this is mostly derived from http://www.stichtingwittemus.nl/huismusHabitat.html
Stichting Witte Mus has practical experience of expanding a colony of sparrows from tens to hundreds. Most of their website is in Dutch but
there is an English PDF presentation of their work On the expansion of a colony of house sparrows in Andijk. I found they
give details of how sparrows use their habitat that I hadn't realised.
to be updated