Assessing the impact of roadkill on the persistence of wildlife populations: A case study on the giant anteater

Human activity is depleting biodiversity, and road networks are directly contributing to this trend due to roadkill. Nevertheless, few studies empirically estimated the impact of roadkill on wildlife populations. We integrated information on roadkill rates, population abundance, and animal movement to estimate the survival rates and the proportion of the population likely to be extirpated due to roadkill, using giant anteater (Myrmecophaga tridactyla) as model species. We then assessed the consequent implications of roadkill on population persistence using population viability analysis (PVA). The yearly survival rate of resident anteaters inhabiting road vicinity areas (0.78; CI: 0.62−0.97) was considerably lower than for those living far from roads (0.95; CI:0.86–1.00). The real number of anteaters being road-killed is considerably higher than the one recorded in previous studies (by a factor of 2.4), with ca. 20% of the population inhabiting road vicinity areas being road-killed every year. According to PVA results, roadkill can greatly affect the persistence of the giant anteater populations by reducing the growth rate down to null or negative values. This study confirms that roads have significant impacts on local population persistence. Such impacts are likely to be common to other large mammals, calling for effective mitigation to reduce roadkill rates.info:eu-repo/semantics/publishedVersio

Cars as a tool for monitoring and protecting biodiversity

Modern cars have an array of sensors that allow different objects to be recognized, including large and small animals. They thus have the potential to become a tool for monitoring biodiversity and improving driver safety. But to achieve this various challenges in computing, communications and privacy need to be addressed.info:eu-repo/semantics/publishedVersio

Wildlife collisions put a dent in road safety

info:eu-repo/semantics/publishedVersio

Proceratium melinum (Roger, 1860): the first record of Proceratiinae ants from Portugal (Hymenoptera, Formicidae).

ABSTRACT: The ant Proceratium melinum (Roger, 1860) is reported for the first time from Portugal. This is also the first record of Proceratiinae in this country, from which a total of 133 ant species are now known. The species was collected in a cork oak stand (montado) using pitfall traps.info:eu-repo/semantics/publishedVersio

Ecologically scaled responses of forest-dwelling vertebrates to habitat fragmentation

Tese de doutoramento, Biologia (Biologia da Conservação), Universidade de Lisboa, Faculdade de Ciências, 2013Road habitat fragmentation has been identified as a major threat for biodiversity conservation. Roads induce a ‘barrier effect’ by representing a physical obstacle or promoting animal-vehicle collisions, disrupting daily and seasonal movements and consequently leading to the depletion and genetic subdivision of animal populations. However, road verges may also provide resources for some species. This thesis aimed to test for an ecologically scaled response of wildlife to road induced habitat fragmentation. The hypothesis under study is that the biological and ecological traits are determinant in predicting the road effects on species persistence. I expected to detect more pronounced negative road-related effects on species with larger body size, lower reproductive rate and greater mobility. To test this hypothesis I analyzed the responses to the road barrier effect by two model species, the wood mouse (Apodemus sylvaticus) and the stone marten (Martes foina), accounting for both potential benefits and negative consequences for species persistence. The major goal was to contribute for a sound scientific basis of road impacts on wildlife and generate advice for improving existing management practices that could benefit the maximum number of species, striving towards a better conciliation of road networks with biological conservation. I estimated the abundance of small mammals inhabiting road verges; quantified the gene flow across roadsides for wood mouse; assessed how roads affect the space use and movement of stone martens living in close vicinity of a highway; and modeled the effectiveness of wildlife-vehicle collision mitigation measures directed to medium-sized carnivores. Consistent evidences were obtained that the species’ responses to roads follow an ecological scale, where small mammals may benefit with road verge presence, although being more vulnerable to genetic isolation; and medium-sized carnivores are more prone to population depletion. I concluded that this latter group should be the focus of road mitigation plans. Highways should be upgraded with exclusionary fence impermeable to carnivores and larger species, in the most part of their length, combined with a sufficient number of open-span structures. The number of open-span passages to be installed or upgraded should consider not only the connectivity at the local scale but also at the landscape perspective in order to guarantee that the accessible habitat area is sufficient to host viable populations.A fragmentação dos habitats resultante da presença de estradas e tráfego associado tem sido identificada como uma das principais ameaças à conservação da biodiversidade. As estradas provocam um ‘efeito de barreira’, uma vez que bloqueiam as deslocações diárias ou sazonais de múltiplas espécies. Este bloqueio faz-se sentir tanto pela colisão dos animais com os veículos, como pelo facto de as estradas e estruturas associadas poderem representar um obstáculo físico à passagem dos animais. Por outro lado, é sabido que as bermas das estradas podem proporcionar recursos a algumas espécies, como abrigo e alimento para invertebrados e pequenos mamíferos. Esta tese teve como principal objectivo testar se existe uma escala ecológica nas respostas dos organismos à fragmentação dos habitats pelas estradas. A hipótese em estudo considera que as características biológicas e ecológicas das espécies são determinantes para prever os principais efeitos das estradas e o seu impacto na persistência dessas espécies. Era esperado um efeito negativo mais pronunciado das estradas em espécies com maior tamanho, menor taxa reprodutora e maior mobilidade. Para testar esta hipótese, analisei as respostas de duas espécies-modelo ao efeito-barreira resultante de autoestradas: rato-do-campo (Apodemus sylvaticus) e a fuinha (Martes foina). Nesta tese é assumido que estas duas espécies-modelo representam grupos ecológicos cujas características biológicas (e.g. tamanho, locomoção), ecológicas (e.g. habitat) e (in)tolerância às estradas são relativamente homogéneas. Desta forma, as espécies modelos representam respectivamente roedores e carnívoros de médio porte. Estas espécies são generalistas, embora geralmente associadas a áreas florestais e em particular ao montado. Sendo generalistas, estas espécies podem fazer um uso mais amplo da matriz envolvente às manchas de habitat favorável (montado). Assim sendo, considera-se que qualquer resposta destas espécies modelo relativamente à presença de estradas será mais intensificada em espécies com estatuto de conservação mais desfavorável. Por exemplo, a fuinha e gato-bravo (Felis sylvestris) partilham muitas características biológicas e ecológicas, mas a segunda espécie tem maiores ‘exigências’ relativamente à qualidade do habitat. A tese é composta por quatro estudos, cada um focando um tema diferente mas complementares no seu todo para a compreensão da hipótese em análise. No primeiro estudo as abundâncias de pequenos mamíferos foram estimadas nas bermas das autoestradas A2 e A6 (Alentejo, Portugal) e nas áreas envolventes a estas infra-estruturas. Foi feita também uma comparação da estrutura da vegetação entre os diferentes tipos de habitat amostrados e uma modelação de como a estrutura da vegetação pode influenciar a presença das espécies nas bermas. Foram amostrados 36 sítios, entre os quais onze troços das autoestradas. Um total de 351 indivíduos foi capturado, incluindo 157 ratos-do-campo. Os dados sugerem que as vedações das autoestradas ao evitar o pastoreio permitem que a vegetação cresça e forneça boas condições para a presença de pequenos mamíferos, nomeadamente alimento, abrigo e proteção de predadores. No segundo estudo examinei a importância relativa do volume de tráfego e da idade da autoestrada no processo de isolamento genético das populações do rato-do-campo. Foram recolhidas amostras de 155 indivíduos genotipadas para nove microssatélites. Foram feitas análises ao nível da estruturação genética, presença de clusters recorrendo a técnicas Bayesianas e multivariada, número de migrantes, e parentesco. Os dados foram depois comparados com um modelo de simulação espacialmente explícito para testar qual o nível de permeabilidade da autoestrada aos movimentos do rato do campo mais provável. Os níveis de diferenciação genética e parentesco revelaram algum isolamento entre os indivíduos dos dois lados da estrada, sugerindo que as autoestradas diminuem significativamente o movimento dos animais entre os lados da estrada relativamente ao cenário onde a autoestrada não está presente. No terceiro estudo foi feita uma avaliação da influência da autoestrada A6 no movimento e uso do espaço pela fuinha. Dados de telemetria relativos a sete indivíduos foram analisados num quadro individual. Mais uma vez os resultados foram comparados com um modelo de simulação espacialmente explícito para testar se os movimentos e o uso do espaço foram de alguma forma constrangidos pela presença da auto-estrada. Todas as fuinhas exploraram as áreas adjacentes à autoestrada, sem que nenhuma tenha mostrado uma preferência por zonas da berma com uma estrutura de vegetação mais desenvolvida. Quatro fuinhas cruzaram regularmente a autoestrada, sendo que as suas áreas vitais eram atravessadas pela mesma. Os dados sugerem que o local onde as fuinhas cruzam a autoestrada é influenciado pelo tipo de actividade em curso, a distância à passagem mais próxima e se a fuinha é residente (tem percepção da presença de veículos e locais de cruzamento como as passagens hidráulicas). No quarto estudo é feita uma análise recorrendo a um modelo de simulação espacialmente explícito para testar qual a melhor forma de mitigação dos atropelamentos de carnívoros de médio porte. Foram criados 125 cenários com diferentes combinações de percentagem de auto-estrada vedada (vedação impermeável à passagem de animais), número de passagens e probabilidade de atropelamento. A eficácia de cada cenário foi avaliada tendo em conta o tamanho da população e nível de diferenciação genético entre as populações dos dois lados da estrada, e comparando estes dados com o cenário onde a estrada não estava presente. Os resultados indicam que o principal factor que determina a diferenciação genética e o tamanho da população é a proporção de autoestrada que é vedada. No seu conjunto, os quatro estudos fornecem evidências que a resposta das espécies à presença das estradas obedece a uma escala ecológica, onde os pequenos mamíferos beneficiam com a presença das bermas, embora sendo mais vulneráveis aos efeitos de isolamento (genético); e onde os carnívoros de médio porte são mais vulneráveis ao impacto por atropelamento e portanto à diminuição do tamanho das populações. De acordo com os resultados obtidos, os carnívoros de médio porte devem ser considerados como grupo prioritário em planos de mitigação do impacto das estradas em mamíferos. Diversas medidas de gestão são sugeridas. Nas autoestradas (e noutras estradas com elevado tráfego) devem ser instaladas redes impermeáveis à passagem de carnívoros de médio porte. As bermas devem ser geridas de forma a proporcionar um habitat favorável à presença de pequenos mamíferos, em particular nas zonas onde a rede impermeável é instalada. Em complemento, devem ser implementadas áreas de exclusão de gado em zonas de sobrepastoreio, para que as populações de micromamíferos possam aí também persistir e proliferar. Estas áreas devem ser ligadas às bermas por elementos lineares naturais ou semi-naturais, como ribeiras e sebes, proporcionando assim uma vasta rede de corredores ecológicos para os pequenos mamíferos. Sendo presas preferênciais para muitos carnívoros, estas medidas de gestão poderão assim beneficiar um grande número de predadores e todo o ecossistema. Em conjunto com a instalação da rede impermeável, devem ser implementadas ou melhoradas passagens que permitam o cruzamento das estradas por todas as espécies terrestres. Estas passagens devem consistir em viadutos sobre linhas de água, com vegetação abundante para diminuir o uso pelos humanos e aumentar a sua utilização pela fauna silvestre. O número de passagens a instalar deve ter em conta a dinâmica populacional, em particular a área necessária para uma população persistir.Fundação para a Ciência e a Tecnologia (FCT, SFRH/BD/38053/2007

Road encroachment mediates species occupancy, trait filtering and dissimilarity of passerine communities

Assessing the road effects on biodiversity is challenging because impacts may depend on both wildlife responses to roads and on the spatial arrangement of roads. We questioned whether an increase in road encroachment leads to significant changes in species occurrence and community composition. Using a large citizen-science dataset of point-counts performed throughout Iberian Peninsula, we modelled the effect of road density on the occurrence of common birds (n = 78 species), while accounting for potential confounding effects of environment and survey effort. We then tested if species' occurrence patterns would be linked to specific traits related to the ability to cope with human presence. Finally, we assessed how road density affects the community compositional dissimilarity. We estimated 36 (46%) and 18 (23%) species to be negatively and positively affected by roads, respectively. Increased road encroachment was positively related with urban dwelling and fecundity, and negatively related with nesting on the ground. Furthermore, increasing road density translated into an increasing community compositional dissimilarity, mostly due to species turnover. Overall, we found that different species-specific responses to roads translate into changes at the community level. Landscape and road-network management should be conceived acknowledging that roads are contributing to biodiversity changes. As so, building upon the concepts of land sharing/land sparing, conservation actions should be tailored according to the different species responses e.g., road verge management targeting species having a positive relation with road density; and compensation actions targeting species showing a negative response toward roads.info:eu-repo/semantics/publishedVersio

The lost road: Do transportation networks imperil wildlife population persistence?

The global road network is rapidly growing associated with human economic development. This growthalso entails a high toll for biodiversity, with several well-documented negative impacts on differentspecies. However, there is still a great lack of knowledge about the effects of roads on the persistenceof wildlife populations. Here, we aimed to summarize our current knowledge on this topic, based onsystematic reviews. We found that only a small proportion of studies (8%) focused on the effects of roadson population persistence. Most of these studies were about large mammals and were performed in high-income countries. Furthermore, these works studied only 2% of those species identified by the IUCN RedList as threatened by roads. Overall, our results show that we are far from understanding how roads affectthe long-term viability of wildlife populations inhabiting road-effect zones. Addressing this challenge willrequire modifying our conceptual perspective, from short-term to long-term studies, from single roadsections to focusing the landscape scale, and strive to obtain empirical data to support sound analysesto assess how road impacts affect the survival of wildlife populations, namely with information requiredto perform approaches such as population viability analyses. We highlight some key studies from ourreviews that have addressed this global conservation concern with population-oriented approaches.info:eu-repo/semantics/publishedVersio

Are road-kills representative of wildlife community obtained from atlas data?

Systematic road-kill surveys are useful to study the impact of roads on wildlife. However, they are time-and budget-consuming, so the use of non-systematic data in road ecology is currently gaining popularity (for instance, by environmental consultants). Some data sources such as atlases (i.e., compilations of species records from a given region), which can include non-systematic and citizen-science data, can entail several intrinsic biases, mostly due to uneven sampling effort and uneven species detectability. Here, we tested this prediction by verifying if data from the Spanish Atlas of Terrestrial Mammals mirror the road-kill patterns obtained from our own systematic roadkill surveys. We focused on the Mediterranean mesocarnivore guild due to its easy identification by citizens involved in atlas-data collection. We tested if the relative abundance of each species, their richness and diversity obtained from Atlas and our systematic surveys were related, using linear models, while controlling for human population and road density (potentially confounding effects). We further compared the patterns of species abundance obtained from both sources. Our results highlight that road-kill patterns do not mirror the Atlas patterns for the three metrics evaluated. This is probably due to survey biases in typical data from wildlife atlases. When analysing species individually, we found that some species are road-killed more (or less) than expected in relation to their abundance in atlas records. These results are probably due to species-specific ecological or behavioural traits such as species morphology or species behaviour when facing the road. We suggest that abundance from atlas data should not be used as a proxy for road-kill rates.info:eu-repo/semantics/publishedVersio

Prioritizing road defragmentation using graph-based tools

Roads are a main cause of habitat fragmentation but mitigating the full road network is unfeasible. A key goal in the road mitigation planning process is to highlight, at the transportation network level, the most problematic roads, i.e. where mitigation measures are most required in order to maximize the benefits for biodiversity while keeping implementation costs as low as possible. Grounded on the concepts of habitat amount and accessible habitat, we prioritized roads for mitigation based on dual spatial graphs, where the land polygons delimited by roads are the nodes and the roads themselves are the links. The rationale was to identify those links (roads) that connect the nodes with higher potential biodiversity (as a proxy for quality habitat). We applied this approach to prioritize the defragmentation of the major road network of the Iberian Peninsula, targeting all native mammalian carnivores inhabiting this region. Our goal was to identify those roads that, by dividing areas with the best habitat quality and/or are major potential barriers for connectivity, should be prioritized in the mitigation process. We used two complementary metrics: Area Weighted Metric and the Integral Index of Connectivity. Highlighted roads bisect regions of high potential biodiversity for carnivores in northern Spain and along the Portugal-Spain border. Thirty-five roads were scored as high-priority by both metrics, suggesting that they have particular impact both in the amount of quality habitat and in overall landscape functional connectivity. This approach is completely scalable, allowing a fast assessment from local to continental scales

Forecasting seasonal peaks in roadkill patterns for improving road management

For several species, roadkill is not spatially aggregated on hotspots, having instead a more diffuse pattern along the roads. For such species, management measures such as road passages may be insufficient for effective mitigation, since a large part of the road crossings is likely to occur outside the influence of those structures. One complementary approach could be to implement temporary mitigation actions, such as traffic calming. This requires understanding when roadkill peaks may occur. We tested the feasibility of predicting seasonal peaks of roadkill using data from a 3-year systematic monitoring (78 surveys over ca. 960 km of roads) from eight non-flying vertebrate species from Mato Grosso do Sul, Brazil, with different body size and life history traits (ca. 6400 records from focal species). We modelled the time-series of the roadkill of these species at large scale (state level) using generalized additive mixed models (GAMMs). We used the data of the first 2 years as training datasets, and the information from the third year of surveys as testing datasets to evaluate the prediction performance of models. Overall, the models of species feed with a higher number of records were able to follow reasonably well the variations of roadkill over time, although they were not able to correctly predict the number of collisions. For species with fewer observations, the models presented a poorer goodness-of-fit and prediction ability. Our results suggest that, at least for those species with higher roadkill rates, it can be possible to forecast periods of higher probability of occurring hot-moments of mortality. Such models can provide valuable information to implement seasonal management actions.info:eu-repo/semantics/publishedVersio