Nest-building is not just instinctive but is a skill that birds learn from experience, research suggests.
University scientists filmed male Southern Masked Weaver birds, in Botswana, building multiple nests out of grass during a breeding season.
Their findings contrast with the commonly held assumption among scientists that nest-building is an innate ability.
The researchers found that individual birds changed their technique from one nest to the next.
They also saw that some birds build their nests from left to right, and others from right to left.
Also, as the birds gained more experience in building nests, they dropped blades of grass less often.
This implies that the art of nest building requires learning and may help to explain how birds approach nest-building.
The study was carried out by the Universities of Edinburgh, St Andrews and Glasgow together with scientists from Botswana.
The research will also determine whether birds have the mental capacity to learn.
Alternatively, it might demonstrate whether their skills are developed through repetition.
Researchers chose the colourful African bird because they build complex nests.
This is potentially a sign of intelligence.
Weaver birds build many nests - often dozens in a season.
This allowed the team to monitor differences in nests built by the same bird.
The research, funded by the Leverhulme Trust, was published in the journal Behavioural Processes.
If birds built their nests according to a genetic template, you would expect all birds to build their nests the same way each time. However this was not the case. Southern Masked Weaver birds displayed strong variations in their approach, revealing a clear role for experience. Even for birds, practice makes perfect.