Waterbirds
Species |
Long-term Trend |
Primary Demographic |
Primary Ecological |
Rapid Increase (UK, Eng) |
Survival |
Other |
|
Rapid Increase (UK) |
Unknown |
Unknown |
|
Rapid Increase (UK) |
Unknown |
Unknown |
|
Rapid Increase (UK, Eng) |
Unknown |
Unknown |
|
Rapid Increase (UK, Eng) |
Unknown |
Unknown |
|
Increase (UK, Eng) |
- |
- |
|
Possible Increase |
Unknown |
Unknown |
|
Rapid Increase (UK) |
Unknown |
Unknown |
|
Increase (UK) |
Unknown |
Unknown |
|
Rapid Increase (UK, Eng) |
Unknown |
Unknown |
|
Possible shallow increase (UK, Eng) Probable moderate decline (Scot, Wales) |
Survival |
Unknown |
|
Uncertain |
Unknown |
Unknown |
|
Stable |
Unknown |
Unknown |
Most waterbird species are increasing in the UK. It is likely that increased water quality and warmer winter temperatures, reducing mortality, are at least partly responsible but there is little direct evidence on the causes of change for most species. For Mute Swan a ban on the use of lead weights substantially reduced mortality in the late 1970s and 1980s, particularly in England, resulting in a population increase (Wood et al 2019). Ingestion of lead shot similarly appears to be associated with population declines in wintering ducks (Green & Pain 2016).
Both Greylag Goose and Canada Goose extensively exploit urban habitats where low mortality rates of adult birds and a relatively high reproductive rate may both contribute to the population increases.
Study of breeding populations of ducks is difficult, the adults are not easy to catch and nest are hard to find and access, so less is known about these species than almost any other group of British birds.
Until the 1990s the Little Egret was a relatively uncommon species, but since the first nesting attempt in 1996 the population has increased rapidly (Musgrove 2002). There is little direct evidence as to why this might be, but a combination of warmer winters, increased water quality and provision of new habitat, in form of remediated gravel pits may all have played a part. It is likely other species, such as Purple Heron, Great White Egret and Cattle Egret may join the Little Egret as British breeding species in the near future, all have successfully bred for the first time in recent years. Herons and egrets, though, are susceptible to cold winters reducing prey availability and increasing mortality (Holt 2012), and the effects of the recent cold winters can be seen in downturns in the trend of both Little Egret and Grey Heron.
Raptors, Owls and Raven
Species |
Long-term Trend |
Primary Demographic |
Primary Ecological |
Rapid Increase (UK, Eng) |
Unknown |
Unknown |
|
Probable Increase (UK) |
Breeding Success |
Other |
|
Moderate Increase (Eng) |
Breeding Success |
Other |
|
Fluctuating (Eng) |
Survival |
Unknown |
|
Probable increase (UK) |
Unknown |
Unknown |
|
Increase (UK, Eng) |
Unknown |
Unknown |
|
Increase (UK, Eng, NI); Decline (Scot, Wales) |
Breeding Success |
Ban on organochlorine pesticides |
|
Rapid Increase (Eng) |
Breeding Success |
Other |
|
Possible Decline (UK) |
Survival |
Other |
|
Rapid Decline (UK, Eng) |
Juvenile Survival |
Agricultural Intensification |
|
Shallow Decline (UK, Eng) |
Unknown |
Unknown |
|
Increase (UK) |
Unknown |
Unknown |
In the last few decades, most birds of prey have increased in number as a result of reduction in the use of certain pesticides, reductions in persecution and, for some species, changes in habitat availability.
During the 1950s and 1960s the widespread use of organochlorine and organophosphate pesticides reduced population numbers of many raptor species, of which the Peregrine and Sparrowhawk were perhaps best studied, by reducing breeding success (Newton 2013). Following a ban on their use, numbers gradually increased. Being towards the top of the food chain, though, birds of prey remain vulnerable to the risk of secondary poisoning, and there are current concerns more recently around the use of anticoagulant rodenticides which bear further investigation.
Concurrent with these changes, increased legal protection of these species led to a reduction in levels of control and persecution, particularly in lowland areas for species such as Buzzard, further contributing to increased numbers (Elliott & Avery 1991). Illegal persecution, in particular of Hen Harrier, remains a problem in some areas though (Murgatroyd et al. 2019). Similar considerations apply to the Raven, which has more also recently been subject to increased licenced control in Scotland; for this species understanding of population dynamics is therefore vital for licencing decisions (Wilson et al. 2019) .
Positive conservation measures have been particularly successful for two species. Provision of nest boxes for Barn Owl increased population numbers from a low-point in the 1960s, however numbers of this of this species fluctuate widely in response to cycles in vole abundance complicating quantification of this effect. Much more clear-cut has been the successful program of re-introductions of Red Kite into areas where they were formerly absent and whose numbers continue to increase (Carter 2001).
The two species found most commonly on farmland (Kestrel and Little Owl) are faring less well, probably due, at least in part, to changes (and intensification) in land management reducing the availability of prey. Habitat availability has apparently played a more positive role in Peregrine populations as they have (re-)colonised urban areas, where individuals have higher breeding success than those nesting in rural areas (Kettel et al 2018b).
Waders
Species |
Long-term Trend |
Primary Demographic |
Primary Ecological |
Moderate Increase (UK) |
Unknown |
Unknown |
|
Probable Decline (UK) |
Unknown |
Unknown |
|
Rapid Decline (UK); Moderate Decline (Eng) |
Breeding Success |
Agricultural Intensification |
|
Decline (UK) |
Breeding Success |
Unknown |
|
Moderate Decline (Eng) |
Breeding Success |
Agricultural Intensification |
|
Moderate Decline (UK) |
Unknown |
Unknown |
|
Decline (UK) |
Unknown |
Agricultural Intensification |
|
Probable Rapid Decline (UK) |
Unknown |
Unknown |
|
Rapid Decline (UK) |
Unknown |
Unknown |
Breeding populations of most waders in Britain are declining, mostly as a result of habitat loss/intensification.
A key reason for the decline in breeding wader species, particularly Lapwing, Redshank, Curlew and Snipe has been the loss of wet grassland through drainage (Wilson et al. 2005a) and more intensive grassland management (Smart et al. 2008).
As they nest on the ground, waders are vulnerable to nest predation and densities of generalist predators are higher in UK than elsewhere in Europe (Roos et al. 2018). Habitat loss has concentrated breeding populations into smaller areas increasing their vulnerability (Bolton et al. 2007). Predation of nests is also an issue in other habitats, such as on the machair of the Uists where populations of Ringed Plover and other species are declining due to predation by (introduced) hedgehogs (Calladine et al. 2017).
Woodland Residents
Species |
Long-term Trend |
Primary Demographic |
Primary Ecological |
Rapid Increase (UK, England) |
Breeding Success |
Decreased Competition for nests |
|
Rapid Decline |
Unknown |
Unknown |
|
Fluctuating (UK, England) |
Unknown |
Unknown |
|
Fluctuating (England) |
Unknown |
Unknown |
|
Shallow Increase (UK, England) |
Survival |
Other |
|
Moderate Increase (UK, England) |
Survival |
Other |
|
Fluctuating (UK, England) |
Unknown |
Unknown |
|
Rapid Decline (UK, England) |
Unknown |
Changes in Woodland |
|
Rapid Decline (UK, England) |
Survival |
Changes in Woodland |
|
Moderate Increase (Eng) |
Survival |
Weather |
|
Rapid Increase (UK, England) |
Breeding Success |
Unknown |
|
Fluctuating (England) |
Survival |
Weather |
|
Rapid Increase (UK, England) |
Survival |
Climate Change |
|
Shallow Decline (UK, England) |
Survival |
Unkown |
|
Song Thrush | Moderate Decline (UK, England) | Juvenile survival | Unknown |
Moderate Increase (UK, England) |
Productivity |
Unknown |
|
Moderate Decline (UK, England) |
Survival |
Agricultural Intensification |
|
Chaffinch | Fluctuating | Survival | Other |
Rapid Decline (England) |
Survival |
Changes in Woodland |
|
Increase (UK) |
Unknown |
Unknown |
Most resident species of woodland habitats are increasing, with the exception of those that have specialised habitat requirements, notably Lesser Spotted Woodpecker, Willow Tit and Marsh Tit.
In part, these increases are due to flexible, generalist nature of the habitat requirements of these species. Most are species of the woodland edge and leafy suburban habitats, in particular, provide a suitable alternative habitat for many, with the extensive provision of food in gardens being an additional attractant. Indeed, those species that have increased their use of gardens the most, such as Great Spotted Woodpecker, Nuthatch and Siskin, have also shown the most positive population trends (Plummer et al. 2019).
In many species this has led to relatively high survival, perhaps particularly overwinter, although warmer winters will also have played a role, contributing to the population increases. One notable recent exception is the Greenfinch, where the population has declined recently as a result of reduced survival induced by a pathogen which is likely to be transmitted at garden feeders (Lawson et al. 2018).
The causes of decline in the woodland specialist species are less clear, but the scale of the changes, especially in Lesser Spotted Woodpecker (which is now so uncommon that we can no longer monitor its population through BBS), Lesser Redpoll and Willow Tit suggest fundamental changes in woodland habitat quality in the last few decades.
Woodland Migratory Species
Species |
Long-term Trend |
Primary Demographic |
Primary Ecological |
Uncertain |
Unknown |
Changes in Heath and woodland |
|
Decline (UK) |
Unknown |
Unknown |
|
Rapid Increase (UK, Eng) |
Survival |
Unknown |
|
Rapid Decline (Eng) |
Breeding Success |
Climate Change? |
|
Rapid Increase (UK, Eng) |
Unknown |
Unknown |
|
Moderate Decline (UK) |
Unknown |
Unknown |
|
Decline (Eng) |
Unknown |
Changes in Woodland |
|
Rapid Decline (UK, England) |
Survival |
Unknown |
|
Decline (UK) |
Survival |
Wintering Habitat Change |
|
Fluctuating (UK, England) |
Productivity |
Unknown |
|
Rapid Decline (England) |
Breeding Success |
Changes in Woodland |
Population trends in migratory species in woodland habitats depend largely on migration distance, those with shorter migratory journeys (wintering in Europe or North Africa) tend to be increasing, while those with longer journeys (wintering in central Africa) tend to be declining (Thaxter et al. 2010).
Increases in the short-distance migratory species are likely a result of climate change and warmer winters, with species such as Chiffchaff and Blackcap able to winter successfully further North than previously, reducing the distance of their migratory journey (Plummer et al. 2015).
Reasons for the declines in the longer distance migratory species are less well known, although in at least some species, such as Nightingale, changes in breeding habitat are thought to be important (Hewson et al. 2005), although this may not be true for all species (Mallord et al. 2016).
Farmland Resident Species
Species |
Long-term Trend |
Primary Demographic |
Primary Ecological |
Rapid Increase (UK, England) |
Survival |
Agricultural Intensification |
|
Rapid Decline (England) |
Juvenile Survival |
Agricultural Intensification |
|
Moderate Decline (UK, England) |
Juvenile Survival |
Unknown |
|
Fluctuating (UK) |
Unknown |
Unknown |
|
Fluctuating (UK) |
Survival |
Other |
|
Moderate Decline (UK, Eng) |
Adult Survival |
Agricultural Intensification |
|
Rapid Increase (Eng) |
Survival |
Availability of Food |
|
Rapid Decline (Eng) |
Breeding Success |
Agricultural Intensification |
|
Rapid Increase (Eng) |
Survival |
Availability of Food |
|
Rapid Decline (UK, England) |
Survival |
Agricultural Intensification |
|
Fluctuating (UK, England) |
Survival |
Agricultural Intensification |
|
Rapid Decline (UK, England) |
Unknown |
Agricultural Intensification |
Most resident species on farmland are declining, or have declined in the past, with trends in these generally reflecting fluctuations in food supply.
The declines in farmland bird are well studied and generally relate to the reduced availability of food resources, especially in seeds in winter for species like Yellowhammer and Corn Bunting (e.g. Robinson & Sutherland 2002). These declines generally reverse earlier increases in the 1950s and 60s as agriculture (particularly arable) expanded in extent from a previous low. Food availability in grassland habitats has also likely reduced affecting those that feed primarily on soil invertebrates such as Song Thrush and Starling. Implementation of agri-environment schemes to address these declines has resulted in some positive benefits, but the overall impact has been less clear-cut (Baker et al. 2012; Dadam & Siriwardena 2019).
In contrast, those species that are increasing have adapted to using other food resources, such as gardens in the case of Goldfinch, Greenfinch and Chaffinch, or oilseed rape in the case of Woodpigeon. Gains in population size of Chaffinch and Greenfinch have largely been reversed in recent years due to the spread of the trichomonosis (Lawson et al. 2018).
Farmland Migratory Species
Species |
Long-term Trend |
Primary Demographic |
Primary Ecological |
Rapid Decline (UK, England) |
Breeding Success |
Agricultural Intensification |
|
Rapid Decline (UK, England) |
Survival |
Changes on Wintering Grounds |
|
Uncertain (UK) |
Unknown |
Unknown |
|
Decline (UK) |
Breeding Success |
Agricultural Intensification |
|
Possible Decline (UK) |
Unknown |
Unknown |
|
Rapid Decline (UK, England) |
Unknown |
Agricultural Intensification |
All migratory species living on farmland, with the possible exception of Lesser Whitethroat, are declining in both numbers and range and some (Whinchat, Wheatear) are now restricted to marginal habitats in more upland areas.
The declines have generally been caused by intensification of agricultural practices in both grass (Whinchat, Yellow Wagtail) (e.g. Vickery et al. 2001) and arable (Turtle Dove) (Browne & Aebischer 2001) habitats. The catastrophic decline of the Whitethroat in the late 1960s was caused by drought conditions on its wintering grounds in the Sahelian region of Africa from which it is yet to recover.
This report should be cited as: 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. (2019) BirdTrends 2019: trends in numbers, breeding success and survival for UK breeding birds. BTO Research Report 722. BTO, Thetford. www.bto.org/birdtrends
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