Guest blog by Dr Mark Eaton, Principal Conservation Scientist, RSPB Centre for Conservation Science

In the UK we are blessed with excellent data on the populations of many of our bird species, and that is thanks to thousands of dedicated volunteers with an enthusiasm for, and expertise in, counting birds, along with the guiding partnerships formed between organisations such as the British Trust for Ornithology (BTO), RSPB, and the UK’s governmental conservation agencies.

These data allow us to track the fortunes of these birds, identifying those that are prospering, and those that are struggling: we can, for example, use this information to provide periodic updates of our Red, Amber and Green lists of Birds of Conservation Concern.

However, sometimes this abundance of information can make it hard to see overall picture – the wood from the trees. One solution is to combine data across many species, into ‘indicators’, which show us the average trend in those species. As well as telling us about broader patterns in bird trends, these indicators may help us to infer what may be happening in wildlife more widely, on trends in the environment around us, and in the pressures that cause such changes.

The UK’s Wild Bird Indicators are produced annually by a partnership of the BTO, RSPB, Joint Nature Conservation Committee (JNCC) and Defra, and the latest updates were published yesterday, 18th May 2017, alongside a matching set for just England.

Photo: The UK’s Wild Bird Indicators report was published yesterday by DEFRA

Data from schemes such as the BTO/JNCC/RSPB Breeding Bird Survey provide trends for the 130 common and widespread breeding species included in the indicator, with a further 46 populations of wildfowl and waders included in the wintering waterbirds indicator. Formal statistical assessments are made of the change from the start of the indicators (in most cases 1970), and over the last 5 years, which in the latest update is between 2009 and 2014. Smoothed versions of the indicators are used to reveal the underlying pattern that can be obscured by between year fluctuations.

Whilst the all species indicator of 130 breeding species show no great change over its course, with species populations being on average 6% lower than the 1970 start point, more substantial changes can be found by looking at specific groups.

Farmland bird indicator has declined

Most obviously, the farmland bird indicator has declined by 55% since 1970. Whilst much of this loss occurred in the late 1970s and early 1980s, with a well-established link between declines in farmland birds and changes in farmland management, the indicator has continued to decline at a steady rate since then; on average, numbers of farmland birds fell by 8% between 2009 and 2014. Of course, within this overall pattern some species have prospered, but turtle dove numbers fell by a shocking 70% over just these five years.

Woodland bird numbers have fallen

News for birds of other habitats is more mixed. Woodland bird numbers have fallen by 21% on average since 1970, and a considerable number such as nightingale, wood warbler and willow tit are on the Red list of highest conservation concern – but over recent years the indicator has been relatively stable. The other three indicators, for breeding water and wetland birds, seabirds, and wintering waterbirds, have all shown significant declines over the recent assessment period.

Drop in numbers of our internationally-important breeding seabirds

Perhaps most worrying of these is the drop in numbers of our internationally-important breeding seabirds, which fell by 5% on average between 2009 and 2014, and by 20% overall since the start of this indicator in 1986.

Graph showing the wild bird indicators for breeding birds in UK, 1970 to 2015. The separation of trends in the ‘all-species’ into four habitat lines illustrates the dramatic differences in the fortunes of birds in these different habitats.