FLOMS (few-long-or-many-short) fences trade-off. Thresholds in the mortality-reduction graphs occurred for some roadkill patterns, but not for others. Thresholds may be useful to consider when determining road-mitigation targets. The existence of thresholds at multiple scales and the FLOMS trade-off have important implications for biodiversity conservation.Un Plan Adaptativo para la Priorización de Secciones de Carretera para Cercar y Reducir la Mortalidad Animal Resumen La mortalidad de los animales en las carreteras es una amenaza muy importante para las poblaciones silvestres y se pronostica que aumentarán enérgicamente debido a la construcción continua y planeada de carreteras. Si estas nuevas carreteras no pueden evitarse, se necesitarán medidas efectivas de mitigación para detener la declinación de la biodiversidad. El cercado a lo largo de las carreteras reduce efectivamente los atropellamientos y se usa frecuentemente junto con los pasos de fauna. Ya que cercar por completo la carretera no siempre es posible debido a las restricciones financieras, es común identificar las áreas con una frecuencia alta de atropellamientos para que la colocación de cercas esté informada al respecto. Diseñamos un plan adaptativo de implementación de cercas para priorizar las secciones de carretera que requieren ser cercadas. En este marco de trabajo, identificamos las áreas a lo largo de las carreteras con un nivel alto, moderado y bajo de mortalidad animal (respectivamente, puntos calientes, cálidos y fríos de atropellamiento) a diferentes escalas (es decir, en círculos de diferentes diámetros [200-2000 m] dentro de los cuales se mide la frecuencia de la mortalidad). El despliegue de cercas está basado en la relación entre la cantidad de cercas que se van añadiendo a la carretera, iniciando en los puntos calientes de atropellamiento, y la reducción potencial de la mortalidad en la carretera (presentada en gráficas de reducción de la mortalidad). Aplicamos nuestra estrategia a los patrones espaciales empíricos y simulados de las colisiones entre vehículos y animales. La escala utilizada para el análisis afectó al número y a la extensión espacial de los puntos calientes, cálidos y fríos de los atropellamientos. A escalas finas (p. ej.: 200 m), se identificaron más puntos calientes que a escalas más amplias (p. ej.: 2000 m), pero combinadas las escalas finas, los puntos calientes cubrieron una superficie menor de la carretera y se necesitaron menos cercas para reducir la mortalidad. Sin embargo, muchas cercas cortas pueden ser menos efectivas en la práctica debido al efecto de fin de valla (es decir, que los animales se muevan alrededor de la cerca con mayor facilidad), lo que resulta en una compensación entre pocas cercas largas y muchas cercas cortas, que denominamos compensación de cercas FLOMS (pocas-largas-o-muchas-cortas). Los umbrales en las gráficas de reducción de la mortalidad se presentaron para algunos patrones de atropellamiento, pero no para otros. Los umbrales pueden ser útiles para considerar cuando se determinan los objetivos de mitigación para las carreteras. La existencia de los umbrales a escalas múltiples y la compensación de FLOMS tienen implicaciones importantes para la conservación de la biodiversidad.动物被路杀是许多野生动物种群面临的一项严重威胁。考虑到正在进行和计划实施的道路建设, 这一问题还将日益加剧。如果无法避免建设新道路, 就必须采取有效的缓解措施来阻止生物多样性下降。在道路两旁修建围栏可以有效减少路杀, 且经常与野生动物通道结合使用。由于资金限制, 通常不能沿整条道路设置围栏, 因此一般会找出路杀高发地段来为围栏的布设提供信息。我们设计了一个适应性的围栏建设实施计划, 来确定优先建设围栏的路段。在这个框架中, 我们在多尺度上 (即在 200-2000 米直径的圆内测量路杀死亡率) 确定了路杀频率高、中、低的道路沿线地区 (分别是路杀热点地区、暖点地区和冷点地区) 。围栏布设是基于道路上从路杀热点地区开始的增加围栏的数量, 与可能的路杀死亡率降低 (通过死亡率下降图来显示) 之间的关系。我们将该方法应用于野生动物-车辆撞击的经验和模拟空间模型中, 发现用于分析的尺度影响了路杀热点、暖点、冷点地区的数量和空间范围。在精细尺度下 (如 200 米) 比在粗糙尺度下 (如 2000 米) 能识别出更多热点地区, 但将精细尺度下的热点地区结合起来只覆盖了较少的道路, 为减少路杀而需要建设的围栏也较少。然而, 由于存在围栏末端效应 (即动物可以更轻易地绕过围栏) , 建设许多短围栏在实践中可能不够有效, 因此需要在少量长围栏和大量短围栏之间进行取舍, 我们称之为 FLOMS (few-long-or-many-short, 少量长围栏或大量短围栏) 的权衡。此外, 某些路杀模式的死亡率下降图中出现了阈值, 而其它模式则没有。在确定减缓路杀影响的目标时, 阈值可能有一定帮助。多尺度下的阈值存在和 FLOMS 权衡对生物多样性保护具有重要意义。【翻译: 胡怡思; 审校: 聂永刚】.

Many connectivity metrics have been used to measure the connectivity of a landscape and to evaluate the effects of land-use changes and potential mitigation measures. However, there are still gaps in our understanding of how to accurately quantify landscape connectivity. A number of metrics only measure between-patch connectivity, i.e. the connectivity between different habitat patches, which can produce misleading results. This paper demonstrates that the inclusion of within-patch connectivity is important for accurate results. The behavior of two metrics is compared: the Connectance Index (CONNECT), which measures only between-patch connectivity, and the effective mesh size (meff), which includes both within-patch and between-patch connectivity. The connectivity values of both metrics were calculated on a set of simulated landscapes. Twenty cities were then added to these landscapes to calculate the resulting changes in connectivity. We found that when using CONNECT counter-intuitive results occurred due to not including within-patch connectivity, such as scenarios where connectivity increased with increasing habitat loss and fragmentation. These counter-intuitive results were resolved when using meff. For example, landscapes with low habitat amount may be particularly sensitive to urban development, but this is not reflected by CONNECT. Applying misleading results from metrics like CONNECT can have detrimental effects on natural ecosystems, because reductions in within-patch connectivity by human activities are neglected. Therefore, this paper provides evidence for the crucial need to consider the balance between within-patch connectivity and between-patch connectivity when calculating the connectivity of landscapes.

Au Québec, certains des premiers passages fauniques pour les petits et moyens mammifères ont été installés lors de l’élargissement de la route 175. L’efficacité de 18 structures et des clôtures près de leur entrée a été évaluée grâce à un suivi continu par des caméras de surveillance et des enquêtes sur les animaux frappés par les véhicules au cours des étés de 2012 à 2015. La plupart des espèces ont utilisé plus souvent les ponceaux secs en béton et ceux avec pied sec de type tablette de bois installée en porte-à-faux que les ponceaux avec pied sec de type tablette de béton. Il y a eu significativement plus de mortalité routière animale aux extrémités des clôtures que dans les tronçons de route clôturés et ceux non clôturés. La mortalité routière animale était moindre dans les tronçons de route clôturés (et aux extrémités de clôtures correspondantes) où la faune utilisait plus souvent les structures. Bien qu’en général, les passages installés aient été couronnés de succès, plusieurs espèces utilisent peu ou pas ces structures, et des améliorations sont nécessaires. Nous présentons plusieurs recommandations visant à améliorer l’atténuation de l’impact des routes sur la faune, ainsi que de futurs programmes de suivi et de recherche., Some of the first designated wildlife passages for small and medium-sized mammals in the province of Québec (Canada) were installed during the widening of the highway Route 175. The effectiveness of 18 passages and short fences on either side of the entrances was evaluated through continuous camera monitoring and roadkill surveys conducted over 4 summers (2012-2015). Most mammal species used concrete pipe culverts and wooden ledge culverts more often than concrete ledge culverts. Roadkill was significantly greater at fence ends than within fenced and unfenced sections, and was less in those fenced road sections (and around the associated fence ends) where wildlife passages were more frequently used. While the passages were successful in general, several species only used the passages infrequently or not at all, and further improvements are needed. Several recommendations are made concerning ways to improve the mitigation of the impact of roads on wildlife, and future monitoring and research.