From the BBC story:
Rooks have already demonstrated their intelligence in lab-based studies that have tested their ability to solve problems and use tools.
This survey will examine if and how wild rooks apply these skills.
While not everyone agrees that bees exhibit what we'd call 'intelligence', people do seem to agree that corvids (crows and their relatives) are 'intelligent', and we've written about this subject recently here, and in previous posts. Why something about intelligent rook behavior would be responsible for their decline is curious, though -- the results of this study will be interesting.
The study will look at six categories of behaviour: feeding, caching (hiding and storing food), tolerance, object play, socialising and vocalisation.
From the above-linked BBC story
Dr Nathan Emery from Queen Mary University of London, an expert in corvid behaviour who is helping run the study, explained that many of the abilities the birds had demonstrated were previously thought to be uniquely human.
"We've done a lot of different studies on a number of corvids looking into their intelligence and behaviour, focusing on their amazing memories, their ability to imagine future scenarios and plan for them," he told BBC News.
"This survey will provide vital information that couldn't be attained any other way into how rooks use our gardens, eat and cache our food and, importantly, whether rooks can produce innovative solutions to novel problems they don't encounter in the wild."