Who hasn’t heard the expression 'Birds of a feather flock together'? However, sometimes birds form mixed flocks.
What is more, they often live their lives as though they belonged to the same species.
A paper published in the journal Behavioral Ecology looks at how two small Australian songbirds – variegated fairy-wrens and splendid fairy-wrens – “not only recognize individual birds from other species, but also form long-term partnerships that help them forage and defend their shared space as a group.”
These wrens have a lot in common. According to Science Daily,
“Both species feed on insects, live in large family groups, and breed during the same time of year. They are also non-migratory, meaning they live in one area for their entire lives, occupying the same eucalyptus scrublands that provide plenty of bushes and trees for cover.
When these territories overlap, the two species interact with each other. They forage together, travel together, and seem to be aware of what the other species is doing. They also help each other defend their territory from rivals. Variegated fairy-wrens will defend their shared territory from both variegated and splendid outsiders; splendid fairy-wrens will do the same, while fending off unfamiliar birds from both species.”
These tiny birds take a very un-Darwinian approach to life.
The paper obviously fails to mention that the term ‘species’ can occasionally be rather fuzzy.
The Australian fairy-wrens confirm the Genesis after its kind principle in that they most probably belong to the same 'min' or kind.
University of Chicago Medical Center. 2018. Birds from different species recognize each other and cooperate: Researchers show for the first time how birds from two different species recognize individuals and cooperate for mutual benefit. Science Daily. (21 May).