Why all the noise?

Updated Friday 16th July 2004

What drives communication in the wild?

It is dusk in a Central American rainforest. The sun drops below the hidden horizon and there is a brief silence as the calls of many birds and diurnal (active during daylight) insects fade away. In the nearby creek, a male toad makes his first, tentative call of the evening, rather like the trilling of a mobile phone. He is soon joined by tens of others of his kind and the contrasting calls of several treefrogs from the leaves overhead.

To a human listener, the multitude of different sounds to be heard under the rainforest canopy represents a bewildering variety of squeaks, chirrups and whistles. How does any animal make sense of the diverse bombardment of sounds in this complex environment? The human analogue might be a busy office where the e-mail has crashed: the boss is shouting for his coffee; the office manager is dictating a memo about desk allocation and Brian from Personnel is chatting up the secretary again.

The rainforest is little different: everybody is shouting because of resources (often food, space and sex). The toad in the creek’s call says many things about him to others of his species. It tells them that he is an adult (and older, larger toads often have deeper voices!); it tells them that he has been successful in his foraging for insects and has accumulated enough energy to expend some of it on calling and it tells them that he is macho enough to defend a good spot in the creek where a female toad might be persuaded to deposit her eggs. Other males should keep away and females should take a look at what he has to offer!

Each animal species which uses sound in this way has evolved its own unique way of communicating its resource status (what it has and what it needs). As well as the advertisement call (here I am, this is what I’ve got), described above, our toad uses a recognisably different aggression call as a direct challenge to an approaching rival male – a very definite “keep away, this is my bit of creek!”.

The females of toads (and other amphibians) rarely call but may give a short squeak if grabbed by an overenthusiastic male. This release call says either “I am not ready to mate” or “I haven’t decided you’re the right one yet”! Female amphibians have been shown to choose potential mates on characteristics of their calls (pitch and length of call, for example). Males with longer (or perhaps deeper, depending on the species) calls tend to father tadpoles which grow faster and into larger youngsters. They therefore have a shorter larval period (time spent as a tadpole) where they are vulnerable to predators, and a greater variety of invertebrate prey available to them when they metamorphose (become terrestrial). The female’s choice of mate, based on the characteristics of his call, may be directly translated into the survival of her offspring!

 

For further information, take a look at our frequently asked questions which may give you the support you need.

Have a question?

Other content you may like

The Greenland white-fronted goose Creative commons image Icon Greenland White Fronted Goose / Hilary Chambers / CC BY-ND 2.0 under Creative-Commons license audio icon

Nature & Environment 

The Greenland white-fronted goose

Waterfowl expert Tony Fox talks to Saving Species about a goose that has been on conservation concern for many years.

Audio
15 mins
Galápagos: Conservation on a World Heritage Site Copyrighted image Icon Copyright: David Robinson article icon

Nature & Environment 

Galápagos: Conservation on a World Heritage Site

What makes the Galápagos archipelago so unique and what is the impact of this uniqueness on its conservation?

Article
Acquired tastes - or why scorpions aren't as tasty as prawns Copyrighted image Icon Copyright: Alessio Moiola | Dreamstime.com article icon

Nature & Environment 

Acquired tastes - or why scorpions aren't as tasty as prawns

Dave Rothery asks what would we be prepared to eat to help save the planet?

Article
Human impacts on the lives of animals Copyrighted image Icon Copyright: Production team article icon

Nature & Environment 

Human impacts on the lives of animals

Tim Halliday explores the human impact upon animals

Article
Meerkat alarm calls Creative commons image Icon The Open University under Creative Commons BY-NC-SA 4.0 license video icon

Nature & Environment 

Meerkat alarm calls

Zoologist Tim Clutton-Brock explains how meerkats use the alarm calls from other species to stay safe - unless it is a Drongo imitating a meerkat!

Video
Saving the mountain gorilla Copyrighted image Icon Copyright: Rick Murphy, University of Wisconsin. Used with permission audio icon

Nature & Environment 

Saving the mountain gorilla

The Saving Species team hear from Ian Redmond on protecting mountain gorillas in Africa, including the deaths of Dian Fossey and Digit

Audio
15 mins
Studying mammals: A winning design Copyrighted image Icon Copyright: Used with permission free course icon Level 1 icon

Nature & Environment 

Studying mammals: A winning design

The term mammal encompasses a huge variety of animals, including humans. But what makes a mammal a mammal? This free course, Studying mammals: A winning design, explores some of the features, such as reproduction, lactation and thermoregulation methods, that mammals have in common. It is the first in a series of ten Studying mammals courses.

Free course
10 hrs
Polar Plankton: indicators of environmental change Creative commons image Icon idua_japan under CC-BY-NC-ND under Creative-Commons license audio icon

Nature & Environment 

Polar Plankton: indicators of environmental change

The Saving Species team talks to Chris Reid and Graham Hosie about studying microscopic polar plankton - the source of all food in the oceans

Audio
15 mins
Research with animals we can’t see and sounds we can’t hear Copyrighted image Icon Copyright: David Robinson audio icon

Nature & Environment 

Research with animals we can’t see and sounds we can’t hear

David Robinson reveals the challenges of research with animals we can’t see and sounds we can’t hear.

Audio
10 mins