UK songbirds play a real role in pollination, research shows

The warblers – those harbingers of spring in the UK – have an unappreciated talent of a different sort.

Common UK birds including chiffchaffs and blackcaps are playing a real role in the pollination of plants, according to new research in the Journal of Ecology.

“Unheralded, some of these birds are making a significant contribution,” says Dr Sandra Anderson, of Waipapa Taumata Rau, University of Auckland in New Zealand. “Their role has been overlooked but it deserves attention.”

Although insects remain the dominant pollinators, birds can be important, especially during early spring when insects may be less active, she says.

In fieldwork at the Wicken Fen National Trust nature reserve in Cambridgeshire, Anderson and her University of Cambridge collaborators sampled birds captured in nets by the Wicken Fen ringers and found that 89 percent carried pollen.

Nine bird species were classified as carrying meaningful amounts. They were a mix of UK residents (wren, blue tit, bullfinch), Mediterranean migrants (blackcap, chiffchaff), African migrants (whitethroat, willow warbler, garden warbler), and passage migrants (redpoll).

Birds most often carried pollen from early‑flowering plants such as goat willow, blackthorn, hawthorn, and buckthorn, which bloom in cooler spring conditions when insect pollinators are less reliable.

Because birds are warm‑blooded and remain active in low temperatures, they may fill a seasonal gap. When researchers prevented birds from visiting some flowers, several species produced significantly less fruit.

“Our study is the first to show that native birds pollinate and contribute to fruit-set in native flowering trees in temperate Europe,” says Anderson. “Understanding this aspect of an ecosystem gives us a better idea of its resilience and how to protect it.”

Anderson came up with the idea of the research when visiting Britain after previously undertaking similar research in New Zealand.

The prevailing theory has traditionally been that flowers ‘match’ their pollinators – so small pale flowers with concentrated nectar suit insects, and big coloured nectar-rich flowers are better at accommodating birds.

“But the things that determine a match actually vary depending on context; a small pale flower can suit a bird very well if it is accessible and abundant at a time when birds have high needs and there is little else available,” says Anderson.