The researchers wanted to test whether city birds had 'higher boldness, reduced neophobia, and enhanced problem-solving and learning skills'. These specific test was done to see whether they could guarantee reproducibility of the results. Something like a control

that still makes no sense as far as 'intelligence' goes. First off, rural and urban birds have different overall diets. if you stick a french fry in front of a rural bird, it might not know its supposed to be 'food'. Same can be said with water-bugs and urban birds. there are too many factors to consider - though they could have and just not reported the specific metrics.