Urban Perils - House Sparrows on the decline

Supertramps are species that have spread around the world in association with humans and they include rats, house mice and a host of weedy plant species.

- By Peter Ryan, Photograpy by Albert Froneman, Zamora/Wikimedia Commons, and Raju Kasambe/Wikimedia Commons

Supertramps are species that have spread around the world in association with humans and they include rats, house mice and a host of weedy plant species. Among birds, arguably the greatest supertramp is the House Sparrow. From its origins in the Middle East, the House Sparrow followed the spread of agriculture throughout Europe and southern Asia and its expansion was only halted in eastern Asia by competition with the closely related Eurasian Tree Sparrow.

During the second half of the 19th century, House Sparrows were introduced to New York, Buenos Aires, Melbourne, Durban and Zanzibar and, aided by further introductions, spread rapidly throughout much of the New World, Australasia and Africa. They are now found in man-modified habitats throughout much of the world and are considered to be one of the most abundant birds on earth.

Much of their success stems from their ability to live in modified habitats. House Sparrows are at home foraging for scraps indoors and are often found inside shopping centres and airport terminals. Most breed in cavities in buildings; indeed, in southern Africa, Dassen Island is the only place they regularly breed in trees, because there are only a few buildings with suitable nesting sites. Famously, a pair even bred 640 metres underground in a Yorkshire coalmine!

However, for the past few decades there have been concerns about decreases in urban House Sparrow populations. This was first highlighted in the United Kingdom, where there is the longest record of sparrow numbers. Populations initially fell in the 1920s, when the shift to motor vehicles reduced the amount of spilled horse food.