The European Ground Squirrel – a key food resource for the Saker Falcon in Bulgaria

A new scientific study confirms that the successful recovery of the endangered Saker Falcon in Bulgaria is closely linked to the availability of one key prey species – the European ground squirrel.
Researchers from Trakia University, Green Balkans and the Bulgarian Society for the Protection of Birds (BSPB) analysed the diet of reintroduced Saker Falcons during the breeding seasons of 2020, 2024 and 2025, using a combination of food-remains analysis, direct field observations and camera traps. The results show that 80% of the recorded prey consists of European ground squirrels, making them the most important food resource for breeding Saker Falcons.
Small mammals dominate the diet overall (89%), while birds account for a relatively small proportion (10.4%). This indicates that the reintroduced falcons have adopted the species’ typical hunting strategy, focusing primarily on small mammals in open grassland habitats. Another important finding is that pigeons make up only 4% of the Saker Falcon’s diet. This is particularly significant in the context of BSPB’s efforts to reduce conflict between birds of prey and the pigeon-fancier community through dialogue, awareness-raising activities and the promotion of good practices to minimise losses.
The study highlights that the long-term survival of the Saker Falcon in Bulgaria depends not only on reducing threats that cause direct mortality, but also on the condition of grassland ecosystems. The European ground squirrel is a species dependent on open grasslands with short vegetation, maintained through traditional grazing and low-intensity agriculture. In recent years, these habitats have been under increasing pressure not only from the abandonment of grazing and ploughing, but also from the conversion of pastures for energy purposes, including the construction of photovoltaic parks, which has been developing at a rapid pace. When these habitats disappear, ground squirrel populations decline, followed by the predators that depend on them.
Therefore, future conservation efforts should also focus on the protection and restoration of open grassland habitats and pastures; maintaining traditional grazing practices; preventing the conversion of grasslands of high biodiversity value for industrial and energy purposes; and targeted monitoring and recovery of ground squirrel colonies in key breeding areas.
These findings support the implementation of integrated conservation approaches that link the recovery of birds of prey with habitat management and the protection of their main food resources. By conserving grasslands and their characteristic species, we not only support the European ground squirrel, but also help secure the future of one of Europe’s most threatened birds of prey.