Better times for House Sparrows

The end of summer always sees a peak in the number of house sparrows visiting my garden, as the young from this year’s breeding attempts join the local flock at my feeding station. Judging by the numbers of young birds present over recent weeks, I suspect that it has been a good breeding season despite the slow start to the year.

More widely, there is also evidence that house sparrows may be doing rather better than they have for a while. The weekly observations made by the BTO’s Garden BirdWatch volunteers (www.bto.org/gbw), for example, suggest that the long-running declines in the house sparrow’s fortunes have levelled off. Of course, any improvement needs to be viewed in the context of several decades of decline – house sparrow populations have fallen from 12 million breeding pairs in the 1970s to just under 6 million breeding pairs now.

The reasons for the longer-term decline are unclear, at least within the urbanised landscapes where the bulk of the breeding population is to be found. Loss of nest sites and feeding opportunities are likely to be the main drivers behind the decline but other factors, such as increased levels of competition, predation and pollution, may have also played their part. Although adult house sparrows feed on seeds, they require invertebrate food for their chicks and this resource is likely to have suffered as gardens have become more tidy, with greater use of pesticides and the preference for exotic plants and shrubs over native ones. Interestingly, a study carried out in urban Bristol showed that house sparrows fared better in areas of lower quality housing than they did in more middle class housing – a reflection, perhaps, of the different levels of house and garden maintenance that come from inequalities in household income.

Just as the reasons behind the decline have yet to be unravelled, it is unclear why things might have improved over recent years. Is the message about wildlife-friendly gardening now hitting home, or could it be that house sparrows now face less competition from a greenfinch population hit by the 2006 outbreak of disease? More work will be needed to find out but, for my part, I am delighted to have my sparrows back.

Sociable sparrows make a welcome return

It is good to see the House Sparrows return to the garden in force. Each morning they arrive from further down the street, a boisterous posse of grey-capped males and chattering females. This chattering becomes all the more evident once the birds have fed, the flock retiring to the thick of next door’s jasmine to indulge in communal banter. ‘Social singing’, as it is known, appears to be an important component of House Sparrow behaviour, its role tied in with social status and flock cohesion.

These are sociable birds and the winter flocks bring together individuals from several local colonies. Many of the youngsters present within these flocks will roost together in thick vegetation, while established pairs often retire to their nest site. Winter flocks of this kind not only provide benefits in the form of greater knowledge of food availability and lower individual risk of predation, but they also serve as the opportunity through which young birds can disperse away from the colony in which they were born.

Cohesion of sparrow society comes from the social hierarchy that is established through plumage and display, and ultimately backed up by force if necessary. In the eyes of a female, the badge which illustrates the suitability (and hence status) of a male is the size of his black bib. The most successful males are those with the biggest bibs and you will see subordinate birds quickly defer to these high-ranking males in many social situations (most notably in access to food, dust bathing opportunities and females).

Our House Sparrows were visitors when we first moved into this house but we lost them soon after, the landscaping of a neighbouring garden removing the cover they favoured and they ceased to venture this far up the street. Now that the vegetation next door has matured, we have seen their return. House Sparrows rarely venture far and for several years it has been frustrating to hear the colony further down the street, knowing they would only rarely reach our garden.

Cover is important for House Sparrows, providing feeding opportunities, protection from predators and a platform for the social singing. Other factors also play a major role in determining House Sparrow numbers, and key changes in the nature of urban landscapes have seen the House Sparrow population effectively halve since the early 1980s. The loss of nest sites, following the introduction of new designs of roofing tile and barge board, coupled with the clearance of scrubby habitats, increased use of pesticides within our gardens and increasing numbers of competitors and predators have all been linked to sparrow decline, even though we have yet to determine which of these is the most important.

Summer heat

July's heat drives me to seek out the shade offered by our young stand of Hazel. These adolescent trees, still untidy in habit, are one of the greenest things left in the garden; everything else looks faded and listless, the bone-dry soil holding little relief for thirsty plants.

It is easy to overlook the impact of the summer heat on our wildlife. While we can retreat to the cool of the thick-walled cottage or the deep shade offered by a patch of woodland, other creatures remain exposed to the full intensity of the sun. This is certainly the case for the Reed Warblers whose reed bed nests often lack covering shade. The females will actively shade their helpless young, perching above them in the nest during the hottest part of the day. The females obviously feel the heat themselves, panting with bill wide open in an attempt to keep cool. Quite suddenly one of the females will 'collapse', tipping from her sitting position onto one side as if in a faint. The bird will then raise a wing high to the vertical. This seems to do the trick, perhaps exposing veins close to the surface under the wing and reducing her body temperature through heat exchange. Just as suddenly she will recover. It will be the youngest chicks - those still naked and helpless - who will suffer most in this incessant heat.

Some creatures clearly revel in the sun's rays; a female Blackbird in the garden basks on the warm slate path, her wing feathers spread and her body feathers fluffed up. Such basking helps to drive out feather parasites but comes at a price, the bird panting heavily in the heat and only able to remain in the open for short bouts before retreating to the relative cool of the summer borders. I have seen other birds indulge in this means of feather maintenance, including one of the local Robins, but others prefer the bird bath or make use of the now dusty soil to bathe. House Sparrows, in particular, seem rather fond of a dust bath.

Many of the insects seem to be doing well and Norfolk's moth traps positively bulge with hundreds of specimens caught on these sultry nights. This bodes well for the local bats, providing an abundance of prey, and presumably for the Nightjars nesting just a few miles away in the forest. Of course, such tinderbox conditions place all of the forest creatures at risk should a careless cigarette butt or piece of discarded glass bring about a forest fire. It is a time for us to be considerate, to keep our bird baths full (and clean) and to think of the consequences of lazy behaviour.

Happy returns

It is wonderful to have the house sparrows back. There was a period of nearly two years when our local house sparrows ceased to visit the garden and the hanging feeders stuffed with tempting food. I am sure that it was the removal of the tall bushes next door that stimulated their disappearance. House sparrows like to feed from cover and they would raid from over the fence, retreating into the bushes if they felt threatened. Now that the new owners next door have reinstated the bushes, the house sparrows have made a welcome return. Bushes also serve another important purpose in sparrow society, providing a venue for the noisy communal gatherings that were once a common feature in our towns and cities. Such gatherings may well have an important social function, perhaps helping to maintain the colonial structure of house sparrow populations.

While the loss of our sparrows was a temporary one, it did mirror a widespread and longer-lasting phenomenon. House sparrow populations have declined across much of the country, the UK breeding population virtually halving in a little over two decades. Worrying though such a decline is, the house sparrow has not faired as badly as its county cousin, the tree sparrow. This now rather scarce bird has suffered from the loss of over-winter stubbles and other changes in farming practices, with a population decline of nearly 80% documented since the 1970s. Such changes stem from the demands that we, as consumers, place on the farming industry.

The two species are fairly easy to tell apart; the male house sparrow with his grey crown, white cheeks and black chinstrap, the latter extending down onto the chest in the form of a black bib. Female house sparrows (and young birds of both sexes) are a light sandy brown in colour with brown and grey streaks on the back and the wings. In tree sparrows the two sexes look identical and can be distinguished from house sparrows by the warm red-brown crown and the black spot that sits within the white cheek patch. There is also a narrow white collar and the black bib is smaller than that seen in the house sparrow. The two species are granivores, feeding on large seeds including cereal grains, and both share the relative large bill that is a feature of such seed-eaters. These immediately distinguish them from another small brown bird that is sometimes, quite wrongly, regarded as a sparrow. This is the dunnock, known by some as the hedge sparrow, a completely unrelated insectivorous species. While the sparrows are happy to feed from our hanging feeders, the solitary dunnock creeps about on the ground below, moving in a mouse-like fashion.