X Close The strong relationship between buzzard populations and small mammal abundance
A fifteen-year investigation in the province of Barcelona has revealed the fascinating dependence of the common buzzard (Buteo buteo) on the abundance of small mammals. Unlike populations in the southern Iberian Peninsula, which feed primarily on rabbits, the Catalan populations of this raptor completely adapt their biology to the life cycles of the wood mouse, the Algerian mouse, and the white-toothed shrew.
The study demonstrates that the abundance of these three prey species determines the buzzard's life cycle: in years of high food availability, females lay their eggs earlier and raise up to twice as many chicks. Conversely, when food is scarce, reproduction is delayed and can trigger siblicide, a process in which the older sibling kills the younger one to ensure that at least one strong individual survives. Furthermore, during the winter, the lack of prey acts as a demographic filter, since resident individuals, thanks to their experience and knowledge of the territory, manage to survive much better than migratory individuals arriving from northern Europe.
Finally, buzzards even conserve energy by renewing fewer secondary feathers during periods of low small mammal availability, although they maintain a rigid molting pattern in their primary feathers (used for flight). Given that the abandonment of traditional agriculture and the closure of forests threaten the open areas that small mammals need, the common buzzard becomes an excellent indicator of the environmental health of our ecosystems.
The detailed results were published in the journal Quercus last April. You can read the full article here.
Joan Grajera, one of the authors of the study, with a common buzzard.
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