A Federal Highway Administration study*indicated that 21 already threatened or endangered species were further threatened due to the risk of being run over by cars, among other factors such as loss of habitat. The wildlife most at risk are as follows:

Mammals
Lower Keys marsh rabbit, Key deer, bighorn sheep (peninsular California), San Joaquin kit fox, Canada lynx, ocelot, Florida panther, red wolf

Reptiles
American crocodile, desert tortoise, gopher tortoise, Alabama red-bellied turtle, bog turtle, copperbelly water snake, eastern indigo snake

Amphibians
California tiger salamander, flatwoods salamander, Houston toad

Birds
Audubon’s crested caracara, Hawaiian goose, Florida scrub jay