Year-round conservation of the Montagu’s Harrier by tracking individual birds using state-of-the-art tracking technologies in combination with old-fashioned fieldwork

Abstract

The breeding population of Montagu’s Harriers we study in the Netherlands was established after the introduction of large-scale fallow land, due to a measure from the European Union to control for the overproduction of wheat. All nests in crops (wheat, alfalfa, rapeseed) are caged in order to protect the young against the harvest. In addition, the harriers rely on agri-environmental schemes that improve food abundance. As a lot of effort was made to conserve the Montagu’s Harrier at the breeding grounds, we realised that a year-round conservation approach was required. This was the main reason to start tracking Montagu’s Harriers using satellite transmitters. Using this technique we mapped migration routes, key migratory stopover sites and wintering areas. This was not only achieved for Dutch breeding birds but actually for breeding birds throughout the northern breeding range, from UK in the west to Belarus in the east. In addition, patterns in mortality were studied. In order to better understand what the harriers were exactly doing at stopover and wintering sites we visited these areas in which we studied diet (by pellet analysis) and prey availability (by transect and point counts). We stress that combining tracking data with field observations is an extremely powerful approach to understand the ecological conditions shaping the harriers’ behaviour. During the last years, we have also started to track Montagu’s Harriers using GPS-loggers, which provides a much more detailed picture about ranging behaviour and habitat use, allowing us to study the behaviour of Montagu’s Harriers at the breeding, stopover and wintering sites in even more detail.

About the speakers

Ben Koks is the founder of the Dutch Montagu’s Harrier foundation. He has developed a lifetime fascination for Montagu’s Harriers and has studied these birds all over Europe and in Africa.

Raymond Klaassen is a researcher at the Dutch Montagu’s Harrier Foundation and the University of Groningen, the Netherlands. His main interest lies in animal movement, in particular bird migration.