In the summer of 2018, Ljusdal, a municipality in central Sweden, was hit by several major forest fires. Approximately 8,400 hectares of forest land burned.
In a new study by SLU and the state-owned forest company Sveaskog, researchers have tracked 51 moose using GPS transmitters to observe how moose landscape use is affected by larger burnt forest areas. This is the first-ever study of GPS-marked moose in and around fire-affected areas in Sweden.
"The moose in the area are in good health, and the burnt areas are popular among the majority of moose. Two-thirds of the transmitter-equipped animals are found to use these areas. Moose seem to thrive in the region, displaying good reproduction rates with a high proportion of twin calves. Some cows even chose to calve within the burnt areas. At the same time, there are many predators in the area affecting calf survival," says Wiebke Neumann, a researcher at SLU.
Many calves are taken by bears
Characteristic of the area is the high presence of large predators, mainly brown bears. Researchers noted that the summer survival of calves until the start of hunting was low, not exceeding 30 percent. Previous studies on moose calf survival in bear areas have shown a survival rate of approximately 40 percent.
Most calves that died or disappeared during the summer were taken early on, primarily by bears, often during the calves' first two weeks of life. Researchers could confirm this through field findings and changes in the female moose's movement patterns. Using GPS transmitters, researchers could observe how moose females with calves behave during a predator attack.
"During a bear attack, we see that the female first runs straight out of the area, sometimes several kilometers away. After a while, she runs back to see if the calf is alive. She returns to the last place she had contact with the calf or calves and revisits multiple times to see if any survived. We have also seen clear signs where some females attempted to defend the calf or calves," says Fredrik Stenbacka, a research engineer at SLU.
Need to balance hunting quotas
In addition to studying ecosystem changes after a major fire and how these changes affect wildlife populations, an overarching goal of this project to produce research results supporting moose management in the area. In moose and forestry management, especially in areas with strong predator influence, significant attention must be given to moose health, numbers, and condition when discussing and deciding the moose population size in balance with forest resources.
"The high predator pressure and low summer survival lead to a limited number of calves in the area that can reach adulthood and, in turn, reproduce. Moose management, therefore, needs to carefully balance hunting quotas to avoid having too few reproductive moose," says Wiebke Neumann.
Moose cross management boundaries
Using GPS transmitters, researchers have also mapped the moose's migration behavior in the areas.
"As expected, we found differences among moose individuals , which resembled what we've seen in other parts of Sweden. Some moose have completely different summer and winter areas, others partially overlap seasonal areas, and some moose don't move at all, spending the whole year in essentially the same area," says Wiebke Neumann.
For migratory moose, researchers have seen that they follow old migration routes, revealed by following old trapping pit systems. Trapping pit systems often lie where humans have long known that moose have their migration routes, providing evidence of how moose have moved for thousands of years.
"The movements of migratory moose sometimes cross current boundary lines between different moose management areas. For moose management, this may necessitate a review of current boundary lines in this part of the study area to have well-coordinated management of the area's moose population," says Wiebke Neumann.
The project will continue until 2026.
