Numbers of wintering waterbirds in Scotland have increased overall but some species, particularly waders, are being affected by our changing climate.
NatureScot’s latest Biodiversity Indicator monitors the populations of 41 species including wildfowl, waders, cormorant, grebes and coot using data from the Wetland Bird Survey.
The research shows that overall numbers have increased by 25% since 1975, but there is considerable variation between groups and individual species. Most waterbirds can be highly mobile and research has shown that some are shifting their distributions in response to environmental changes.
Numbers of waders – including species such as dunlin, knot, golden plover and lapwing - have declined by 10%, after peaking around 1997/98.
Part of the reason for this is climate related - Scotland is in an important position within the East Atlantic Flyway, the migration route used by these waders, and climate change has resulted in some species shifting wintering sites.
Knot and dunlin, for example, are highly mobile, with milder winters allowing birds to remain on continental wintering sites rather than coming to Scotland.
Wildfowl numbers have remained relatively stable, but while species such as swans and red-breasted merganser have increased, goosander, goldeneye and scaup have declined.
Mallard numbers in Scotland have also declined by 40%, matching the UK national trend. The reasons are unclear, but some mallard migrate from the continent and may be choosing to remain there during milder winters. Further research is required to understand the reasons for the decrease.