Protecting Wildlife along Route 245, Osa Peninsula, Costa Rica

In the Osa Peninsula, roads represent a growing threat to wildlife, particularly for species such as the Central American squirrel monkey (Saimiri oerstedii), whose survival depends on forest connectivity. Due to recent roadkill incidents in the region, Fundación Saimiri has initiated a monitoring process in 2026 along Route 245, from Banegas to Carbonera, with the goal of identifying critical crossing points and generating key data for their protection. Through this effort, the aim is to support the implementation of mitigation measures that reduce the risk of roadkill and strengthen the conservation of local biodiversity.

In this space, we share scientific studies and technical reports that address the impact of roads on wildlife, as well as solutions applied in different contexts. This information is intended to support decision-making, promote concrete actions, and contribute to the protection of wildlife.

Authors: Fernanda Zimmermann Teixeira, Rodrigo Cambará Printes, João Cláudio Godoy Fagundes, André Chein Alonso, Andreas Kindel

Journal: Biota Neotropica

Year: 2013

Abstract: The article evaluates the effectiveness of canopy bridges (rope-based structures) in Porto Alegre, Brazil. These structures are installed over roads to allow arboreal wildlife to cross fragmented urban areas without descending to the ground, thereby reducing roadkill and electrocution.

Results: The bridges functioned as aerial corridors, allowing animals to move between forest fragments. Bridges located in areas with greater forest cover and less urbanization showed higher usage. The presence of connected vegetation on both sides of the bridge increased their effectiveness.

Reference:

Teixeira, F. Z., Printes, R. C., Fagundes, J. C. G., Alonso, A. C., & Kindel, A. (2013). Canopy bridges as road overpasses for wildlife in urban fragmented landscapes. Biota Neotropica, 13(1), 117–123. https://www.researchgate.net/publication/262468456_Canopy_bridges_as_road_overpasses_for_wildlife_in_urban_fragmented_landscapes

Authors: Jaime De La Ossa-V. and Silvia Galván-Guevara

Journal: Biota Colombiana

Abstract:  The study evaluates wildlife mortality caused by vehicle collisions on a road in the Colombian Caribbean. Through systematic sampling over a six-month period, different groups of affected vertebrates (mammals, birds, reptiles, and amphibians) were recorded, analyzing their distribution according to landscape type (dry forest, savannas, and mangroves). Additionally, factors associated with roadkill events were identified, such as traffic volume, road characteristics, and species behavior, with the aim of proposing mitigation measures to reduce this impact.

Results: The results showed a total of 431 road-killed individuals belonging to 31 species, with birds (28.8%) and mammals (28.1%) being the most affected groups, followed by reptiles (21.8%) and amphibians (21.3%). The species with the highest incidence was the crab-eating fox (Cerdocyon thous), followed by the green iguana (Iguana iguana), the smooth-billed ani (Crotophaga ani), the northern tamandua (Tamandua mexicana), and the common opossum (Didelphis marsupialis). The highest number of roadkill events was recorded in anthropogenic savanna areas, and the roadkill rate was relatively high (0.32 individuals/km/day). It was determined that factors such as traffic volume, speed, road width, vegetation cover, and species behavior significantly influence the occurrence of these events.

Reference

De La Ossa-V., J., & Galván-Guevara, S. (2015). Registro de mortalidad de fauna silvestre por colisión vehicular en la carretera Toluviejo – ciénaga La Caimanera, Sucre, Colombia. Biota Colombiana, 16(1), 67–74. https://revistas.humboldt.org.co/index.php/biota/article/view/368/366

Authors: Daniela Araya-Gamboa & Roberto Salom-Pérez

Journal: Revista Infraestructura Vial

Year: 2015

Abstract: The study identifies three wildlife crossing sites and five crossing sectors along a 15 km section of Route 415, located within the Barbilla–Destierro Biological Subcorridor, part of the “Jaguar Corridor.” Using field surveys, interviews, structural connectivity analysis, and camera traps between 2011 and 2012, the authors documented 64 wildlife species, including jaguar (Panthera onca), ocelot, and raccoon. The findings suggest that future paving would increase traffic volume, roadkill incidents, and reduce road permeability for wildlife. Therefore, mitigation measures such as underpasses, canopy crossings, restoration of forest cover, and road signage are recommended.

Results: The results show that the gravel section of Route 415 maintains high wildlife activity, with 149 animal activity points and 44 species recorded, in contrast to the paved section, where only 27 points and 12 species were documented. Three wildlife crossing sites and five crossing sectors were identified, based on the overlap of field surveys, interviews, and structural connectivity analysis. Camera traps confirmed the crossing of a male jaguar, as well as the frequent use of a culvert by raccoons, demonstrating the functionality of these natural underpasses. Overall, paving is associated with increased traffic, higher roadkill rates, and a decline in wildlife presence, indicating a stronger barrier effect for sensitive species.

Reference: 

Araya-Gamboa, D., & Salom-Pérez, R. (2015). Identificación de sitios de cruce de fauna en la ruta 415, en el “Paso del Jaguar”, Costa Rica. Revista Infraestructura Vial, 17(30), 5–12. https://revistas.ucr.ac.cr/index.php/rvial/article/view/3549

Authors: Daniela Araya-Gamboa & Roberto Salom-Pérez

Journal: Revista Infraestructura Vial (LanammeUCR)

Year: 2015

Abstract: The study identifies three wildlife crossing sites and five crossing sectors along a 15 km section of Route 415, located within the Barbilla–Destierro Biological Subcorridor, part of the “Jaguar Corridor.” Using field surveys, interviews, structural connectivity analysis, and camera traps between 2011 and 2012, the authors documented 64 wildlife species, including jaguar (Panthera onca), ocelot, and raccoon. The findings indicate that future paving would increase traffic volume, roadkill incidents, and reduce road permeability for wildlife. Therefore, mitigation measures such as underpasses, canopy crossings, restoration of forest cover, and road signage are recommended.

Results: The results show that the gravel section of Route 415 maintains high wildlife activity, with 149 animal activity points and 44 species recorded, in contrast to the paved section, where only 27 points and 12 species were documented. Three wildlife crossing sites and five crossing sectors were identified, based on the overlap of field surveys, interviews, and structural connectivity analysis. Camera traps confirmed the crossing of a male jaguar, as well as the frequent use of a culvert by raccoons, demonstrating the functionality of these natural underpasses. Overall, paving is associated with increased traffic, higher roadkill rates, and a decline in wildlife presence, indicating a stronger barrier effect for sensitive species.

Reference:

Araya-Gamboa, D., & Salom-Pérez, R. (2015). Identificación de sitios de cruce de fauna en la ruta 415, en el “Paso del Jaguar”, Costa Rica. Revista Infraestructura Vial, 17(30), 5–12. https://revistas.ucr.ac.cr/index.php/rvial/article/view/3549

Authors: Daniela Araya-Gamboa, Esmeralda Arévalo-Huezo, Esther Pomareda-García

Year: 2015

Abstract: The technical-scientific report identifies and proposes environmental measures to reduce the impact of road expansion on wildlife associated with the widening of Route 32, between Río Frío and Moín.

Results: A total of 24 Environmentally Fragile Areas and 16 species vulnerable to road impacts were identified, highlighting the need to ensure safe crossing structures for wildlife. Through conservation prioritization and structural connectivity analysis, 38 wildlife crossing sites were identified, encompassing amphibians, reptiles, flying species, arboreal mammals, and terrestrial mammals. The document recommends the implementation of underpasses, canopy crossings, signage, and fencing to reduce roadkill, improve road safety, and maintain biological connectivity along a route that currently functions as a partial barrier for species such as the jaguar (Panthera onca).

Reference: 

Araya-Gamboa, D., Arévalo-Huezo, E., & Pomareda-García, E. (2015). Informe técnico-científico: Medidas ambientales para disminuir el impacto en la fauna silvestre, de la ampliación en la carretera nacional Ruta 32, Limón, Costa Rica. Grupo Vías Amigables con la Vida Silvestre. https://pantheracostarica.org/wp-content/uploads/docs/InformeRuta32.pdf

Authors: J. Edgardo Arévalo, Wataru Honda, Adrián Arce-Arias, Achim Häger

Year: 2017

Journal: Revista de Biología Tropical

Abstract: The study analyzes wildlife mortality due to roadkill along a 4 km section of National Route 34, located adjacent to Carara National Park in Costa Rica. A total of 81 surveys were conducted between June 2010 and May 2011.

Results: The results show that roads generate significant negative impacts on biodiversity, particularly on amphibians. Mortality varies over time (according to season) and across space (specific sections of the road). Additionally, factors such as traffic volume, proximity to the park, and lack of speed control directly influence the number of roadkill events.

Reference:

Arévalo, J. E., Honda, W., Arce-Arias, A., & Häger, A. (2017). Spatiotemporal variation of roadkills show mass mortality events for amphibians in a highly trafficked road adjacent to a national park, Costa Rica. Revista de Biología Tropical, 65(4), 1261–1276. https://www.scielo.sa.cr/pdf/rbt/v65n4/0034-7744-rbt-65-04-01261.pdf

Authors: Isabel Granada, Katya Barrantes, Paola Ortiz

Institution: Inter-American Development Bank (IDB)

Abstract: The document analyzes the importance of integrating socio-environmental criteria into road infrastructure in Costa Rica, highlighting the negative impacts of roads on wildlife, such as habitat fragmentation and roadkill. It proposes the implementation of wildlife crossings as the main solution—structures that enable ecological connectivity. Additionally, it presents national and international experiences, the role of the IDB in financing these projects, and guidelines for their proper planning, execution, and monitoring, with the aim of promoting sustainable development in harmony with biodiversity.

Results: The study results show that the implementation of wildlife crossings in Costa Rica has been an effective measure to mitigate the impacts of road infrastructure on biodiversity. A total of 98 wildlife crossings have been constructed, contributing to improved ecological connectivity and reduced species mortality, particularly among felids, for which 478 roadkill events were recorded in the past decade, with an 88% mortality rate. Furthermore, international experiences support their effectiveness, demonstrating significant reductions in animal mortality and high usage of these structures by various species, confirming their importance as a conservation strategy.

Reference:

Granada, I., Barrantes, K., & Ortiz, P. (2022). Aportes socio-ambientales de las infraestructuras viales en Costa Rica: Tomo 1. Carreteras amigables con la fauna silvestre. Banco Interamericano de Desarrollo (BID)

Authors: José Pablo Carvajal-Sánchez, Elizabeth Cambronero-Peña, Jonathan José Sibaja-Umaña, Deiver Espinoza-Muñoz

Journal: Yulök Journal of Academic Innovation

Abstract: The study analyzes the mortality of wild mammals due to roadkill along Route 720 in Balsa de Atenas, Costa Rica, during the period 2015–2022. The incidence of these events and their relationship with road topographic variables and land use were evaluated. The results show that roads represent a significant threat to wildlife, especially in rural landscapes where animals use live fences and forest fragments as biological corridors.

Results: The study recorded a total of 13 individuals belonging to 8 mammal species killed on Route 720, with the common opossum (Didelphis marsupialis) being the most affected species, with five cases. The highest number of roadkill events occurred on straight sections of the road (n = 9), followed by curved sections (n = 4). Additionally, roadkill incidents were mainly concentrated in areas near riparian forests and tree-covered pastures, as well as along roads aligned with vegetation, highlighting the relationship between landscape structure and the incidence of these events.

Reference:

Carvajal-Sanchez, J., Cambronero-Peña, E., Sibaja-Umaña, J., Espinoza-Muñoz, D. (2023). Mortalidad de mamíferos silvestres por atropellamientos en un agropaisaje de Balsa de Atenas, Costa Rica. Yulök Revista de Innovación Académica, Vol. 7 (1), 85-90. https://revistas.utn.ac.cr/index.php/yulok/article/view/572/931

Authors: Vanessa Carvajal Alfaro, Fátima Díaz Quesada

Journal: Biocenosis

Abstract: The study analyzes the mortality of wild mammals caused by roadkill on roads in La Fortuna, Costa Rica. Surveys were conducted between February and December 2008 using direct counts, recording both road-killed animals and the type of nearby habitat. Multiple species were identified, demonstrating that roads represent a significant threat to wildlife, affecting population dynamics and ecosystem structure.

Results: The study recorded a total of 337 road-killed animals during the sampling period, of which 74 corresponded to wild mammals, distributed across 12 species, 9 families, and 6 orders. Additionally, it was determined that most roadkill events (61%) occurred in areas near forest patches, followed by areas close to rural settlements (27%), and to a lesser extent in sectors with tree-lined fences (12%). This highlights the relationship between wildlife mortality and the type of habitat surrounding roads.

Reference en APA 7: 

Carvajal Alfaro, V., & Díaz Quesada, F. (2016). Registro de mamíferos silvestres atropellados y hábitat asociados en el cantón de La Fortuna, San Carlos, Costa Rica. Biocenosis, 30(1-2), 49–58.

Author: Esteban Rojas Chacón

Journal: UNED Research Journal

Abstract: The study analyzes the impact of roads on wildlife, focusing on vertebrate roadkill along a section of a secondary road in the Central Valley of Costa Rica. Road-killed animals were recorded over a two-month period, demonstrating that roads generate negative effects such as habitat fragmentation, loss of ecological connectivity, and direct mortality of individuals. The study highlights that roadkill is one of the most visible and measurable impacts on wildlife.

Results: During the study, 13 road-killed vertebrates were recorded, including mammals, reptiles, birds, and amphibians, with amphibians being the most affected group. A negative correlation was observed between the number of vehicles and roadkill events (r = -0.545), suggesting that traffic noise may cause some animals to avoid the road. Additionally, slow-moving species, such as amphibians and reptiles, were identified as being more vulnerable to roadkill.

Reference:

Rojas Chacón, E. (2011). Atropello de vertebrados en una carretera secundaria en Costa Rica. UNED Research Journal, 3(1), 81–84. https://www.redalyc.org/pdf/5156/515651983009.pdf