There are fewer willow warblers singing their distinctive songs in the Suffolk countryside. Graham Appleton from the BTO in Thetford, explains what might be happening.
My wife is Scottish and finds it amusing that I have to admit that life for many birds seems a lot better north of the border than it is in England.
For the willow warbler, a migrant that travels to and from sub-Saharan Africa each year, things still look fine in Scotland, with a slight increase in numbers since 1995. Compare this to the story for the East of England, where we have lost two-thirds of our birds in the same period – which is just about as bad as it gets anywhere in the country.
Sadly, nesting attempts are not as successful as they used to be, potentially because of habitat changes caused by a drying out of the countryside and by increasing numbers of deer, which eat the grass in which willow warblers build their nests, and eggs too if they come across them.
There are two tiny warblers that can be found in and around Suffolk, the chiffchaff and the willow warbler. They are sleek in outline and weigh about the same as a 10 piece, which is a little lighter than a blue tit. Both are greenish birds and the differences are really quite subtle; check out the lighter legs on the willow warbler if you have a pair of binoculars. Fortunately, the two species can be separated easily by song; one cries out ‘chiff-chaff, chiff-chaff, chiff-chaff’ and the other produces a simple, descending trill of notes. It’s great that we can still hear plenty of chiffchaffs but I do miss the cheerful song of the willow warbler. If there’s one singing in your village please stop and listen; it might not be back next year.
According to BirdTrack, the first willow warbler arrived back in Suffolk on March 26 and, by now, most should be setting up territories. It’s a short breeding season and there is a real sense of urgency for migrant birds. If I use the old name of willow wren then it will probably be no surprise that the nest is spherical in shape with an entrance in the side. It’s a little easier to catch a glimpse of the five to seven eggs than in the wren’s more enclosed nest but, as it’s probably hidden in the grass at the base of a bush, this is not a nest that you are often going to come across by accident.
It’s a tough life being a willow warbler. For youngsters which successfully fledge from a nest, the chance of surviving long enough to return to breed 12 months later is just about one quarter, which implies that three-quarters won’t make it. Even for adult birds, which have been through the process at least once before, the annual survival rate is just 31 per cent. It’s amazing, therefore that the longevity record was set by a bird that was ringed as a youngster in 1999 and still known to be alive in 2010, when caught in Scotland. Even for a Scottish bird, that’s very good going!
To confirm that the warbler in your garden is a willow warbler, not a chiffchaff, you can check out the YouTube video, linked to the BTO website, at http://www.bto.org/about-birds/bird-id