The latest results published today in the 2018 Breeding Bird Survey (BBS) report, suggest that the Beast from the East and Saharan winds may have had a big impact on both resident and migrant birds.
The short, sharp impact of the snow and ice that came with the Beast from the East may have affected some of our smallest birds in particular. Goldcrest, the smallest UK bird, saw a population decline of 38% and Wren and Long-tailed Tit were both down by 21% and 22% respectively in comparison with 2017 figures. As a group these birds are the real lightweights of the bird world, weighing in at between 5-10g. As such they can be particularly vulnerable to cold weather, and even though the Beast delivered a brief shock, it appears this was enough to hit these birds hard.
It looks as though the very cold spell also hit one of UK’s most colourful birds, the Kingfisher. The sudden freezing of shallow water can prevent them from accessing the small fish they feed on; the 2018 breeding population was down by 38% on the previous year.
While all this was unfolding in the UK, our summer visitors were safely ensconced in sub-Saharan Africa, thousands of miles from any snow and ice. However, when the time came to head back to the UK, the Sahara desert was experiencing strong northerly winds, seemingly hampering the northward return journey and many were late back or arrived in lower numbers. This appears to have had quite an impact on the number of returning birds and House Martin was down by 17%, Sand Martin down by 42% and Swift down by 20% during the 2018 breeding season surveys. It wasn’t just the aerial feeders that were affected; two of our commonest warblers, Whitethroat and Willow Warbler were down too, by 18 and 23% respectively. Whilst some of these birds may have been affected by the weather during migration, it is unknown what effect conditions in their over-wintering grounds might have had on these year-to-year population changes. .
It wasn’t all bad news and some birds apparently managed to either tough it out through the snow and ice, or find a window in the winds to cross the desert. Grey Heron is a species that is vulnerable to cold weather and over the years its breeding population has seesawed with cold and mild winters. However, the large size of the Grey Heron, standing around a metre tall, may have allowed it to weather the storm and its 2018 breeding population remained stable.
The Cuckoo was one of the long-distance migrants that managed to time its flight across the desert to coincide with better winds. Not only did they arrive back on cue, they returned to breed in good numbers; up by 22% on 2017. A welcome break for a species suffering a long-term decline of 41% (1995–2017).
Sarah Harris, Breeding Bird Survey Organiser at the British Trust for Ornithology (BTO), said, “It is thanks to the thousands of volunteers who give up their time to count birds for the survey that we are able to follow the ups and downs of our breeding birds so closely. While things didn’t look great for some of our smaller birds in 2018 they do have the capacity to bounce back quickly from short-term declines and I can’t wait to see the 2019 results. Thank you to all who take part”
Mark Eaton, RSPB Principal Conservation Scientist, said “Knowing how bird populations are increasing or decreasing is fundamental to bird conservation and the long term trends for population changes in this new BBS report are a very important indicator of the health of our countryside. BBS trends shows how our bird populations have fared since 1994 and are used to identify the species most needing conservation help: they are a crucial component of the Birds of Conservation Concern assessments which identify the red list, of species of greatest conservation concern.”
Paul Woodcock, Joint Nature Conservation Committee, said, “The great work done by volunteers on the Breeding Bird Survey means that we now have information on UK breeding bird species from over 4000 sites across the UK. The annual data provided by the BBS – which goes back as far as the mid-1990s in many sites – is therefore an invaluable conservation resource for helping to understand how and why UK bird populations are changing as a result of environmental pressures and conservation activities”.
The BTO/JNCC/RSPB Breeding Bird Survey is a partnership jointly funded by the BTO, RSPB and JNCC, and the report is published by BTO annually on behalf of the partnership. The full report can be accessed here.