NOTE: Species accounts are no longer included within the BirdTrends report and all links to individual species in this BirdTrends report now point to the relevant species page in BirdFacts. Species trends can now be viewed in the "Trends Explorer" which allows you to view a range of temporal trends for each species.
In the current report, there are 30 species for which our best long-term trends show statistically significant population declines of greater than 50% over periods of 31–53 years (see Latest long-term alerts).
These are Grey Partridge, Little Grebe, Lapwing, Snipe, Common Sandpiper, Redshank, Turtle Dove, Cuckoo, Little Owl, Lesser Spotted Woodpecker, Willow Tit, Marsh Tit, Skylark, House Martin, Willow Warbler, Whitethroat, Starling, Mistle Thrush, Spotted Flycatcher, Nightingale, House Sparrow, Tree Sparrow, Yellow Wagtail, Meadow Pipit, Tree Pipit, Greenfinch, Linnet, Lesser Redpoll, Yellowhammer and Corn Bunting (taxonomic order).
Common Sandpiper has been added to this list as the 45-year WBS/WBBS decline was greater than 50%. Little Grebe has also been added to the list in the current report as the 45-year WBS/WBBS trend again raised a formal alert; this species previously a formal alert in both 2017 and 2019 but there are wide confidence intervals around the estimates and it was dropped from the list in the subsequent reports both times as the trends were no longer statististically significant.
The steepest long-term populations declines we have measured are for Turtle Dove, Tree Sparrow, Willow Tit, Grey Partridge, Tree Pipit, Spotted Flycatcher, Lesser Spotted Woodpecker and Nightingale, which have all declined by 90% or more since 1967. Turtle Dove shows the biggest decline of any species in this report (99%) and its rate of decline suggests it may soon disappear as a British breeding bird.
These 30 species that have halved in population size outweigh the 21 species found to show an equivalent increase, i.e. a doubling of population size, over similar periods. The gap between the numbers of species halving and doubling over the long-term has decreased by one species in this year's report.
Except for Whitethroat, which has shown sustained, though still limited, recovery following considerable losses in the late 1960s, all but one of these rapidly declining species already benefit from listing as either red or amber Birds of Conservation Concern (PSoB/BoCC5).
The other exception is the green-listed Little Grebe: although this species raises a high alert based on the WBS/WBBS trend following a decline in the 1980s, this is based on a small sample and the subsequent WBS/WBBS trend (a moderate, though not statistically significant, decline ) conflicts with the BBS trend which suggests that, although declines may have occurred along linear waterways, the species is stable or increasing in the wider countryside.
Four other species listed as amber for population decline after the 2021 review (BoCC5) all arguably meet red-list criteria for breeding population decline based on the figures presented in this report: these are Common Sandpiper, Redshank, Willow Warbler and Meadow Pipit. However, it should be noted that Common Sandpiper is the only newly listed species which meets red-list criteria for the first time in this report.
The other three of these four species all already met red-list criteria at the time of the 2021 review based on the trends presented in this report, but were not upgraded as the headline trends used in this report are not necessarily representative of the UK as a whole and other information available to the reviewers suggested that the UK-wide decline did not meet red-list criteria. The early years of the long-term trends for both Willow Warbler and Meadow Pipit are based largely on English CBC plots and hence the long-term trend data presented here is for England and may not reflect trends for the UK as a whole, particularly for Willow Warbler which is increasing in Scotland.
Similarly, the headline trends used for Redshank are based on habitats along linear waterways and may not be representative of the wider population: the latest BBS data suggest a UK decline of 49% over the period 1995-2020, just below the threshold for red-listing.
Snipe, which is currently amber-listed though not for population decline, also arguably meets red-list criteria, although it should be noted that the WBS/WBBS decline reported for this species is based on a small sample; like the three species discussed above this species arguably met red-list criteria at the time of the 2021 and hence potential red-listing would have been considered and rejected.
A further seven species raise lower-level concern, as a result of statistically significant long-term declines of between 25% and 50%. These are Swallow, Sedge Warbler, Song Thrush, Dipper, Dunnock, Grey Wagtail and Bullfinch. These species are already on the amber list on account of their population declines, except for Swallow which is currently on the green list.
Swallow has been in sharp decline for around ten years but this followed increases during the 1990s and 2000s and hence it did not meet amber-list criteria at the time of the 2021 review. Recent increases by Song Thrush, Dunnock, Grey Wagtail and Bullfinch have been insufficient to fully reverse earlier declines, although both Song Thrush and Grey Wagtail were downgraded from the red list to the amber list following the 2021 review.
Five further species which do not raise alerts over the long-term (53-year) period have recorded statistically significant declines of between 25% and 50% over the 25-year period and hence also raise lower-level alerts. These are Oystercatcher, Tawny Owl, Sparrowhawk, Garden Warbler and Chaffinch. The first three of these species are already amber-listed, whereas Garden Warbler and Chaffinch are both currently still green-listed.
In addition, Curlew (now red listed) has declined by more than 25% (as also shown by atlas data), but raises no formal long-term alert because the confidence intervals around its change estimates are too wide.
Three species with much shorter monitoring histories have also decreased by more than half during just a 25-year period. All of these are already red listed in BoCC5 (Swift, Wood Warbler and Whinchat). Set against these three species are nine that have more than doubled over equivalent shorter periods (see Positive changes).
In addition, Pied Flycatcher and Wheatear, which also have a shorter monitoring history, declined by between 25% and 50% over a 25-year period, as measured by the BTO/JNCC/RSBP Breeding Bird Survey. The former species is currently red-listed whereas the latter is amber-listed and shows a fluctuating trend over this period.
Many of the declining species are farmland and woodland specialists, and some of the alerts may therefore relate to common pressures in these habitats which are reflected in the negative trends for both habitats in the UK Biodiversity Indicators, although some farmland and woodland species may be subject to more specific issues which are detailed in the species accounts, for example the Greenfinch decline has been linked to trichomonasis disease. Four species commonly associated with urban habitats (Swift, House Martin, Starling and House Sparrow) are also declining.
This report should be cited as: Massimino, D., Woodward, I.D., Hammond, M.J., Barber, L., Barimore, C., Harris, S.J., Leech, D.I., Noble, D.G., Walker, R.H., Baillie, S.R. & Robinson, R.A. (2020) BirdTrends 2020: trends in numbers, breeding success and survival for UK breeding birds. BTO Research Report 732. BTO, Thetford. www.bto.org/birdtrends