Additional info
Grey Wagtail
Motacilla cinerea
Key facts
| Conservation listings: | Global: Least Concern Europe: Least Concern UK: red (breeding population decline) |
| Long-term trend: | UK waterways: moderate decline |
| Population size: | 38,000 pairs in 2009 (APEP13: 1988-91 Atlas estimate updated using CBC/BBS trend) |
Status summary
Grey Wagtails occur at highest densities along fast-flowing upland streams. WBS/WBBS shows a fluctuating population size along waterways, with a fall during the late 1970s and early 1980s from an initial high point in 1974, some increase since the late 1990s, and another steep drop around 2010. The BBS trend matches WBS/WBBS closely: there was an initial increase but from 2002 the trend was steeply downward, especially in Scotland. The species was moved from the green to the amber list in 2002, and subsequently from amber to the UK red list at the latest review in 2015 (Eaton et al. 2015). However, the long term decline is now categorised as moderate rather than rapid, as a result of a slight upturn since around 2012.
The trends for Grey Wagtail are very similar to those for Pied Wagtail, suggesting that similar factors may be affecting these two species. Clutch and brood size of Grey Wagtails rose as the population fell, and are now getting smaller again. Nest failure rates have dropped substantially, and there has been linear increase in the number of fledglings per breeding attempt, suggesting that reduced survival is the likely driver of decline. Numbers across Europe have been broadly stable since 1980 (PECBMS: PECBMS 2017a).
Data and graphs from this page may be downloaded and their source cited - please read this information
Population changes in detail
| Source | Period (yrs) |
Years | Plots (n) |
Change (%) |
Lower limit |
Upper limit |
Alert | Comment |
| WBS/WBBS waterways | 41 | 1975-2016 | 101 | -36 | -52 | -19 | >25 | |
| 25 | 1991-2016 | 131 | 2 | -12 | 16 | |||
| 10 | 2006-2016 | 144 | -14 | -25 | -2 | |||
| 5 | 2011-2016 | 128 | 39 | 16 | 59 | |||
| BBS UK | 21 | 1995-2016 | 230 | 1 | -12 | 19 | ||
| 10 | 2006-2016 | 271 | -25 | -34 | -17 | >25 | ||
| 5 | 2011-2016 | 236 | 28 | 15 | 43 | |||
| BBS England | 21 | 1995-2016 | 156 | 13 | -6 | 37 | ||
| 10 | 2006-2016 | 190 | -16 | -27 | -7 | |||
| 5 | 2011-2016 | 169 | 22 | 8 | 38 | |||
| BBS Scotland | 21 | 1995-2016 | 33 | -11 | -34 | 27 | ||
| 10 | 2006-2016 | 37 | -41 | -55 | -19 | >25 |
Demographic trends
More on demographic trends
| Variable | Period (yrs) |
Years | Mean annual sample |
Trend | Modelled in first year |
Modelled in 2016 |
Change | Alert | Comment |
| Fledglings per breeding attempt | 49 | 1967-2016 | 56 | Linear increase | 2.63 fledglings | 3.38 fledglings | 28.7% | ||
| Clutch size | 49 | 1967-2016 | 40 | Curvilinear | 4.79 eggs | 4.77 eggs | -0.4% | ||
| Brood size | 49 | 1967-2016 | 83 | Curvilinear | 4.05 chicks | 4.15 chicks | 2.5% | ||
| Nest failure rate at egg stage | 49 | 1967-2016 | 60 | Linear decline | 1.72% nests/day | 0.97% nests/day | -43.6% | ||
| Nest failure rate at chick stage | 49 | 1967-2016 | 59 | Linear decline | 2.05% nests/day | 0.80% nests/day | -61.0% | ||
| Laying date | 49 | 1967-2016 | 63 | Linear decline | May 7 | Apr 29 | -8 days |
For details of analytical methods for the Nest Record Scheme, the Constant Effort Sites (CES) and the Retrapping Adults for Survival (RAS) scheme, please follow links here.
Causes of change
Causes of population decline and fluctuation may be related to survival rates of juveniles or adults. At present there are not enough data to investigate this idea and more targeted studies, for example RAS projects or analyses to relate survival to weather variables, are needed.
| Change factor | Primary driver | Secondary driver |
| Demographic | Overwinter survival | |
| Ecological | Unknown |
Further information on causes of change
Research has focused on the possible effects of water quality on this species. No correlation was found between Grey Wagtail breeding density and pH of streams in Scotland (Vickery 1991), a result supported by other authors who established that river acidity was less important than stream width, area of riffle and presence of bankside trees in influencing Grey Wagtail presence (Ormerod & Tyler 1987a). Laying date was three weeks later in acidic rivers than elsewhere in Wales, however, although clutch size, hatching success and brood size did not vary (Ormerod & Tyler 1991).
The species can feed in a range of habitats adjacent to rivers (Vickery 1991, Ormerod & Tyler 1987b) and do not rely on aquatic food sources (Ormerod & Tyler 1991): this may explain why they are less influenced by acidity of rivers, which has been associated with lower invertebrate abundance but not with Grey Wagtail abundance (Ormerod & Tyler 1991). Unhatched eggs collected over two years in Wales, Scotland and southwest Ireland did not contain toxic level of PCBs (Ormerod & Tyler 1992).
Causes of population decline and fluctuation appear to be related to survival rates. Targeted studies, for example RAS projects or analyses to relate survival to weather variables, have the potential to shed light on the population changes of this species.
Woodward, I.D., Massimino, D., Hammond, M.J., Harris, S.J., Leech, D.I., Noble, D.G., Walker, R.H., Barimore, C., Dadam, D., Eglington, S.M., Marchant, J.H., Sullivan, M.J.P., Baillie, S.R. & Robinson, R.A. (2018) BirdTrends 2018: trends in numbers, breeding success and survival for UK breeding birds. Research Report 708. BTO, Thetford. www.bto.org/birdtrends



