DNA-monitoring improves knowledge on large carnivores
For more than 20 years researchers have used DNA to gain more knowledge on large carnivores in Norway.
The likelihood of running into a large carnivore in Norway is very low. Fortunately, we do not need to see them or have direct contact to study them!
In parts of Norway, large carnivores and humans co-exist. There is overall a strong interest to get information on how many animals live in different areas of the country.
DNA-technology is a brilliant tool to learn where the animals roam, how many individuals we have, and which ones are related.
Species specific management goals, decided by the Parliament of Norway, determine how many individuals of large carnivores and golden eagle we should have. For instance, the Parliament has decided that Norway should have maximum 13 brown bear litters per year.
Rovbase is a public website where you can see how large predators roam, how many there are (minimum), and which individual was identified in livestock depredation.
To assess these numbers and control the management goals, brown bear, grey wolf, wolverine, Eurasian lynx and the golden eagle are monitored under the Norwegian Large Predator Monitoring Program, operated by Rovdata . The large carnivore populations are regularly examined to provide the administration, media and public with knowledge. Most of them are monitored using DNA-analyses of feces, fur, feathers or other biological samples. Based on this information, Rovdata provides updated numbers on wolf, lynx , wolverine, brown bear and golden eagle populations.
Rovdata publishes updated numbers on wolf, lynx , wolverine, brown bear and golden eagle in Norway.
Sample collection
For more than 20 years, the Norwegian Nature Inspectorate (SNO) and volunteers have contributed to the collection of feces, feathers, and hair from large carnivores and the golden eagle. The samples are submitted to Rovdata to be analyzed with advanced DNA technology.
In this video, Tore Solstad from SNO explains how the collection of feces samples for DNA analysis is done.
More information:
How does DNA-monitoring work?
DNA contains the building instructions of all living organisms. It is found in body cells of organisms across the globe.
DNA is short for deoxyribonucleic acid.
DNA consists of four building blocks, so-called nucleotides:
Cytosine, guanine, adenine and thymine.
DNA is organized in larger molecules, called chromosomes.
Øystein Flagstad, senior researcher Rovdata, explains how DNA works.
DNA has revolutionized how we monitor carnivores
Researchers have mapped the entire genome (all the genes) of most large carnivore species. However, a genome contains an enormous amount of information, so not all of it is needed when analyzing a DNA-sample to monitor large carnivores.
Therefore, researchers focus on specific parts of the genome using so-called genetic markers. Such markers provide enough information for us to get a genetic or DNA-profile, which is unique for each individual animal.
Simplified model of a DNA double helix; the structure of the DNA molecule.
In order to get a DNA-profile, a biological sample is required. Biological samples are samples that contain body cells of the animal in question. It can be feces, hair, urine, saliva, tissue, blood, or feathers. Most samples used in the DNA-based monitoring of large carnivores in Norway are feces, hair, and urine samples. These samples can actually be collected several weeks after the animal has left them.
One of the biggest advantages to monitoring large carnivores with their DNA is the fact that animals can be identified without being in direct contact with them.
Combined with information on the location (coordinates) and time (date) when the DNA-sample is been found, we can estimate how many different individuals have been in an area.
Tissue and blood samples can be also used, however, they usually require direct contact with the animal and are therefore usually collected when an animal was captured to mark it, e.g. with a GPS-collar, or from dead animals, during legal harvest or from road kills.
Although large carnivores such as wolves, brown bears, and wolverines occasionally can be observed and photographed, their shy and elusive nature make them notoriously difficult to detect and thus challenging to study in the wild. Here, the use of DNA has revolutionized how we monitor and identify individual large carnivores today.
How to find "genetically important" animals?
Genetic variation or genetic diversity, the number of genetic variants in the genes of individuals of a population, is pivotal for the long-term survival of a species.
Genetic diversity is one of the cornerstones of our planet's biological diversity, besides species diversity and ecosystem diversity.
DNA enables us to look at relationships and kinship in a population.
This allows the identification of families and groups, which also helps distinguish animals from other populations, which may have migrated from another region or population into the area where its sample was found.
Low genetic variation, as observed in Scandinavian wolves , for example, can have negative effects on individuals and the population as a whole.
Especially threatened are small populations. Small populations have only a few individuals reproducing and which are thus often closely related; inbred.
Long-term monitoring of carnivores
To meet the large carnivore population targets and management goals set by the Parlament of Norway, we need a good overview of their numbers and status.
Regular, annual DNA-based monitoring is applied in Norway to estimate population size , number of litters, and distribution. Also, the parameters are studied over time to understand what affects them and to monitor also their trajectory.
What could go wrong?
Unfortunately, not every sample collected delivers a complete DNA-profile.
There are several factors that can potentially affect the quality of a DNA-sample and therefore this has influence on the results.
Obviously, the environment a can have effects on biological samples.
The longer a DNA-sample is laying around in nature, the longer it is exposed to the environment and its often changing conditions.
Heat, fluctuating temperatures, sunlight, humidity, and dry weather all have an effect and can potentially break down the DNA-molecule.
Such environmental factors are especially a great challenge for hair samples, which contain DNA only in the cell of the hair follicle (yellow circles).
Hairs and their roots are usually exposed to a large degree to the environment, as they are often collected from fences, barbed wire or trees, and wooden poles.
Another factor can be the diet of the large carnivore. The quality of a feces sample is also influenced by what the animal has eaten. For instance, large amounts of fat or meat consumed and thus contained in the feces sample, can interfer with the DNA-analysis and may lead to difficulties to interpret a DNA-profile.
The genetic markers used are usually species-specific, which means they deliver results only for the species they are supposed to be used with. For example, if accidentally a red fox sample is labelled or collected wrongly as a brown bear sample, the DNA-analysis will lead to a negative result; a negative result for brown bears.
Furthermore, the sample collection itself can affect the results, depending on how the sample is collected and how it is stored.
It is crucial that each DNA-sample is collected with simple care and separately to avoid contamination and mixing different samples. Feces can be collected in a clean plastic bag and should be stored frozen if they cannot be handed over the same day. Hairs can be collected into a paper envelope and should be kept in a cool and dark place until further handling. The same applies to feathers.
What happens to the sample?
When Rovdata receives a DNA-sample, it is genotyped (genetically analyzed) in the laboratory. The resulting DNA-profile is checked against DNA-profiles from other, already recorded animals to identify if the individual has been detected earlier or if it is a new animal.
The procedure is as follows:
1: At arrival, the DNA-sample arrives and is checked to see if it is already registered at Rovbase.
2: Before analysis, feces samples are kept frozen at -80 degrees Celsius for three days to kill possible parasites.
3: In the laboratory, only a tiny amount of the delivered sample is taken for the so-called DNA-extraction, in which the DNA contained in the sample will be isolated from the rest of the sample material.
4: In the next step, the extracted DNA is then copied to million of copies with the so called PCR (polymerase chain reaction).
Copying the small amount of DNA usually found in feces improves the analysis considerably. Today, PCR is a standard procedure in most DNA analyzes, also in human medicine and criminal cases. Its inventor, Kary Mullis, was awarded the Nobel Prize in Chemistry in 1993).
5: The result after PCR is then examined to determine the unique DNA-profile of the animal.
6: The DNA-profile is stored in a common Scandinavian database, where it is checked against the other, already known and recorded, DNA-profiles.
7: The results of identification, such as the identification number, are stored in Rovbase , where everyone, including the person who has found the sample, can check the results from "their" sample.
Why is this information important for us, our society?
The technology behind DNA and its analysis is getting better and constantly evolves. It does not solve all the challenges we have with humans and carnivores sharing the same space. However, these methods provide us with valuable and especially important information that can increase and improve our knowledge on large carnivores.
This knowledge allows for a more efficient monitoring and management of large carnivores and ensures the survival of the species and local populations. With that it contributes to better conflict solutions. The additional knowledge provides us with a much better basis for sustainable management of large carnivores.
Brown bear
The brown bear (Ursus arctos) is the largest of the carnivore species on the Norwegian mainland.
The species is endangered in Norway.
In 2019, a minimum number of 148 brown bears were detected in Norway using DNA analyzes. 57 were female bears, and 91 were male bears. At Rovdata you will find updated population numbers .
Adult male bears weigh 100 to 300 kilo, while adult female bears weigh less; about 60 to 200 kilo.
Brown bears are omnivors, which means they eat plants and animals. Most of their energy needs they fuel with berries, ants, moose, and reindeer calves. If brown bears get the chance, they may also prey on other livestock, such as sheep. In addition, brown bears also feed on herbs and grass.
Photo: Arne Nævra
Wolverine
The wolverine (Gulo gulo) is the largest Mustelidae, marten species, in Norway. It can be mainly found in mountainous and alpine areas.
The species is endangered and is listed on the Norwegian Red List of threatened species 2015.
In 2020, the population consisted of 382 adults, which meant an increase of 48 animals compared to the year before.
At first glance, a wolverine may be mistaken for a small brown bear. Male wolverines weigh between 12 to 18 kilo, and adult females weigh 8 to12 kilo. These animals can be between 70 to 85 centimeter in length and can be recognized also by their bushy tail.
The wolverine can prey on animals several times larger than itself. In winter, its food consists mainly of reindeer, which it consumes as a scavenger or hunts itself.
During summer the wolverine's diet is more varied and includes birds, small and medium-sized mammals, plants, reindeer, and sheep.
Wolverines killing moose is rare, but has been reported on a few occassions.
The animal tends to keep food stored for later use and is able to transport entire prey across several kilometers.
The wolverine lives mostly solitary, and has a comparably large home range. Females without cubs, and males, roam in areas that can range from 200 to 1,500 square kilometers.
Photo: Kjetil Schjølberg
Wolf
The Grey wolf (Canis lupus) is a social species where most animals live in pairs or packs that occupy a territory as their home range.
The Norwegian Red List of Species lists the wolf as critically endangered.
In the winter of 2019-2020, 56 wolves were registered within the borders of Norway. In addition, 47-50 wolves have been registered on border areas between Norway and Sweden.
The wolf is a skilled hunter and preys mainly on ungulates. In Scandinavia, 95 percent of the diet consists of moose and a pair or pack of wolves can hunt more than 100 moose per year.
In other areas, e.g. with a lot of deer, these can make up a large part of the wolf's diet. The wolf also consumes small game, such as beavers, badgers, hares, and forest birds, as well as small rodents. Wolves prey on sheep and reindeer, when available.
Genetic analyzes show that the wolf population in Norway is strongly characterized by inbreeding. Until 2008, the entire Scandinavian wolf population descended from only three animals.
Therefore, it evokes great interest when wolves enter from other areas, such as Finland. Such animals are usually carrying different genetic material which can improve the genetic variation of the Scandinavian wolf population. Therefore, such wolves are called "genetically important" wolves.
Foto: Arne Nævra
Lynx
The Eurasian lynx (Lynx lynx) is the only wild cat species in Norway.
The species is widespread over large parts of Europe and Asia. In Norway, it is highly endangered and therefore on the Norwegian Red List of Species.
In 2020, approximately 393 animals were estimated in Norway (before quota hunting), which was based on 66.5 registered family groups. It is the first time in eight years that the number of family groups exceeds the national population target of 65 annual family groups.
The lynx can be up to 1.2 meters long, and weigh between 17 kilos (females) and 23 kilos (males).
The most important prey animals are deer and domestic reindeer. The lynx can also prey on sheep during the summer. It can also consume smaller animals, such as hares, birds, and foxes.
The lynx is a very quick and efficient hunter, but not very enduring. Two out of three hunting attempts are successful when the distance between lynx and prey is only 20 to 30 meters.
The lynx prefers to eat the meat fresh and therefore does not hoard or store prey. If left undisturbed, some individuals may remain at a carcass until most of the meat has been eaten up.
Foto: Espen Lie Dahl
Golden eagle
The golden eagle (Aquila chrysaetos) is the second largest bird of prey we have in Norway. Only the white-tailed eagle is larger.
The species lives in pairs in fixed territories and is widespread over large parts of the country.
The Norwegian population is considered viable, and therefore the species is not listed on the Norwegian Red List.
It was estimated that between 914 to 1,145 of these territories were occupied by a breeding pair of golden eagles more than once during the last five years.
The golden eagle preys mainly on medium-sized mammals, birds and scavengers.
Body size differens considerably between females and males. Females are larger than males and usually weigh about 5 kilograms and have a wingspan of around 2.2 meters. The male is slightly smaller, and shows a weight of about 4 kilograms and has a wingspan of about 2 meters.
Foto: Espen Lie Dahl
About Rovdata
Rovdata disseminates information of large predators populations in Norway to the administration, organizations, the media and the public.
Rovdata is an independent unit with its own manager and staff, at the Norwegian Institute for Nature Research (NINA) in Trondheim. We are responsible for the dissemination, operation and development of the National Large Carnivore Monitoring Program, on behalf of the Norwegian Environment Agency, Miljødirektoratet .
Contact:
Jonas Kindberg , leader Rovdata, mobile 404 51 540
Øystein Flagstad , senior researcher, mobile 917 18 309
Alexander Kopatz , researcher and project leader for the film on DNA-based monitoring, mobile. 451 32 514
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