The economic importance of the house sparrow, Passer domesticus L.: a review

The present paper summarizes what is known about the economic importance and diet of the house sparrow. The species is widespread in the Old World, and in the last 100 years has more than doubled its original range through introductions, settling most abundantly in grain‐producing areas of the world. Owing to a prolonged breeding season, its productivity is high and one pair will fledge about eight young per annum. The consequent very high density of the population in many areas is a major factor in making the sparrow a grain pest. Movements, migratory or local, are not marked in British sparrow populations. A single sparrow eats about 6 1/2 lb. of food per year, and as this is only partly and seasonally grain, it is the great numbers of the bird which constitute the economic menace. Cases are recorded in which 25% of an acre of wheat was destroyed by sparrows and in Russia up to 30% of a crop is generally lost. Table 1 gives a summary of the information available in the literature from stomach analyses. Grain. Data are not very satisfactory for Britain, but in arable areas sparrows' food consists of 75‐80% of grain. A lot of this is waste corn and poultry feed (three‐quarters according to American figures), so that the limitation of such sources of food might form an important first step in controlling sparrows. In fruit‐growing, garden and suburban districts far less grain is eaten (17%). Nestlings eat very little grain: in arable areas it may be as much as 40%, but in non‐arable areas the diet is almost wholly animal. Data for other countries are more complete. Specimens examined from grain‐growing areas (America, Turkestan) show that corn generally comprises half or more of the diet. In America the figure is 78%, but three‐quarters of this is waste grain or feed. In Turkestan two authors give about 50% and one 13%. In the latter case, owing to its great density, the sparrow was still a major crop pest In park and suburban districts results are much like those from Britain: 30‐40% grain is about an average figure. The same differences apply to nestlings: they may exceptionally take up to 50% grain but usually insects predominate, especially during the days just after hatching (50‐78%). Weed seeds. These are not eaten by nestlings. In Britain 10% in arable, 20% in non‐arable arm are the figures given. The same percentage is given for America, but in Germany authors give 34%. and in Turkestan 46 and 83%. It is not certain that this part of the diet is entirely beneficial economically, since some of these seeds pass through the gut in a viable condition, so that the sparrow may be an agent for spreading weeds. Insect food. The proportion of this item in the sparrow's diet varies greatly with locality and season. In non‐arable areas 35% of the food may consist of insects, and this is taken mainly in the summer. In exceptional cases very large numbers of insects may be eaten. The food of nestlings consists mostly of insects in all localities, but in non‐arable areas practically all the food is animal. Most of the species of insects taken are harmful to agriculture. Damage to fruit buds, green vegetables and flowers may be of importance sporadically, but does not call for more than local action. Apart from this, urban sparrows do no great damage and are useful scavengers. It is not thought that big flocks of sparrows in die harvest fields have moved out of the towns temporarily. In competition with other species of birds the sparrow probably menaces only the house martin (Delichon urbica) seriously by appropriating its nest. The evidence examined, though badly needing amplification, especially for Britain, suggests that house sparrows need controlling in arable, but not in other areas.