1. WHY DO THEY LIVE IN HERDS ?
ANIMALS
WHY DO THEY LIVE IN HERDS ?

2. INTRODUCTION
Many animals live in herds also known as social groups. This is mainly done in order to survive on a day-to-day basis.
When living in social groups it is such easier to communicate with other individuals and this increases the efficiency of the whole group.

3. Introduction cont…
The sizes of social groups varies from species to species.
There are numerous reasons why animals live in groups and these are all inter linked.
Even though there are many advantages to living in social groups, there are also some disadvantages.

4. THERE ARE NUMEROUS REASONS AS TO WHY HERBIVORES LIVE IN HERDS..

5. Feeding efficiency
protection from predators
Reproductive efficiency
Division of labour
Social transmission of information

6. Reproduction efficiency
There are advantages that animals obtain from being social, however these advantages are different within each species and each has its own pattern of social organization, D Barash (1982).

7. Benefits amongst species does not occur across-the-board.
Thereby meaning that each species reaps its own benefits in its own unique set of ways. Different species displays different social patterns. For example some species only provides adult sociality and this may differ for other species, Barash (1982).

8. Within social groups male and female encounters are easily facilitated and this makes reproduction more efficient, as no time is wasted searching for mates, Barash (1982).

9. Males and females that do not live in organized colonies often find it difficult to integrate with the opposite sex and the entire process of finding a suitable partner is rather time consuming.
An example would be the Indian rhinoceros, this species is endangered due to its habitat being destroyed and over hunting. As a result it has ended up solitary and now relies mainly on chance encounters between males and females for reproduction. This results in the population decreasing and this makes chance encounters even less frequent. Barash (1982).

10. “Nothing is all good or all bad”, according to Barash (1982).
Even though social groups do provide frequent male and female encounters, it can also decrease the chance of any particular individual from breeding successfully as the competition between species for sexual partners becomes greater and greater. Some species which are asocial especially males who disperse and leave their reproductive social units, forms bachelor groups. This happens because if these individuals remain in their social group there is a greater chance of being reproductively excluded and so by seeking other reproductive encounters within other social units are more likely to increase their fitness, Barash (1982).

11. Avoiding Predation
Predation is an important factor which plays a major role in the structuring of social groups.

12. There is safety in numbers.
When individuals remain in large groups it is much easier to avoid predators.
The larger the social group, the greater the chances of escaping predators.
Once prey have detected predators there is a greater chance that prey will be able to defend themselves when in a group than when they are alone. Each species relies on its own eyes, ears and nose to detect potential predators. When living in a group each individual does not only rely on its own senses but also depends on the senses of all the members within the group. The confusion effect occurs when the prey numbers become so large that it makes it difficult for the predator to single out a particular individual. Barash (1982)

13. The confusion effect decreases the likelihood of predation.
When avoiding predators, social groups spend less time in antipredator vigilance.
Once prey have detected predators there is a greater chance that prey will be able to defend themselves when in a group than when they are alone. Each species relies on its own eyes, ears and nose to detect potential predators. When living in a group each individual does not only rely on its own senses but also depends on the senses of all the members within the group. The confusion effect occurs when the prey numbers become so large that it makes it difficult for the predator to single out a particular individual. Barash (1982)

14. Alarm calls . . .
Animals which live in large groups often make use of alarm calls to let individuals of the same group know when predators are spotted.
Alarm calls contains information that is quiet precise, this results in alarm call for specific animals to be very unique. Barash (1982)

15. Efficient feeding
Animals should not only ensure that they reproduce successfully and avoid being captured by prey, but they should also ensure that they receive enough food to survive, Barash (1982).
Barash (1982)

16. When individuals search for food it is much easier to find food when in part of a group as a larger area can be covered and at the same time there is enough protection.
Barash (1982)

17. Animals living in social groups have an advantage over animals who are solitary when it comes to feeding.
Animals within social groups are able to share information about the areas where food is is present with other group members. This exchanging of information is something that solitary individuals do not have. Barash (1982)

18. Individuals which are part of a group are able to capture prey larger than them irrespective of the average size of individuals in the group.
Social individuals are able to capture prey much,much bigger than themselves. An example would be hyenas, their hunting success is mainly due to their large social group, their large group size enables them to catch prey up to several times their size, Barash (1982).

19. Conditioning their environment
The biological conditioning of the environment is an effect that animals use to modify their environments.
In order for organisms to be highly successful they sometimes need to change their environments in order for them to survive. According to King (1955) and Barash (1973), examples of organisms who modifies their environments are the prairie dogs and the marmots. They are live in extensive burrow systems,which have been dug by members of a colony. By eating on brushy plants (prairie dogs) and true seedlings (marmots), they help maintain an environment that is appropriate for them and in the process prevents their grasslands from being altered to a habitat less suitable, Barash (1982).

20. Division of labour
Amongst large social groups there is a greater chance of labour being split between the individual within the group, according to Barash (1982).
As individuals specialize in their behaviour, they increase the efficiency of the group, according to Deag (1980).

21. Social transmission of information
Within social groups individuals are able to obtain information by watching and imitating other individuals.
Some individuals are able to avoid being killed , due to transmission of information. Rats for example are very difficult to trap or poison this is mainly due to their ability to transmit information. When a rat has had a bad experience or observed another individual having one with traps or poison , it will not go near that substance or object again and this behaviour will then be copied by other rats as well, Barash (1982).

22. Warthog- Phacochoerus aethiopicus
They occur in Northern and Southern savannas.
Adult female and male do not always live together all the time and get together for mating.
Some social groups are small and some are large
Adult females live together and share the areas in which they live. The males stays in the same area in which they were born and only leave after living with brothers and other males to whom it not related after four years, it will then join a group of adult females while they are on heat. .(

23. Elephants Species Loxodonta africana
Their societies are made up of Matriarchal clans
General composed of cow herds
Males live alone
Matriarchal clans are clans which consist of a mother and her offspring as well as daughters with their offspring. Male make up bachelor herd or live by themselves. Cow herd are generally composed of 9 to 11 elephants. There are larger herds that will split in two, but will occupy the same area range. Two or three family units make up the larger herds, these herd could contain as much as 28 individuals.(

24. References
Barash DP (1982) Social biology and behaviour. Elsevier Science Publishing Co.,Inc., pp: ISBN
Deag JM Social behaviour of animals. The Camelot Press Ltd, Southampton. Pp 75 ; 82. ISBN

25. References cont…
King JA (1955) Social behaviour and social organization, and population dynamics in a black tailed prairie dog town in Black Hills of South Dakota. Contribution of the Laboratory of Vertebrates Biology. Ann Arbor: university of Michigan, Rep. No. 67