Blog by Dr Mark Eaton, Principal Conservation Scientist, RSPB Centre for Conservation Science
The beginning of December 2017 has seen the near simultaneous release of two reports on birds in the UK. One is The State of the UK’s Birds 2017 (SUKB 2017), the annual one-stop shop of the latest monitoring news on the countries breeding and wintering birds. This year’s report has a special focus on climate change and the considerable impact it has had, is having, and will have on our bird populations.
The second is the annual report from the Rare Breeding Birds Panel, published in the December issue of the journal British Birds. This report – which given the lags in the submission, collation and analysis of records covers the year 2015 – features data on 100 of the UK’s rarest breeding birds. The RBBP is an independent body, formed in 1972 to facilitate the collection and reporting of information on rare and scarce breeding birds in the UK. Funded by the Joint Nature Conservation Committee (on behalf to the UK’s statutory nature conservation agencies) and the RSPB, with additional support from the British Trust for Ornithology, the Panel collates data from a wide range of sources, principally from the priceless efforts of volunteer birdwatchers who submit records through the county bird recorder network. This collated data forms a valuable resource to support conservation and research on the country’s rarer breeding birds.
Data from the RBBP, combined with that from special surveys such as those for species of high conservation concern run under the Statutory Conservation Agency and RSPB Annual Breeding Bird Scheme (an unwieldy title if there ever was one, so best known by the acronym SCARABBS) enables us to monitor the populations of most of our rare and scarce breeding birds, many of which are amongst our highest conservation priorities.
Photo: Climate change will increase the pressures on species already in decline. Slavonian grebe, and other declining rare breeding birds, are likely to be at a higher risk of extinction in the UK, based on projections of how climate will become less suitable for them. (RSPB Images)
These trends are summarised in SUKB 2017 (page 18), revealing how widely the fortunes of our rarest breeding birds vary. Eleven species have at least halved in numbers over the last 25 years: Slavonian grebe, dotterel, ruff, lesser spotted woodpecker, golden oriole, red-backed shrike, Savi’s warbler, marsh warbler, ring ouzel, fieldfare and redwing. Conversely, an impressive 24 species have either become newly established as breeding species in the UK, or have at least doubled in numbers over the same 25-year period: whooper swan, pochard, bittern, little egret, spoonbill, honey buzzard, white-tailed eagle, marsh harrier, goshawk, osprey, corn crake, crane, stone-curlew, avocet, red-necked phalarope, green sandpiper, wood sandpiper, Mediterranean gull, yellow-legged gull, hobby, firecrest, woodlark, Cetti’s warbler and cirl bunting.
These lists of ‘winners’ and ‘losers’ tell us a lot about the pressures on wildlife in the UK, and the work being done to tackle those pressures. Certainly, there are number amongst amongst the list of winners which owe their recent increases to targeted conservation action. Bitterns have reached record levels thanks to improved reedbed management and ambitious habitat creation, white-tailed eagles have been brought back through successful reintroduction schemes (as has the red kite, which has prospered to the extent it is no longer considered a rare species), and corn crakes, stone-curlews, and cirl buntings have thrived thanks to the efforts of farmers working alongside conservation organisations and scientists. But possibly the biggest influence on the ups and downs of our rarest species comes from our changing climate.
Birds and climate change
SUKB 2017 tells us how the impacts of climate change can be detected in the changes that much of our birdlife is experiencing, from changes in egg-laying dates of some of our commonest birds, through the declining productivity of seabirds, and the changing distributions of wintering waterbirds. Species currently only found to the south of the UK are projected to shift north and east, and to higher elevations as the climate there becomes more suitable. Conversely, those birds which have their southern, “trailing” range edge within the UK are likely to decline as that edge moves north, or even moves out of the UK altogether.
These changes are perhaps most obvious through the varying fortunes of our rare breeding birds. There is a trend towards declines in species of northern Britain, and upland areas, for which the projected shifts in the suitable ‘climate space’ means the UK will become less suitable – of the biggest losers listed above, this includes Slavonian grebe, dotterel, ruff and redwing, as well as other strugglers including purple sandpiper and capercaillie. Of course, climate change may not be the only factor involved in their declines, and much may still be done to mitigate the negative impacts that the changing climate might have. We need to know more, for example, about the impact of atmospheric pollution and grazing pressure on the delicate montane habitats used by dotterel, for example, to understand the role climate change may or may not be playing in their decline.
On the flip side, our list of winners includes many for which we suspect climate might be providing a helping hand; many rare breeders which have the northern edge of their distribution within the UK are increasing, as that ‘leading’ edge pushes north in response to our warming climate.
Some of these are expanding northwards and increasing rapidly despite only having colonised the UK relatively recently: firecrests (first bred in 1962), Mediterranean gull (1968), Cetti’s warblers (1973) and little egrets (1996). And there are signs that more species are arriving – notably, many are wetland birds, which may be benefitting from increased protection in Europe, and the development of new large wetlands in southern Britain, as much as they are from climate change.
As both SUKB and the latest RBBP report show, spoonbills and great white egrets are gaining an increasing secure toehold in our wetlands, black-winged stilts are arriving in greater numbers, and other such as cattle egrets, purple herons and glossy ibises may be hot on their heels. The work of the RBBP and other volunteer-based monitoring will continue to be crucial in monitoring these changes in decades to come.
To read the full SUKB report visit rspb.org.uk/sukb