More food = more aggression

This is about a study done on sparrows, both from the city and the country and, what they found was that the city sparrows were more aggressive than their country cousins BUT it’s not because of the size of the population, the noise or anything - it’s that they get much more food! I wonder if the plentiful food we feed our parrots acts the same way on them - I mean, we know that protein makes them aggressive (and I wonder if they measured that on the study) but just more food?http://www.sciencemag.org/news/2015/07/ … irds?rss=1