In 2025, a government evaluation is planned to assess the current hunting periods for various small mammal species (SEPA). To support this effort with updated data and insights on the reproductive periods of these species, a research program titled “Reproductive timing in relation to hunting season in small mammals” was launched this year. The program includes several sub-projects (post docs), each using different methods and focusing on different species.
For a long time, a general rule has applied: no species may be hunted during their reproductive period. The dates for the respective hunting seasons have remained largely unchanged for many years. However, there are growing concerns that reproductive periods may have shifted over time and across regions, for example due to climate change. Thus, an important objective of these studies is to define more accurately when reproduction starts and ends for these species, which can then inform decisions on whether hunting seasons need to be adjusted.
Species under investigation include, for example, the red fox (Vulpes vulpes), badger (Meles meles), pine marten (Martes martes) and beaver (Castor fiber). Data will be collected through various methods such as genetic analyses (scats), camera traps and observations from field staff at institutions such as county boards and the public (citizen science).
Several sub-projects are being conducted at Grimsö, with one focused on pine marten also gathering data at Asa and Svartberget. This part of the project uses camera trap stations designed to attract martens in order to obtain pictures of the bellies of adult females to determine if they are lactating (i.e. period length). These images and short videos can also reveal how long young martens remain in family groups during the autumn. The point at which the young become independent is one way to define the end of the reproductive period.
At Grimsö, two additional sub-projects within the program utilize long-term data series on fox and badger dens, both to locate animals for tagging and to collect scat samples for genetic analyses and measurements of hormone levels of females across different seasons. These projects further demonstrate how the SITES station network constitutes an effective partnership for external researchers, offering access to existing data, study areas for new data collections or experiments and local support.
Camera station designed to attract martens, with bait (peanut butter) placed in a jar attached to a frame positioned well above the ground. The high placement helps in preventing that animals like badgers from eating the bait. The frame and the position of the jar (with the opening facing away from the camera) are intended to “force” the martens to stand on their back legs and thus exposing their belly for the camera. Video clips are triggered by movements detected in front of the camera. Photo: Gunnar Jansson