You can salvage roadkill any time of year:
By notifying the Idaho Dept. of Fish and Game within 24 hours and completing reporting requirements within 72 hours (to obtain a free permit), Idaho residents and nonresidents can now recover and keep wildlife species classified as upland birds, upland game animals, big game, furbearers, unprotected wildlife, and predators that may be lawfully hunted or trapped that have been killed by accidental vehicle-collisions. A list of wildlife species that can be salvaged can be viewed by going online at https://fishandgame.idaho.gov/roadkill. Protected non-game wildlife, Threatened or Endangered species, migratory birds (which are federally protected), and other wildlife species not lawfully hunted or trapped may not be recovered, possessed, or salvaged.
The language of this rule is specific to “accidental kills caused by wildlife vehicle-collisions”, and does not include other man-caused mortalities such as crippling loss, train collisions, fence kills, and others.