BRIEF COMUNICATION
Roadkill hotspots in a protected area of Cerrado in Brazil: planning actions to conservation
Zonas de alto impacto de atropellamientos en un área protegida de Cerrado (Brasil): planeando acciones para la conservacián
Bruno H Saranholi,1* M.Sc. Mariano M Bergel,2 Esp, Paulo HP Ruffino,2 M.Sc, Karen G Rodríguez-C,1 M.Sc, Lucas A Ramazzotto,1 Biotec, Patrícia D de Freitas,1 Ph.D, Pedro M Galetti Jr,1 Ph.D..
1Universidade Federal de São Carlos, Depto. de Genética e Evolução, CEP 13565-905 São Carlos-SP, Brasil.
2Instituto Florestal, Secretaria do Meio Ambiente do Governo do Estado de São Paulo, CEP: 02377-000, Brasil.
*Correspondence: bruno.saranholi@gmail.com
Received: March 2015; Accepted: September 2015.
ABSTRACT
Objective. Here we aimed to identify the main points of animal death by roadkill in the view of helping mitigation plans and reducing the impact over the local fauna of a protected area. Materials and methods. We surveyed the roads around a protected area of Cerrado (São Paulo, Brazil) from May 2012 to August 2013. We recorded the local of roadkills, biometric and morphologic data of the animals, and collected samples of tissue for molecular species confirmation. Results. Thirty-one roadkilled animals were registered, including threatened species: Leopardus pardalis; Cuniculus paca and Chrysocyon brachyurus. Most roadkills were represented by mammals (54.8%) and reptiles (38.7%), and the mortality rate was 1.46 animals/km/year. Three roadkill hotspots were detected, suggesting that they were important points of animal crossing, probably because of the existence of natural remnant vegetation and intersection of roads by riparian vegetation. Conclusions. This work provided strong evidence of the most critical points where mitigation strategies should be immediately implemented and highlighted the importance of detecting roadkill hotspots and the species or taxonomic groups more affected, helping to elaborate effective actions that can improve fauna conservation.
Key words: Fragmentation, mitigation, road ecology, road mortality, wildlife conservation (Sources: Agrovoc, CAB).
Objetivos. Identificar los principales puntos donde mueren animales para proponer planes de mitigacián. Materiales y métodos. Se recorrieron las vías alrededor de una área protegida de Cerrado (São Paulo, Brasil) entre Mayo de 2012 y Agosto de 2013. Se registrá el lugar del atropellamiento, datos biométricos y morfolágicos de los animales y se colectaron muestras de tejido para la confirmacián molecular de la especie. Resultados. Se registraron 31 animales atropellados (muertos), incluyendo especies amenazadas: Leopardus pardalis; Cuniculus paca y Chrysocyon brachyurus. La mayoría de los atropellamientos fueron representados por mamíferos (54.8%) y reptiles (38.7%) y la tasa de mortalidad fue de 1.46 animales/km/año. Fueron detectados tres hotspots de atropellamiento, sugiriendo que son puntos importantes en la probabilidad de cruce de animales, debido a un remanente de vegetacián natural y la intercepcián de la carretera con bosques de galería. Conclusiones. Este trabajo proporciona fuerte evidencia de los puntos más críticos donde las estrategias de mitigacián deben ser implementadas inmediatamente y resalta la importancia de detectar hotspots de atropellamiento, las especies y los grupos taxonámicos más afectados ayudando a elaborar acciones efectivas que pueden mejorar la conservacián de la fauna.
Palabras clave: Conservacián de la vida silvestre, ecología, fragmentacián, mortalidad, reduccián (Fuentes: Agrovoc, CAB).
INTRODUCTION
Roads may represent an important factor of economic and social development for a region (1,2). However, their presence may result in strong environmental impact, such as the removal of natural vegetation to their construction (3), isolation of the natural populations and loss of animals by roadkill (4).
It is estimated about one million of vertebrates annually killed by vehicles on roads in the United States (4). In Brazil, roadkill estimations are still scarce (5).
Therefore, fauna roadkill is recognized as the main cause of vertebrate mortality, surpassing even the hunting (6). Some studies also suggest that the presence of roads can represent a major threat to wildlife when near to conservation areas due to the high abundance of species and individuals (7).
The reduction of natural populations by roadkill increases their risk of extinction (2). Estimating and monitoring this impact over the fauna is essential to propose mitigation actions (8). In this context, the molecular analysis is a powerful tool to correct species identification (9) and it could be used whenever morphological species identification is difficult.
In this work we surveyed roadkill vertebrates around a Cerrado protected area in Southeastern Brazil and identified roadkill hotspots, which could be used in mitigation plans in order to reduce the impact over the local fauna.
MATERIAL AND METHODS
Study site. Roadkills in two municipal wide-lane roads (Domingos Innocentini and Ayrton Senna roads) around an important area for Cerrado biome conservation (Itirapina city, São Paulo, Brazil) were surveyed. This area is one of the few remaining protected areas of this biome at São Paulo State where are located the Itirapina Ecological Station (IEcS) and the Itirapina Experimental Station (IES), surrounded by a buffer area comprised by Cerrado and riparian vegetation. The IEcS (22°11’S, 47°51’W) covers 2300 ha with many threatened species, such as, maned wolf (Chrysocyon brachyurus), rhea (Rhea americana) and cougar (Puma concolor) (10). The IES (22°15’S, 47°45’W) encompasses 3212 ha in which about 2000 ha are used for scientific research and cultivation of exotic vegetation (Pinus sp. and Eucalyptus sp.).
Data collection. The sampling sites were chosen considering the proximity to the protected area of Cerrado in Itirapina. We surveyed 12 km (seven km inside the protected area and five km in the buffer area) at the Ayrton Senna road and four km around the limits of the protected area at Domingos Innocentini road.
The roads were checked twice everyday during five days/week from May 2012 to August 2013. We registered the local of roadkills with a GPS, photographed the animals and registered biometric and morphologic data (paw size, tail size, weight) and sex. We also collected samples of tissue (muscle, skin or hair) in order to confirm molecularly the species identification and create of a genetic database for future molecular analyses. Threat status of species was categorized following the list of threatened fauna of São Paulo State (10).
Molecular species identification. DNA was extracted from tissue samples using fenol-cloroformio protocol (11). The DNA integrity was verified using 1% (w/v) agarose gel and the quantification was conducted with BioPhotometer (Eppendorf Corporation®). We used 16S (12) and COI (13) universal primers to molecular species identification. The PCR (polymerase chain reaction) protocol was similar for both primer sets as it follows: 1X buffer tris-KCl 10X (Tris-HCl 200 mM pH 8.4 and KCl 500 mM), 4 mM MgCl2, 0.25 mM dNTPs, 0.3 pmol of each primer, 1 U Taq DNA Polymerase Platinum (Invitrogen) and 50 ng of DNA template for a final volume of 25 μl. The DNA amplifications were carried out in an Applied Biosystems Veriti® Thermal Cycler under the following conditions: 94°C for 4 min, 35 cycles at 94°C for 45 s, 50-51°C for 45 s, 72°C for 45 s and a final extension at 72°C for 10 min.
PCR products sequencing was performed in an automated sequencer (ABI3730XL, Applied Biosystems) by Macrogen, Inc., in South Korea (www.macrogen.com). The nucleotide sequences were compared to databases from NCBI (National Center for Biotechnology Information) and BOLD (Barcode of Life Data Systems) to the species identification.
Data analyzes. The frequency of roadkill was calculated dividing the number of killed animals by the number of kilometers covered during the whole study period.
The roadkills were plotted over the local road map using Siriema software (Spatial Evaluation of Road Morality Software) (14) to identify the hotspots of occurrences. We used the Ripley’s K statistics (15) to evaluate the non-random distribution of roadkills. Although the road linearization causes loss of dimensionality, with this transformation the formation of false clusters at the curves was prevented (14).
Influence of landscape characteristics on the roadkill hotspots was also evaluated. A land cover map of the studied area was constructed by using satellite images from Google Earth (16) and the Quantum GIS program (17) with five meters final resolution. The distance between a hotspot and its nearest land cover was calculated. Land cover was classified as natural vegetation (including Cerrado and riparian vegetation), river, lakes, sugar cane, silviculture, pastures and urbanized areas. The association between hotspot and land cover was tested by ANOVA and significant association was evaluated by Tukey test, after data log transformation.
Linear regression between the monthly average temperature obtained from the registers of Itirapina Ecological Station (IEcS) and the number of roadkills per month, with log transformed data to fit the parametric tests requirements was also performed to investigate whether there are influence of the environmental temperature on number of roadkills.
RESULTS
We registered 31 roadkilled animals of 21 different species in 16 months (Table 1). From the total of species, Leopardus pardalis (vulnerable), Cuniculus paca (near threatened) and Chrysocyon brachyurus (vulnerable) were stated according to the list of threatened fauna of São Paulo State (10).
Table 1. Species and number of roadkilled individuals.
The mortality rate was 1.46 animals/km/year and three significant clusters of roadkill were detected in 0-1 km, 3-3.5 km and 13-14 km along the 16 km sampled (Figure. 1). In one of these points (0-1 km) for example, we registered seven roadkilled animals, which represents 22.6% of total records. Positive association between the presence of natural vegetation and roadkill hotspots (p=0.009) was detected.
Figure 1. Geographical location and detail of roadkill hotspots. IEcS (Itirapina Ecological Station); IES (Itirapina Experimental Station).
The number of roadkills was higher according to the environmental temperature increasing (F1.14 = 8.39, R2 = 0.375, p = 0.012). The months with higher mean temperature (October and November 2012, with 26.1°C and 25.1°C, respectively) presented eight roadkilled animals, which represent 25.8% of total roadkilling.
DISCUSSION
The local fauna inhabiting the area here studied is over a strong roadkill pressure. The mortality rate observed (1.46 animals/km/year) was much higher than reported by Da Cunha et al. (18) in an unprotected area of Cerrado (0.014 animals/km/year), suggesting that road impact is more drastic around protected area where fauna abundance is expectedly higher. This observed difference in roadkill intensity makes important to survey and elaborate specific mitigation actions for each target location.
A large number of records and species were here detected, including species with great ecological importance, such as the maned wolf and the ocelot. Since these species are top predators, they are vital in maintaining the equilibrium of other species populations and the loss of individuals can result in ecological consequences to the local fauna, such as disequilibrium on herbivorous density and consequently on plant community (19). It is imperative to highlight that the number of roadkilled animals may be much higher than reported here because some animals may not be detected or carcass could possibly be removed due to weather conditions, for example.
Mammal and reptile species represented 54.8% and 38.7%, respectively, of the roadkilled animals. Only five species could not be confirmed by molecular analysis probably due to bad conservation of tissue samples, which impaired the DNA amplification in PCR, although these seven individuals could be morphologically identified. In contrast, the success in identifying most of samples demonstrated the great potential of the DNA analysis, mainly for those specimens hard to identify morphologically because of their level of degradation or when the taxonomic group needs a specialist for correct identification.
Roadkill number was higher during the warmer months and such outcome was mainly influenced by Tupinambis merianae roadkills, probably due to the animal movement for reproduction often associated to the warmer temperatures season (20). Then, strategies to facilitate or avoid road crossing by animals should be more effective if they take into account the known reproductive periods that turns the animals more vulnerable to the roadkills.
The three detected roadkill hotspots were associated to the natural vegetation presence, which suggests that they are important points of animal crossing. At the 0-1 km hotspot, the main local of roadkills, natural remnant of Cerrado on both sides of the road is predominant. At the others two hotspots, the road intersects small streams with riparian vegetation. It is suggested that more roadkills near to natural vegetation than near to sugar cane plantations and pasture, is associated to preferential animal moving through this type of land cover. Open areas usually offer lesser resources for the animals, besides risk to be exposed is increased. Similar results were also found by Bueno et al (21) showing strong correlation between landscape characteristics on capybara (Hydrochoerus hydrochaeris) roadkill on other Brazilian highway.
Such studies demonstrate the importance of monitoring wildlife in linear infrastructure, especially around protected areas, since roadkill may represent a strong threat to the local fauna. The roadkill hotspots determination is the first step to reduce these impacts on wildlife. A number of strategies can be efficient to reduce or prevent animal roadkills: Wildlife crossing as underpass tunnels, overpasses with fences to drive the animals as well as, velocity control sensor and warning traffic signs at these hotspots, contributing to reduce deaths on the road.
In sum, our work provides a strong evidence of the most critical points where the mitigation strategies should be implemented immediately to reduce the roadkills in the studied area. This study highlights the importance of detecting the main points of roadkill and the more affected species or taxonomic groups, supporting the elaboration of effective actions that can improve the fauna conservation.
Acknowledgements
This work was supported by the SISBIOTA− Top predator network. The authors thank Conselho Nacional de Desenvolvimento Científico e Tecnolágico (CNPq) and Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) for financial support.
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