Marking and Tracking
Target animals
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A primary goal of the SBBRP is to follow individual bears through their life cycle from birth to death. The project has largely focused on following females and their cubs, often marking cubs early in life and recapturing them later-on to maintain their presence in the study, although we have collared many males over the years as well. Bears are generally captured in early spring after they have emerged from their dens, although more recent efforts have also included summer and in-den winter captures to collect data for human medicine research.​​
Capture, immobilization, and marking
The SBBRP has been capturing and marking brown bears since 1984. Methods have evolved over the years but have always used the most recent and available protocols approved by the Swedish Ethical Committee on Animal Research. Current methods include darting bears via helicopter using a remote drug delivery system (DANiNJECT®). All precautions are taken to decrease the stress from the capture event and maintain safety for both the animal and crew. Once immobilized, each individual is clinically examined and their vital signs (e.g., body temperature, heart rate, breathing rate) monitored throughout. GPS collars are fitted according to the size, age, and sex of the bear. The weight of the radio collar and other equipment do not exceed 2% of the animal's body mass. Bears are also marked
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with a microchip and an inner-lip tattoo so they can be identified in future captures. Surgically implanted VHF abdominal transmitters were also used in the past to facilitate recapturing specific individuals; however, this is only performed sparingly now. Biological samples from all marked individuals are also taken. This includes blood, hair, skin, feces, and urine samples, as well as the upper 1st premolar tooth to determine the age of animals not followed from birth.
Physiological monitoring
Starting in 2010, a subsample of bears has been fit with temperature loggers and heart rate monitors, respectively. Temperature loggers are surgically placed into the abdominal cavity, while heart rate monitors are placed under the skin (subcutaneous) in the chest just above the heart. Temperature loggers monitor fluctuations in body temperature that are recorded every temperature every 2-4 or 30 minutes. Heart rate monitors record heart rate average daily, one at night and one during the day, although some newer models record heart rate every 2 minutes. Temperature and heart rate monitoring was discontinued in 2024.
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​​Tracking
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Bears are currently fit with GPS collars from Vectronic Aerospace. Multiple models of collars have been placed on bears, which offer a variety of functions. The current baseline function of collars includes GPS-satellite tracking with locations uploaded remotely to the WRAM database at SLU at regular intervals. In general, bear collars are set to take positions every 30 minutes or 1 hour, however, this baseline setting is changed to a more fine-scale fix rate for more intensive studies. All collars are also equipped with a VHF beacon which can be used to locate the animal during capture or the collar when the GPS battery is depleted. All current GPS collars are also equipped with accelerometers which measure ‘animal’ activity. Many GPS collars also offer a ‘proximity function’ which emits a weak UHF signal and detects UHF signals from other collars; once detected, the collar will temporarily switch to
predefined fix rates. The collars also have a ‘virtual fence’ function whereby collars will switch to predefined fix rates when they come into a predefined area. The functions that automatically change into predefined fix rates give an opportunity to save battery or get finer scale data when needed. GPS locational data are core part of our data collection efforts and have been used to explore a wide variety of questions related to brown bear biology, ecology, and behavior. Early in the project we also tracked bears using collars equipped only with a VHF beacon (1984-2010), which provided key early information on brown bear biology. However, this technology is now outdated and is no longer used.