Daniels said the sparrow was introduced to Adelaide in 1860 by the South Australian Climatisation Society in a bid to make the city more like England. The bird's population subsequently exploded and pushed out native small birds. Natural birds started to come back again after the war when there were a lot more gum trees about. But in the last 10 years the numbers have nosedived again. We just can't find them in Adelaide.
Large birds seem to be doing well but all the little ones have dropped away.
Daniels suspects young birds may be more vulnerable than adults, and Griffiths agrees that the smaller the bird, the higher the risk. The pollutants get concentrated in their lungs. It's also probably got something to do with the size of the lungs. This is only an abstract. Link was good on date posted here, but some news sources only allow free access to articles for a week or so, then articles are removed or a charge made for access.