Successful reproduction of eagle owl (bubo bubo) and dynamics of rodents number

What is it about?

Thus, the eagle owl population in Mordovia is stable, despite significant chronological changes in breeding success. The abundance of their preferred food, i.e., rodents, in different years has a considerable impact on the breeding success. At the peak numbers of rodents, large clutches and high survival rates of fledglings are observed. In 52% of the cases, the nesting pairs laid three eggs; in 31%, two eggs; in 9%, four eggs; in 4%, one egg or five eggs. The average clutch size was 2.78 ± 0.17. The average number of grown chicks to a successful nest was 2.41 ± 0.27. It was revealed that after a year of depression in rodent numbers, the couples did not nest at all or their breeding success was minimal. That is, a “lag effect” was observed: a delay of the consumer response to changes in the amount of food (Shilov, 2001). The study of the breeding success of the eagle owl and the abundance of rodents while taking into account the dietary preferences of the bird of prey revealed that B. bubo depends on the population numbers of the common vole. The occurrence of this rodent in the eagle owl’s droppings is proportional to the relative abundance of the voles in the environment. The high number of this prey species produces a greater number of breeding pairs of the predator. The high survival rate of chicks in large clutches is due to the high numbers of rodents and especially M. arvalis.

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Photo by Jongsun Lee on Unsplash

Photo by Jongsun Lee on Unsplash

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