Assessing the effects of rabbits on Cycladic islets

(2022) 2.500€ awarded

The Aegean Sea and the Cycladic archipelago, in particular, are parts of the Mediterranean biodiversity hotspot, harbouring thousands of unique plant and animal species. Many of these species presently survive only on the small islets, that have been free of human habitation, and act as the last refuges for numerous threatened organisms.
With this project, planned in 2020 but paused due to the pandemic until spring-summer of 2022, when travel and field-visits became a possibility again, the University of Michigan is investigating the effects of invasive rabbits to the biodiversity of Cycladic islets. As no such data exists for invasive rabbits nor for an appropriate management plan to address the problem. The University’s team, lead by Mr Johannes Foufopoulos, is assessing the situation on the ground to develop appropriate measures to protect these last wild arks of
biodiversity in the Cyclades.


This project was led by Angelina Kossoff (a second-year Master’s student at the University of Michigan School for Environment and Sustainability). Over the summer of 2022, with the help of several research assistants, she visited and quantified the ecological impacts of invasive European rabbits (Oryctolagus cuniculus) in the Cyclades.

Background: Larger islands in the Cyclades experience regular herbivory by native species. These islandssupport plant communities that have evolved to resist herbivory. In contrast, small islands that lack native herbivores harbor important plant endemic species that are highly susceptible to invasive herbivores like rabbits.

Methods: The University of Michigan team travelled to twelve islands in the Cyclades and compared ecological characteristics from: 1. Grazed islands (i.e. islands with present-day rabbit populations); 2. Ungrazed islands (intact islands free of rabbits), and, 3. Post-rabbit islands (islands with past, but now extirpated, rabbit populations). By comparing plant and insect biodiversity, soil samples etc., the team assessed impacts of invasive rabbits, as well as the potential for island recovery after rabbits are gone.

Preliminary Results: The UM team found that rabbits have been released on numerous uninhabited Cycladic islands for the purpose of hunting. Preliminary data indicate that these releases -instead of ‘giving life to the islands’ as intended by hunters – have a devastating impact on island vegetation and especially on the small herbaceous and annual plant species. However, our research reveals that the most damaging effect comes from the rabbits’ digging habits, which loosen the scarce soil and lead to massive wind erosion, therefore causing progressive desertification and undermining the long-term ability of islands recover. In line with this, we discovered that islands on which rabbits had died-out (because they had eaten themselves out of existence), were in even worse shape than islands occupied by rabbits at present. This indicates a very low ability for recovery once the soil is gone, and strongly suggests that to protect island ecosystems, rabbits need to be removed as soon as possible to prevent permanent damage.