Behavioural Ecology and Socio Behaviour of Animals | Psychology

In this article we will discuss about the behavioural ecology and socio behaviour of animals.

Behavioural Ecology of Animals:

Behavioural ecologists investigate how animals find their way about (orientation and navigation), how they find a place to live (habitat selection), what foods they select to eat (foraging behaviour), and the ways in which behaviour can influence population biology.

Habitat Selection:

Habitat selection refers to the animal’s choice of a place to live. Two types of factors affect where animals of a particular species live. First are the animal’s physiological tolerance limits, which are determined by the species evolutionary history and may involve temperature, humidity, water salinity, and other environmental parameters.

Within those constraints, a second set of psychological factors are important- Animals make choices about where to reside based on available food resources, nest sites, lack of predators, and past experience. For example, woodland deer, mice may be constrained to live in forests rather than fields because they cannot tolerate the high temperatures in the field environment.

Within the forest, they may prefer (choose to live in) areas with larger trees because these trees provide more food in the form of acorns and beechnuts, in addition to better shelter and more nest sites.

Foraging Behaviour:

All animals must consume food to survive. For most organisms, a large portion of their daily routine involves finding and consuming food. The process of locating food resources is called foraging behaviour.

Animals face the following choices:

i. What items should be included in the diet?

ii. Given that food is not often distributed evenly in the environment, but occurs in patches or clumps, what path should an animal take between patches, and how should it locate new patches of food?

iii. As the food in a patch is depleted, when should the animal depart from that location and seek another patch of food?

Hummingbirds and various species of bees that visit clumps of flowers to obtain nectar must make each of these decisions. Owls that forage for small rodents in different habitats, including fields and forests, must make similar decisions.

Although animals do not calculate their personal energy budgets as they forage, there are energy costs and gains in finding and consuming food. These considerations include energy needed to search for food, energy used to pursue or handle the food, and energy required to digest the food.

If the animal is to survive, then the energy gain from digesting a particular set of food items must exceed the costs. Thus, a praying mantis must expend energy to locate a moth, to strike the moth, to remove the moth’s wings, to consume the moth’s body, and finally, to digest the meal.

The mantis will survive if the energy derived from digesting the moth is greater than these costs. This is particularly true if extra energy is needed for searching for a mate or laying eggs.

Specialists and Generalists:

Some animals are specialists with respect to diet and habitat selection. Evolution has resulted in these animals being very efficient at utilizing a particular resource. The koala, an Australian marsupial, eats the leaves of only certain species of eucalyptus trees. Its digestive system is adapted to derive energy from the leaves of these trees more efficiently than are the digestive systems of other animals.

Although being a specialist means successfully exploiting a particular resource, it is also risky. If a plant disease invades and kills trees of the eucalyptus species that form the koalas’ diet, koalas may not be able to survive.

At the other end of the continuum are generalists, animals capable of eating a variety of foods or living in a variety of habitats. These animals can survive under a wide range of conditions. Humans are a good example of a generalist species.

So, too, are some pest species, like European starlings, introduced into the United States a century ago and now living in almost every available type of habitat. The disadvantage for generalists is that almost everywhere they eat and live, they face competition from other organisms, something that specialists often avoid.

Social Behaviour of Animals:

Social behaviour typically refers to any interactions among members of the same species, but it also applies to animals of different species, excluding predator-prey interactions.

Living in Groups:

Animal populations are often organized into groups. A group of animals may form an aggregation for some simple purpose, such as feeding, drinking, or mating. Several Drosophila flies on a piece of rotting fruit are an example of an aggregation.

A true animal society is a stable group of individuals of the same species that maintains a cooperative social relationship. This association typically extends beyond the level of mating and taking care of young. Social behaviour has evolved independently in many species of animals; invertebrates as well as vertebrates have complex social organizations.

One major benefit of belonging to a group may be that it offers protection against predators. There is safety in numbers, and predator detection may be enhanced by having several group members on alert to warn against an intruder. Also, cooperative hunting and capture of prey increase the feeding efficiency of predators.

Living in social groups is also advantageous in some instances due to the ability to gain protection from the elements (e.g., huddling together in cold weather) and during the processes of mate finding and rearing of young. In many species, most notably the social insects, living in groups have resulted in the evolutionary division of labour, with specific individuals performing specialized tasks (e.g., defense, food procurement, feeding of young).

A disadvantage of group living may be competition for resources. Other disadvantages include the diseases and parasites that may spread more rapidly in group-living animals, and interference between individuals with regard to reproduction and rearing of young. The value of group living depends on the species and behaviours involved.

Agonistic Behaviour, Territories, and Dominance Hierarchies:

A society of animals usually has some maintenance of social structure and spacing of group members. Agonistic behaviour, in which one animal is aggressive or attacks another animal, which responds by either returning the aggression or submitting, is often responsible for these patterns.

In rare cases, agonistic behaviour is lethal, but usually, animals are not killed or even severely injured. In many species, males vent much of their aggression in the form of threat displays. Displays typically involve signals that warn other males of an intention to defend an area or territory.

In dominance hierarchies, a group of animals is organized so that some members of the group have greater access to resources, such as food or mates, than do others. Those near the top of the order have first choice of resources, whereas those near the bottom go last and may do without if resources are in short supply.

An example of a dominance hierarchy is the “pecking order” of chickens in a pen. When chickens are placed together, they fight among themselves until a linear hierarchy of dominance is established.

Higher-ranked chickens are among the first to eat and may peck lower-ranked chickens. Once the hierarchy is set, peaceful coexistence is possible. Occasional fights will occur if a bird tries to move up in the order.

Dominance hierarchies exist in many vertebrate groups, the most common being in the form of linear relationships, although triangular relationships may form. In baboons, the strongest male is usually highest in the rank order. But sometimes, older males may form coalitions to subdue a stronger male and lead the troop.

Altruism:

In altruism, an individual gives up or sacrifices some of its own reproductive potential to benefit another individual. For example, one individual of a group of crows gives an alarm call to warn other individuals of the group of an approaching predator, even though the call may attract the predator to the sender of the signal. How did such behaviour evolve? Are normal natural selection processes at work here?

To be successful in a biological sense, an animal must produce as many young as possible, thereby passing its genes to succeeding generations. However, genes can be passed on by aiding a relative and its young because they probably share some genes. In terms of reproductive potential or output, an individual may theoretically pass more genes to the next generation by aiding the survival of relatives than rearing its own young.

A well-known example of altruism occurs in societies of hymenopteran insects, such as honeybees. The male drones are haploid, and the female workers and queen are diploid, resulting in a genetic asymmetry. Diploid workers share, on the average, three-fourths of their genes with their full sisters.

If they reproduced, they would share only half of their genes with hypothetical offspring. Thus, female honeybees may have more genes in common with their sisters than they would with their own offspring. The workers may pass more genes to the next generation by helping their mother produce more full sisters, some of whom may become reproductive queens, than if they produce their own young.

William Hamilton proposed the idea of kin selection to explain how selection acting on related animals can affect the fitness of an individual. In this way, a gene that a particular individual carries may pass to the next generation through a related animal. An individual’s fitness is therefore based on the genes it passes on, as well as those common genes its relatives pass on.

A genetically based tendency to be altruistic could therefore be passed on by the individual carrying it or by a relative who also carries it. Obviously, for kin selection to work, individuals of a group must be able to identify relatives, as can small groups of primates and social insects.