You are asking for three very different types of activity. Nordic skiing is a very aerobic activity. Hiking can be considered aerobic but it is mostly a low impact activity that affects the muscular/skeletal systems before the heart/lungs. (This does not consider the individual fitness, amount of weight being carried, temperature, altitude and elevation.) Hunting also has a wide variance of aerobic potential but is is mostly a walking, stalking, sitting environment. Depending on the animal, birds would add very little to effort but hauling a deer would be quite taxing physically.

All this activity also does not include how each individuals body processes exertion, heat and sweat rates.

Still with me? So all this being said as a general rule of thumb I recommend drinking between 4-6oz of water every hour awake. This is not guzzling a liter every 4 hours, this is consistent imbibing every hour. This is also in line with most philosophy of drinking 12 oz of water 6x per day or 8oz of water 8x per day. With increases in consistent activity, nordic skiing by example, a person could/probably should be looking at closer to 1 liter per hour.

It is not advisable to 'pound' water or guzzle a liter at a time, regardless of activity. Consistent sipping will allow the kidneys to flush toxins out of the blood and keep your core temperature lower.