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In a survival situation is it actually efficient to eat edible plants? Assume late spring to early fall in a temperate climate.

We have plenty of questions about where to find edible plants and how to identify them, but I have read that one would expend more energy in gathering them than it would be worth and that the energy would be better spent trying to get back to civilization.

If I remember correctly, nuts are energy efficient enough to be worth gathering, but berries are not.

Is there any evidence to back this up one way or another?

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    I don't see how there can be any general answer to this question. It depends on many factors, each with huge variability: how many edible plants are in the area, how easy they are to gather, their nutritional value, what preparation they need, how many calories you're burning per day (depends on weather, terrain, equipment etc.), how lengthy and difficult your journey to civilization might be, your chances of being found/rescued if you don't hike out yourself, what your other food options are (fish, game, own supplies etc.), how big your body's fat reserves are... – Pont Oct 16 '18 at 15:18
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    In the right place and in season, blackberries (for example) are locally plentiful, and help with not just nutrition but hydration. This suggests quite strongly that your penultimate paragraph is oversimplified at best – Chris H Oct 16 '18 at 16:34
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    If you are travelling back to civilization, and there is an edible plant along your path, are you asking if you should or shouldn't eat it? Or are you asking about allocating time and effort to searching for edible plants instead of (self)rescue? Also, should we take terrain into account? Edible plants are more abundant in a termperate rainforrest vs the Saraha desert. – B540Glenn Oct 16 '18 at 18:56
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    There IS an answer to this question, but it will take some calculation and assumptions have to be laid out -- but reasonable assumptions can be specified for reasonable conditions. Of course the answer will differ for the high arctic and for the tropical rain forest. So what? Pick summer in a temperate climate. And remember that bears put on a great deal of their body fat from berries. – ab2 Oct 16 '18 at 20:20
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    I like this topic—I feel like it would be easier to answer if the question were phrased “when / under what circumstances is it efficient...” – mmcc Oct 16 '18 at 22:41
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I looked first at bears to get a handle on this question, because it is well known that bears get a significant part of their caloric intake from berries. I should have looked first at berries!

According to Blueberry Nutrition Facts, one quart of blueberries has 340 calories.

Let's assume that the lost person of the Q expends 4,000 calories per day trying to get unlost. Let's also assume that he or she started out, like most of us, a little bit too well fed, so some of his caloric requirements are met by body fat.

In one month of being lost (probably a large overestimate), assume 2,000 calories per day of body fat are mobilized, 62,000 calories for the month, which is the equivalent of 18 pounds. (One pound of fat has about 3,500 calories. Ignore mobilization efficiency.) Unless the person started out extremely thin, losing 18 pounds is not a serious problem.

In that month, the person has to eat 2,000 calories per day of berries to make up his 4,000 calorie per day requirements. That is 6 quarts of blueberries per day.

How long does it take to pick 6 quarts of blueberries? According to Stewart's Berry Patch:

An experienced picker can generally pick about 8 - 10 pounds of blueberries in an hour. This is the equivalent to filling two plastic 4 litre ice cream buckets. In order to pick this many berries in an hour, one needs to be using both hands.

This, of course, is on a berry farm, where the berry bushes are extremely close together and bred for high yield. But it suggests that if you hit a dense patch of blueberries, you can easily pick 2,000 calories worth in a few hours.

But the catch is: There will be bears in that berry patch.

So the answer to the question is: if you are in an area with abundant berries, you can easily survive for the length of the berry season, (possibly without loss of weight) if you can survive the bears. If you are in an area with only scattered berries, you probably cannot get 2,000 calories per day (6 quarts per day) from berries, and will need nuts and even more holes in your belt.

TLDR: The original version of this answer used data about grizzly bear caloric requirements, black bear berry consumption and human caloric requirements to get an answer of 10 quarts (2.5 gallons) of berries per day for 2,000 calories per day, as opposed to the more direct calculation of 6 quarts per day. I estimated an error bar of a factor of 2, and the direct calculation (above) was 60% of the baroque calculation.

I used the following data:

From The North American Bear Center:

Bears around Ely [Minnesota] gain weight most rapidly during July and August when berries and hazelnuts are abundant. When the berries run out in September, there is little else to eat. The bears usually enter dens in September or October.

According to Animal Answers, grizzly bears eat about 20,000 calories a day. The answer from The North American Bear Center (link above) estimates that black bears eat about 30,000 berries a day.

Using a rough grizzly/black bear calories per day to berries per day conversion, the person has to eat roughly 3,000 berries per day.

According to Produce Converter:

The size of these berries ran between .25 to .5 inches in diameter. We found that a 1 pound container (450g) holds about 3 to 3.5 cups or 195 to 210 fresh blueberries. For a 1 quart measurement you would need to purchase about 1.5 pounds which equals about 4.25 cups.

So 300 blueberries need a one quart container. 3,000 blueberries thus occupies 10 quarts or 2.5 gallons.

  • I like what you did there. I kept thinking you were going off the deep end at first, but then it becomes apparent you are finding edge cases and comparing against them. Good idea. So a full day's worth of picking could get approximately 100 times more than you need for the day in an unlikely best case scenario. But you need to feed yourself for more than just the day, as you need to perform other activities too, so that is 20-50 times more than you need. But searching for wild berries will probably result in more than 20-50 times less yield... but that is just a wild guess. Good perspective. – Loduwijk Oct 16 '18 at 21:46
  • This also makes me envious of the bear's nose (or any similar animal), as it suggests that if we could just smell the food from afar we would have way more than needed and it would be very easy to survive. – Loduwijk Oct 16 '18 at 21:46
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    One thing you don't cover is that running on pure fat burning, apart from being a fair bit of water, only provides energy at a low rate. This rate is increased with even a small input from sugars, so there may be some margin to picking berries when you see them, even in a purely metabolic sense. – Chris H Oct 17 '18 at 6:19
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    From paulkirtley.co.uk/2013/survival-foraging-a-realistic-approach - "Studies have shown, however, that taking on only 500 calories of starchy, carbohydrate-filled plant food per day will maintain your digestive functions and provide enough energy to significantly reduce muscle loss compared to eating nothing." – aucuparia Oct 17 '18 at 11:26
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    @Loduwijk: we can substitute this at least partly by knowledge about which berries like to grow where, e.g. when on limestone, don't waste time looking for blueberries as they like sour soil. – cbeleites Jul 10 at 12:39
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People make lots of claims. You can find all kinds of suggestions when you research this, some of it even from people who are considered experts. In the end, all you can do is use some basic logic and look at some real, anecdotal events.

For long term survival, if you can attempt to get back to civilization, that is always recommended. People often suggest that you sit tight and wait for help if it is a survival situation, but that only applies until dying of starvation sounds more likely than being rescued.


In the case of Geraldine Largay, who got lost on the Appalachian trail:

Multiple agencies and volunteers joined the hunt, with searchers on foot, on horseback and in helicopters. She was less than a mile from the trail, close enough that searchers probably passed near her without realizing it.

They were searching for her but could not find her. She stayed put since she had a bad sense of direction, but before the end if she had just walked in a random direction she may have had a roughly 50% chance of hitting the nearby trail. Obviously, she should have tried to get back.


Another high profile case in which someone would have died had they not self-rescued, but in this case where he did self-rescue and survived because of it, is the case of Aron Ralston. You've probably heard of him. He is the guy that we don't like to think about because

(spoiler because it's gruesome)

he had to cut off his own arm with a dull knife to save himself.

If he had continued to wait for rescue, he would have perished like Geraldine.


More support comes from watching survival experts (albeit self-proclaimed generally) try to survive in the wilderness and starving. Many have died.

You can watch this for yourself (starving, not dying) on the TV show Alone, in which contestants try to be the longest to survive alone in the wilderness. The contestants receive periodic medical checkups, and people have been pulled medically for being too badly starved. One season was won this way, and the winner was on the verge of being pulled medically as well.

Alone is an interesting source for examining your question, as there have been several plant expert survivalists on the show. They have shown us that if you are an expert in locating and identifying plants and if you combine this with some other food, such as a few fish, that you can survive for a long time, much longer than if you were to sit still and conserve energy. But even then, they slowly lose mass and would probably eventually die, especially once winter reduces their food supplies.

I do not recall if anyone has ever survived on 100% edible plants on the show, but some of them do survive on predominantly plants. There are a few people who do plants, including sea kelp, and bugs or slugs.

There are other evidences as well, including actual survival, which back up this assessment based on Alone, but I think this one is sufficient as it shows us dozens of actual accounts and you can see the survival first hand on video.

Summary

Based on the case of Geraldine Largay and similar cases, it seems highly inadvisable to avoid self-rescue forever, no matter how uncertain you are: eventually you need to at least attempt to rescue yourself.

Based on the survivors in Alone, it is evidence that edible plants can prolong your survival, but it is also evidence that the vast majority of people will not survive indefinitely that way. The plants could help you wait longer in the hopes of being rescued in place, but even so eventually you still need to fall back eventually on self rescue if enough time passes.

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    Aaron, thanks so much for the spoiler and the warning! I was able to read the answer comfortably without seeing something that I'm sensitive to! – Sue Oct 16 '18 at 23:01
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There are a couple of long quality answers. This is the short simple version.

There are either berries or not, if there are berries, and you know they are safe, eat them.

If your sitting and waiting to be rescued, you might as well spend your time eating the nearby berries if they are there. There no reason not to.

If you are traveling and there are berries stop and eat them, you need to rest anyway, and there is no better way to rest then eating berries.

Berries exist therefore they provide nutrition. A non-nutritious berry would not support the animal distributing the seeds, an evolutionary dead end...

Also consider berries are mostly fluid (i.e. water) berries are the flavored water of nature.

The above is very berrie centric answer. But it really doesn't matter, if you are not moving, and near a known safe food source, you should eat it. Humans evolved as Hunter-gatherers with some still following it.

Hunting and gathering was humanity's first and most successful adaptation, occupying at least 90 percent of human history.

See Related When to know it's worth to start with agriculture?

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