Costa Rica’s Wildlife Crossing Law: A New Route for Biodiversity

Costa Rica has approved a landmark law requiring wildlife crossings and other mitigation measures in public infrastructure projects when scientific evidence shows that roads or other structures disrupt animal movement.

On 4 August 2026, the Costa Rica Legislative Assembly unanimously approved a measure that seeks to make wildlife crossings part of infrastructure planning rather than an afterthought.

The law adds a new Article 31 bis to Costa Rica’s Organic Environmental Law. It applies to new and existing public infrastructure, including national and municipal roads, particularly where projects cross forests, protected areas, biological corridors or other ecologically sensitive locations.

The requirement is not that every road must receive an animal bridge. Instead, technical and scientific studies must determine whether infrastructure is affecting wildlife movement or creating a significant risk of animal mortality.

Where such impacts are demonstrated, the project must incorporate suitable mitigation measures. These could include aerial canopy bridges, underpasses, modified culverts, fencing, wildlife-guidance systems and other structures designed for the species found in that landscape.

The Ministry of Public Works and Transport, municipalities and other public agencies must coordinate with the National System of Conservation Areas, known as SINAC, to decide where crossings are needed.

Costa Rica’s environmental authority, SETENA, will also be expected to verify that the measures are included in environmental approval processes.

Importantly, wildlife crossings must be considered from the planning and pre-investment stages, with funding included in project budgets. 

Costa Rica’s wildlife crossing law also covers existing infrastructure. When roads undergo maintenance, expansion, rehabilitation or reconstruction, developers must introduce appropriate mitigation measures where necessary.

Why is it important?

Roads divide habitats, interrupt migration routes and isolate animal populations. They also expose wildlife to vehicle collisions and, in some cases, electrocution from poorly designed electricity infrastructure.

For animals such as sloths, monkeys, anteaters, felids and amphibians, a road can transform a natural movement corridor into a lethal barrier.

The scale of the problem is visible in Costa Rica’s roadkill data. Studies have indicated more than 19,000 records of wildlife collisions between 1996 and 2025.

On a little more than 20-kilometre section of the Cañas–Limón road, specialists estimated that more than 16,000 animals are killed by vehicles each year, including thousands of frogs and toads.

Researchers recorded 88 vertebrate species in the area, at least 14 of which are considered threatened or highly vulnerable.

Costa Rica’s wildlife crossing law could therefore shift conservation from isolated rescue projects to systematic planning.

It recognises that bridges and tunnels work best as part of a complete system: fences must guide animals towards crossings, culverts need dry passages, structures require maintenance, and designs must reflect the behaviour of particular species.

A bridge without these supporting measures may exist on paper while animals continue to die on the road.

Wrapping Up

It is not the first time a country has made a wildlife crossing law. Mexico added Article 22 Bis to its Federal Roads, Bridges and Federal Motor Transport Law in 2023.

The provision requires new roads, highways and motorways, as well as the modernisation of existing infrastructure, to include wildlife crossings in their design and conservation plans. 

The United States has also enacted national transportation provisions supporting wildlife crossings, although its federal framework authorises and funds such projects rather than universally requiring them.

Costa Rica’s wildlife crossing law is nevertheless significant. Its law places wildlife connectivity directly within environmental legislation and links scientific evidence, infrastructure approval, budgeting, construction and maintenance.

It may not be the world’s first wildlife-crossing law, but it represents an important step towards making roads compatible with one of the planet’s richest concentrations of biodiversity.