Introduction

Behaviour is all the observable actions of an animal. Anything that we see, hear or smell an animal doing is part of its behaviour. We can eavesdrop on an animal's actions. We can use electronic devices, to gather sounds above or below the limits of human hearing, to view wavelengths of light not resolved by the human eye, or to slow down actions too fast to interpret. The end result is that the study of behaviour has a vast subject matter drawn from the huge diversity of animals, and their equally diverse repertoires of behaviour. Furthermore, behavioural acts may vary from one instance to the next, between individuals at some moment in time, and across an individual's lifetime.

Behaviour is generated by the neuromuscular system. It is not confined to the somatic nervous system and striated muscles since autonomic responses (e.g. piloerection) and glandular secretion at the periphery are important components of behaviour. Behaviour plays the pivotal role in an animal's biology because it is through behaviour that the animal solves ecological problems. No matter how elegant its form and inner workings may be, nor how complex its external environment is, an animal's survival and reproductive success depend on finding a place to live, getting energy and nutrients, avoiding injury and predation, and finding a suitable mate and rearing offspring. Behaviour is the key to achieving all these goals; behaviour is at the cutting edge between the animal and its environment.

Why conserve marsupials?

What is biological diversity and why is its conservation vital for human wellbeing?

The conservation of biological diversity (biodiversity) has become a major objective of most nations in the world in recent years and was adopted as an aim by the many nations that have ratified the Convention on Biological Diversity (the Rio Convention). There are four main arguments for conserving living things and the ecosystems that they form.

The first is that simple compassion demands their preservation. Compassion develops from the view that other species have a right to exist – the needs and desires of humans should not be the only basis for ethical decisions. The second argument is based on aesthetics. Plants and animals should be preserved because of their beauty, symbolic value or intrinsic interest. Most people would feel a loss if the world's beautiful and interesting plants and animals, and the wild places they inhabit, disappeared.

Compassion and a sense of wonder are two qualities that distinguish humans from other animals, but unfortunately not all people share these attributes to the same degree. The third argument, however, is one that nearly everyone can understand – money. Unique plants and animals attract tourists to different parts of the world. Plants, animals and microorganisms provide nearly all our food and almost all our medicines and drugs. They also provide renewable resources like paper, leather, fuel and building materials. So far we have used only a minute proportion of nature's storehouse.