Data from: Under the snow: a new camera trap opens the white box of subnivean ecology

Snow covers the ground over large parts of the world for a substantial
portion of the year. Yet very few methods are available to quantify biotic
variables below the snow, with most studies of subnivean ecological
processes relying on comparisons of data before and after the snow cover
season. We developed a camera trap prototype to quantify subnivean small
mammal activity. The trap consists of a camera that is attached facing
downward from the ceiling of a box, which is designed to function as a
snow-free tunnel. We tested it by placing nine traps with passive infrared
sensors in a subarctic habitat where snow cover lasted for about 6 months.
The traps were functional for the whole winter, permitting continuous data
collection of site-specific presence and temporal activity patterns of all
three small mammal species present (the insectivorous common shrew, Sorex
araneus, the herbivorous tundra vole, Microtus oeconomus, and the
carnivorous stoat, Mustela erminea) as well as abiotic conditions
(presence/absence of snow cover and subnivean temperature). Based on their
successful functioning (only 6% of the photographs appeared empty or were
of poor quality, whereas ca 80% were of small mammals and the remaining of
birds and invertebrates), we discuss how the new camera trap can enable
subnivean studies of small mammal communities. This greatly increases the
temporal resolution and extent of data collection and thereby provides
unpreceded opportunities to understand population and food web dynamics in
ecosystems with snow cover.