Norway Lemming Fact File
Average 1-2 years
Record 3.3 years
Moss, Lichen, Grass
Norway lemmings are known for their boom and bust population cycles. Every few years they will breed to such abundance that they eat all of the food in their habitat and must migrate to another area. On these large migrations a number of them pass way due to environmental factors and predation.
A habit of predators to kill lemmings and leave them scattered around without eating them gave rise to a myth that lemmings would explode.
They feed on a range of lichens, mosses and grasses. Norway lemmings will seek shelter in a burrow which is tunneled in to snow. To assist this one of their toes is enlarged and flattened to help dig.
Learn more about these marvellous mammals by reading on below.
Their body is colored brown and black with gold streaks running across it. On the underside they are lighter than the rest of their fur.
At the end of their body is a short stumpy tail. The body is thick with a coat that helps to keep in body heat.
Their legs are short and tucked under the body. On each paw their first digit is enlarged and flattened helping them to tunnel in the snow. Each toe ends with a long claw.
Adult Norway lemmings reach a maximum length of 13.5cm (5.25in) long. An average adult will weigh between 20 and 130g (0.7-4.6oz).
Norway lemmings are herbivores. Their diet includes mosses, lichen and grasses.
Europe is the native home of the Norway lemming. Here they can be found through Norway, Sweden, Finland and Russia.
Their range is highly variable owing to the large migrations which these animals undertake annually.
Norway lemmings make their home in alpine and subarctic habitats such as peat bogs, shrub heath and slopes or ridges.
In summer they show a preference for moist habitat but in winter they must find other habitats as these areas will freeze.
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Breeding can occur year round. Females can breed once again within a month of giving birth. As many as 8 litters may be reared each year.
Between 5 and 13 young are born after a 2 to 3 week gestation period. They are able to produce multiple broods each year.
During a good year the Norway lemming will produce so many young that it can lead to food shortages in an area. This tends to occur once every 3-4 years.
This will cause them to undertake mass migrations to colonize new areas with more moving from the mountains down to the valleys.
Sexual maturity is reached within four weeks of being born.
After a large breeding season the Norway lemming will undertake mass migrations before the winter sets in. During this period lemmings have become well known due to what appears to be a mass suicide event. This is caused by a number of unfortunate combinations mainly the animals winding up in unusual habitats due to their movements. Large numbers die as they try to cross rivers and lakes.
Periods of activity occur both at day and night. They tend to be active for six hours each day. In the northern parts of their range they may be exposed to days with 24 hours of daylight during summer.
When food is scarce the males will engage in bouts of boxing and wrestling.
They burrow in to hardpacked snow during winter. When this melts in the spring they must move either to higher ground or lower ground where they spend summer.
Outside of the breeding season these animals spend much of their time alone.
Predators and Threats
Their main way to avoid predation is to hide in their burrow.
In Sweden these lemmings are affected by reindeers grazing in parts of their habitat.
Climate change is thought to be a developing threat to this species going forward. A recent increase in length of time between population peaks has been attributed to climate change.
A common myth suggests that Norway lemmings are prone to exploding. This comes from the habit of predators moving through fields with a number of lemmings in them and killing them all. They may not eat the whole lemming leaving a body which looks like its exploded.
kgleditsch, CC BY-SA 2.0 <https://creativecommons.org/licenses/by-sa/2.0>, via Wikimedia Commons
Lakkahillo, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons
johsgrd, CC BY-SA 2.0 <https://creativecommons.org/licenses/by-sa/2.0>, via Wikimedia Commons
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