Winged Foresters - Scientists around Prof. Dr. Nina Farwig from LOEWE-Tree-M study seed dispersal by fruit-eating birds

The song thrush belongs to the fruit-eating bird species
© Dr. Sascha Rösner
The song thrush belongs to the fruit-eating bird species

What do blackbirds, blackcaps, ravens and woodpigeons have in common? They are among the most frugivorous birds in Europe and are thus significantly involved in the seed dispersal of plants. A research team of 14 scientists from all over Europe, including Professor Dr. Nina Farwig, spokesperson of the LOEWE priority program Tree-M, studied the occurrence of fruit-eating birds and their contribution to seed dispersal in seven areas in Europe over a period of one year.

"Little has been known about how communities of frugivorous birds change from forests to the now predominant 'deforested landscapes' of fields, pastures and settlements, where forest areas are embedded only as small patches," said conservation ecologist Nina Farwig of Philipps University. "We were interested in whether animal species with traits that are less advantageous in these open habitats are lost or replaced, and whether such changes ultimately affect which plant species are spread by the animals," Farwig continued.

For this purpose, the team collected fecal samples under isolated trees and was thus able to identify the animal species that spread the corresponding seeds on the basis of DNA analyses. According to the analyses, the number of fruit-eating birds in and around forests is similar, but the composition of the bird groups is very different. For example, the birds in deforested areas were larger and more mobile than their forest-dwelling relatives.

The scientists' recommendation following the study, which was published in the scientific journal "PNAS," is therefore that reforestation measures should focus on planting isolated trees as "starting areas" for forests and on those plant species that are otherwise difficult to spread in open landscapes, according to Professor Jörg Albrecht of the Senckenberg Biodiversity and Climate Research Center in Frankfurt. In addition, renaturation sites should be closer to intact forests, which would facilitate seed dispersal by the "winged foragers."