Proposal for a joint experiment
to determine the variability in granivore identity

1- Background

Knowing the identity of the dominant granivore in a specific location can be important for a number of reasons, for example, because the identity may:
- influence the level of overall weed seed losses due to differences in seed removal efficiency
- explain spatial and temporal variability in seed predation
- influence the weed floral composition due to differential dietary preferences
- mean that measures aimed at enhancing seed predation will have to be tailor-made, as different granivores respond differently to environmental factors, management or landscape complexity

The identity of the dominant granivore seems to be spatially extremely variable and identifying the factors that influence the composition of the granivore guilt is necessary.
The initiative, therefore, involves two components;

  1. Identifying the main granivores
  2. Relating the identity of the granivores to environmental and management factors, and landscape context.


2- Brief history of WG joint activity

During the meeting of the WG Weeds and Biodiversity in Pisa in November 2014, I introduced the problem to the members of the WG, and we briefly discussed the possibility of cooperating to identify granivores. Several people indicated that they were interested and would support the initiative. During the ERWS Symposium in Montpellier in June 2015, we met with six people to discuss possibilities and obstacles. It became clear at that point that most people simply wanted to have clear instructions on how to conduct the trials (see attached).


3- Participants

Involved are currently [name (country, crop)];

  • Zane Mintale (Latvia; cereals)
  • Stephano Carlesi (Italy; orchards)
  • Jordi Izquierdo (Spain; irrigated vegetables)
  • Therese Berge (Norway; cereals)
  • Roland Gerhards, Matthias Schumacher (Germany; cereals)
  • Lars Andersson (Sweden; cereals)
  • Sarak Cook (UK; cereals)
  • Matteo Mota (Switzerland; vineyards)
  • Paula Westerman (Germany; maize)


  • Pavel Saska (Czech Republic)
  • Josiane LeCorff (France)
  • Helmut Meiss (France)
  • Denise Dostatny (Poland)

In the case that I forgot to list somebody, I apologize; please send me an e-mail and I’ll add you asap.


4- Joint trials to identify the main granivores

I proposed a tiered system, where we start with simple, labour-extensive trials involving exclusion cages to differentiate between vertebrate and invertebrate granivores (level 1; see next page).

Once people gain experience, we can progress to more advanced trials;
- Level 2. Same as level 1 but with more types of exclusions with the purpose of differentiating between the main groups of granivores, e.g., rodents, birds, carabids, slugs
- Level 3. Same as level 2 but with targeted sampling of specific groups of granivores (pitfall trapping for carabid beetles, life-trapping for rodents, transect observations for birds, etc.)