CONSERVATION (Part 3 of 5)

How Soil Conservation Works

Groups interested in improving farming practices have been around for many years. But the federal government did not get involved in soil conservation until the early 1930s.

Problems that occurred during the 1930s, such as the Dust Bowl, caused people to recognize the need for government leadership in the areas of soil conservation and farming.

• Agricultural acts passed by lawmakers in 1929 and 1932 provided money to be used for erosion research.
• In 1933, during the Great Depression, Congress passed a bill that would allow people without jobs to work in erosion control for the government. In this way, soil conservation could be put into practice and the unemployed would have work.
• The Soil Erosion Service, later renamed the Soil Conservation Service, was created in 1935 as a result of this bill and has been responsible for managing conservation programs.

In 1933 the Soil Erosion Service (soon renamed the Soil Conservation Service) was created as a major division of the United States Department of Agriculture. The Soil Conservation Service has devised a land classification system that offers guidance in the proper use of land. Such factors as slope, type of soil, amount of rainfall, humidity, and vegetation type are considered when determining land use for maximum productivity. Of the eight government-designated land classifications, classes I, II, III, and IV may be used for cultivated crops; however, classes III and IV require skilful management to avoid serious erosion. Classes V through VII can be used for forests and for grazing. Class VIII land, which includes sandy shores and extremely rocky places, is considered suitable only for wildlife or for scenic and recreational purposes.

Covering the ground with plants is one of the key elements in soil conservation. To prove this, the Department of Agriculture experimented with two steep plots of adjacent land one planted with crops and the other thickly covered with grass. The cultivated plot lost 7 inches (18 centimetres) of topsoil in 11 years. By contrast, it was estimated that it would take 34,000 years to lose the same amount of topsoil from the grass-covered plot.

Plant cover tends to hold rainwater where it falls and thus prevents the soil from blowing or washing away. Gullies can be healed in many cases by planting new plants. They provide a tangle of leaves and stems that trap and hold in place part of the soil carried by run-off Another way to heal gullies is to build brush dams across them at regular intervals.

Then soil and water running down the gully are caught behind the dams and held in place.

To help prevent the start of erosion, farmers may use a variety of conservation measures:

Contouring. This practice involves ploughing, planting, and cultivating sloping fields around hillsides, with curving furrows horizontal to the hill, instead of furrows running straight uphill and downhill. The curved furrows catch rainfall and allow much of it to soak into the ground. They also catch soil washing down from higher levels.

Strip-cropping. Strips of close-growing plants, such as grasses or clover, are alternated between strips of clean-tilled row crops, such as corn and soy beans The strips of close-growing plants hold water and keep it from eroding the cultivated strip below. These strips are planted on the contour.

Terrace, in geology, stretch of elevated, level land along banks of a river, lake, or ocean; frequently occur in series, one rising above the other; artificial terraces are used effectively in landscape gardening and in agriculture to hold moisture and prevent erosion.

Terracing. On long slopes a low ridge, or terrace, thrown along the outer side of the slope catches soil and rainwater and retards run-off Encouraging plant growth on a terrace will help hold soil.

Listing. In dry regions a Lister plough can be used to throw a ridge of dirt to each side, creating a trough about 18 inches (46 centimetres) wide and 7 inches deep. Crops are planted in the bottom of the trough.

Shelter belts On treeless plains, belts of trees planted at the edges of fields break the force of winds across the fields and reduce wind erosion.

Deep tillage (also called stubble mulching, or primary tillage), method of ploughing to conserve the land.

Deep tillage, stubble mulching. Instead of turning over the soil with a mouldboard plough, a deep-tillage plough breaks the soil below the surface. It leaves the surface vegetation or harvest remains from the previous crop to act as a cover.

Different crops need different substances, called nutrients, to enable them to grow.

Crops get these needed nutrients from the soil. If the same crop is grown in the same field every year, the soil will soon lose nutrients needed by that crop.

Crop rotation is the practice of planting different crops in a field each year or every few years.

With careful planning, crops can be rotated in a way that builds up nutrients in the soil for the next crop. Here's an example:

Many crops need nitrogen to grow, and they take it from the soil. Other plants, like legumes, take nitrogen out of the air and put it back into the soil. By rotating legumes with other crops, the nitrogen in the soil can be replaced.

Crop rotation. Planting different crops each year on a piece of land keeps the soil productive. One crop can benefit the next. For example, nitrogen is essential for plant growth and is added to the soil by legumes, such as clover, alfalfa, soy beans, and cow peas These combine nitrogen from the air with other elements and store it in the soil through their roots. In a year or two the plants can be ploughed under. This is called green manuring.

After the roots have rotted, other plants that need nitrogen but cannot use nitrogen in the air for example, corn and potatoes can use the stored nitrogen for growth. Rotations are programmed with strip-cropping by shifting the close-growing strips and the tilled strips at fixed intervals.

Water can be polluted by many things. One of these is the topsoil or silt that washes into streams and rivers. This silt washes into streams and rivers from land that has been badly managed.

When silt washes into streams and rivers, two harmful things may happen.

1) Silt that floats in the water limits the amount of air in the water. Fish need air to breathe. When silt limits the air in the water, the fish die.

2) As the movement of water slows down, silt drops to the bottom of the stream beds

There are ways of controlling erosion of silt from land into streams and reservoirs. Conservationists try to make sure that the right steps are taken to prevent the silting of streams.

Cover crops. Land is kept covered in winter and summer with either a growing crop or the residue, such as corn stalks, from the crop previously grown. When cover crops are ploughed under for green manuring, the plant foods added to the soil improve its water-holding capacity and increase its fertility.

Fertilization. Chemical or natural fertilizers replace the soil substances used up by crops.

Erosion on Urban Land

Crop land is not the only soil subject to erosion. The land on which housing and other urban projects are built is particularly susceptible because its protective cover is generally removed.

Mulch, material such as manure, leaves, pulverized earth, placed on surface of soil to retain moisture and to protect plant roots from frost.

To prevent erosion on construction sites, builders should take corrective action. For example, mulches placed on steeply excavated slopes usually prevent soil from washing or blowing away. Straw or fibre netting may be used as mulches. On sites where erosion control is more difficult, hydro seeding can be used. Grass seed, fertilizer, and mulch are power-sprayed on excavated slopes. The quick-growing grass then stabilizes the soil against erosion.

WILDLIFE CONSERVATION

The preservation of wildlife greatly depends upon water and soil conservation. All native plants and animals constitute the wildlife of a region and are a product of the land resources and habitat conditions. But, like humans, wild animals must have food, water, and shelter. Destroying the forests, marshes, ponds, and grasslands destroys their food and water supplies and the places in which they live.

1872: Yellowstone National Park. Although the concept of national parks was first suggested in 1832 by American artist George Catlin, it was not until March 1, 1872, that the first national park in the United States was established by Congress. Yellowstone Park was the beginning of a large system of 49 parks that today can be found in nearly all parts of the country. These parks, as well as other monuments, are managed by the National Park Service.

Once Yellowstone was opened, other countries began setting aside nature preserves similar to America's national parks. Canada, for example, established a 10-square-mile area of hot springs at Banff, Alberta, in 1885 as a national park. Today there are national parks on all continents, except Antarctica.

Yellowstone is located in parts of three states: north-western Wyoming, southern Montana, and eastern Idaho; it covers 2,219,823 acres (898,329 hectares). Several sub ranges of the Rocky Mountains are in or around the park's borders: the Snow Mountains, the Gallatin Range, the Absaroka Range, and the Tetons. Several national forests surround Yellowstone. The Grand Canyon of the Yellowstone River is a 19-mile gorge running through the park. Among Yellowstone's other distinctive features are 10,000 hot springs, including 200 geysers, many of which erupt to heights of 100 feet (30 meters). The most famous geyser is Old Faithful, named for the regularity of its eruptions.

The park is heavily forested, and in 1988 a series of disastrous fires destroyed much of its vegetation and animal life.

Of the original native wildlife of the United States many species are now extinct. These include the passenger pigeon, the Carolina parakeet, the great auk, the Labrador duck, the Pallas cormorant, the dusky seaside sparrow, and the heath hen. Mammals gone forever include the Eastern elk, the Plains wolf, the sea mink, and the Bad Lands bighorn. Many smaller birds and mammals have also become extinct in the wild. Populations of the ivory-billed woodpecker and the California condor no longer exist in the wild in the United

States.

The number of moose, caribou, wild sheep and goats, and grizzly and Alaska brown bears grows smaller every year. Much wildlife is now protected by law from over hunting and overfishing. However, if habitat destruction of their natural homes continues, many will be unable to survive.

The United States Fish and Wildlife Service maintains a list of endangered and threatened species of the United States. Environmental concerns for a variety of reptiles, amphibians, small fishes, insects, and molluscs is reflected in the number of species classed as threatened or endangered.

The Endangered Species Act has been effective for preserving some species that seemed destined for extinction. For example, the American alligator had been reduced to a relatively small number by the early 1960s due to illegal hunting for hides and meat. After 20 years of protection, the species recovered to such a large extent in many parts of its range that it led to a relaxation of the laws in the 1980s so that limited hunting was permitted.

Many events can cause a species of animal to become endangered. For example, some animals are killed because people want trophies or desire to wear clothing made from furs and skins.

However, the main reason many creatures have become endangered is because humans are destroying their habitats. Two such habitats are the Florida Everglades and the rain forests of Brazil. Too often, places that are attractive to animals are just as attractive to people, who want to build various facilities.

Unfortunately, nothing can bring back a species that has been lost. Such extinct creatures will only be seen in museums or pictures.

Worldwide, the International Union for Conservation of Nature and Natural Resources keeps track of species threatened with extinction. Endangered species include many of the world's great cats, whales, certain species of rhinoceros, tapirs, and many other mammals, birds, and reptiles. Housing and other facilities needed by an expanding human population are encroaching on their habitats.

Many species are the victims of the illegal pet trade and of the trade in exotic pelts and skins; the increasing availability of guns and poisons is responsible for the extermination of other species. The African elephant, once common throughout the sub-Saharan region of the African continent, has been greatly reduced in numbers due to illegal poaching for the ivory trade.

CONSERVATION (Part 4 of 5)

Refuges for Wildlife

Some governments have established national wildlife reservations and game refuges. Many refuges are established in places to which animals, especially migratory birds, have long been attracted. In the United States, many of these are administered by the Fish and Wildlife Service. All the national parks and national monuments are wildlife refuges.

Individuals can help restore wildlife to the countryside simply by providing birds, fish, and animals with natural breeding sites. They can do even more by encouraging their state and federal governments to provide effective laws for habitat protection.

For a long time, many people believed salt marshes were just worthless land. Salt marshes became dumps for garbage, or they were filled in to make the land more useful to humans.

Now we know that marshes are habitats for many different land and water creatures. They often act as "nurseries," providing a safe shelter where animals can hide, and their young can grow into adults.

These marshes may produce and protect the greatest numbers and variety of wildlife on Earth.

Brush piles scattered through a wood lot provide retreats for cottontails, weasels, mink, and woodchucks. Fence rows can provide a haven for many kinds of birds. Marshes seldom make good crop lands, but they provide homes for muskrats and certain birds. Unfortunately, many of the salt marshes of the Atlantic coast have become dumping grounds for litter and industry. Others have been filled in to provide land for housing or for boat marinas. The birds and other animals that lived in those marshes, such as marsh hawks and short-eared owls, had to seek other habitats because their food supply and cover were gone. Continued exploitation of the marshes will further reduce the number of wildlife species.

FOREST CONSERVATION

Among the most valuable of nature's resources are forests. They play a key role in the maintenance of the watersheds that are essential to water and soil conservation. They shelter many forms of wildlife. They supply lumber for construction, cord wood for fuel, and pulp for paper. Forests also provide the raw materials used in many synthetic products considered essential for modern life, including fibres, plastics, and medicines.

Fire can be a major scourge of a forest. Although lightning is sometimes responsible for kindling forest fires, human carelessness is most often the cause. Ground fires can destroy the organic soil of the forest and render it incapable of supporting tree life. When crown fires rage through the leafy tops of trees, they destroy timber and its resident wildlife.

However, fire can also be a natural occurrence, and most forests rebound from occasional fires and the wildlife returns.

Insect infestation can also threaten the life of a forest. The Forest Pest Control Act of 1947 authorized surveys of public and private forests so that insect-borne diseases of trees could be detected and suppressed before they became epidemic.

Forests are a renewable resource that can provide us with goods for many years if logging is done carefully.

Most loggers cut small patches of trees out of a forest, leaving mature trees around the cut area. The mature trees ...

• reseed the cut area and produce new trees.
• form a net with their roots that keeps the soil in place, thus controlling erosion.
• provide a canopy of leaves that keeps rain from hitting the ground as hard as it would if there were no mature trees. If the rain beats down too hard, it erodes soil and prevents seeds from growing.

A more serious threat than fire or insects is indiscriminate logging. When every tree of a stand is cut without any provision for natural reseeding or manual replanting, no canopy is left to protect the soil against the splash erosion of rainfall. The loose soil soon becomes deposited as silt in nearby streams. Timber must be treated as a renewable crop, carefully harvested to ensure a sustained yield of trees. In this way, a balance is struck between the cutting of mature trees and the growth of saplings.

MINERAL CONSERVATION

Minerals are non-renewable resources. Once exhausted, they can never be replaced. The United States has valuable stores of coal, oil, natural gas, and minerals. Until the Mineral Leasing Act was passed in 1920, the resources on public lands were transferred to private individuals, who sometimes exploited them. Government regulation now helps private industry make proper use of these resources.

Coal, gas, and oil are non-renewable resources that we may soon run out of. We have tried to conserve coal, gas, and oil by ...

• making mining processes less wasteful.
• using other sources, such as nuclear power, for energy.
• improving the machines that burn coal, oil, and gas so that they don't need as much fuel to run.

One machine we have improved is the car engine. Today cars travel more miles on one gallon of gasoline than cars of the past did.

While one method of conserving resources may seem to make only a small difference, the use of many different methods can add up to big resource savings.

For years coal was mined as though it were inexhaustible about one ton wasted for each ton mined. The Bureau of Mines and other government agencies have promoted more efficient mining methods. In addition, the use of other sources of energy in home construction and in industry, and to generate electricity, has greatly extended the life of the coal supply. In order to conserve the dwindling supplies of natural gas and petroleum, in 1978 the government established requirements for conversion from these fuels to coal. But coal burning can create pollution problems.

Natural gas and petroleum were once carelessly wasted also. In earlier days, for example, because no use for natural gas had been found, it was burned off or allowed to escape into the air. Several government agencies now carry out programs to conserve these resources by replacing them with more abundant sources of energy. In 1978 the government established restrictions on the use of natural gas and petroleum in new industrial facilities and power plants.

Like other conservation needs, the wise management of mineral resources has become more pressing because of the growing number of consumers. As the human population increases, a need is generated for more consumer goods, such as household appliances and automobiles. Manufacturers must meet these rising demands from already dwindling deposits of metal ore. Under the Office of Fossil Energy Research, a program was set up that is concerned with increasing domestic supplies.

Some mineral resources, particularly metals, may be recycled that is, salvaged and reused. The recycling of waste metals is an important conservation practice that has become a major business. It is known as secondary production.

Throughout most of its history the United States has had ample, inexpensive supplies of fuels to provide energy. During the 20th century the country gradually shifted from reliance on coal as its principal fuel to dependence on natural gas and petroleum. By the late 1970s the United States was consuming more than one third of the world's supply of these two fuels and was dependent on them for three fourths of its energy.

As it became more apparent during the 1970s that natural gas and petroleum resources might be depleted within the foreseeable future, energy conservation became an important government policy. Conservation measures were also adopted because of political and economic developments. About one half of the petroleum used by the United States was imported, much of it from Middle Eastern countries that opposed certain United States foreign policies. In addition, oil-exporting countries increased oil prices by more than 1,500 percent between 1970 and 1980.

In 1977 President Jimmy Carter established a Cabinet-level Department of Energy and proposed a comprehensive energy program. As passed by Congress in 1978, the program included measures to discourage energy consumption, particularly of natural gas and petroleum, and provided incentives for alternative energy sources. An Energy Security Act, to develop synthetic fuels, was passed in 1980.

Government, industry, and private citizens all took steps to conserve energy. To meet new government standards, smaller and more efficient automobiles were produced. There was renewed emphasis on improving the country's mass transportation systems.

Grants, loans, and tax credits were offered for the installation of insulation and other energy-saving devices in homes and commercial properties. Efficiency standards for appliances were adopted. The government mandated minimum and maximum temperatures for non-residential buildings and suggested maintenance of similar temperatures in homes.

Until the energy crisis of the 1970s, people did not realize how much oil comes from sources outside the United States.

Many United States citizens don't want to be dependent on others for energy. They fear such dependence might give foreign nations too much power over the United States.

If the United States can find other sources of energy that will always be available, there will be less worry about using so much foreign oil. This is why the government has supported research to find new ways to get energy from sources such as the wind, the sun, and the ocean.

The energy crisis of the 1970s led to increased emphasis on alternative sources of power. The government supported further development of solar, geothermal, and wind power. Industries and utilities were encouraged, and in certain circumstances required, to use coal as an alternative to natural gas and petroleum. The government encouraged long-range research programs, including the development of economical methods of producing gas and oil from coal and shale. Gasohol a mixture of alcohol produced from grain and gasoline was tried as an alternative fuel for automobiles, and development of a battery-powered automobile continued.

With the election of Ronald Reagan in 1980, the government support for most of these programs was ended. Instead, the government promoted the expansion of nuclear energy and a return to imported petroleum.

CONSERVATION (Part 5 of 5)

THE CONSERVATION MOVEMENT

EFFECTS OF GOOD CONSERVATION

1. Good forestry prevents the depletion of timber and the siltation of streams.
2. Wilderness areas provide shelter for wildlife and a place for people to relax.
3. Reservoirs control floods, provide plentiful drinking water, and generate power.
4. Properly ploughed and well-managed farms keep the soil fertile and in place.
5. Land irrigated with water from diversion dams becomes suitable for crop raising.
6. Well-planned industrial clusters utilize control devices to lessen pollution.
7. Hatcheries provide fish to supplement stocks in reservoirs, streams, and lakes.
8. Self-contained satellite communities maintain the beauty of natural terrain.
9. Treatment plants help keep rivers clean by processing wastes from city sewers.
10. Area-wide master plans for work and housing developments enhance city living.
11. Underground express ways link cities and suburbs without destroying surface land.
12. Expansive parks provide space and facilities for cultural and recreational activities.
13. Mass interurban transportation systems move people and goods efficiently.
14. Footpaths and bicycle trails offer opportunities for stimulating outdoor exercise.
15. Green spaces established by city zoning hold soil and provide natural beauty.
16. Rivers kept clean by effective pollution control can be used for recreation.
17. Scenic easements along riverbanks aid anti-pollution efforts and help stem erosion.

Prepared by the U.S. Department of the Interior

Pinchot, Gifford (1865-1946), U.S. forestry expert, born in Simsbury, Conn.; studied forestry in Europe; president National Conservation Association 1910-25; active supporter of T. Roosevelt; negotiator of coal-strike settlement 1923; governor of Pennsylvania 1923-27, 1931-35.

Conservation in the United States began as a movement to save the country's vanishing forests, but the concept was soon broadened to include other resources. Gifford Pinchot, the head of the United States Forest Service from 1898 to 1910, was an early conservationist. He strongly influenced President Theodore Roosevelt, who established the National Conservation Commission. Some 234 million acres (95 million hectares) of government-owned timber, coal, oil, and phosphate lands were set apart as public lands, never to be sold to private interests.

During President Franklin D. Roosevelt's first term, with a severe drought in the Plains states, reforestation and erosion control were undertaken by the Civilian Conservation Corps and the Soil Conservation Service. The government took over abandoned and non-productive farms; many acres were reforested and set aside as game reserves. The Taylor Grazing Act of 1934 regulated livestock grazing on public lands to prevent overgrazing and soil deterioration.

Under President Harry S. Truman a national program was established to control water pollution. Later legislation required states to set and enforce standards to maintain clean natural waters.

The Endangered Species Act of 1966 …

• was one of the first laws passed in the United States intended to protect endangered animals.

• provided for the publication of lists that name every endangered plant and animal.
• was strengthened in 1969, when penalties were set for people who hurt endangered species.
• was enhanced in 1973 when laws were established to protect animal habitats.

The Endangered Species Act has been a very important law because conservation groups can use it to prevent people from destroying the land that animals must have to live.

Efforts to save native wildlife from extinction were aided by management programs provided in the Endangered Species Preservation Act of 1966. Beginning in 1969 the importation of endangered species and the interstate shipment of illegally captured wildlife were prohibited. Thus the pet, fur, and hide markets for native and foreign species of potentially extinct animals were outlawed.

The National Environmental Policy Act of 1970, a far-reaching conservation measure, was supported by President Richard M. Nixon. It reflected the need for a high-quality environment, emphasized recycling of non-renewable resources, and advocated attempts to equalize population and resource use. In 1970 the Environmental Protection Agency (EPA) was formed to establish standards of environmental quality.

Greenpeace Foundation, international organization for the protection of the environment.

An international organization, the Greenpeace Foundation, was established in 1971 to protect the quality of the Earth's environment. Its special concerns include protesting against radioactive and toxic waste dumping, the use of nuclear weapons, and acid rain.

Watt, James Gaius (born 1938), U.S. executive and public official, born in Lusk, Wyo.; director U.S. Bureau of Outdoor Recreation 1972-75; member Federal Power Commission 1975-77; president and chief legal officer Mountain States Legal Foundation in Denver 1977-81; U.S. secretary of the interior 1981-83.

The worldwide recession of the early 1980s had an unfavourable effect on national conservation programs because environmental restrictions were viewed as hindrances to economic recovery. The controversial policies of President Ronald Reagan's Secretary of the Interior, James Watt, who repeatedly favoured land development and exploitation over conservation, were widely opposed, and he resigned in 1983. Public opinion also forced other changes in the personnel and operation of the EPA.

In 1984 Reagan rejected a bill to establish an American Conservation Corps, similar to the Civilian Conservation Corps of the 1930s. However, he supported bills to expand the federal wilderness preservation system by more than 8 million acres (3.2 million hectares).

In 1990, under President George Bush's administration, legislation was passed that amended the Clean Air Act of 1970 to focus more on reducing acid rain, emissions from fossil fuel burning, and nitrogen oxide emissions. Also passed were a number of new automobile pollution controls, such as stricter tail-pipe emissions standards and installation of vapour-recovery nozzles at gasoline pumps. Also part of Bush's policies were new legislation to strengthen controls of chemicals that destroy the ozone layer and plans to study radon and other indoor air pollution problems.

Assisted by Herbert A. Smith, Associate Dean for Education, Colorado State University. Also reviewed by J. Whitfield Gibbons, Senior Research Ecologist, Professor of Zoology, Savannah River Ecology Laboratory, University of Georgia.

BIBLIOGRAPHY FOR CONSERVATION

Baker, Mark and others. The World Environment Handbook (World Environment Center, 1985).

Bittinger, Gayle. Learning and Caring About Our World (Warren, 1990).

Boy Scouts of America. Conservation Skill Book (BSA, 1979).

Curtis, Will. The Nature of Things (Ecco Press, 1988).

Durrell, Lee. State of the Ark (Doubleday, 1986).

Gates, Richard. Conservation (Childrens, 1982).

Graphic Learning International Staff. Concise Earthbook (Graphic Learning, 1987).

Long, R.E., ed. Energy and Conservation (Wilson, 1989).

Middleton, Nick. Atlas of Environmental Issues (Facts on File, 1989).

Owen, O.S. and Chiras, D.D. Natural Resource Conservation: An Ecological Approach, 5th ed. (Macmillan, 1990).

Prescott-Allen, Robert. How to Save the World: Strategy for World Conservation (Littlefield, Adams, 1981).

Schwartz, Linda. Earth Book for Kids: Activities to Help Heal the Environment (Learning Works, 1990).

ANIMAL BEHAVIOUR (Part 1 of 3)

 Man has always been fascinated by the amazingly varied behaviour of animals. Ancient man observed the habits of animals, partly out of curiosity but primarily in order to hunt and to domesticate some animals. Most people today have a less practical interest in animal behaviour They simply enjoy the antics and activities of pets, of animals in zoos, and of wildlife. But in modern times animal behaviour has also become a scientific speciality The biologists and psychologists who study animal behaviour try to find out why animals act in the specific ways they do and how their behaviour helps them and their offspring survive. Some of them feel that the behaviour of animals provides clues to the behaviour of man.

Anthropomorphism, the ascribing of human form or qualities to gods or things, as when ancient people attributed powers to fire, stones, and trees, and as animals in fables have the gift of speech.

A great deal of fanciful "animal lore" has arisen over the years in the mistaken belief that animals behave for the same reasons as man. The view that non-human things have human attributes is called anthropomorphism. An example of anthropomorphism is found in the following passage written by the 1st century AD Roman author Pliny the Elder:

The largest land animal is the elephant. It is the nearest to man in intelligence; it understands the language of its country and obeys orders, remembers duties that it has been taught, is pleased by affection and by marks of honour, nay more it possesses virtues rare even for man, honesty, wisdom, justice, also respect for the stars and reverence for the sun and moon.

Undeniably, the elephant can be taught to perform certain tasks, but no one today seriously believes that it reveres the sun and the moon.

Animal behaviour can be studied in natural settings or in the laboratory. Often, laboratory experiments are designed to test notions based on outdoor observation. The study of animal behaviour from the viewpoint of observing instinctive behaviour in the animal's natural habitat is called ethology. (The ways in which animals solve their common problems for example, eating, drinking, protecting themselves and their offspring from predators, reproducing, and grooming are all the concerns of an ethologist, a scientist who studies animal behaviour) A contrasting viewpoint on behaviour, practised in the United States particularly, has concentrated mainly on learning processes, behavioural development, and the influence of behaviour on an animal's internal workings the action of nerve impulses and hormones, for example. Both approaches are important.

What Is Behaviour?

Simply defined, animal behaviour is anything an animal does its feeding habits, its reproductive actions, the way it rears its young, and a host of other activities. Behaviour is always an organized action. It is the whole animal's adjustment to changes inside its body or in its surroundings.

The group activities of animals are an important aspect of animal behaviour Bees, for example, communicate with each other about food, and birds may flock during migratory flights. Group activities are often adaptations to a new set of circumstances. Without adaptation, a species could not survive in an ever-changing environment.

Behaviour can also be thought of as a response to a stimulus some change in the body or in the environment. All animals, even those too small to be seen without a microscope, respond to stimuli.

How an Animal Reacts to a Stimulus

A stimulus is a signal from the animal's body or its environment. It is a form of energy light waves or sound vibrations, for example. All but the simplest animals receive a stimulus light, sound, taste, touch, or smell through special cells called receptors, located in many places on or in the body. For example, fish have taste buds over much of their body, sometimes even on the tail. These buds enable fish to taste the water they swim through and thus to detect nearby food. Cats, which prowl the dark, rely on sensitive touch organs associated with their whiskers.

At the receptors the incoming energy is changed into nerve impulses. In complex animals these impulses may travel either to the brain or through reflex arcs to trigger the hormone or muscle actions of a response.

Conditioning - A Way of Modifying Behaviour

The behaviour of many, perhaps all, animals can be modified by a kind of training called conditioning. Two types of conditioning have been studied classical conditioning and operand conditioning. The first type was discovered by the Russian physiologist Ivan Pavlov; the second, by the American psychologist B.F. Skinner.

In classical conditioning, an animal can be made to respond to a stimulus in an unorthodox manner. For example, a sea anemone can be conditioned to open its mouth when its tentacles are touched a response that it does not ordinarily make to this stimulus. When undergoing such conditioning, an animal is repeatedly offered two different stimuli in timed sequences. The first, called the neutral, or conditioned, stimulus, does not usually cause the animal to respond in the desired way. In the sea anemone experiment, touch is the neutral stimulus. The second, called the unconditioned stimulus, does cause the desired behaviour Squid juice is the unconditioned stimulus because it will cause the sea anemone to open its mouth. In classical conditioning, the neutral stimulus is followed by the unconditioned stimulus. The unconditioned stimulus may be given while the neutral stimulus is being delivered or afterwards The sea anemone was touched first, then given squid juice. After hundreds of such trials, it opened its mouth when touched even though no squid juice was offered.

In operand conditioning, an animal is given some type of reward or punishment whenever it behaves in a certain way for example, whenever it pushes a lever, presses a bar, or moves from one place to another. The reward or punishment, called a reinforcement, follows the action. Food or water may be used as rewards; an electric shock, as a punishment. Rewarding the animal increases the probability that it will repeat the action; punishment decreases the probability. Operand conditioning has been used not only with animals but also in programmed instruction and teaching machines.

Role of the Nervous System in Behaviour

An important relationship exists between an animal's nervous system and its ability to respond to environmental changes. Animals with a fairly simple nervous system, such as ants, respond in a relatively fixed, or stereotyped, fashion as compared with animals that have a more highly developed and specialized nervous system, such as rats. A rat can link up, or integrate, different stimuli from the environment and can store and use the information from past experience to solve simple and complex problems far better than an ant can. However, the rat does not do as well as a higher mammal, such as a chimpanzee.

For example, a rat, an ant, and a chimpanzee can each learn a complicated pattern of responses to reach food. The rat is trained to run a maze a number of pathways toward a goal, all but one of which end in blind alleys to find food. Then the rat begins at the end of the maze and must learn to run the course backward in order to reach food placed at the starting point. The rat takes less trials to learn the maze backward than forward. An ant given the same training cannot benefit from its past experience. It must learn the backward path as though it were a new one. The chimpanzee shows the greatest learning ability of the three. When the chimpanzee solves a problem, such as discriminating between two geometric shapes, it can do so by generalizing from a "set to learn." That is, after it has learned that it can obtain food by making the correct choice between the two shapes, it easily makes the correct response on the next try. A rat requires a number of trials before it can associate "shape" with "food."

The Evolution of Behaviour

Behavioural scientists arrange living things according to the complexity of their behaviour and the extent to which it can be modified. They have found that animals with more complex body and nervous systems have more complex and more modifiable behaviour In addition, however, the behavioural patterns that have evolved among living things are particular ways of adapting to their environments the places where they develop and reproduce. For example, though all animals feed, there are evident differences in the way they feed. Marine worms sift sand for edible organisms. An army ant stings a beetle and brings it back to the colony's bivouac, where it is dismembered by other members of the colony. A chimpanzee peels a banana before eating it.

It is possible to observe living animals and find out why they act as they do, but can anyone know how extinct animals behaved? There are fossil remains of extinct animals, but behavioural patterns cannot be left as fossils. Yet, equipped only with such fossil remains, scientists can get inklings about the behaviour of extinct species. They achieve this by studying living species in the laboratory or in their natural habitats to determine their behavioural similarities and differences. Then they try to uncover the relationship between the structure of the body parts of these species and the particular function of each body part. Thus, if particular characteristics of the structure of a wing or a leg, for example, can be identified with a particular activity of a living animal, a scientist studying the evolution of behaviour can make plausible guesses about the possible function of fossil bones. He can then develop notions about the possible behaviour of extinct species that were ancestors of certain living animals.

For example, by studying the different groups of passerine, or perching birds, researchers have identified the evolutionary relationships among them. One way is to use tail flick as a taxonomic character a structural trait employed in analysing the relationships among different species. Perching birds flick their tails in a particular way as they move through trees. By analysis of the extent of tail-feather spread during a tail flick and the direction and amount of tail movement, evolutionary relationships can be seen among such passerines as cardinals, buntings, weaver birds, wax bills, and finches.

Evolutionary relationships among species may also be studied by analysing different behavioural patterns. Among the most important behavioural patterns are orientation, social organization, and communication. All species exhibit each of these. However, within species considerable variation exists in the stimuli to which individuals respond, the age at which they respond, and the patterns of their response.

ANIMAL BEHAVIOUR (Part 2 of 3)

Orienting Behaviour

An animal orients by adjusting its posture and position in space. It does so in relation to the source of different forms of energy in its environment. These forms include light, heat, and chemicals in the air or water, pressure, electric current, air or water currents, gravity, radiation, and magnetic fields.

Tropism, involuntary turning of a cell or organism in response to a stimulus.

Orienting behaviour may take the form of a tropism an action in which the animal simply orients its body toward or away from the source of energy without changing location. Plants can also respond in this way. However, the orienting response may take the form of a taxis a movement toward or away from the source of energy by swimming, flying, or locomotion. As a rule, only animals are capable of such responses. Still another type of orienting response is called a kinesics an increase or decrease in an animal's activity, but in no particular direction.

Prefixes are usually added to the root words tropism, taxis, and kinesics to indicate the kind of energy to which the organism is responding. For example, geotropism is response to gravity; photo taxis, response to light. Prefixes may also indicate the type of response made. Thus klinokinesis refers to turning activities. In addition, the direction or intensity of a response may be described as positive, if directed toward a stimulus, or negative, if directed away from it.

Orientation makes it possible for an animal to feed, to exhibit social behaviour, and to avoid obstacles and barriers. Some organisms, such as the bat, use sonar reflected sound to locate prey and to avoid obstacles. Some fish can navigate through tight crevices by detecting changes in their electric field. Electronic instruments enable researchers to detect and record the sound frequencies and electricity emitted by different species.

When foraging for food, the honeybee orients to the odour of flowers and the polarization of light. It also responds to cues from the sun's position off the horizon. This type of activity is called sun compass orientation. On returning to the hive the bee performs certain "dances" a variety of motor patterns that vary with the distance and direction of the food.

These dances stimulate the other bees to travel the path of the returning bee.

Fish and birds also exhibit compass orientation when homing or migrating. However, scientists are not sure that animals navigate in the same way as man. When humans navigate, they use such instruments as the sextant to find the altitude of the sun and stars and a chronometer for timekeeping. It has not yet been demonstrated that homing and migrating animals can "shoot an azimuth" and "tell time."

Some animals are known to return to the areas where they were born or spawned. The salmon, for example, upon reaching sexual maturity responds to the chemical characteristics of the stream in which it was spawned. The hormonal changes associated with sexual maturity are a cause of this new sensitivity. The stickleback moves from salty to brackish water to reproduce. Its behaviour is related to endocrine gland responses to seasonal fluctuations in light. Similar hormonal changes in birds lead to migration and reproduction. These cyclic changes in behaviour due to hormonal regulation are considered evidence of a chronometer that might enable migrating or homing animals to correlate changes in visual cues during compass orientation with changes in internal rhythms and thus make navigation possible.

Social Behaviour

All living things relate to other members of their species. In an amoeba, the relationship occurs only during the short time it takes the animal to split into two animals. In other species, such as the social insects, the relationship is so necessary that they cannot survive as individuals. This is true also of humans, who are dependent on others until they reach maturity. Social organization of some kind is common to all animals. However, the type of organization varies with the nervous system of the species. And in true social organization, animals of the same species react to each other.

Con-specifics, or animals of the same species, may at times be close to each other without exhibiting social behaviour For example, mollusc larvae may respond to changes in the intensity of light by swimming to the water surface. The resultant grouping, called an aggregation, stems from a common response to a physical aspect of the environment. But a response is truly social only when it is a response to visual, chemical, auditory, or other stimuli emanating from a con-specific As a result of such stimuli, animals may approach each other to form a bond or to fight. Although dissimilar, both reactions are examples of social behaviour

Goby, any of numerous, widely distributed, spiny-finned fishes constituting family Gobiidae, having wide, flat head, large mouth, and ventral fins often united in funnel-shaped disk.

The type of bond formed by con-specifics is a measure of their nervous and hormonal systems. Organisms with relatively simple systems may respond to each other only as long as they give off attractive or offensive stimuli. For example, a worm will approach another worm during the reproductive state because certain chemicals are released. Once mating has occurred, they have nothing further to do with each other. A goby will remain near its eggs only as long as the hormonal state of the fish and the chemical and visual features of the eggs remain the same. Once the fry, or young, hatch, the fish responds to them as it would toward any small fish and tries to eat them. The goby does not recognize the fry as its own offspring.

Although orientation, changing hormonal levels, and other processes play a part, social bonding depends primarily on a mutual exchange of stimulation and food between animals. The give-and-take stimulation of a pair or a group is fundamental to the organization of social groups.

The Army Ant Colony - An Example of a Social Group

An army ant colony consists of many thousands of workers and a queen. The queen is capable of laying large batches of infertile eggs when she is fed sufficiently. These eggs hatch into workers, females incapable of sexual reproduction. However, at a certain stage of the queen's development she produces a brood of males and females capable of reproducing and starting new colonies.

The colony has a two-phase cycle of activity. The nomadic phase lasts about 18 days. By late afternoon or early evening, the larger workers cluster and leave the bivouac area where they spent the previous night. They move out over many yards in the area around the bivouac. As they crawl, they lay a chemical trail. Other ants in the colony travel over the trail, and as the trail becomes more frequently travelled the concentration of chemical stimuli on it becomes stronger. The entire colony, queen and all, eventually move out from the bivouac along the trail. The ants range over large areas, preying on other insects and their young.

Army ants take in considerable food during the nomadic phase. The queen receives a good deal of it. She does not usually forage but is able to feed on the food brought back by medium-size workers. They return to the bivouac to lick the queen for the highly attractive chemicals she exudes. Chemicals that attract or repel con-specifics and heterospecifics (members of other species) are called pheromones. The exchanges of food and secretions between the queen and the workers produce a strong social bond that aids in keeping the colony together. The queen's increased food intake enables her to lay a batch of eggs.

However, this affects her relationship with the workers. She becomes less stimulating to them, and their foraging, therefore, begins to decrease. Now the colony enters the other phase of its cycle the statuary phase. The number, frequency, distance, and area of foraging decreases considerably. The level of the entire colony's activity drops to a minimum.

After about 21 days the eggs hatch, and the larvae emerge. These squirming, active young are an intense source of stimulation to the workers. The workers are driven out of the bivouac and the nomadic phase starts again. They are now attracted by the pheromones of the larvae and the queen. When the workers return from foraging, they drop their food and feel and handle the larvae with their antennae and legs. As a result of this excitation, the number and frequency of raids again increase. The colony travels great distances, the larvae are fed, and the queen is overfed. At this point, the colony consists of the queen, workers, and larvae.

About 18 days after the eggs have hatched, the larvae enclose themselves in cocoons and become pupae. At about the same time, the queen lays her next batch of eggs. Now the colony consists of the queen, workers, pupae, and developing eggs. However, the pupae and the eggs offer little stimulation for the workers, and the statuary slowdown begins. But the queen continues to secrete pheromones that socially bind the colony.

Dominance

In communities of certain animals the ruling, or dominant, animal is the largest, strongest, or most aggressive and thereby exerts the most influence on the other animals in the group. The dominant animal enjoys the greatest and most preferential access to members of the opposite sex and control of the best territory for feeding and breeding. Many groups of animals, most notably baboons, birds, foxes, lions, and crocodiles, establish dominance hierarchies. The best-known example is the pecking order of chickens. Flock members are arranged on the "rungs" of a social ladder, with each chicken superior to those below and subordinate to those above. The top animal has primary access to the necessities of life, such as the best food, mates, and living quarters. Submissive animals are left with less-desirable food, mates, and living quarters. Such animals may even be expected to groom dominant members and to help care for the offspring of more dominant animals, because subordinates are often prevented from having offspring of their own.

In other animal groups, dominance hierarchies are more complicated. Wolf packs, for example, are led by two dominants who have three subclasses of subordinates below them. Other animals have only one dominant leader with all other animals below him or her being exactly equal. Once an animal has established dominance, challenges to the order are rarely made from within the group, since animals are reluctant to fight other animals that are bigger, stronger, or more aggressive than they are themselves. Sometimes, however, animals from outside the group can successfully challenge and overthrow a long-time leader, but this is rare.

In more intelligent species, such as baboons, factors beyond mere size and strength determine the dominance hierarchy. Age seniority, hormonal condition, maternal lineage, and personality are sometimes factors that affect dominance in more intelligent animals. In baboon groups, furthermore, hierarchies are often elaborate. Adult males are dominant over less mature males and females; yet a fully mature female can be dominant over a less mature male. A dominant baboon displays its superiority with rapid "fencing" manoeuvres, open-jaw displays, and hitting.

Close Bonds Among Animals

Animals with complex nervous systems, ranging from some fish to mammals, may form monogamous bonds. The mates of such species stay together for a breeding season or even for a lifetime. Their social ties are not restricted by the time-bound, immediate stimulation that simpler animals need. However, monogamous pairs must be able to identify their mates from other con-specifics This requires the intricate action of an advanced nervous system.

Some birds and many mammals band in large groups, such as herds and families. These groups include adult males and females and offspring of different ages. The offspring in most mammalian groups remain with the group until they reach sexual maturity. The females frequently remain until the group splits up. Some socially bonded groups of mammals consist of an older male, a number of younger males, many females, and immature offspring. Among the howler monkeys and some other mammals, the younger males band together into a marginal bachelor group until each establishes himself as the older male in a new social group.

Not all mammals maintain elaborate group arrangements. Many live fairly solitary lives, coming together only for mating. Afterwards, the female remains with the litter until the young become juveniles or are sexually mature. In some instances, the mating pair stay together until the young are born. Beavers behave in this way. In other instances, the male and the female separate immediately after mating. This is true of many other rodents.

ANIMAL BEHAVIOUR (Part 3 of 3)

The Prairie Dog Coterie - A Complex Social Group

The prairie dog is a rodent that maintains an elaborate social organization. Bond formation among prairie dogs depends on the exchange of auditory, visual, and chemical stimuli. The coterie the social unit of the prairie dog is maintained in a network of burrows occupying a fairly restricted area.

Prairie dog pups are altricial at birth that is, they are so undeveloped that they need adult aid for survival. When the pup is born, its mother is attracted to the helpless young organism. She licks the pup as it emerges from the birth canal, thus replenishing the salts she lost before and during birth. While licking the pup, she breaks the sac in which it developed as an embryo and thus stimulates its breathing response. The pup, still wet from birth, is attracted to the warmth of the mother's body. Moments after birth, the mother and her offspring are exchanging highly attractive stimuli, quickly forming a social bond.

As the pup nurses, it relieves the pressure in the mother's milk gland. Again, the exchange of stimulation strengthens the bond between the mother and her offspring, thus helping to ensure the infant's survival.

As the pup matures, other stimuli become attractive. When it is able to see and hear, the pup begins to recognize the relationship between stimuli that occur at the same time. Soon it leaves its burrow and encounters other adults that it stimulates. From birth, the prairie dog is constantly nuzzled and licked by its mother. When it emerges from its burrow, it is handled similarly by other prairie dogs.

Grazing land, non farm area where animals feed on grass or other plants.

These behavioural patterns maintain prairie dogs in a well-organized life space. There, the family unit reproduces, finds shelter, and feeds. Being grazers, prairie dogs check the growth of tall grasses that would prevent them from easily spotting predators. At the same time, their grazing habits encourage the dominance of fast-growing plants. Thus, the social organization of prairie dogs influences the ecological balances in their environment.

Limited grazing space soon forces maturing prairie dogs to seek new areas. When they enter the burrows of another coterie their odour marks them as strangers, and they are rejected. Pairs of rebuffed animals band together to form new coteries.

The Chimpanzee Family

The chimpanzee is one of the great apes. It lives in a family unit even more complex than that of the prairie dog. The chimpanzee family moves as a group through familiar feeding and resting areas. It has also evolved effective ways of defending itself against predators or from belligerent chimpanzees attempting to mate with the family's females.

When a chimpanzee has been attacked or has spotted a predator, it lets out an intense cry that raises the level of excitement of the other members of the family. They scream at the predator, throw rocks and other objects, and scamper off. As they flee, the females and the youngest chimpanzees are surrounded by the juveniles and the young males. The largest males guard the group. Thus, the action of a single chimpanzee serves as a signal that affects the behaviour of the rest of the family.

Animal Communication

Communication in the animal world takes many forms. These include chemical, visual, and audible signals. Attacked insects secrete a pheromone that so excites their con-specifics that they either attack or escape from the predator. Flocks of birds behave similarly, except that sounds rather than chemicals trigger the response. Vocalization also evokes social responses in the porpoise, an aquatic mammal. Porpoises communicate by means of whistles and other sounds. When a porpoise is born, females may be attracted by the mother's whistles. They swim to the baby and nuzzle it. The mother does not attack other females at this time. Possibly, this experience with many adult porpoises in the earliest days of infancy helps form the tight social bond of porpoises.

Reciprocal stimulation affects the behaviour of any animal, whether briefly or for a long time. Each organism is the source of environmental changes that affect other organisms. For example, after an amoeba ingests a food particle, it excretes a metabolic by-product that changes the chemical characteristics of the environment. If another amoeba is nearby, it tends to approach the first, though it will not do so if the chemical concentration is too intense. A sexually mature male cricket stridulates rubs its legs together and produces a sound whether or not another cricket stimulates it. However, it is more likely to stridulate when it hears another cricket.

When one animal can prompt an anticipated response in another, it displays a more advanced type of communication. For example, in an experiment a chimpanzee was trained to obtain a banana by pulling on a rope attached to a weight. Then the experimenter increased the weight so that one chimpanzee could not raise it but two could. If the second chimpanzee had already been trained to pull the rope, the first was able to stimulate it to do so by gesture, vocalization, and shoving. The two would then pull together and get the banana. In this case, the consequence of the second chimpanzee's behaviour was in some way anticipated by the first.

The directed activity of one animal toward another for the solution of a problem or the attainment of a planned goal is evident only in advanced species. Furthermore, man is the only species capable of transmitting ideas through a complex system of speech and writing.

The study of the evolution of language has given rise to a science called semiotics. This science attempts to understand the similarities and the differences among the many forms of communication.

Heredity and Behaviour

The evolutionary principle of selective adaptation holds that a species survives when it is able to adapt to environmental changes and when it is able to transmit to its offspring the genetic information that makes such adaptations possible. But how do genetic processes contribute to the development of behavioural patterns? Which behavioural patterns are hereditary? Which must be learned by each new generation?

In an effort to answer such questions, behavioural scientists have designed a number of experiments. In one type of experiment, closely related species with distinctly different behaviour patterns are hybridized. For example, two species of parakeets that practically share a natural habitat but do not interbreed were crossed in the laboratory. The parakeets of one species ordinarily tuck nesting material under their tail feathers. The others carry it in their beaks. The hybrid female offspring made inadequate tucking motions with the nesting material, and the twigs fell out from their feathers. However, all the hybrids carried the nesting material successfully in their beaks. Scientists felt that since all the hybrids performed some part of the tucking behaviour, it was probably the earlier form of behaviour in the evolution of these species.

The relationship between heredity and behaviour has fuelled an old but continuing controversy in the behavioural sciences. Some scientists believe that genetic processes underlie every kind of behaviour, while others think that the environment can modify genetically influenced behaviour In one type of experiment testing these views, animals with different genetic backgrounds are reared in the same environment. In another type, animals with the same genetic backgrounds are raised in different environments.

Chaffinch, European bird of the finch family, sought as a cage bird because of its beauty of voice and its ability in learning to sing tunes.

Cross-fostering is used to rear species with different genetic backgrounds in the same environment that is, the young of one species are raised by a female of another species. In one cross-fostering study, a female great tit reared a baby chaffinch with her own babies. Great tits and chaffinches are closely related birds that feed in different ways. The great tit holds food under its feet; the chaffinch does not. A chaffinch hatched by a great tit did not use its feet during feeding, while its nest mates did. Its feeding behaviour remained typical for its species, although it had no opportunity to observe other chaffinches.

However, when a great tit was reared in isolation, though it too demonstrated species-typical behaviour by holding its food down, it did so very clumsily. Only after repeated tries did its performance improve. This experiment showed that experience may be important even in genetically determined behavioural patterns.

Manipulation of the physical environment was used to study the subspecies of deer mice. One subspecies lives in the forest, is a climbing animal, and has a longer tail and larger ears than the other, a prairie subspecies that lives in grassy fields. The two subspecies were reared in the same laboratory and then released in a room containing artificial grass and wooden posts with flat tops. Although neither subspecies had experienced its species-typical environment, the forest deer mice organized their life space around the "trees," and the prairie deer mice settled under the "grass." However, when prairie deer mice were bred in a laboratory for more than a dozen generations, they no longer showed a preference for the field. The environment eventually so altered the genetic processes of these experimental animals as to change their species-typical behaviour.

Meadowlark, bird of the genus Sturnella, family Icteridae; sharp-billed, 8 to 11 in. (20 to 28 cm) long; two North American species streaked brown above, with yellow breast crossed by black V; western meadowlark (S. neglecta) known for intricate fluting call.

Bird-song patterns are species-specific and have, therefore, been regarded as genetically determined. Studies of the development of species-typical song patterns have helped to clarify the relative roles of heredity and experience in the development of such patterns. For example, if a meadowlark is exposed to another bird's song while it is learning to sing it will learn the other bird's song; however, if the meadowlark is exposed to the songs of other meadowlarks along with those of another species, it will learn only its own species-typical song. The bird instinctively chooses its species-typical song when it is in a situation in which there is a choice.

The response patterns of birds are so varied that the contributions made by genetic processes and by the auditory and other experiences of a bird during singing are hard to separate. It may be that in the course of its development a bird produces certain sounds that are a function of its peculiar body make-up These sounds may be the fundamental vocalization of the bird's species. Additional experience by the bird with hearing and producing its own song, as well as hearing those of other birds in a social setting, may yield the "dialect," or song pattern, associated with the species. However, genes do not carry this pattern as such. Rather, they carry the code for the biochemical processes that develop certain body systems that, aided by experience, will affect the animal's behaviour in its typical environment.

Assisted by Ethel Tobach, Curator, Department of Mammalogy, American Museum of Natural History, New York City.

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