An adaptive plan for prioritizing road sections for fencing to reduce animal mortality.

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.

Wild vertebrates roadkill aggregations on the BR-050 highway, state of Minas Gerais, Brazil / Agregações de atropelamentos de vertebrados silvestres na rodovia BR-050, Minas Gerais, Brasil

Researches on roadkill aggregations are important tools for wildlife conservation. The objective of this study was to determine wild vertebrate roadkill aggregations on a stretch of 96 kilometers of the BR-050 highway, between the cities of Uberlândia and Uberaba, State of Minas Gerais, Brazil. The survey was conducted between April 2012 and March 2013. Roadkill monitoring was performed by car, at a speed of approximately 60 km/h, and forty two (42) weekly trips, totaling 8064 km, were performed. The 2D Ripley's K-Statistics test from the Siriema v1.1 program was used to detect the scales of roadkill aggregations and 2D HotSpot Identification test was used to identify the location of these hotspots. Aggregations extended from the following kms: 14 to 33, 38, 41 to 51, 66 to 70 and 78 to 94. We found roadkill aggregations for wild vertebrates and mammals. The roadkill aggregations were significant for Euphractus sexcinctus, Conepatus semistriatus, Procyon cancrivorus, Hydrochoerus hydrochoerus, Cariama cristata, Boa constrictor amarali and Crotalus durissus collilineatus according to the taxonomic specific level. Thus, it is suggested that mitigation measures for vertebrate conservation must be implemented in the indicated areas.

Pesquisas sobre agregações de atropelamento são ferramentas importantes para a conservação da vida selvagem. O objetivo deste estudo foi determinar agregações de atropelamentos de vertebrados silvestres em um trecho de 96 km da rodovia BR-050, entre as cidades de Uberlândia e Uberaba (MG), na região central do Brasil. A pesquisa foi realizada a partir de abril de 2012 a março de 2013. O monitoramento foi realizado de carro e o trecho foi investigado a uma velocidade de aproximadamente 60 km/h. Realizamos 42 viagens semanais, num total de 8064 km percorridos. O teste 2D Ripley's K-Statistics do programa Siriema v1.1 foi utilizado para detectar as escalas de agregações de atropelamentos e o teste 2D HotSpot Identification foi utilizado para identificar a localização destes hotspots. Agregações de atropelamento se extenderam nos seguintes quilômetros: 14-33, 38-41 a 51, 66 a 70 e 78-94. Encontramos agregações de vertebrados e mamíferos silvestres. Em nível taxonômico específico foram encontradas agregações de atropelamentos significativas para Euphractus sexcinctus, Conepatus semistriatus, Procyon cancrivorus, Hydrochoerus hydrochaeris, Cariama cristata, Boa constrictor amarali, Crotalus durissus collilineatus. Assim, sugere-se que medidas de mitigação para a conservação de vertebrados devem ser implementadas nas áreas indicadas.