More studies

http://www.springerlink.com/content/g451880j47nx3h70/
This is an extract from a review on the status of the urban House Sparrow, specifically in north-western Europe as this is the more built up area. One interesting thing it says (which I have read in other studies) is that the change from using horse to cars and tractors ect must have had an impact, what with the amount of seeds from feed which would have been ,particularly with house sparrows which have always had a close relationship with humans, a substantial part of they're diet, as well as the increasing amount of dangerous gases in the air (though this was in the 20s and 30s, it may have been a breaking point in the population of rural sparrows). When considering the urban decline there are less clear cut explanations, as the decline is still going and not stabilising like the rural one has. I need to find the whole paper, whether as a hard or digital copy, as it looks like it would consider the reasons as well as the current state of the population.