Unlocking the ‘time capsules’ of migrating warblers

Published on 09 August 2014 in News and comment

Research has revealed fascinating results about migratory warblers carrying ‘time capsules’ of their travels around the world.

At the University of Gloucestershire, scientists have been working on unlocking these secrets and finding out more about where they go on their migratory travels.

Birds frequently arrive in the UK carrying sticky encrustations on the feathers around their bill, which derive from foraging on insects and nectar of flowers. This provides a ‘time capsule’ of their recent behaviour.

Ecologists, ornithologists and pollen experts from the university’s Biosciences team and the Centre for Environmental Change and Quaternary Research teamed up with the Portland Bird Observatory in Dorset to study the pollen carried by four species of warbler – Chiffchaffs, Willow Warblers, Blackcaps and Garden Warblers.

Common Chiffchaff carrying dark Eucalyptus pollen 'horns' on the feathers around its bill. Pic by Martin Cade

Common Chiffchaff carrying dark Eucalyptus pollen ‘horns’ on the feathers around its bill. Pic by Martin Cade

Pollen from 19 different types of plant was found, dominated by eucalyptus and citrus pollen, presumably from plantations in North Africa, Spain and Portugal. Each bird species carried a different suite of pollen types, indicating their different foraging behaviour.

The research shows how commercial and garden flowering trees are an important resource from migrating warblers. The information gathered by researchers may help to inform planting and conservation decisions at stopover sites, giving the birds some extra support on their long journeys.

Project leader Dr Matt Wood, Senior Lecturer in Biosciences, said: ‘This study highlights the importance of forestry plantations and fruit growing for these tiny long-distance travellers – migratory warblers are vulnerable to habitat change as they rely on sites with plenty of insect food to breed in the UK, to survive the winter further south and to refuel while on migration.’

The abstract of the paper is available here http://www.tandfonline.com/doi/abs/10.1080/00063657.2014.938017

For a full copy email Matt on mjwood@glos.ac.uk