28 JULY 2014

Ethology

Ethology

Ethology is the study of animal behavior in natural conditions. Ethologists observe animals as they migrate, interact with one another, feed, chose mates and care for their young. Knowledge of a species’ behaviour is important if an animal becomes endangered and conservation measures are needed.

On any list of iconic animals from different continents, you might see giant pandas from Asia, the Oryx from Arabia or the Australian kangaroo and most people would also select the lion (Pathero leo) as a key species from the grasslands of Africa. Lions were once found over most of Africa and parts of Asia and Europe but today they are confined to sub-Saharan Africa. Today they are listed as Vulnerable by the IUCN (and Endangered in west Africa); lion populations are declining rapidly.

Lions are the only big cats that live in social groups or ‘prides’ consisting of up to 15 members, usually related lionesses (mothers, sisters, cousins) with their cubs and a few unrelated males that have successfully fought for access to them. This social arrangement gives the lions a better chance of survival because, as top carnivores, they must guard their territory with its precious food resources. Only females hunt, working together to capture wildebeest, zebra or antelopes. Females have no mane and can move easily and stealthily. The different appearance of males and females is known as sexual dimorphism. A large mane is an encumbrance for hunting but is a valuable protection for a male against bites and scratches during fights. Males will protect cubs within the group from attack by males from outside the pride.

If a pride is attacked and the males driven out by a stronger male, the new male will also kill the cubs. He will dominate the pride and mate with the females to produce his own offspring, carrying his genes. If their cubs are lost, all the females in the pride ovulate at the same time, an event known as synchronized estrous. All will produce new cubs at about the same time, an unusual arrangement, but one which benefits the cubs who are cared for by their mothers and aunts. They grow up together and leave the pride as young adults in the company of other youngsters they know. Lionesses give birth to litters of three or four cubs, which take about two years to learn how to survive on their own.

Despite these reproductive strategies, lion numbers are falling as more and more of their habitat outside national parks is taken for farmland and livestock production, and populations of wild prey like gazelles and zebras fall. Estimates put the number of wild lions at about only 30,000 which is half the figure of 10 years ago. Habitat loss and poaching for bushmeat are the main threats but many lions are killed or poisoned by herdsmen for attacking and killing their livestock. Closer contact with humans and domestic animals has also led to the infection of lions with canine distemper and bovine TB.

In situ conservation measures are used to protect and monitor animals in national parks. In some cases fences have been put up to keep wild lions away from domestic animals. Although the situation is not critical yet, it may be that ex situ conservation of lions from zoos maybe needed to maintain genetic diversity if the population falls dangerously low. The Arabian Oryx was saved in this way and has now been re-introduced in its native habitat where it is protected by law from hunters.

You can learn more about ethology and social behaviour in Option A Neurobiology and Behaviour and about in situ and ex situ conservation strategies, including how the Oryx was saved from extinction, in Option C Ecology and Conservation of the IB course.

 


Brenda Walpole has 20 years experience of teaching IB biology and has written over 30 science books. She is currently an independent consultant in science education.

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