As I write this I am eagerly awaiting the return of one of my favourite summer visitors, and another Bracknell Forest Council Biodiversity Action Plan species, the swift. We do see, and hear, these magnificent creatures in the skies above Binfield, but it is a rare treat.
There is a small nesting colony of swifts at the Bracknell end of Binfield Road and they can often be seen performing their high-speed acrobatics above this part of Bracknell. However, the best places to see swifts are Wokingham town centre (the developers of the new plaza have put up nest boxes), Windsor (to the south of the town centre), and Reading (to the west of the Oracle).
Swifts are migratory birds spending less than a third of their year in the UK. They arrive around the start of May and leave again in August, migrating from and to sub-Saharan Africa. Their brief time here is just long enough to breed and raise a family. These incredible birds sleep and mate on the wing, and only set foot on solid ground to nest and feed their family. The young birds launch themselves from the nest, and it can be up to three years before they land again.
Where swifts are found in reasonable numbers, they treat us to the spectacle of "screaming parties" where gangs of swifts tear around making the noise that led to one of their nicknames - the devil bird. Unfortunately, the sound of a screaming swift is becoming less common. According to the British Trust for Ornithology, swift numbers have declined by approximately 40% across the UK since 1995, with steeper declines in Scotland. It seems likely that there are two main causes for this decline: a lack of insect food; and a reduction in suitable nest sites.
Swifts feed on air-borne insects ranging in size from aphids to dragonflies. Swift’s migration routes have evolved to take them to where insects are plentiful, from bugs stirred up by a storm in sub-Saharan Africa, to the flying ants of a British summer. There seems to be a general decline in UK insect numbers, which may be due to the increased use of insecticides in farming.
Swifts like to nest in high cavities that can be accessed easily from the air. As a result, they nest under the eaves of tall (greater than two storey) buildings. The birds also show loyalty to a nest-site and will use the same building for all of their breeding life, which can be between 10 and 15 years. Unfortunately, as old buildings are demolished or renovated, swift nest-sites are often destroyed.
If you own a building suitable for swifts you can buy special swift nest-boxes. Alternatively, you can help their conservation by taking part in the RSPB’s annual swift survey (https://swiftsurvey.org/Rspb/Home/Index).
If you are spending a summer evening somewhere where swifts still gather for screaming parties take a moment to watch the birds and think about what you can do to make sure that future generations have the opportunity to see and hear swifts too.