The House Sparrow is a small but sturdily built bird with a stout bill designed for eating seeds. The overall appearance is somewhat scruffy due to the loose nature of the plumage. Adult males are distinctive, the crown and nape are grey and only the sides of the head are brown. The black bib is wide and extends down onto the chest. The back is warm brown, streaked with black but with a few white wing feathers. In winter, the bib is reduced and the brown at the sides of the head becomes flecked with grey. Adult females and juvenile birds of both sexes are typically sandy brown in colour with brown and grey streaks on the back and wings.
House Sparrows make a wide range of chirping and chattering sounds; the courtship song being rather unkindly described as ‘a monotonous series of the [chirp] call note'.
The decline in House Sparrows has been going on for several decades and there appear to be different factors influencing rural and suburban populations. Agricultural change, loss of nest sites and reduced food availability appears to have influenced rural populations. However, the factors behind the urban and suburban declines are more difficult to isolate.
BTO Research, such as that carried out through the BTO House Sparrow Survey, has highlighted the importance of urban greenspace (notably allotments and houses with large gardens) for feeding and the presence of suitable nesting opportunities. Work elsewhere suggests that a decline in the availability of invertebrates may have reduced productivity.
The individual territory of the male House Sparrow really only consists of the nesting hole and a very small area around it. This is defended vigorously and used as the ultimate come-on for the female. She will judge the male by his vigorous behaviour and also by his plumage. The black bib is the badge he uses and this is very important for him. It seems that males with small bibs can be induced to behave more boldly if they have bigger and blacker bibs painted on them!
The normal nest sites are holes in buildings but if these are not available they regularly build untidy detached nests within ivy. These are really very characteristic and show the House Sparrow’s quite close relationship to the weaver birds which build similar nests in the tropics.
Making the most of BirdTrack data
We have been working to produce useful summaries for bird reports using data from the millions of annual BirdTrack records.