A wolf with a GPS-collar just awakening after immobilization. Photo: Barbara Zimmermann.
The most intense field survey work at Grimsö Wildlife Research Station is in spring and summer, although important work is also being done during the winter months. A number of surveys at Grimsö run throughout the year, some of which peak in winter. Some fieldwork and data collection are facilitated by snow, and for some methods snow is required. Typical winter activities at Grimsö are, for example, to catch and mark roe deer (Capreolus capreolus) and wolves (Canis lupus). Due to limited food availability in winter, especially if there is lots of snow, roe deer are more easily trapped. Roe deer monitoring has been ongoing for more than 40 years and over 1,000 roe deer have been captured during this time. The data collected includes life history traits, kinship and body measurements. A photo from one of the wildlife cameras at Grimsö, showing two roe deer, one collared and one inside the trap (not trigged at the time). The data series on marked roe deer started in 1976 and is one of the longest time-series in the Grimsö base program.One of the wildlife cameras in the camera trap system covered by snow and in need of some “cleaning”. Photo: Gunnar Jansson.
The dominating method to catch wolves is via darting (immobilization) from a helicopter, which is easier during winter as the wolves are easier to spot when the ground is covered by snow. The same goes for obtaining reliable results from aerial surveys of moose (Alces alces). However, too much snow can create some problems or delays in sampling, such as difficulty in reaching the study area due to road closures. Therefore, snowmobiles are sometimes used during winter. Another problem that may occur is that wildlife camera becomes covered by snow, resulting in blacked out pictures until they are cleaned.
Winter is also the time for planning for upcoming field work. At Grimsö, plans to start the sampling for the LIFEPLAN project, along with other SITES stations, is already underway.
