Wind power is Germany's most important source of electricity, and its expansion keeps colliding with species protection. The red kite is the bird most often at the centre of that conflict. Researchers are therefore fitting the raptors with GPS transmitters and pooling the data in the MoveBank database. More than 5.3 million location points have been recorded there.
The red kite (Milvus milvus) is easy to identify by its forked tail and is roughly the size of a buzzard. In Germany it counts as a "species of particular national responsibility". According to Simon Thorn, head of the State Bird Protection Station for Hesse in Gießen, more than half the world population breeds in Germany, a substantial part of it in Hesse. The Hesse state agency for nature conservation gives a more cautious figure of 37 to 50 percent.
Numbers are currently considered comparatively stable. Biologists still regard the species as vulnerable, because it is so heavily concentrated in central Europe. Intensive agriculture is changing its habitat, and unsecured power poles and wind turbines add further risks.
Why this particular bird
How badly turbines threaten the population is disputed. Conservation groups warn of significant risks to individual populations, while other researchers point to avoidance behaviour in many birds. The Hesse state agency takes the opposite view, recording that the red kite shows no avoidance behaviour towards turbines and, relative to its population size, is among the most frequent collision victims.
Thorn explains it through the way the bird hunts. "The red kite is a raptor that flies comparatively low when searching for prey. The birds are always looking at the ground, and that makes them vulnerable to being struck by wind power. They simply do not notice when they approach a turbine on a search flight."
The transmitters are small enough to be fitted to young kites like miniature backpacks. They report where the animals are and how they move. The location points reveal preferred hunting grounds and flight routes. "That way we recognise a potential risk earlier," Thorn says. In practice, the siting of a turbine can take account of where the birds actually fly.
A research group at Philipps-Universität Marburg led by Nina Farwig is also working on the analysis, in a project called RoniaH. It aims to quantify where red kites are likely to be, across space and time, and to derive robust survey standards for species assessments. The goal is to stop treating wind expansion and protection of the species as a choice between the two.