The Willow Warbler (Phylloscopus trochilus)

Status in UK: ( A )
Migrant Breeder, Passage Visitor
Order: Passeriformes
Family: Sylviidae

Number in Britain: 2.1 million pairs (Summer)

Length: 11 cm
Wingspan: 19 cm
Weight: M/F: 10 g

World Distribution: BREEDS: Europe, nw Asia, WINTERS: tropical & s Africa
Habitat: Open woodland, scrub, shrubby tundra
Diet: Insects and spiders, also berries in autumn

Conservation Status: UK and Wales: AMBER

There has been a -34% decline in Willow warbler numbers in Wales over the last 10 years.

At the Wales Biomass Centre we are researching various aspects of biomass as a renewable energy source. Of particular interest are willows as a crop and its effect on birds. This spring we have been radio-tracking individual Willow warblers to compare territory size and breeding success in open woodland (their natural habitat) with a planted willow biomass coppice (a man-made, alternative habitat) at Fforest Farm, to determine whether the coppice plays an important role in maintaining the breeding populations of these migrants. The two sites are both within 10 minutes walk of the campsite.

Attachment of radio-transmitters takes approximately 10 minutes. Radio-tracking has not been performed on this species before, and will give us a fascinating insight into their breeding behaviour. Each transmitter has been custom built specifically for this species and weighs a mere 0.5g which is as small and light as possible.


We are then able to track the birds using the receiver equipment shown here:

If you are staying at the campsite you may see us around during April and May 2007. We may look very strange but we are friendly (honestly!) and are more than willing to answer any questions you may have.



Other species present at the sites:

Open Woodland		Willow plantation
Blackbird		Blackbird
Blue Tit		Blackcap
Bullfinch		Blue Tit
Coal Tit		Bullfinch
Cuckoo		Chaffinch
Great Tit		Chiffchaff
Great Spotted Woodpecker		Coal Tit
Green Woodpecker		Dunnock
Jay		Garden Warbler
Long-tailed Tit		Goldcrest
Meadow Pipit		Goldfinch
Pied Flycatcher		Great Tit
Raven		Long-tailed Tit
Redpoll		Magpie
Redstart		Marsh tit
Robin		Redpoll
Siskin		Redstart
Treecreeper		Redwing
Tree Pipit		Reed Bunting
Willow Tit		Robin
Willow Warbler		Song Thrush
Wood Warbler		Treecreeper
Wren		Willow Warbler
		Wren

For more information on the Willow warbler and its population status visit: www.bto.org.
To find out more about energy crops and our research at the Wales Biomass Centre visit: www.walesbiomass.org