How animals communicate to work together across species boundaries

Banded mongooses (Mungos mungo) can cooperate with common warthogs (Phacochoerus africanus) by cleaning them, removing ticks and other parasites, while the warthogs provide access to food and safety from predators through their vigilance and presence. Example footage from Queen Elizabeth National Park, Uganda. Credit: Leela Channer

An international team of researchers have published a new review in Animal Behavior revealing how communication enables cooperation between different animal species. The review, titled "The ecology and evolution of cues and signals in animal interspecies cooperation," highlights how movements, visual displays, calls, and other behavioral cues and signals help partners coordinate interactions and align interests across species boundaries.

From birds guiding humans to bees' nests in return for access to beeswax, to cleaner fish removing ectoparasites from larger reef fishes in exchange for a meal, cooperation between species occurs across a remarkable range of ecological settings. By gathering examples from birds, fish, insects and mammals, the authors highlight the diverse ways that animals exchange information to organize their actions and sustain mutually beneficial partnerships.

Active teamwork between species

Cooperation between animal species requires individuals to coordinate the timing of their actions to achieve shared benefits, often across distinct sensory worlds. For example, the greater honeyguide bird (Indicator indicator) uses specialized calls to guide humans to bees' nests and responds to human calls in return, while warthogs actively solicit cleaning from bird and mammal cleaners through distinctive body poses.

"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 Dr. Katie Dunkley, lead author and researcher at the University of Oxford. "We were particularly interested in how sharing information allows such close coordination between species."

Human honey-hunters (Homo sapiens) can cooperate with greater honeyguides (Indicator indicator) by following their calls and flight to locate hidden bees' nests, then harvesting the honey while leaving behind wax and larvae that the birds feed on. Example footage from Niassa Special Reserve, northern Mozambique. Credit: Dominic Cram

Balancing benefits and risks

Cues and signals help animals identify cooperative partners, initiate interactions, and ensure they benefit from the partnership. Because interacting with members of another species can carry risks, communication is also important for avoiding individuals that might exploit them.

For example, some cleaner fish (e.g. Labroides dimidiatus) and shrimp (e.g. Urocaridella sp.) are brightly colored and use distinctive body movements to safely clean predatory fish species, while lycaenid butterfly larvae employ chemical and vibrational signals to persuade ants to protect them instead of eating them.

Many species rely on multiple senses to improve communication, and the review suggests that focusing only on obvious visual signals may overlook important ways animals exchange information across species.

Flexible communication

Some signals are stable and predictable, like the head or tail-stand postures of fish seeking cleaning services, while others vary across locations and ecological contexts, such as the dolphin behaviors fishermen interpret as indicators of when to cast their nets.

"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 senior author Dr. van der Wal, a researcher affiliated with UCT's FitzPatrick Institute of African Ornithology. "This highlights just how flexible and adaptable interspecies communication can be."

Evolution of cooperation across species

The review also explores how communication systems between species may evolve. Some signals begin as simple cues, features or behaviors that influence how others respond, even though they did not originally evolve for communication.

Over time, these cues can develop into clear signals. Other signals originate as behaviors used in different contexts, such as settling conflicts or caring for young, before being adapted for communication in interspecies cooperation.

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

Collaborative effort

The review paper grew out of an interdisciplinary workshop on interspecies cooperation held in Cambridge in July 2023, where researchers studying a wide variety of systems came together. The paper includes 58 authors spanning multiple disciplines, including anthropology, biology and linguistics, as well as researchers studying animal interspecies cooperation, mixed-species behaviors and systems whe…