Cetti’s Warbler
16th January 2012
Usually glimpsed diving for cover Cetti’s Warbler (pronounced ‘chetty’) is a small stocky bird with short wings and rounded tail, its plumage is primarily dark brown with a grey throat and breast. While the adults’ appearance may be nondescript the eggs of Cetti’s Warbler are unique amongst British birds due to their bright red colour. Difficult to see due to its shy nature its presence is usually given away by its song characterised by short loud bursts often stopping for several minutes before suddenly starting up again.
Now considered a resident species they weren’t seen in the UK until the early 1960’s and didn’t make an appearance in Wiltshire until 20 years later with the first breeding successful breeding attempt in the county not recorded until 1987.
Latin name: Cettia cetti
Population Numbers: In 2000 UK numbers were recorded at 678 pairs (Birds of Wiltshire, 2007), with numbers in Europe varying between 430,000 to 1.3 million, as such they are not considered to be an at risk species.
Where to see and when: Preferring damp habitats close to wetland areas, in Wiltshire they appear to favour river environments over lakes and ponds. Breeding occurs in April and May when males may be seen pursuing females in flight; nests are then constructed within dense, tangled scrub usually less than one metre above the ground. Foraging for insects and larvae occurs primarily at ground level often at the muddy edges of this scrub.
Seeing this shy little bird can be a challenge but at WWT's Nadder Island reserve its loud and characteristic song can be heard standing out as one of the lone voices announcing its territory during the winter months. It is the only warbler to over-winter here presently and this may be an early indicator of the effects climate change is having on our winter temperatures.
Nadder Island, a man-made island created when a second channel for the Avon was dug in 1969, provides ideal habitat for Cetti’s Warbler with thick scrub of primarily alder, willow and mixed shrubs and damp surroundings. While access to Nadder Island is restricted the site can be viewed from the north bank or the footpath on the south side and such is the volume of the Cetti’s Warbler’s song it can be clearly heard from either side.
What’s being done: Due to the inaccessible nature of Nadder Island little active management is carried out. This is an ideal example of how under the right circumstances human intervention on a reserve is not always required to produce suitable wildlife habitats. By allowing scrub to develop naturally on the island forming part of a complex network of river channels and scrub it provides ideal habitat for Cetti’s Warbler. The balance comes in doing just enough management to ensure the site does not become overgrown whilst still allowing natural habitats to develop.
