Wild boar

The wild boar is a hardy animal that copes with both snow and cold as long as it can find food. Photo: Jørgen Rosvold

Wild boar

The wild boar is considered an alien species in Norway. NINA  is working to increase the knowledge base to achieve a better management of wild boar in the country.

Norwegian nature management has a goal of having as few wild boars as possible in the smallest possible area. Solid data on their occurrence, distribution, population composition, health and ecological effects are important prerequisites for achieving knowledge-based management of the species.

Alien species in Norway

Wild boar existed naturally in Norwegian nature until they went extinct about 1000 years ago. Now the wild boar is back. Since it re-established itself in Norway after 1800, it is by definition considered an alien species.

Its re-establishment is due to immigration from Sweden. The wild boar was also extinct in Sweden for a short period, and today's wild boar population originated from individual animals that escaped from enclosures. In Sweden, the population has increased rapidly since the 1990s, and more wild boar than elk are now harvested here every year. The wild boar is today considered part of Sweden’s native fauna, and animals will probably continue to cross the border into Norway.

Wild boar are extremely adaptable and have a high reproductive capacity. The wild boar is already sexually mature by 10 months old and gives birth to three to eight piglets in each litter. In productive areas, wild boar can have young all year round, but most are born during the spring. They are social animals, and the females live in groups called sounders, led by an older sow.

Wild boars are omnivores and find their food in or on the ground. High-energy food is important, and wild boar readily turn to agricultural crops to meet that need. For this reason, and due to fear that wild boar can spread diseases, the wild boar has been designated as an undesirable species in Norway. This is linked to concerns that wild boar could lead to negative consequences for indigenous species, but currently very little is actually known about the impact of wild boar on Nordic natural habitats.

NINA focuses on key questions about wild boar in Norway:

  • What is the wild boar’s population size and composition, distribution and reproduction rate?
  • What is the wild boar’s actual spread potential in Norway and what can limit the spread?
  • Which areas do they use the most, and are we able to document where wild boar found in new areas come from?
  • What does the wild boar eat in Norway and what is the proportion of agricultural crops in their diet?
  • What impact do wild boar have on Norwegian nature?
  • What attitudes do we have towards the wild boar?

NINA is working to establish better mapping and monitoring of wild boar in Norway.

Systematic camera surveillance

Wild boar are a demanding species to monitor. They are shy, nocturnal and can disperse over large areas. To date, Norway has not carried out any systematic monitoring of the wild boar population. NINA is now collaborating with the Department for Nature Management to develop and adapt existing monitoring methods for Scandinavian conditions.

Other countries employ many different methods for monitoring wild boar, which include estimating prevalence and density or following population development using population indices. Many of these methods are inefficient. The most relevant methods for monitoring wild boar in Norway within the entire population area seem to be a combination of game camera use, hunting statistics and genetic analyses. More intensive monitoring to estimate densities can possibly be carried out in conjunction with other methods in parts of the distribution area. NINA is currently testing game cameras as a surveillance method on two scales:

Large-scale monitoring of wild boar prevalence

This trial is using the SCANDCAM research project's large network of game cameras in south-eastern Norway. SCANDCAM was developed as a tool for monitoring lynx in low-snow areas, but has proven to be able to be used in monitoring additional mammal communities in forests. The study areas are organized into a grid with 50 km2 cells, and local crews place a game camera within each cell. Cells containing contiguous mountain areas or densely populated areas are left out. Cameras are located where we expect animals to travel, including cart roads, forest roads and game trails. The game cameras are activated year round, and the pictures are posted on the viltkamera.nina.no website

Intensive monitoring area

An intensive monitoring area of approx. 1500 km2, which includes Halden and Aremark municipalities and 75 game cameras, was established in 2019/2020. These game cameras are moved to new random positions periodically, with a total of 300 positions being monitored. The data can be used to model the prevalence of reproducing wild boar and their habitat use. The layout is constantly being improved. The project will be completed in the autumn of 2021.

Genetic analyses of kinship and diet

Since July 2020, we have sent out test kits to collect faeces and tissue samples from wild boar that are killed during hunting and from fallen game. This collection is coordinated with the Norwegian Veterinary Institute's collection of samples for monitoring the health of the same animals. The dung samples are used in genetic analysis (DNA barcoding) to examine the wild boar's diet. The goal is to gain more knowledge about what wild boars in different areas eat and about the presence of agricultural crops in the diet. The tissue samples are used for genetic analyses that can help us learn about kinship and genetic similarity in wild boar in different areas. From these samples we will also try to identify which geographical areas the wide-ranging wild boar come from. Do they disperse mainly from the core area in south-eastern Norway or come across the border from several different parts of Sweden?



Jørgen Rosvold (Ass. Research Director)

John Odden (camera surveillance, monitoring) 

Christer Moe Rolandsen (genetic analyses of kinship and diet) 

Oddmund Kleven (genetic analyses of kinship and diet) 

Inger Maren Rivrud (monitoring)

Norwegian Institute for Nature Research

NINA is an independent foundation for nature research and research on the interaction between human society, natural resources and biodiversity.
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