A peak shows the diversity of a forest

White-backed woodpeckers love saproxylic beetles. (photo: Simon Niederbacher)
White-backed woodpeckers love saproxylic beetles. (photo: Simon Niederbacher)
Its preservation benefits many others: the umbrella species. This is the role played by the white-backed woodpecker for beetles that feed on dead wood. This rare bird is therefore an indirect indicator of biodiversity, as researchers at BFH-HAFL have shown.

Deciduous or mixed forests with lots of dead wood - this is the preferred habitat of the White-backed Woodpecker. Due to intensive logging since the early 19th century, this bird had disappeared from many areas. Today, the white-backed woodpecker is once again colonizing the forests of eastern Switzerland, Vorarlberg and Liechtenstein, as forest management in Europe has become more extensive in recent decades, leaving more standing dead trees and wood on the ground", explains Romain Angeleri, ecologist at the BFH-HAFL University of Applied Sciences in Agriculture, Forestry and Food.

More beetles in woodpecker habitat

As this woodpecker mainly consumes so-called ’saproxylic’ insects (which feed on dead wood), it is associated with the presence of large quantities of dead wood in forests. The researchers therefore wanted to know whether forests where the woodpecker was present had more saproxylic beetles which, in addition to feeding woodpeckers, are important for the forest: these insects which decompose dead wood, thus contributing to the natural cycle of the forest ecosystem, are a sign of biodiversity.

If the number of saproxylic beetles is higher, then the woodpecker can be considered an umbrella species for this type of insect, found in habitats of high ecological value. A species is said to be an ’umbrella’ if protecting its habitat also benefits other species living in the same territory.

Protect one to save many

In their new publication in ’ Ecological Indicators ’, forest ecologists Romain Angeleri and Thibault Lachat prove the link between white-backed woodpeckers and beetles: they found more red-listed beetle species in the woodpecker’s nesting areas than in those where it is absent. Thus, 17 species, including 4 threatened species, are closely linked to the presence of the bird, compared with just 3 non-threatened species in areas without woodpeckers. The researchers’ study confirms that the white-backed woodpecker is an umbrella species for saproxylic beetles: ’Protecting this bird means protecting many species of deadwood beetle. ’

We have also observed that important habitats of high ecological value are not only forest reserves, but also forests used for timber production and protection against natural hazards," says Romain Angeleri.

Research, capture, measurement, determination

To study the relationship between the white-backed woodpecker and saproxylic beetles, R. Angeleri and his team analyzed data collected from woodpeckers that researchers at the Swiss Ornithological Institute had fitted with radio transmitters. This enabled them to identify forest areas where woodpeckers were active. They also trapped, determined and examined over 20,000 beetles belonging to more than 400 species, characterized habitats and measured the quantity and stage of decomposition of dead wood. The study is the fruit of collaboration between scientists at BFH-HAFL, the Swiss Ornithological Institute and the Conservation Biology Division of the University of Berne.

Romain Angeleri and Thibault Lachat hope that their results will inspire action on behalf of the White-backed Woodpecker, which is still very rare and ’vulnerable’ according to the Swiss Red List. ’ This commitment benefits both saproxylic insects and forest biodiversity. ’