Some rarer birds have grown in number over last 30 years due to conservation efforts while some well known species have fallen

A skylark, one of the 144 species looked at in the study. The skylark population has fallen by 46% since 1980. Photograph: Michael Finn/PA

by Azeen Ghorayshi, The Guardian

Bird populations across Europe have decreased by over 420 million in the past 30 years, according to a study that brings together the results of scientific surveys in 25 countries While some rarer species have seen an increase in numbers due to concerted conservation efforts, more common species across Europe are facing a steep decline.

Some of the birds that have suffered the most alarming declines are the most well known species including the house sparrow which has fallen in number by 147m or 62%, the starling (53%) and skylark (46%).

The study looked at 144 species across Europe between 1980 and 2009. Dividing the species up into four groups, from extremely rare to most common, analysts found that a small number of common species declined by over 350 million –over 80% of the total population decline of birds in that time period overall. Rarer birds, in contrast, increased by over 21,000 in the same time period.

The results indicate that efforts at conserving rarer species seem to be having an impact but may be too narrow an approach, possibly at the expense of more common species.

“The focus up to this point has very much been on conserving rare species,” says the lead author, Richard Inger, from the University of Exeter. “That’s what it should be, in many ways, but the issue there is that if you’re not careful, you can spend all of your conservation dollars on just protecting the rare things. You can take your eye off the ball, if you will.”

Birds which increased over the course of the study include the blackcap (up 114%), common chiffchaff (up 76%) and wren (56%).

A male blackcap. Photograph: Andrew Darrington/Alamy

The issue is complicated by the fact that conserving rare bird species is relatively easy in comparison to more widespread efforts required to conserve common ones.

“If the species is very localised, there may be very strong conservation measures,” says Graham Madge, a spokesman for the Royal Society for the Preservation of Birds, which collaborated on the study. “Whereas for a species like the skylark, which will occur in most countries across Europe, it’s much harder to bring in a rescue measure because it requires the rollout of broad, landscape-scale conservation measures.”

The most commonly cited reason for this vast decline in bird species is agricultural intensification which has squeezed out areas that birds need for feeding and nesting.

But Inger emphasises that this can’t be seen as the only problem. “People have tended to concentrate on farmland, but some of these species that don’t use farmland habitats at all are also declining. It’s a sign of wider scale environmental issues, such as increases in urbanisation, and the only way we’re going to protect these widespread species is a more holistic approach to how we manage the environment in general.”

Nevertheless, Madge and Inger agree that wildlife-friendly farming schemes like the UK’s will be necessary to focus conservation efforts beyond token rarer species. But the repercussions extend beyond just bird biodiversity, as birds play vital roles in ecosystem processes such as decomposition, pest control, pollination, and seed dispersal. Since common species exist in higher numbers, they play a bigger role in maintaining the ecosystem as well.

“This was a bit of a wake-up call really,” says Inger. “We knew we were going to see a big decline in bird populations, but to see how big that number really was and how focused the declines were on this small number of common species was really very surprising.”