How animal species cooperate and communicate in nature

A small brown bird calls as it flies through the African bush, guiding a person towards a wild bees’ nest until they both reach it.

On the water in southern Brazil, a dolphin arches its back and, at precisely that moment, a fisher casts a net.

Neither encounter is accidental. Both are partnerships between different species, sustained by a continuous exchange of information.

A wide-ranging new review published in Animal Behaviour brings together examples from across the animal world.

It explores a question that sounds simple but is not: how do animals belonging to entirely different species manage to cooperate?

Animal partnerships are widespread in nature

Cooperation between species appears in unexpected settings. Birds lead people to honey, small fish remove parasites from larger fish, and ants protect insects that reward them with sugar.

The review draws on examples involving birds, fish, insects and mammals. In each case, the partners exchange signals to coordinate what they do and maintain their arrangement.

“From the examples we know, individuals coordinate their actions to access shared resources, like food, or to exchange resources for services, such as protection from predators,” said lead author Dr Katie Dunkley, a researcher at Oxford.

“We were particularly interested in how sharing information allows such close coordination between species.”

How partners find one another

First, an animal must recognise a partner willing to cooperate. Some cleaner fish have bright, contrasting colours that identify them as cleaners rather than prey.

Client fish respond with signals of their own. By holding a head-up or tail-up position next to a cleaner, they indicate that they want its services; the cleaner then chooses whether to come closer.

Animals select the best partner

Animals also assess how useful a prospective partner might be. In Brazil, fishers prefer dolphins they know to be dependable, recognising them by their body markings and behaviour.

Cleaner fish give clues about their quality too. Client fish generally favour wrasse with a deeper blue colour, which could indicate a better cleaning service.

When partners are near one another, one often gives a signal to get started. Coral trout and groupers make a rapid body shimmy to summon eels or octopuses for a shared hunt.

The risks are greater if a partner might be dangerous. Some cleaner shrimp sway their bodies towards predatory fish, signalling that they are valuable cleaners rather than an easy meal.

Preventing partners from cheating

Cooperation can break down if one participant cheats. Client fish pursue cleaners that bite rather than clean them, while an octopus may punch a fish that does not contribute enough to a hunt.

Such corrections appear to help preserve the partnership by warning that poor behaviour comes at a cost.

Some signals remain consistent and predictable throughout a species’ range. Others differ between communities, as with dolphin movements interpreted differently by fishing towns.

Senior study author Dr Jessica van der Wal is a researcher affiliated with the University of Cape Town’s FitzPatrick Institute of African Ornithology.

“In some forms of interspecies cooperation, cues and signals vary depending on the ecological context, the species involved, and whether the signal is inherited or learned,” said Dr van der Wal.

“This highlights just how flexible and adaptable interspecies communication can be.”

Sight, sound, touch and smell

Visual and sound signals feature most often in the known examples, in part because people can readily detect them. But touch, chemical cues and vibration are equally important in many partnerships.

Shrimp and gobies live together in a burrow, keeping in contact through touch and chemical cues. Ants identify the distinctive chemical coatings of the insects they protect, allowing them to distinguish a genuine partner from a stranger.

A signal broadcast openly may attract an unwanted audience. The loud call a honeyguide uses to lead people can also bring in rival birds, which eat the wax without contributing any work.

Other species cheat by imitating a partner. Some blennies copy the colours of cleaner wrasse, then bite the clients they attract.

How signals develop

Many signals probably began as simple cues. The sound of a person chopping a tree may initially have alerted honeyguides to someone near honey; over time, people began deliberately making those sounds to summon the birds.

Other signals were adapted from existing behaviours. A fish posture once used to resolve disputes with members of the same species may have been reused to approach a cleaner peacefully.

Some abilities are innate. Young honeyguides approach people and call without being taught, while client fish adopt cleaning poses without prior practice.

Learning refines other abilities. Fishers and honey-hunters learn their partners’ signals by observing others, and ants learn to associate particular insects with a reward.

When cooperation is lost

Signals that must be learned can disappear when knowledge is no longer passed on. In south-eastern Australia, a well-known partnership once involved orcas herding large whales towards hunters in return for a portion of the carcass.

The cooperation ended after the local Indigenous community was displaced, an important orca was killed and prey became scarce. The shared knowledge that had sustained it was lost.

These partnerships are more than a collection of curiosities. They reveal how a signal can arise, pass between species and reshape both partners over time.

“Studying how information flows between species gives us a powerful window into how communication systems originate, change and sometimes coevolve,” said Dr Dunkley.

What comes next

The review emerged from a workshop held in Cambridge in 2023 and united 58 authors working across anthropology, biology and linguistics.

The authors argue that research has focused largely on a small number of familiar systems, leaving substantial gaps elsewhere.

“We still have much to learn about how these systems function and evolve,” said Dr van der Wal.

“We look forward to future research revealing both these interactions and other forms of interspecies cooperation yet to be discovered.”