Buzzard Chick Taken to Nest as Prey Is Eventually Raised by the Eagles

Nature conservation professionals in Hungary noticed something very peculiar in the spring: a common buzzard chick being raised by Eastern imperial eagles.

The strange nesting site was discovered in the Dévaványa area of Hungary by a joint team of the Hungarian Ornithological and Nature Conservation Society (MME) and the nature conservation guard service of the Körös-Maros National Park Directorate during routine inspections in May. Three healthy Eastern imperial eagle (Aquila heliaca) chicks were rearing alongside an equally healthy common buzzard (Buteo buteo) chick.

During a second check in June, the buzzard chick was already flying around the nest in apparent health, while the three eagle chicks – as is typical for the species – were only to leave the nest in July.

According to statement by the MME, the buzzard chick was probably originally brought into the nest as prey by the eagles, but as it remained intact and, like the eaglets, continued to ask for food, the eagle parents carried on feeding it along with their own three chicks.

Buzzards are very rarely raised by eagles, but the case is not unprecedented. In Hungary, according to MME records, out of the more than 10,000 (!) eagle nest inspections carried out over the last 30 years, only six live common buzzard nestlings have been observed in Eastern imperial eagle nests and five in white-tailed eagle (Haliaeetus albicilla) nests.

The common buzzard is the most common bird of prey in Europe, and is found in varying numbers in almost all habitats. Approximately 1% of the prey animals identified in Eastern imperial eagle nests are common buzzards, the majority of which are nestlings, so it is relatively common for buzzard chicks to end up in eagle nests. However, the chances of survival of such chicks are extremely low, as they need to survive being captured and transported to the nest without serious injury. In addition, the parent birds need to be disturbed by something to prevent them from starting feeding buzzard chick to their own immediately, and the nest mates also need to accept the new arrival.

If all these conditions are met, the parent birds may encounter one more feeding chick when they arrive at the nest at the next feeding. They may then instinctively start feeding the smaller buzzard chick, which resembles their own chicks, and raise and protect the newcomer in the nest as their own.

The Eastern imperial eagle is a globally threatened species, with two-thirds of its European Union population nesting in Hungary. The Hungarian nests have been regularly monitored by the MME and National Park Authority experts since the 1970s.