Population Ecology Research Group, University of Aberdeen, UK Coordinator: Xavier Lambin
Dept. of Arctic and Marine Biology, University of Tromsø, Norway
Institute of Research in Game Resources, CSIC/UCLM, Spain
Chizé Centre for Biological Studies, CNRS/University of La Rochelle, France
ETSIIAA, University of Valladoid, Spain
Many ecosystems are dominated by regular fluctuations in abundance of grass-eating small rodents, which are prey for many predator species. These ecosystem “heartbeats” have been changing recently, raising concern about their drivers and possible broader effects on ecosystems. The Ecocycles team has studied the causes and consequences of changing rodent abundance cycles, by testing that:
1. There has been strong changes in small rodent cycles during the last decades all over Europe, due to land use and climate change;
2. These changes have disproportionate impacts on the demography of predator species, challenging their viability;
3. These demographic changes in prey and predator species have cascading effects on the whole ecosystem food-web;
4. Conservation measures need to account for these ecosystem “heartbeats”.
Researchers in France, Norway, Spain and the UK worked on understanding these changes by testing the hypotheses above, following a step-by-step approach to:
1. Determine the patterns and correlations in prey dynamics changes by analysing long records on the abundance of grassland voles, some going back 50 years;
2. Characterise the impacts on predator demography and predict responses of different types of predator species;
3. Explore potential for profound ecosystem disturbance under joint climate and land use change impacts;
4. Suggest evidence-based conservation measures.
• The Ecocycles team demonstrated a consistent dampening of the amplitude of rodent cycles in many places across Europe, probably reflecting common climatic driver and involving a reduction of winter population growth.
• Locally, human activities such as the irrigation of arid areas in Spain, and grazing pressure by cattle or agri-environmental schemes, influence rodent dynamics. Yet global patterns are tending to override their effect.
• Ecocycles established that vole predator populations – such as owls and skuas – will decline in response to such changes in prey dynamics, with varying time frames reflecting species’ specific habits.
• The Ecocycles team also identified spreading effects of these changes, notably a now reduced spillover predation following low abundance cycles, meaning that some endangered predators such as the Arctic fox face a heightened competition with other predators, eventually challenging the survival of these endangered species.
The Ecocycles team analysed the temporal trends of vole abundance series for spring and autumn in several sites across Europe* (see the dark and grey curves, respectively, in the Figure). The variation in the amplitude of fluctuations for spring and autumn (red and green curves, respectively) decreased over time all over the continent, which suggests a major role of a continental-scale environmental change like climate.
* Cornulier et al. (2013) Europe-wide dampening of popula- tion cycles in keystone herbivores. Science 340: 63-66
• Ecocycles researchers worked with a wide range of stakeholders (see Figure), involving and consulting local authorities, NGOs, farmers’ organisations and natural resource managers through national consultative fora in Spain, Norway, France and the UK.
• In several countries, farmers and regional authorities were directly involved in vole monitoring and manage- ment experiments, for example with the participation of rangers from the Forestry Commission in the UK, which also provided data to the project.
• In Spain (Junta de Castilla y Leon), Ecocycles allowed overcoming past conflicts and provided the initial steps and framework for a positive collaboration between farmers and local authorities concerning the impact of vole outbreaks on agriculture thanks to evidence- based information and sustained dialogue.
• Ecocycles lead to the funding of a number of subsequent projects with and by NGOs and local authorities involved in the project in Spain, France and the UK.
Ecocycles produced a set of tools adapted for use by their stakeholders in a proactive manner:
• A report co-produced with National Consultative Fora on research priorities for upland management
• Contributions to forging agreements for experimental management in biological control of outbreaks between NGOs and Regional Government Farmland Managers in Spain.
• Leaflet on state-of-the-art knowledge and recommendations for management of vole outbreaks: disseminated widely in the Junta de Castilla y Leon in Spain, this comprehensive leaflet provided evidence-based information on vole outbreaks and their role, and on management by the local community.
• “Ecocycles protocols”: specific vole monitoring methodologies produced by the project were applied jointly by NGOs and Junta de Castilla y Leon in Spain.
• Contributions to the National management plan for Arctic fox in Norway: the Ecocycles team wrote parts of the Norwegian management plan to conserve this predator species relying heavily on small rodent preys.