Winter survival of a small predator is determined by the amount of food in hoards

The hoarding behaviour of animals has evolved to reduce starvation risk when food resources are scarce, but food limitation on survival of hoarding animals is poorly understood.
Eurasian pygmy owls (Glaucidium passerinum) hoard small mammals and birds in natural cavities and nest-boxes in late autumn for later use in the following winter. We studied the relative influence of the food biomass in hoards of pygmy owls on their over-winter and over-summer apparent survival. We also tested whether this influence is modulated by intrinsic (age, sex) traits or extrinsic factors (winter temperature, snow depth).
We measured biomass of prey items in pygmy owl food-hoards during autumns 2003 – 2023 in west-central Finland. We individually marked and recaptured pygmy owls both at nests in the breeding season and at food-hoards. Our dataset included a total of 407 pygmy owls which were all captured from a food-hoard at least once during their capture history. The mean biomass of the annual food-hoa..., , , # Winter survival of a small predator is determined by the amount of food in hoards

[https://doi.org/10.5061/dryad.ksn02v7fk](https://doi.org/10.5061/dryad.ksn02v7fk)

## Description of the data and file structure

This dataset contains data used in the following publication: Korpimaki, E., Piironen, A. & Laaksonen, T. 2025: Winter survival of a small predator is determined by the amount of food in hoards. Journal of Animal Ecology.

The data is a capture-mark-recapture data collected by catching pygmy owls from the nest boxes during spring and fall. Also, the biomass of prey items in the food hoards was recorded as well as relative vole density in the field in every spring and fall. See a detailed description of the methods from the manuscript.

##### Author information for the data:

Name: Antti Piironen

Institution: University of Saskatchewan, University of Turku

Email: [[e-mail]](mailto:[e-mail]), [[e-mail]](mailto:antti.p.piiro...