Survival

The ranger is exceptionally skilled at surviving harsh conditions associated with his primary terrain. In game terms, the ranger is considered to automatically have the Survival proficiency in his primary terrain. This skill costs no proficiency slots. A ranger can spend slots in the Survival proficiency to acquire survival skills in environments other than his primary terrain. The ranger's survival skill helps in the following ways, all of which apply only in the primary terrain. In certain cases, the DM may require a Survival check (which is equivalent to an Intelligence check). A ranger rolling less than or equal to his Intelligence score on 1d20 succeeds in the check.

• The ranger knows the basic precautions necessary to enhance the chances of survival, and can instruct and assist any companions accordingly. For example, a ranger whose primary terrain is Mountains realizes that physical exertion in high altitudes may result in headaches and fatigue (due to low air pressure). A Desert ranger knows that in arid climates, it's better to rest in the still air than exposed to a strong wind (wind promotes evaporation from the skin, increasing the degree of dehydration). An Aquatic ranger understands that saltwater can't be used for drinking. An Arctic ranger realizes that temporary protection can be had from a bitter wind by tunneling inside a snow drift. This knowledge doesn't guarantee survival by any means; it merely improves the odds. If the ranger wonders about any particular piece of information, the DM will decide if he knows it, requiring a Survival check if necessary.
• The ranger can stave off starvation by finding small amounts of food. A successful Survival check locates enough food to feed himself or one other character. He can locate food in this way once per day.
• The ranger can find enough water to keep himself or another character alive for one day by making a successful Survival check. This assumes that the water is there to be found.
• The ranger can interpret subtle changes in the environment to anticipate natural disasters. A Plains ranger can recognize the appearance of the sky associated with a coming tornado. A Mountain ranger can identify the rumbling sound that precedes an avalanche. The DM may require Survival checks to verify a ranger's interpretations.

Optional Rule: One way in which a DM can use the Survival ability in a "quick-and-dirty" fashion is to set up special penalties (cumulative penalties for fatigue for fatigue or exposure) in especially harsh climes. A party with a ranger or one that is properly prepared and outfitted, simply avoids the potential penalties. Those who are unprepared take the penalties until the DM decides they have acclimated to the setting, or until they take other appropriate actions determined by the DM.

[Complete Ranger's Handbook]