Chapter 71 Living Off the Land
The ability to be completely self-sufficient in the wilderness and live off the land for an indefinite length of time is a fantasy of many. This fantasy can turn into an intentional or unintentional reality for some. The success of this reality is in large part determined by a person’s capacity to procure, prepare, and store food and water, as well as have a basic understanding of human nutritional needs.
Meeting a person’s nutritional needs is significant in the context of wilderness survival and living off the land. Human survival has always been held hostage to its own nutritional needs, and the success of the human species is directly related to a continued emphasis on achieving a balanced diet.1,21
The Dietary Reference Intake for energy for moderately active men aged 19 to 50 years is 2900 kilocalories per day, and for moderately active women of the same age group is 2200 kilocalories per day8 (Table 71-1). Energy needs increase with greater physical activity and decrease in ambient temperature. Current dietary recommendations set forth by the U.S. Food and Drug Administration call for daily intake of energy-yielding macronutrients to be composed of 60% carbohydrates, 30% fat, and 10% protein.12 The U.S. Department of Agriculture also suggests that food choices be based on variety and balance, with emphasis on plant foods, primarily grains.23 However, these recommendations may not have realistic application to wilderness survival and living off the land. To get a better idea of the probable composition of daily energy-yielding nutrients under these conditions, it may be best to look at the macronutrient intakes of hunter-gatherers.
|Gender||Age (yr)||Kilocalories per Day*|
Anthropologic analyses of hunter-gatherer diets show that 45% to 65% of their macronutrients were derived from animal food, both hunted and fished. The remaining 35% to 55% was made up of wild plants. It is also estimated that the average macronutrient composition of hunter-gatherers was 38% to 49% fat, 20% to 31% protein, and 31% carbohydrate.3 For hunter-gatherer societies living at more than 40 degrees latitude north or south, there was increasing latitudinal dependence on fished animal foods and decreased dependence on plant foods. Although hunter-gatherer diets were composed primarily of animal foods with a high intake of fat, field studies of 20th-century hunter-gatherers showed them to be generally free of the signs and symptoms of cardiovascular disease.2
Whatever the dietary intake comes to be in wilderness survival and living off the land, there are commonsense considerations to achieving a balanced diet. Of these considerations, variety is probably the most important. Variety can help ensure that the requirements for energy-yielding macronutrients (fat, protein, and carbohydrates) and micronutrients (vitamins and minerals) are met. Variety essentially translates to a balance between the intake of animal and plant foods. This balance depends on factors of climate, competition, and food-type availability, and is worth every effort to attain.
Historically, people who foraged for food from the environment were victims of aircraft accidents isolated in far-off regions of the world. They needed to supplement meager rations—the food in their pockets and possibly the food contained in a survival kit (if they had one). Castaways who washed up onshore after their boats sank were forced to collect food from the coastal environment. Others who have scavenged for food included people who became lost, although most of these were seldom lost long enough for the lack of food to become a real life-or-death issue. For those who were not found within the typical 72-hour window, the ability to recognize and gather locally available wild food may have enhanced their ability to fend off the assaults of the environment and prolonged their lives. Anecdotal reports of these survivors describe how many of them scavenged for berries, roots, and various forms of animal life to satisfy their hunger. Gathering food from the environment becomes important when people find themselves unable to obtain food from conventional sources and a long-term survival situation is anticipated.
There are other circumstances in which being able to gather wild foods could prove very valuable. For example, during periods of civil unrest, particularly when traveling overseas, it is possible to find oneself in a situation in which grocery stores, supermarkets, and other sources of food are not accessible. Being able to forage for food could provide a viable alternative to jeopardizing safety by coming into contact with unfriendly locals. Knowing how to procure food could be a valuable skill in areas where natural disasters have caused extensive damage to the affected community’s infrastructure and food supply. Being able to live off the land and consume unusual foods could also become important if one is taken hostage by a terrorist or criminal group. Self-sufficiency in the gathering of food and water could be particularly important to an escaped hostage attempting to return to friendly hands, as opposed to depending on hostile locals or terrorist sympathizers. In each of these situations, one may need to live off the land to augment provisions, or, in a worst-case scenario, to replace food that is no longer available.
Although being able to gather food can be important, a person should not believe that he or she will definitely be able to live off the land. Believing that foraging for one’s own food is possible in all situations is not realistic. The time of year, environment, inadequate knowledge, lack of skill, and injury may severely limit a person’s capability to forage for food. In fact, it may be more beneficial to limit activity by not aggressively searching for food rather than expending the limited amount of energy stored in the body in trying to procure food that may provide only meager energy in return.
Most survival manuals contain numerous pages devoted to identification of edible and toxic plants, techniques used to trap animals for food, and primitive fishing methods used to procure aquatic animal life. The techniques commonly described are usually those used by indigenous people who still live off the land for their sustenance. The techniques depicted are presented as though they are methods that the average person could use when in an emergency and needing food. The fallacy lies in the belief that, based on a diagram or two accompanied by a paragraph of narrative, the techniques can be learned, remembered, and then used by the reader at some later date. More often than not, the techniques described cannot be learned by reading a book. A lifetime of training (or certainly months of practice) is needed for the techniques to become truly effective for the individual. Few people are willing to devote the time needed to develop expertise in the use of primitive food-gathering methods to a level of proficiency necessary in a survival situation.
During certain periods of the year in many parts of the world, very little, if any, natural food is available. The local people in these areas stockpile sufficient food to last through the lean times until natural sources of food are once again available. Even a well-trained and equipped survivor who arrives during these “lean times” is hard pressed to live off the land and can only hope that rescuers arrive promptly.
Living off the land is usually thought of as a task required to maintain life during a long-term survival experience in a remote corner of the world while awaiting rescue. Although this scenario occasionally happens, most of the survival experiences in North America are short-term, during which the need to gather food from within the environment is not a survivor’s primary focus. However, even in a short-term experience, knowing how to live off the land could prove beneficial to the survivor’s physiologic need for food and to his or her psychological peace of mind. In some instances, being able to live off the land could mean the difference between surviving and dying.
The methods presented in this chapter are simple, practical, require a minimum of equipment, and, most importantly, relatively easy to use in the field. Some practice will be required, but these procedures and techniques do not require a huge investment of time to develop basic skills.
Beside the need for energy-yielding macronutrients and micronutrients, the requirement for water must not be overlooked, because water is the most essential nutrient. Current recommendations on water intake recently released by the Institute of Medicine suggest daily intake of about 11 cups of total water for women and 16 cups for men.7 These recommendations are based on the assumption that about 80% of a person’s daily water intake comes from drinking beverages and the other 20% comes from water contained in food. Prolonged physical activity, heat exposure, extreme cold, and higher altitude increase water losses and therefore may raise daily fluid needs.
Many survivors begin their emergency already dehydrated (hypohydrated) and continue to dehydrate further when water supplies are limited and the quality of the available water is suspect. There have also been cases in which individuals needed water but, because of their fear that the water source was contaminated with Giardia, Cryptosporidium, or other harmful pathogens, delayed drinking or chose not to use the water at all. As a general rule, because dehydration can very quickly reduce a survivor’s ability to function efficiently and safely, it is usually better to drink the impure water. If the water was contaminated, the onset of symptoms will be days away. Hopefully, by then the individual will have access to medical care for treatment. Remember, doctors can cure giardiasis or cryptosporidiosis, but they can’t cure “dead”! It should also be noted that gastrointestinal problems usually associated with drinking contaminated water are more commonly a result of poor personal hygiene habits.
The need to maintain body water levels and the physiologic impact of dehydration have both been well documented in the medical literature (see Chapters 10, 11, and 70). In priority order after shelter and defending body temperature, the need to locate, procure, treat, and preserve water is the survivor’s next most important need. Although water is important in every environment, lack of water becomes critical very quickly in hot, dry environments. Dehydration is also a critical problem at high altitude and at high latitudes where ice and snow must be melted to produce water. People who travel in these areas frequently have great difficulty obtaining water because of the hassles involved in collecting snow and ice, often under extreme weather conditions, and then having to produce the heat needed to melt it. In hot arid regions, where no surface water exists and only infrequent precipitation occurs, depending on tanks, springs, or other natural sources for water is a very questionable practice. Experienced desert travelers abide by the adage, “If you don’t have it with you, you won’t have it!” Lack of water in extreme conditions can lead to incapacitation within hours and death within days. Locating sources of water should be an important priority for the survivor.
Throughout much of North America, water is usually available from open sources of water, such as lakes, ponds, rivers, and streams, and it can usually be obtained fairly easily. Despite this abundance of water, there have been cases in which survivors were unable to reach a water source because of their injuries.
Fundamental to finding water is the recognition that it will always seek the lowest level possible and that, if present, some form of vegetation most likely indicates its presence. A good strategy to locate water is to first find a vantage point from which it is possible to scan the surrounding countryside. A person should slowly and methodically search for any indicators of water, such as green vegetation, birds flocking to specific areas, trails left by domestic or wild animals, and even large rock formations from which springs may originate or where water can become trapped. Human-made sources of water, such as windmills, tanks, dams, and irrigation canals, might also be observed. Look for water in low-lying areas, such as depressions, sinks, or tanks, where rainfall or melting snow is likely to collect. Water can often be found in these areas long after the last precipitation, especially if the areas are shaded. In arid areas where there is little vegetation to obstruct a person’s view, a pair of binoculars can save a lot of walking.
Although the presence of any living vegetation is an indicator of subsurface water, the amounts of water are usually miniscule, and it is not available in sufficient quantity to justify any expenditure of energy in an attempt to dig for it. Most arid-area plants survive because their deep roots extend well below the earth’s surface to gather small quantities of water available in the soil. Although it may not be appropriate to dig for this water, the process of plant transpiration can be capitalized upon to collect a significant amount of water in a relatively short period of time. This process is described later in the chapter.
Most animals require water at regular intervals, usually once a day. By observing the movement of animals, it may be possible to determine the specific location of nearby water sources. Distinct trails are developed over time by both wild and domestic animals that travel to and from water sources on a regular schedule. Pay attention to forks in animal trails because they often indicate the direction of a water source. If an animal trail forks into two trails, then it is possibly leading a person away from a source of water. Conversely, if trails come together, an individual may be walking toward a source of water or food. Even though the direction to a water source can be determined, the distance to that source may be too far for the survivor to realistically reach on foot. Birds and animals have a far greater capability to travel long distances without water than does a human. Consequently, it is usually better to stay in one place, as opposed to wandering around the desert looking for uncertain water sources.
Most birds require water at least once per day. By watching their movement, especially in morning and evening hours of the day, a general direction of a water source may be determined. Once again, the urge to travel must be weighed against unknown distances and the questionable quality of water sources.
Collecting water from open sources is usually the easiest method available to the survivor. However, caution should be exercised. Lakeshores and the edges of rivers can be hazardous. Crashing waves, swift-moving water, undercut river banks, and unstable footing can all create problems. Swampy shorelines, heavy vegetation, lakes, streams, or ponds surrounded by cliffs, other difficult terrain, or unsafe ice conditions may preclude a person from getting close enough to a water source. Don’t risk life and limb trying to climb or reach the water’s edge when safer strategies can be used. Tie a line to a water bottle or container of some type and throw it or lower it into a water source from a safe location or vantage point. Because most water containers do not come with a reliable attachment point when the container is uncapped, make one by duct taping a loop of parachute cord or nylon line to the side of the water container (Figure 71-1). Do not use the retaining strap that connects the cap to the water bottle for this purpose. In many cases, this strap will break or pull free from the full bottle as it is being retrieved from the water source, resulting in loss of the bottle.
In some instances, water sources may be very muddy or silty and need filtering or settling before they can be used (Figure 71-2, online). Rivers originating from glaciers carry large amounts of “glacial flour” that should be removed before consumption (Figure 71-3). This is best accomplished by allowing the water to settle overnight and then filtering it through fabric before drinking.
(Courtesy Peter Kummerfeldt.)
The water in some lakes, particularly those in the western United States, contains high concentrations of calcium carbonate and calcium bicarbonate in solution, which make the water nonpotable. Lakes of this nature are usually easy to identify because the calcium salts that are leached from the ground are deposited in the form of white powder around the perimeter of the lake as the water evaporates (Figure 71-4). Water containing high concentrations of calcium carbonate and bicarbonate tastes terrible and should not be consumed.
(Courtesy Peter Kummerfeldt.)
Water collected from rivers and streams should not be considered “pure” (Figure 71-5). Giardia, Cryptosporidium, and other harmful pathogens found in water sources are not deactivated by aeration or exposure to ultraviolet rays. All water should be disinfected and purified using methods described in Chapter 67.
The quantity of water produced by seeps and springs varies tremendously. In some cases, the amount will be only a few teaspoons per hour (Figure 71-6). In other cases, gallons of water can flow from the ground in minutes (Figure 71-7, online). Where the quantities are small, the flat edge of the opening of a plastic bag can be used to scoop the water from a shallow source, or if it is flowing, to collect the water as it runs into the bag. A short piece of vinyl aquarium hose also works well for sucking water from shallow collections or to recover water from narrow cracks in the rocks.
After a rain, water collects in low-lying areas and may be found long after the last storms have passed through the area (Figure 71-8). Check out any depressions, sinks, or other low places where water could gather. Remember, the presence of vegetation and animals could provide a clue to the presence of a water source. Water sources like these should be checked carefully because they are frequently contaminated with debris that has been washed into the drainage. Finding the remains of animals that have died nearby or in the water, animal droppings, or other similar contaminants necessitates boiling, the use of halogens, or a filtration system designed to disinfect water (see Chapter 67).
It may be possible to locate abandoned open wells from which water may be obtained. Commonly, the rope and bucket used to lift water from these wells will be missing and a person will have to improvise a means to lowering a container down into the well to retrieve the water. With a closed well, where the pump handle is present but secured, or where the water is piped to another location, it may be necessary to dismantle or damage the plumbing to access the water. This may not be possible without tools.
Windmills that could provide a ready source of water are a common sight across North America, especially where there exists little surface water (Figure 71-9, online). Commonly, the water pumped to the surface is collected in a nearby tank or pumped directly into a trough from which livestock can drink (Figure 71-10). If this is not the case, then it may be necessary to dismantle or damage the pipes associated with the windmill to gain access to the water. Without tools, this may not be possible.
In arid areas, particularly in the western and southwestern United States, state wildlife agencies and conservation organizations have installed rainwater collectors called guzzlers. These water tanks can hold hundreds of gallons of water long after seasonal rains have passed (Figure 71-11). A guzzler consists of a concrete, metal, or fiberglass apron designed to gather precipitation and feed it into a holding tank, where it remains until it is consumed by thirsty animals or it evaporates.
Dew forms on clear nights when the air temperature decreases and the water held in vapor or air suspension condenses on cool metal surfaces or on vegetation. Dew can be collected as it drains from inclined surfaces on which it has formed, or it can be sponged up using an absorbent material. Campers’ towels (Figure 71-12, online) are one of the best materials for collecting dew. These highly absorbent towels quickly absorb moisture and can then be wrung out into a container or squeezed directly into a person’s mouth. A sponge is also very useful for collecting dew. Dew must be collected early in the morning before it is evaporated by the sun’s heat.
Rain water can be easily collected by erecting a flat surface (Figure 71-13). Water collects on the upper surfaces of any material (it doesn’t have to be waterproof) and drains to the lowest point, where it is collected.
For a normothermic person, there is no reason not to “eat” snow as an auxiliary source of water. However, for a person close to being hypothermic or who is already hypothermic, eating snow may increase loss of body heat and exacerbate the medical condition. Survival case studies reflect that individuals who chose to eat snow frequently experienced cuts and abrasions to the mouth mucosa as a result. If snow is the only source of water on hand, and there are no alternative methods available to melt it, the snow should be collected, compacted by hand, and consumed in small enough quantities for heat within the mouth to melt the snow.
When snow falls and settles on the ground, it undergoes constant metamorphosis. During very cold periods, there may be very little moisture in the dry, fine, or wind-blown snow that accumulates on the ground. Over time, as snow accumulates, the weight of the upper layers of snow and the earth’s latent heat cause the snow closer to the ground to change. It becomes more granular in nature and more like ice than snow. When comparing equal volumes of snow, snow collected from lower levels near the ground produces more water than does snow collected near the surface (Figure 71-14). Also, less heat will be needed to convert this snow to water.
(Courtesy Peter Kummerfeldt.)
The most efficient technique to convert snow into water is with what military survival schools call “a water machine” (Figure 71-15). A bag made from any available porous fabric (a T-shirt with the neck and armholes sewn shut has been used) is filled with snow and ice and hung near, but not directly over, a fire. The fire’s radiant heat melts the snow in the bag and the water runs down to the lowest point of the bag, where it drains into a container. Continually refilling the bag with snow prevents it from burning. Gallons of water can be produced quickly and safely using this method. The following are the major advantages of using the water machine method:
(Courtesy Peter Kummerfeldt.)
Traditionally, snow is melted by placing it in a metal container and then applying heat (Figure 71-16, online). Several problems soon become apparent when using this method:
(Courtesy Peter Kummerfeldt.)
This is a very slow, inefficient method of procuring water. If this process is the only one available, a small quantity of snow (several cups) is placed in any available waterproof container. Preferably, this should be a soft plastic water bag, zipper-type bag, or other similar container that is then placed between layers of clothing. Because the amount of heat needed to convert snow to water is large and the amount of body heat available is finite, only small quantities can be melted at a time. Large quantities of snow will not melt fast enough to provide the survivor any benefit. Large quantities of snow may also cool the body too much.
Another method, frequently used in winter recreation, involves using a sheet of black plastic. A thin layer of snow placed on a piece of black plastic (or other dark-colored waterproof fabric) positioned in the sun will melt. The waterproof material should be positioned on an incline so that the melt water runs to the lower edge of the fabric and drains into a container (Figure 71-17).
Even though water is not visible on the surface of the ground, it may still be present in the soil in sufficient quantity to be collected. Locate low-lying areas where water is most likely to have accumulated and dig down until damp layers of soil are located (Figure 71-18). Over time, water may seep into the hole, where it can be collected. If no indicators of the presence of subsurface water are present, dig a hole in the outside bend of a dry river bed. Look for a location where the centrifugal force of water flowing down river has eroded the outer bend of a curve and created a depression, where the last remnants of water flowing down the river will have accumulated.
In a coastal, saltwater environment, it is possible to locate water sources near a beach that are fresh and potable. A hole dug behind the first line of sand dunes adjacent to the high-water mark will often fill with fresh water. Fresh water, which is less dense than sea water, will collect in the hole. Holes dug in sandy soils are very tenuous and tend to cave in constantly, which may make it necessary to shore up the sides of any hole dug in sandy areas with driftwood (Figure 71-19).
Solar stills use a sheet of plastic and the sun’s heat to capture evaporation from soil or plants or to distill nonpotable water. The water evaporates from its source (e.g., soil, plants, or urine), condenses on the plastic sheet, and runs down the sheet into a collector, from where it is retrieved (Figure 71-20). Solar stills are not a reliable method of obtaining water in arid areas. The quantity of water produced by a solar still depends on the amount of water contained in the ground. Because desert soils tend to hold little or no water, the amount that a survivor is likely to obtain must be balanced against the amount lost in the sweating process while constructing the device. In most cases, a person will likely lose more water than can be recovered from the still. Even if a solar still is constructed in ground that is saturated with water, its productivity in relation to the amount of effort expended is still questionable. If the ground is saturated, the other methods of water procurement described here will most likely work.
A person’s ability to collect water trapped by plants or contained within them can be a valuable aid to combating dehydration. Once again, a line must be drawn between methods that are practical and those that are more myth-based. Extracting water from a barrel cactus is a classic example of a survival “myth.” Barrel cacti have been long featured in survival literature as a reliable source of water in arid regions (Figure 71-21). Several issues make this practice very questionable. First and most important, the quantity of fluid that can be extracted from a barrel cactus is very limited. Second, the fluid that is removed is not beneficial and may in fact be detrimental to an individual’s health. Third, accessing the interior of a barrel cactus requires a substantial knife or other cutting tool. The outer skin of the cactus is very tough and covered with long spines. Barrel cactus should not be considered a source of water.
Throughout tropical and subtropical regions of the world, vines can be found that can provide a reliable supply of pure water when other sources are not available. Water-producing vines varying in size from pencil thickness up to the thickness of an adult man’s forearm can even be found throughout much of the southeastern United States. Select vines with a large diameter. The greater the thickness of the vine, the more water it is capable of producing. Because water vines are woody and tough, they can be difficult to cut. A sharp knife or, better yet, a machete, will be needed to sever the vine.
To determine whether a vine is a suitable water source, the outer layers of the vine should be deeply scored with a knife. Vines that exude a white latex sap or a colored or foul-smelling sap should be avoided. If no sap is observed, or if the sap observed is clear and without aroma, a section of the vine can be cut as a water source. A 24-inch-long piece of vine should be cut by severing the higher end first and then cutting the lower end. If the lower end is cut first, the water contained within the vine is drawn up by capillary action, and far less water will drain out by the time that the upper end is severed. This becomes apparent when the available knife is not large enough to cut through the tough vine quickly. In one test conducted in Florida by the first author, a 24- by 4-inch section of water vine produced more than 1 cup of water.
Once detached, the section of vine is held vertically, and the water contained within the vine is allowed to drain into a container (perhaps a cupped hand), where it should be further evaluated. Liquid that is colored should not be consumed. Liquid that has an unpleasant aroma, other than a faint “woody” smell, also should be discarded. A small amount of the water should be tasted. Water that has a disagreeable flavor, other than a slightly “earthy” or “woody” taste, should not be used for drinking. This source could be used to satisfy external hygiene needs. If the water is still being considered for consumption, a small amount should then be held in the mouth for a few moments to determine if there is any burning or other disagreeable sensation. If any irritating sensation occurs, the water should be discarded. Ultimately, plant liquid that looks like water, smells like water, and tastes like water can be safely consumed in large quantities without further purification (Figure 71-22).
The use of clear plastic bags to enclose living vegetation and capture the moisture transpired by the leaves can be an effective method of collecting water (Figure 71-23). A plant’s survival depends on its ability to gather water from the soil. This water is passed up through the plant’s roots, stems, and branches and is finally released as water vapor back to the atmosphere through pores in the leaves. This process is called transpiration. Water vapor is captured by enclosing as much living vegetation as possible within a clear plastic bag and sealing the opening shut with a cord or duct tape. The vegetation should be given a vigorous shake before placing it in the plastic bag to remove any insects, bird droppings, or other materials that might contaminate the water. Within a short period of time, water will begin to condense on the inner surface of the bag and collect into water droplets.
(Courtesy Peter Kummerfeldt.)
Over a period of hours, the droplets accumulate and drain to the lowest point. The quantity of water obtained in this manner depends on the amount of water in the ground and the type of vegetation used. Other factors that determine water production include the amount of sunlight available, clarity of the plastic bag, and length of time the process is allowed to work. It is not uncommon to find that 2 or 3 cups of water, and sometimes much more, have accumulated over a 6- to 8-hour daylight period (Figure 71-24). This water is contamination free and does not require further purification.
Figure 71-24 Enclose a large amount of leafy vegetation in a clear plastic bag and seal the neck (A). Water transpired by the plant condenses on the inner surfaces of the bag and drains to the lowest point (B), where it can be sucked out using a piece of vinyl hose (C).
(Courtesy Peter Kummerfeldt.)
Transpiration bags do not work at night, and they do not work well when opaque or colored bags are used. The process of transpiration slows down when it becomes dark. Depending on the temperature, the plastic bag can be left in place for 2 to 3 days, at which point the leaves become damaged by the heat that develops inside the bag, causing the process to stop. The water that collects can be removed from the bag by disassembling the apparatus and pouring out the water, or by punching a small hole at the lowest point in the bag and allowing the water to drain out. Neither of these procedures is optimal because one requires that the bag be reassembled and the other necessitates repairing the hole in the plastic bag. The best way to remove the water without disturbing the bag is to insert a length of vinyl aquarium hose through the neck of the bag down to the lowest point where water will collect. The water can then be sucked out or possibly siphoned into a container. When enclosing vegetation in the plastic bag, it is advisable to place a chicken egg–sized stone in the lower corner where the water will collect. The weight of the stone creates a separation between the enclosed plant life and the water and precludes the plant saps from leaching into the water.
Using the transpiration process is a practical method of collecting water in desert areas, but it is also useful in other areas where surface water is not available. Unlike in deserts in other parts of the world, a considerable amount of vegetation is found in North American deserts. This is vegetation that can be used in the transpiration bag process. Most vegetation in desert areas is thorny, so considerable care should be taken to keep these thorns from tearing the plastic bag. Desert willow, a non-thorny shrub commonly found throughout the American southwest, is an excellent source of water. The poplar family of trees, including aspen and cottonwood, found in more temperate areas, is another good source when using this method of water procurement. Because the trees and shrubs that produce the most water are deciduous (lose their leaves in winter), the transpiration bag process is generally limited to the time of year when vegetation is in leaf.
Other than external factors, such as wind, precipitation, and temperature extremes, individual physiology and tenacity to live remain the primary determinants for survival without food or with limited caloric intake. An obese person carrying a large amount of body fat who arrives in a survival situation will have more fuel to burn than will a thin person. Other factors notwithstanding, this individual should live longer. Skinny but determined survivors might live longer than expected because of their tenacity.
A distinction must be made between having no food available and having limited supplies. If consumption of food is lower than the rate at which energy is expended, the body uses its reserves of fat, carbohydrates, and proteins at a pace directly related to the rate at which the energy is depleted. Without any food, most people die within 40 to 60 days. Self-imposed food fasts, such as those endured in Irish prisons by IRA militants, ranged from 50 to 60 days with no caloric intake before death. When sleep deprivation and danger are combined with little or no food, a person’s awareness, judgment, and ability to concentrate decrease rapidly. Individuals attempting to survive with little or no food become apathetic, lethargic, confused, and indifferent. Consequently, they are not likely to stay alive for very long in a physiologically challenging environment.
How long a person can live without any food varies tremendously. In adult volunteers who fasted for 30 to 40 days, weight loss was marked (25% of initial body weight). During more prolonged starvation, weight loss may reach 50% in adults and possibly more in children. Loss of organ weight is greatest in the liver and intestine, moderate in the heart and kidneys, and least in the nervous system. Emaciation is most obvious in areas where prominent fat deposits normally exist. Muscle mass shrinks, and bones protrude. The skin becomes thin, dry, inelastic, pale, and cold. The hair is dry and sparse and falls out easily.
Most body systems are affected. Achlorhydria and diarrhea are common. Heart size and cardiac output are reduced, the pulse slows, and blood pressure falls. Respiratory rate and vital capacity decrease. The main endocrine disturbances are gonadal atrophy, loss of libido in men and women, and amenorrhea in women. Intellect remains clear, but apathy and irritability are common. The victim feels weak. Work capacity is diminished because of muscle destruction and eventually is worsened by cardiorespiratory failure. Anemia is usually mild, normochromic, and normocytic. Reduction in body temperature frequently contributes to death. In famine edema, serum proteins are usually normal, but loss of fat and muscle results in increased extracellular water, low tissue tensile strength, and inelastic skin. Cell-mediated immunity is compromised, and wound healing is impaired. Total starvation is fatal in 8 to 12 weeks. For more information on starvation, see Chapter 69.
The season and weather establish additional constraints on a survivor’s longevity. In a benign setting, with warm temperatures both day and night, no precipitation, plenty of water available, and wood for a fire, the physiologic need for food is not as great. On the other hand, a survivor in a cold, wet, and windy environment, with inadequate clothing and no shelter, fire, or food to generate heat, will quickly succumb to hypothermia. With food, the survival outcome for an individual is still not guaranteed. However, provided that other priorities are met, life may continue long enough for a survivor to be found alive.
In a cold environment, generating heat to preserve body core temperature can be very difficult without adequate food intake. Shivering, which is a primary mechanism by which the body generates heat, rapidly depletes glycogen stored in the liver and muscles unless adequate food is available. Lacking sufficient clothing and food to protect against environmental insult, survivors must rely on their ability to build a shelter and start a fire to maintain core temperature.
Survival situations demonstrate the law of diminishing returns. During the initial hours of an emergency situation, survivors are in the best condition they will enjoy during their survival experience. The impact of the environment and the lack of food, water, and sleep result in continuous degradation of the body’s ability to function normally and eventually take a toll on the survivor’s ability to accomplish the tasks needed to survive. Any “heavy work” should be accomplished early. Strength, mobility, balance, and dexterity diminish as each day passes. The survivor’s objective is to delay this degradation for as long as possible through the intelligent use of practical food- and water-gathering techniques, and in so doing increase the chances of being rescued alive.
The ability to select, gather, and prepare natural foods, even in short-term experiences, is valuable physiologically, but perhaps even more valuable psychologically. When gathering food, survivors are actively involved in surviving, contributing to their own well-being. Although the amount of food gathered may be small, the satisfaction derived from catching a fish, snaring a squirrel, or gathering a hatful of edible berries can be a great morale builder.
People who are used to having all their food come from packages, cans, or other containers may need to overcome their reluctance to eat nontraditional foods that now come packaged in skin, hair, scales, or feathers. These aversions cause people to avoid consuming available wild foods that would enhance their chances of survival. Reluctance to eat insects, for example, is based in large part on the Western cultural belief that insects are “dirty” and that eating insects is done only by those who cannot afford better food. Additionally, the vast quantities of processed food available in developed countries have produced feeding habits in which people only consume the very best of the available foods and discard the rest. Survivors will not be so fortunate that they can pick and choose what they eat. They may have to capitalize on any potential food that comes their way.
Procuring wild foods involves procedures and techniques that some might view as cruel, unethical, or even illegal. For example, with the exception of trapping fur-bearing animals during legal seasons and the use of traps by licensed animal control personnel to remove “problem” animals, the use of snares to obtain food is against the law. Trapping and snaring techniques have been determined to be illegal because they are so effective and because they are virtually impossible for wildlife managers to monitor. Their effectiveness is the very reason they are highly recommended for survival. Under normal circumstances, procuring food from the environment is governed by federal, state, and local laws and regulations. Killing animals for food outside of prescribed hunting seasons is forbidden. Gathering plant foods and killing animals is specifically prohibited in national parks and other similar sanctuaries. Accepted hunting conventions also disfavor killing females with babies and younger animals. When faced with starvation and the choice between killing an animal and digging up enough plant bulbs to make a meal, it becomes a question of common sense. The survivor should gather necessary food and leave legal issues to be sorted out after the fact. It is extremely unlikely that a survivor who could clearly demonstrate a legitimate need would be charged with an infraction of the law. This does not mean that, in a short-term survival experience, it is appropriate to disobey the law, particularly if there are reasonable alternatives.
Feeding oneself in a long-term survival experience may necessitate harvesting and butchering wild game animals. These skills were once common in Western culture but nowadays are unusual. To some people, the act of taking any life is reprehensible, so even in a survival situation, when faced with killing an animal for food, they will have great difficulty or even may be unable to accomplish the task. But most commonly, hunger drives survivors to carry out what they need to do to stay alive.
When considering what should be eaten in a survival situation, some people focus all their efforts on plant foods. This misguided approach may be the result of advice given in out-of-date survival manuals and from well-intentioned, but ill-informed, writers of contemporary “how-to-survive” articles. Many of these articles devote numerous pages to identification and use of plants to sustain life. Except for the short term, it is almost impossible to survive indefinitely on gathered plant life alone, if it is even available. Fats and proteins provided by eating meat are far more sustaining than are the carbohydrates provided by eating vegetable matter. If plant and animal foods are both available, survivors should attempt to balance their diets by consuming fat, proteins, and carbohydrates in order to maintain health for as long as possible.