Vehicle collisions are a common cause of death for animals such as the endangered Florida panther and the state’s black bears, and a new international study has quantified just how threatening roads can be to the nation. survival of animal populations around the world.
The study identified four animal populations around the world that are most vulnerable to extinction over the next 50 years if observed levels of road deaths persist:
- The leopard Panthera pardus from northern India (83% increased risk of extinction due to road mortality)
- Brazilian maned wolf (34% increased risk of extinction)
- Small spotted cat from Brazil (increased risk of extinction ranging from 0 to 75%)
- Southern African brown hyena (increased risk of extinction ranging from 0 to 75%).
The study appears in the journal Global ecology and biogeography and is co-authored by Eric Goolsby, a research fellow at the University of Central Florida.
Roads are critical infrastructure that connect people and move supplies, but when they intersect with nature, the impact on species survival can be fatal; However, until this study, it was not known how great the mortality was.
Certain traits, such as the early age of sexual maturity and large litter sizes, can help species recover from road fatalities, says Clara Grilo, lead author of the study and postdoctoral researcher at the ‘Universidade de Lisboa in Portugal.
But for others, like brown and black bears that have a late maturity age and small litters, road mortality can have a big impact on their population.
âUsing phylogenetic models, we were able to predict which species are most vulnerable to road accidents and found that brown and black bears are particularly vulnerable,â says Grilo. âIf there is at least 20% of the population killed on the roads, it can increase the risk of local extinction by 10%. “
In Florida, vehicle collisions are responsible for 90% of known bear deaths, according to the Florida Fish and Wildlife Conservation Commission.
For the endangered Florida panther, more than 85% of recorded panther deaths were due to vehicles in 2020, according to the Florida Fish and Wildlife Conservation Commission.
Florida panthers share a similar increased risk of extinction with bears based on study data for their species, Puma concolor, where a 10% increased risk of extinction for the species occurs if at least 27% of the population is killed by traffic.
âIt is important to protect the diversity of species on Earth because each species has a role in ecosystems, and the loss of species triggers the loss of other species within its ecosystem,â says Grilo. âHumans depend on healthy ecosystems like healthy soils, forests, grasslands, rivers and oceans. Otherwise, we are risking our own health.
Knowing which animal populations are most vulnerable to road crash extinction can inform infrastructure management decisions, such as where new roads are going and how to protect vulnerable animal populations in those areas.
These protections can include combinations of underpasses or overpasses with fences to guide animals to use those passages, Grilo explains.
To carry out the study, the researchers used existing data on road mortality for near threatened to critically endangered mammal species on six continents: North America, Central and South America, Europe, Africa, Asia and Oceania.
Then, taking into account data such as population density and road mortality rates as well as animal characteristics such as age of sexual maturity and litter size, the researchers were able to calculate an extinction risk. increased due to road fatalities. This information was then used to create global road accident vulnerability maps.
Goolsby, an assistant professor in the Department of Biology at UCF and co-author of the study, was responsible for much of the phylogenetic work that estimated the missing trait values ââfor the species in the study using data traits on closely related parents.
âWe used a missing data imputation approach based on trait correlations and evolutionary relationship,â Goolsby explains. âI developed a software package in the R programming language that allowed us to perform these calculations on large data sets. Our dataset, which consists of multiple traits spanning thousands of species, would otherwise have been computationally infeasible to analyze using existing software implementations. “
“Dr. Grilo read some of my posts on efficient comparative phylogenetic methods and asked me if it would be possible to take his dataset and use it to try to predict their trait values ââthat we could use to estimate the vulnerability of species to road mortality and extinction risks, “he says.” And I said it would be absolutely possible. So I joined as a collaborator, and we’ve been working on this project ever since.
Grilo says the next steps in the research are to develop user-friendly software to display observed road mortality data and show areas where species are more vulnerable to vehicle deaths.
“It will be a valuable tool for road planners and managers to identify road segments in order to implement mitigation measures in developing countries in Asia, Africa and Latin America,” said she declared. âWe are looking for funding to develop the software because we already know how to do it. “
Goolsby received his doctorate in toxicology from the University of Georgia. He joined the Biology Department at UCF, which is part of the College of Sciences, in 2018.