A week before World Sparrow Day, journalism student Carly Read met with a Croydon bird expert to find out why the species is in decline.
Stepping onto the platform from the overcrowded train this morning, I bumped into a girl I had noticed tweeting on her mobile phone throughout the journey to Norwood Junction.
As we walked the same way, the common noises of beeping car horns and thundering trains became a distant sound.
It was at that point when I realised the girl and I had something in common: we were both pre-occupied with tweets, although the tweets I followed were not from celebrities, but the calls of the birds from South Norwood Country Park.
March 20 is World Sparrow Day and, to mark the occasion, I met John Birkett, 61, from Croydon RSPB at the park to gain an insight into sparrows and to find out why their future is in jeopardy.
"There are many theories, including the additives in lead free petrol, home improvements such as sealing up roof spaces and a lack of insect food for the young," said John when asked about the decline of sparrows in the Croydon area.
A former forensic biologist who moved to Sanderstead from Lincolnshire in 1973, John also states that sightings of the common sparrow in recent years have rapidly declined.
Mr Birkett explained that, in 1995, house sparrows were reported in 91 per cent of gardens. By 2000, this was down to 70 per cent. According to a BTO Garden BirdWatch survey, the species' decline has levelled off since 2009.
John, who has been bird watching since 1980 and is the author of the book Two Centuries of Croydon's Birds. He added that between 1977 and 2008 the national sparrow population has dropped by 71 per cent.
The 116-acre South Norwood Country Park opened in 1989. As we walked through the nature reserve, mixed with morning joggers, photographers and dog walkers, I was stunned by the colourful array of different birds so casually inhabiting its fields, trees and lakes.
In the afternoon I left John in the beauty of the park on what was a particularly sunny Spring day in March.
Looking up I noticed two yellow parakeets casually sat on the top of the Shell petrol station.
This posed one, simple question. Why would these bird brains would ever want to leave Croydon's little bit of paradise?
