How Different Species Team Up: Shared Signals Help Animals Drive Off Predators

When danger appears, many animals act as if following the old adage “the enemy of my enemy is my friend.” Recent research reveals that species across habitats use shared signals—vocal, visual, and chemical—to warn one another and form informal alliances against common predators and parasites.

Shared Alarm Calls and Mobbing

A study published in Nature Ecology & Evolution found that more than 20 bird species on four continents produce virtually identical “whining” calls when they detect brood parasites such as cuckoos. James Kennerley, a co-lead author and ornithologist at Cornell University, describes the sound as effectively “the word for ‘cuckoo,’” recruiting multiple species to join the defense.

Tawny-flanked Prinia Responding to a Cuckoo Finch

At an Australian field site, mixed-species mobs responding to these whining calls can be so intense that researchers must enclose a taxidermied cuckoo used in experiments to prevent it from being destroyed. Kennerley recounts that, without protection, the attacking birds would have “just completely shredded it to pieces.”

High-Pitched 'Seet' Alarms

Other shared signals include the high-pitched “seet” call used by various songbirds—and even by red squirrels—to warn of raptors in flight. These calls are pitched so high that raptors have difficulty hearing them, allowing alarm information to travel through the habitat without alerting the predator. If a raptor perches, animals often switch to lower-frequency “mobbing” calls that recruit defenders to harass and drive the threat away.

Superb Fairy Wren Responding to a Shining Bronze-Cuckoo

Cross-Taxa Recognition and Coral Reef Cues

Recognition of other species’ alarms crosses many taxonomic boundaries: monkeys, lemurs and chipmunks can respond to alarm calls from species they share space with. In coral reefs, unrelated fish appear to exchange visual and chemical cues that warn of hunters like barracudas, creating rapid, cooperative escape responses.

Foraging Benefits and Mixed-Species Teams

Shared signalling isn’t only for defense. Cooperative associations can improve feeding success and aid navigation. A PNAS study found that visually acute seabirds (e.g., black-browed albatrosses) foraging alongside scent-oriented species (e.g., white-chinned petrels) captured far more krill than when foraging alone. Whether such associations reflect intentional signaling or one species opportunistically following another remains uncertain, says Jesse Granger, the study’s lead author and an organismal biophysicist at Duke University.

Complex Communication Networks

Wildlife ecologist Erick Greene notes that “very complex multispecies communication networks are pervasive.” Paying attention to the signals of other species, he adds, can confer critical survival advantages: “It can save their lives.” These findings underscore how interconnected animal communities are—and how cooperation can evolve even between unlikely partners.