Population trends
Over a 25 year period the house sparrow population has declined by 62%.
The house sparrow is common through most of its world range. It is tolerant of climatic changes and high mortality, provided that adequate food supply is always available. Sparrow populations have fluctuated greatly over the centuries, with a gradual decline over the last 100 years. Change from horse-drawn vehicles to motorised ones caused the sparrow population in many cities to drop by two thirds, with the removal of an important food supply - the cereal fed to horses. Recent declines have been caused by a combination of reduced plant food in winter, reduced insect availability for chicks, and reduction in available nest sites. On farmland, these are attributed to changes in agricultural practices. Housing of livestock in inaccessible buildings, mechanisation of grain harvest and more effective storage of grain and animal feeds all reduced sparrows access to food. Recent cereal hygiene regulations mean that farm buildings are sealed, and therefore offer fewer nesting sites. In towns lack of food and nest sites are contributing to the decline, but we do not yet fully understand the decline. In the 1950s, the UK house sparrow population was estimated at 9.5 million. They increased to 12 million by the early 1970s, then declined. The population crashed during the 1990s. Over 25 years the population has declined by 62%. Because of this decline in numbers, the house sparrow is now red listed as a species of high conservation concern.
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