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.

Reptile road-kills in Southern Brazil: Composition, hot moments and hotspots.

Understanding road-kill patterns is the first step to assess the potential effects of road mortality on wildlife populations, as well as to define the need for mitigation and support its planning. Reptiles are one of the vertebrate groups most affected by roads through vehicle collisions, both because they are intentionally killed by drivers, and due to their biological needs, such as thermoregulation, which make them more prone to collisions. We conducted monthly road surveys (33months), searching for carcasses of freshwater turtles, lizards, and snakes on a 277-km stretch of BR-101 road in Southernmost Brazil to estimate road-kill composition and magnitude and to describe the main periods and locations of road-kills. We modeled the distribution of road-kills in space according to land cover classes and local traffic volume. Considering the detection capacity of our method and carcass persistence probability, we estimated that 15,377 reptiles are road-killed per year (55reptiles/km/year). Road-kills, especially lizards and snakes, were concentrated during summer, probably due to their higher activity in this period. Road-kill hotspots were coincident among freshwater turtles, lizards, and snakes. Road-kill distribution was negatively related to pine plantations, and positively related to rice plantations and traffic volume. A cost-benefit analysis highlighted that if mitigation measures were installed at road-kill hotspots, which correspond to 21% of the road, they could have avoided up to 45% of recorded reptile fatalities, assuming a 100% mitigation effectiveness. Given the congruent patterns found for all three taxa, the same mitigation measures could be used to minimize the impacts of collision on local herpetofauna.

Canopy bridges as road overpasses for wildlife in urban fragmented landscapes / Pontes de corda como passagens para animais silvestres em paisagens urbanas fragmentadas

The effects of habitat fragmentation and deforestation are exacerbated by some elements, such as roads and power lines, which may become filters or barriers to wildlife movements. In order to mitigate mortality and restore connectivity, wildlife passages are being constructed as linear corridors. The installation of these mitigation measures must be followed by systematic monitoring, in order to evaluate their use and effectiveness, to assist in their management, and to convince stakeholders of their value. In this paper we present the results of a monitoring study of the use of rope overpasses developed near a protected area in Porto Alegre, southern Brazil. The canopy bridges were installed by the Urban Monkeys Program in places where electric hazards and road-kills of brown howler monkeys (Alouatta guariba clamitans Cabrera, 1940) were recorded. Camera traps were installed at each bridge, and local people were selected and trained to monitor overpass use over 15 months, from August 2008 to October 2009. Three species were recorded using canopy bridges: brown howler monkey (Alouatta guariba clamitans Cabrera, 1940), white-eared opossum (Didelphis albiventris Lund, 1840) and porcupine (Sphiggurus villosus Cuvier, 1823). Rope bridges with the highest number of species recorded had more forest cover and lower urban area around them than overpasses little used. Our results indicate that overpasses, in Porto Alegre, work as a linear corridor between forest remnants, although the outcomes for individual survival, group persistence, population demography or gene flow have not been measured. Furthermore, canopy bridges may be important to mitigate the impact of roads and power lines on wildlife, but electric cables also need to be completely isolated when present, to warrant animals' physical integrity.

Os efeitos do desmatamento e da fragmentação de hábitats são exacerbados por elementos como rodovias e redes elétricas, que podem atuar como filtros ou barreiras aos movimentos da vida silvestre. Com o objetivo de mitigar a mortalidade e restaurar a conectividade, passagens de fauna têm sido construídas como corredores lineares. A instalação dessas estruturas deve ser seguida de monitoramento sistemático, visando à avaliação de seu uso e efetividade e a geração de informações para seu manejo e para convencer os tomadores de decisão sobre seu valor. Neste artigo, apresentamos os resultados do monitoramento do uso de seis pontes de corda, realizado durante 15 meses, entre agosto de 2008 e outubro de 2009, nas imediações da Reserva Biológica do Lami José Lutzenberger, em Porto Alegre, Brasil. As pontes de dossel foram instaladas pelo Núcleo de Extensão Macacos Urbanos em locais com registros de atropelamentos e choques elétricos de bugios-ruivos (Alouatta guariba clamitans Cabrera, 1940). Instalamos armadilhas fotográficas em cada ponte e selecionamos moradores locais para registrarem seu uso. Três espécies foram registradas usando as pontes de corda: o bugio-ruivo (Alouatta guariba clamitans Cabrera, 1940), o gambá-de-orelha-branca (Didelphis albiventris Lund, 1840) e o ouriço-cacheiro (Sphiggurus villosus Cuvier, 1823). As pontes de corda mais usadas por maior número de espécies são aquelas situadas nas áreas de maior cobertura florestal e menor área urbanizada, em relação às pontes menos usadas pelas espécies. Nossos resultados indicam que as pontes de corda funcionam como um corredor linear entre os remanescentes florestais, embora não tenhamos avaliado os efeitos das pontes sobre a sobrevivência dos indivíduos, persistência e demografia dos grupos e fluxo gênico na população. Além disso, as pontes podem ser usadas para mitigar o impacto de redes elétricas e rodovias sobre a mortalidade, mas os cabos elétricos também devem ser completamente isolados quando presentes.

Anuran road-kills neighboring a peri-urban reserve in the Atlantic Forest, Brazil.

Mortality from road-kills may figure among the important causes of decline in amphibian populations and species extinctions worldwide. Evaluation of the magnitude, composition, and temporal and spatial distributions of amphibian road-kills is a key step for mitigation planning, especially in peri-urban reserves. Once a month for 16 months, we surveyed, on foot, a 4.4 km section of state road ERS-389 bordering the Itapeva reserve in the southern Atlantic Forest. We recorded 1433 anuran road-kills and estimated a mortality rate of 9002 road-kills/km/year. The species most often recorded were the largest ones: Leptodactylus latrans, Rhinella icterica, Leptodactylus gracilis and Hypsiboas faber; 54.5% of the carcasses could not be identified. Anuran mortality was concentrated in summer, and was associated with temperature, rainfall and photoperiod. Leptodactylus road-kills were strongly influenced by vehicle traffic, probably because of its high abundance during the entire study period. Road-kill hotspots differed for anurans as a group and for single species, and we found an association among spatial patterns of mortality and types of land cover, distance from the nearest waterbody, roadside ditches, and artificial light. Traffic should be banned temporarily during periods of high mortality, which can be forecasted based on meteorological data. A comprehensive mitigation approach should take into account hotspots of all anuran records, and also of target species for selecting locations for amphibian passages and fencing. Roadside ditches, artificial waterbodies, and conventional street lights should be reduced as much as possible, since they may represent ecological traps for anuran populations.