These traps can reveal the family lives of brown bears

Since 2009, researchers at the Norwegian Institute of Bioeconomy Research (NIBIO) have used hair traps and DNA analyses to gain more knowledge about the occurrence of brown bears in different parts of Karasjok municipality, far north in Norway.

“In total, we have carried out 12 different hair trap projects,” says Ida Fløystad.

She is a laboratory manager at NIBIO.

“Most of the surveys have been conducted in the central and southern parts of the municipality, south of the Karasjohka River. In addition, we have carried out some surveys in the Anárjohka area and in the northern parts of Karasjok, toward the borders with Tana and Porsanger,” she says.

Fløystad explains that the overall goal of the hair-trap projects is to gain more knowledge about the number of bears, their sex, and which individuals are present. 

The researchers also aim to gather more information about the bears’ movements in the area and about possible family relationships between individuals.

A total of 45 hair snares in 2025

Last year’s study area of 1,100 square kilometres was divided into 45 grid cells measuring 5 by 5 kilometres: 16 cells south of the Karasjohka River (South Karasjok) and 29 cells north of the river (North Karasjok).

“We have previously conducted hair-trap projects in these areas as well, but the results are only partly comparable because the number of grid cells and their placement have varied somewhat from year to year,” the researcher says.

One hair snare was installed within each grid cell. The traps were active for two months, from mid-June to mid-August, but after one month the snares were moved to another location within the same grid cell.

“A new feature this year was that we also deployed wildlife cameras in connection with 17 of the hair traps,” says Fløystad.

16 different brown bears detected in 2025

In total, 248 hair samples and three fecal samples were collected in Karasjok in 2025. 

DNA analyses showed that these came from 16 different brown bears – seven males and nine females. 

This gives an estimated bear density of 1.5 bears per 100 square kilometres across the entire study area.

Six of the bears were detected in both South Karasjok and North Karasjok.

In South Karasjok, 11 different bears were detected based on 101 hair samples. Here the density was clearly higher, at 2.8 bears per 100 square kilometres. 

Two of the females were completely new individuals that had not previously been registered in the area.

“When we combine this year’s findings with data from the past six years, we see a clear pattern,” Fløystad says. “Bear density is highest in the southern parts of Karasjok, particularly farthest away from the river. The fewest bears are found near the town centre of Karasjok.”

Stable populations in the north

North of the Karasjohka River, 147 hair samples and three fecal samples were collected. 

These turned out to come from a total of 11 bears, all known individuals from previous years. Bear density in this area was 1.6 bears per 100 square kilometres.

“When we look at data from the past four years combined, it's especially the northeastern grid cells in North Karasjok that stand out as areas with high bear activity,” Fløystad says.

Researchers now know more about the bears' family life

Fløystad notes that last year’s hair trap projects showed consistent differences in bear density and sex distribution between South Karasjok and North Karasjok.

“South Karasjok has higher density and more female bears, which is beneficial for reproduction and long-term population stability. North Karasjok has lower density and more male bears,” she says.

“Most of the detected bears are previously registered individuals, which suggests that the bear population in Karasjok is local and relatively site-faithful. One of the detected bears, FI258, had previously been registered in Sør-Varanger municipality,” she adds.

By combining genetic analyses with images from wildlife cameras, the researchers have gained better insight into the bears’ family life. 

The project has identified female bears with cubs, sibling pairs, possible fathers, and new individuals that have appeared both in new areas and at new times.

Important knowledge for management

This type of systematic monitoring provides valuable knowledge about the distribution and population development of the brown bear. 

The method makes it possible to follow individual animals over time without disturbing them, and provides a solid foundation for the continued management of one of Norway’s most iconic predator species.

Reference:

Fløystad et al. DNA-overvåking av brunbjørn i Karasjok sør og nord ved bruk av hårfeller og viltkamera (DNA monitoring of brown bears in South Karasjok and North Karasjok using hair traps and wildlife cameras), NIBIO Report, 2025.

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