How do the frogs cross the road?

Cover Photo from the Cary Institute of Ecosystem Studies website

By Adele Labbe, Environmental Planner, City of Guelph


How do the frogs cross the road?

Carefully with the help of the City of Guelph.

Figure 1. Eastview road wildlife crossings

Through policies, the City is able to reduce and mitigate habitat fragmentation by protecting space for animals to move between natural habitats and requiring wildlife crossings to be built where roads cross natural migration paths. A recent road reconstruction project has highlighted the City’s commitment to supporting biodiversity through implementation of these policies.
Eastview Road was originally established through a large swamp in the mid-1800s. The road crosses through a large wetland that is made up of mixed swamp on one side and a deciduous swamp and Hadati creek on the other. The road was identified as needing upgrades including new storm sewers, sidewalks and bike infrastructure through several City studies (Figure 1).

Through ecological studies, which were done to inform the road reconstruction design, the City learned that frogs were being killed as they crossed the road to get from their over-wintering habitat to their spring breeding ponds. To protect the frogs, and reduce roadkill, wildlife crossings were designed and installed as part the road reconstruction.

Photo 1. Wildlife crossing during construction

So, what’s a wildlife crossing? They’re tunnels for animals. They run under the road with funnel fencing along the road to direct critters to the tunnel (Photo 1).

The three tunnels on Eastview Road have been specially designed to have daylight slots along the top to allow for ambient light, temperature and humidity inside the tunnel, which is found to increase the use of the tunnel by animals. It basically makes a cold, dark tunnel more appealing by adding light, warmth, moisture and by placing natural substrates within them (Photo 2).

Funnel fencing is really important part of wildlife crossings. Without them, the animals won’t know to look for the crossings! The City had to get creative with the funnel fencing for this project because of the creek that runs parallel to the road on the north side. In effort not to interfere with hydraulics and to ensure the funnel fencing solution is robust enough to have a reasonable life cycle, the design included cutting culverts in half and embedding them into the road shoulder. On the other side of the road, where it is only swamp habitat and not creek, solid post-consumer plastic funnel fencing is adhered to chain link fence which allows for a permanent and long-lasting design.

Photo 2. Wildlife culvert with slots

The science behind wildlife crossings is relatively young and complex. There are species-specific considerations and infrastructure challenges with every site. To make this project happen, it took policy, teamwork and the willingness to try new things. From the design to implementation it was a true coming together of ecologists, environmental planners, infrastructure engineers, contractors and construction inspectors.

The City will be monitoring the Eastview Road culverts to gain a better understanding on the effectiveness of the design. For more information contact the City of Guelph’s environmental planning team at 519-822-1260 extension 5616 or




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