Excavator: Ground. Females generally prefer level ground with short grass (especially where there are open patches of bare soil) as a nesting site. The species usually nests in sparse, but extensive aggregations. For example, S.P.M. Roberts (pers. comm.) estimated a maximum density of about five nests per square metre in the grounds of a church in Salisbury, Wiltshire. The total population in this site in 1991 was approximately eight hundred nests in the hectare of lawn.