Projecte SEMICE

X Close The feeding of scops owl (Otus scops) chicks: selective predation and provisioning rhythms

The study was based on observations made in a nest box located in a periurban forest in the province of Barcelona, using an infrared camera to continuously monitor the breeding period of a pair of scops owl. The results indicate that these nocturnal birds of prey are not simple opportunists, but apply a sophisticated strategy to maximize the energy they obtain from prey.

The 724 prey contributions made by adults were exclusively nocturnal, concentrated at the beginning (orthopteran contribution) and at the end of the night (mice contribution). In terms of prey number, 98% of the recorded captures were invertebrates. However, the study shows that the real contribution of biomass and energy for the chicks depends on high-calorie prey, such as Algerian mice (Mus spretus) and female great bush crickets (Tettigonia viridissima).

The graph on the left shows the percentages calculated with the number of prey. On the right, the percentages according to the biomass that prey offer.

A significant bias towards the contribution of female orthopterans has also been observed, a fact that is associated with a greater energy gain offered by this group of orthopterans, since despite being small prey, they can acquire considerable weight. On the other hand, the contribution of mice seems to be a strategy linked to the accumulation of alternative prey in years of high availability of small rodents, such as 2025.

Finally, the recordings have allowed us to document an unprecedented behavior of prey manipulation by adults, who perform preventive "surgery" by removing the ovipositor —the needle for laying eggs— from the female bush crickets before giving them to the chicks, to avoid internal wounds. This is a key detail of parental behavior that traditional methods based on the analysis of pellets overlooked.

The study has been published in the journal Diversity and can be accessed through this link.

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