Traffic accidents are a major cause of human-induced wildlife mortality, but this negative human impact on nature can be significantly reduced, for the good of both people and animals. The road prisms we have been installing on roads in Velebit and its foothills for two years are highly effective in reducing the number of accidents, as well as in mitigating habitat fragmentation.
In the last five years, over four thousand, and in some years over five thousand, traffic accidents involving wildlife have been officially recorded in the territory of the Republic of Croatia. Approximately one wild animal is hurt in each accident, most often fatally. Most frequently—in three-quarters of cases—it is a roe deer (male or female), followed by wild boars at about 10 percent of cases, and then red deer and hinds at about five percent. In the area of Lika-Senj County, the number of traffic accidents with wild animals is around 200 per year.
A very simple solution for this truly sad and large number is road prisms. These are simple devices added to existing road infrastructure. This passive road signalling works by reflecting vehicle light off the road at an angle of about 90 degrees on both sides into the surrounding forest, thicket, rocky area, or grassland next to the road. These beams of light in the middle of the night and nature warn wild animals of the danger on the road. Once the vehicle passes and the danger is gone, animals can safely cross the road. Prisms are significant because a large part of wildlife movement occurs at dusk, at night, and at dawn, when vehicle lights are certainly on and their reflection off the prisms is most intense.
Studies conducted outside the Republic of Croatia have shown that prisms reduce the number of traffic accidents with wildlife by as much as 90 to 100 percent. In the area of Lika and Velebit alone, this could mean dozens of surviving animals each year, but for such an effect, other organisations would also need to be involved in securing roadways. If this program were implemented across the entire territory of the Republic of Croatia, it would mean hundreds, if not thousands, of animals that would not perish in traffic accidents. This would also preserve human property, and in some cases of more severe accidents, human health, and perhaps even life.
Roadways are one of the strongest factors in habitat fragmentation, from roads that cut through Velebit in its upper parts, thereby separating the wildlife corridor that runs along the spine of Velebit, to roads in the lower parts of the mountain that animals cross in search of water or during summer-winter migrations. The corridors created in the zones of roads secured with prisms effectively connect parts of the fragmented habitat, thus enabling animal migrations in search of shelter, food, water, or reproduction.
By the autumn of 2025, in two years of our road security program using prisms in the Velebit and Velebit foothills area, the Rewilding Velebit Foundation has secured 19 kilometres of roads in this way. Given the length of roads in this area and the frequency of accidents, we are going to continue this program by securing additional kilometres of roadways.