Sparrow Post Breeding Biology

During later summer when the final brood has left the nest hole, house sparrows and tree sparrows often disappear from the immediate breeding area. This sudden desertion of colonies can at first seem quite chaotic to the casual observer. House sparrows tend to be more associated with man of the two species and nest further into towns and cities, they are rarely found in natural situations in Britain.  Whereas the smaller tree sparrow tend to nest more on the outskirts of towns and villages occurring well into agricultural land, away from man. This in part is largely due to house sparrows being the more domineering of the two species, forcing tree sparrows into surrounding areas. Tree sparrow habitat in Yorkshire is typically along/near to the coast, with concentrations around wetlands, which have suitable trees for nesting and areas of farmland plantation in which they can breed and forage on adjacent land.


House sparrow - the larger domineering of the two species

Both species of sparrows are gregarious throughout the year, breeding in lose colonies and wintering in larger flocks. Once fledged the young form small foraging flocks which later merge with other flocks of similar birds from other colonies to form larger flocks. These grow throughout the summer and are eventually joined by the adults in early Autumn, when they have finished breeding. These large aggregations typically disperse onto agricultural land rich in food, like spilt grains after the harvest. The flocks typically roost close to the foraging area, resulting in the breeding areas becoming completely abandoned in some cases throughout this period.  Adults soon return once they have completed a full (annual) moult to reclaim old nest sites, young may remain on feeding areas and slowly return back to breeding colonies later in the autumn (typically around mid-late October). At this point sexual behaviour begins again, with males roosting at nest sites and then displaying the following morning, this activity increases as the winter draws on. Both species regularly group together at this time of year, in these feeding flocks, which can be quite spectacular. In addition finches and buntings often associate with these flocks.  



Mixed feeding flock, coming to feed in a bean crop. Note the larger house sparrow (3rd bird from the left).

Currently these flocks at Filey appear to be centred around a bean crop north of the Old Tip area. It is unknown whether they are foraging directly on the beans or associated insects (or both), sparrows will certainly feed on legumes. The flock offers a fantastic opportunity to study this annual behavioural pattern, currently the large mixed sparrow flock has good numbers of reed buntings associating with it. The flock is at its peak where hedgerows or areas of linear scrub bound the field offering a quick escape from predators, it is presumably these areas in which the birds roost. Both sparrow species typically roost in bushes like hawthorn, moving into more evergreen species and tree holes/buildings, where possible, as the winter draws on.