Forest raptor population dynamics: how sentinel species, their prey and landscapes interact

During the late 1800s and early 1900s, many raptor species were legally killed in Europe as they were considered 'vermin'. Several species became extinct while others suffered severe range contraction, which were further in the mid-20th Century following the introduction of organochlorine pesticides for agriculture, of which raptors have meanwhile recovered. However, despite decades of legal protection, some raptor populations are still under threat from loss of food resources and habitat quality, the impact of forest management, and illegal persecution. To date, it is unclear what the exact mechanisms behind local declines are, and how the observed variation between areas can be explained.

To investigate the relationship between land use, food resources, breeding success, nestling condition, and temporal trends therein, we examine population dynamics of forest raptors, notably goshawk. We assess breeding success, measure chicks and study diet, and colour ring adults for examination of replacement and survival rates. The available long-term data gathered since the 1970s allow us to examine such relationships, and how these have changed, over the course of several decades. Recently GSM transmitters have been deployed on 7 goshawks to investigate in more detail their seasonal ranging behaviour and habitat use.

Activities in 2019/2020

  • Nest surveys, ringing, monitoring, diet studies, measurements of breeding success and nestling condition of over 70 breeding pairs
  • Colour ringing adult breeding birds to estimate survival and replacement rates
  • Analyses of goshawk GSM tracking data to evaluate seasonal habitat use and preference in relation to diet, breeding success
  • Analyses of breeding success in relation to habitat in three different long-term study areas in the Netherlands