Mystery of the vanishing sparrows still baffles scientists 10 years on

A A A

The greenfinch may be declining because of a parasitic disease, but nobody knows – still – the reason for the decline of the house sparrow.

It was once our most common and familiar bird. Now, in many places, it has vanished. Yet, more than 10 years after The Independent offered a prize of £5,000 for a proper scientific explanation of the house sparrow's widespread disappearance from many of our towns and cities, London above all, its vanishing remains one of the great environmental mysteries.

Yesterday, for example, there were no sparrows visible in London's Trafalgar Square, whereas 25 years ago the major tourist destination scattered with sandwich crumbs was full of them – as similar sites in major cities around the world are full of them still.

In the 1990s London's house sparrows entered a sudden and sharp decline until, by the turn of the century, they had virtually disappeared from the capital – the last pair of sparrows in St James's Park, packed with other birds, nested in 1998.

When this newspaper launched its "Save The Sparrow" campaign on 16 May 2000, it made international headlines. The fact that the cheeky "Cockney sparrer", the street smart urban survivor par excellence, was no longer surviving in urban habitats, caught people's imagination, not least because their disappearance may resemble the miner's canary – a warning of some unknown and wider danger. If something in the urban environment was devastating sparrows, what was it doing to us?

However, we did not succeed immediately in drawing out definitive explanations. Suggestions for the reason behind the decline ranged from the increase in suburban predators such as magpies, sparrowhawks and cats to the trend in "tidying up" houses and gardens leaving fewer nesting spaces. Disease, mobile phone radiation and insect decline were also posited.

It was not until 2008 that we had a serious entry for the prize, for which the rules were fairly stiff – the explanation had to be in a paper published in a peer-reviewed scientific journal, and accepted by our referees, the Royal Society for the Protection of Birds (RSPB), the British Trust for Ornithology, and the world expert on sparrows, Dr Denis Summers-Smith.

The 2008 entry was based in the work of a young postgraduate student, Kate Vincent, whose 2005 PhD thesis at De Montfort University in Leicester showed that sparrow chicks in some places were dying of starvation in their nests because of the lack of suitable insect food, such as aphids.

Her data, analysed intensively by senior ornithologists led by Dr Will Peach of the RSPB, formed the basis of a paper in the journal Animal Conservation which was submitted for the prize. But of our three referees, one thought it merited the award, one thought it did not, and one thought it merited half the award. It was certainly a serious contender, but as it was possible that another entry might secure the prize unanimously, we felt the award should be held back.

The other entry, submitted earlier this year from Christopher Bell, an independent scientific researcher, and other scientists, was published as a paper in the online version of Auk, the journal of the American Ornithologists' Union, and suggested that the cause of the decline was predation by sparrowhawks. It was rejected by all three referees.

In March, Dr Summers-Smith circulated a note to researchers interested in the sparrow's disappearance, summarising all the theories and suggestions of the last 10 years. His own view is that insect decline, leading to chick mortality, is "a primary factor" but as he says himself: "It is a necessary, but not a sufficient condition."

He feels that other factors must be involved, and that the insect decline has not been properly explained (his own belief is atmospheric pollution).

The most puzzling aspect of the affair remains the suddenness of the decline in the 1990s, when London's sparrow population fell off a cliff. What can have caused it? The introduction of lead-free petrol (containing other harmful chemicals)? The introduction of mobile phones? That does not explain why house sparrows are still numerous, for example, in New York and Washington.

You tell us. The prize remains to be claimed.

News
people'It can last and it's terrifying'
Sport
Danny Welbeck's Manchester United future is in doubt
footballGunners confirm signing from Manchester United
Sport
footballStriker has moved on loan for the remainder of the season
Sport
footballFeaturing Bart Simpson
PROMOTED VIDEO
Have you tried new the Independent Digital Edition apps?
New Articles
Olivia Colman topped the list of the 30 most influential females in broadcasting
tv
News
Kelly Brook
peopleA spokesperson said the support group was 'extremely disappointed'
News
The five geckos were launched into space to find out about the effects of weightlessness on the creatures’ sex lives
i100
Life and Style
techIf those brochure kitchens look a little too perfect to be true, well, that’s probably because they are
Sport
Andy Murray celebrates a shot while playing Jo-Wilfried Tsonga
TennisWin sets up blockbuster US Open quarter-final against Djokovic
Arts and Entertainment
Hare’s a riddle: Kit Williams with the treasure linked to Masquerade
booksRiddling trilogy could net you $3m
Arts and Entertainment
Alex Kapranos of Franz Ferdinand performs live
music Pro-independence show to take place four days before vote
News
news Video - hailed as 'most original' since Benedict Cumberbatch's
News
i100
Life and Style
The longer David Sedaris had his Fitbit, the further afield his walks took him through the West Sussex countryside
lifeDavid Sedaris: What I learnt from my fitness tracker about the world
Arts and Entertainment
Word master: Self holds up a copy of his novel ‘Umbrella’
booksUnlike 'talented mediocrity' George Orwell, you must approach this writer dictionary in hand
News
i100
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
iJobs Job Widget
iJobs General

SQL Implementation Consultant (VB,C#, SQL, Java, Eclipse, integ

£40000 - £50000 per annum + benefits+bonus+package: Harrington Starr: SQL Impl...

SQL Technical Implementation Consultant (Java, BA, Oracle, VBA)

£45000 - £55000 per annum + Benefits + Bonus: Harrington Starr: SQL Technical ...

Head of IT (Windows, Server, VMware, SAN, Fidessa, Equities)

£85000 per annum: Harrington Starr: Head of IT (Windows, Server, VMware, SAN, ...

Lead C# Developer (.Net, nHibernate, MVC, SQL) Surrey

£55000 - £60000 per annum + Benefits + Bonus: Harrington Starr: Lead C# Develo...

Day In a Page

'I’ll tell you what I would not serve - lamb and potatoes': US ambassador hits out at stodgy British food served at diplomatic dinners

'I’ll tell you what I would not serve - lamb and potatoes'

US ambassador hits out at stodgy British food
Radio Times female powerlist: A 'revolution' in TV gender roles

A 'revolution' in TV gender roles

Inside the Radio Times female powerlist
Endgame: James Frey's literary treasure hunt

James Frey's literary treasure hunt

Riddling trilogy could net you $3m
Fitbit: Because the tingle feels so good

Fitbit: Because the tingle feels so good

What David Sedaris learnt about the world from his fitness tracker
Saudis risk new Muslim division with proposal to move Mohamed’s tomb

Saudis risk new Muslim division with proposal to move Mohamed’s tomb

Second-holiest site in Islam attracts millions of pilgrims each year
Alexander Fury: The designer names to look for at fashion week this season

The big names to look for this fashion week

This week, designers begin to show their spring 2015 collections in New York
Will Self: 'I like Orwell's writing as much as the next talented mediocrity'

'I like Orwell's writing as much as the next talented mediocrity'

Will Self takes aim at Orwell's rules for writing plain English
Meet Afghanistan's middle-class paint-ballers

Meet Afghanistan's middle-class paint-ballers

Toy guns proving a popular diversion in a country flooded with the real thing
Al Pacino wows Venice

Al Pacino wows Venice

Ham among the brilliance as actor premieres two films at festival
Neil Lawson Baker interview: ‘I’ve gained so much from art. It’s only right to give something back’.

Neil Lawson Baker interview

‘I’ve gained so much from art. It’s only right to give something back’.
The other Mugabe who is lining up for the Zimbabwean presidency

The other Mugabe who is lining up for the Zimbabwean presidency

Wife of President Robert Mugabe appears to have her sights set on succeeding her husband
The model of a gadget launch: Cultivate an atmosphere of mystery and excitement to sell stuff people didn't realise they needed

The model for a gadget launch

Cultivate an atmosphere of mystery and excitement to sell stuff people didn't realise they needed
Alice Roberts: She's done pretty well, for a boffin without a beard

She's done pretty well, for a boffin without a beard

Alice Roberts talks about her new book on evolution - and why her early TV work drew flak from (mostly male) colleagues
Get well soon, Joan Rivers - an inspiration, whether she likes it or not

Get well soon, Joan Rivers

She is awful. But she's also wonderful, not in spite of but because of the fact she's forever saying appalling things, argues Ellen E Jones
Doctor Who Into the Dalek review: A classic sci-fi adventure with all the spectacle of a blockbuster

A fresh take on an old foe

Doctor Who Into the Dalek more than compensated for last week's nonsensical offering