A major project to find out more about how birds behave in the wild is set to continue.
Researchers want to find out how birds change from one year to the next, and how long they survive for.
The team have been trapping and tagging birds at the Blair Drummond estate in Stirling to find out more about their individual condition.
The birds are fitted with a ring bearing a unique number, which allows researchers to identify them if they are recaught.
The birds are weighed and measured, and their age and sex is also recorded.
It is hoped that the same birds will be retrapped next year, when they will be examined again and the two sets of data compared.
The findings will help the team monitor the condition and lifespan of individual birds, and build up a picture of how long they survive in the wild. They will then be able to feed their findings into a conservation strategy.
The project has no fixed end point and the team hope to collect as much information as possible about individual birds as they can.
Involving a research team from Glasgow University, the Tay Ringing Group and the British Trust for Ornithology, the project began in autumn last year and about 400 birds have been tagged so far. They include common species such as blue tits, robins and blackbirds, but also summer migratory species such as willow warblers and whitethroats.
Doctor Stewart White, from the University of Glasgow, said: "The results allow you to look at how a bird's condition has changed, and how long it survives for. It allows you to build up a picture of the biodiversity of birds.
"The longer we keep doing the study, and the more often we collect the birds, the more we can work out things about them.
"The more we know and the more knowledge we have means we are better able to protect them — ultimately it is all about conservation.
"The hope is that we will retrap the same birds next year. It's amazing to hold a bird in your hand and think that it has been to Africa and back."