What is published in hunting "guide books" is typically the boiled down version of the actual law or regulation or code. Here is what applies in this case:
Idaho Administrative Code, IDAPA 13.01.08 - Rules Governing the Taking of Big Game Animals states, in part, that the tag must be attached to the hide until the mandatory check is completed, and "350 (e) For black bear, grizzly bear, mountain lion, and gray wolf, external evidence of sex (either scrotum, penis or testicles for males, or udder or vulva for females) must be left naturally attached to the hide until the mandatory check has been complied with."
Further, "420. MANDATORY CHECK AND REPORT REQUIREMENTS.
Any person killing black bear, moose, bighorn sheep, mountain goat, gray wolf, or mountain lion in a unit with no quota, must, within ten (10) days of the date of kill, or any person killing mountain lion in a unit with a quota, or a grizzly bear, must, within five (5) days of the date of kill comply with the mandatory check and report requirements by:
01. Harvest Report. Completing the relevant harvest report (big game mortality report or other report form as required) for the species taken.
02. Presentation of Animal Parts. Presenting the following animal parts so that Department personnel may collect biological data and mark the animal parts:
a. Black Bear: Skull and hide to be presented to a conservation officer, regional office or official check point for removal and retention of premolar tooth and to have the hide marked."