Research finds birds form lasting friendships beyond family relationships

A 20-year study published by nature shows that birds form long-term, interrelationships that are very similar to human friendships. Researchers at Columbia University found that African starlings have partnered with relatives and non-attachers, challenging long-term assumptions about animal social behavior.

Twenty years of observation reveal hidden patterns

The extensive study led by Professors Alexis Earl and Dustin Rubenstein tracks thousands of interactions between hundreds of Lamprotornis Superbus in East Africa from 2002 to 2021. Their findings reveal something great – birds consistently exchange reciprocity between “helpers” and “breeders” to make people any help, thus benefiting both.

“Starling society is not only a simple family, but also a more complex one, with a mix of related and unrelated people, just like humans do,” Rubenstein explained in a study released on May 7, 2025.

This finding represents a significant shift in our understanding of animal cooperation. Although scientists have long known that animals help blood relatives promote their genetic heritage, so far the evidence of non-family reciprocity remains elusive.

Reciprocity takes time to detect

The research team carefully recorded over 12,000 help activities for 563 assistants in 40 breeding seasons. By combining behavioral observations with DNA analysis, they can distinguish the interrelationships between family-based aid and unrelated birds.

Data shows that while starlings do help relatives, they often assist specific non-factions even if their family can help. Even more surprisingly, these partnerships have been around for years, with birds taking turns supporting each other.

Why does it take twenty years to discover this pattern? The study found that although kinship-based help became statistically significant after only three breeding seasons, it was found that the interrelationship required at least 27 seasons to observe. This explains why this behavior is still hidden from researchers who conducted shorter studies.

Adapt to harsh environments through cooperation

Superb starlings live in challenging East Africa, unpredictable Savannahs – in this environment, collaboration can mean the difference between survival and death. The study shows that these friendship-like bonds may be particularly favorable under such harsh conditions.

In this demanding landscape, the group of starlings improves its size and stability by acknowledging unrelated immigrants who can breed almost immediately. These unrelated birds then form reciprocity, helping to have relationships with existing group members, thus strengthening the entire community.

“Many of these birds are basically forming friendships over time,” Rubenstein noted. “Our next step is to explore how these relationships form, how long they last, and why some people stay strong while others collapse.”

Meaning beyond birds

These findings raise an interesting question: How common are these friendship-like bonds throughout the animal kingdom? Rubenstein’s team studied social behaviors in a variety of species around the world, including shrimp, wasps, beetles, mice, and lizards.

“I think that many animal societies may have this mutual helping behavior, and people just haven’t studied them long enough to detect it,” Rubenstein said.

This study provides interesting similarities to human social structures. Like humans, Starlings maintains a strong family bond while also establishing meaningful relationships beyond immediate family members. These non-family connections seem to be as important for group stability and personal success as kinship.

The main findings of this 20-year study:

• The brothers form a mutually helpful relationship
• Over the years, birds have often switched between the “Assistant” and “Baiter” roles
• Non-family help can occur even if relatives can help
• Mutually helpful relationships require at least 27 breeding seasons to be detected
• After 40 breeding seasons, mutual help proves to be a powerful predictor of helping behavior, not kinship
• Both male and female immigrant birds show higher reciprocity rates

As researchers develop more complex technologies for long-term observations, we may find that in the animal world, friendship-like bonds are much wider than previously thought. This Starling study shows that many animal societies may have a level of social complexity that is more like our own than we realize – we just don’t have long enough viewing time to see it.