Black rat confirmed in Finland for the first time in decades
A black rat (Rattus rattus), a species long considered extinct in Finland, has been discovered in Jyväskylä. The rat was found dead in an electric trap on the premises of a company importing goods from the Middle East, Helsingin Sanomat reports.
A DNA test conducted at the University of Oulu confirmed the species, ruling out misidentification. Emeritus professor of forest zoology Heikki Henttonen stated that, to his knowledge, this is the first confirmed sighting of a black rat in Finland in decades. While isolated reports of the species have surfaced over the years, Henttonen suggested that previous observations were likely erroneous (Helsingin Sanomat).
Historical significance and ecological impact
The black rat is Finland’s native rat species, believed to have arrived in Europe from Southeast Asia via trade routes. During the Middle Ages, it played a key role in spreading the plague bacterium, including during the Black Death in the 14th century. However, by the early 20th century, the species was largely displaced by the brown rat (Rattus norvegicus), which is now dominant in Finland.
Henttonen estimates that the black rat is unlikely to re-establish itself in Finland due to the country’s harsh climate and the competitive dominance of the brown rat (Iltalehti).
Rise in brown rat sightings
The discovery of the black rat comes amid an unusually high number of brown rat sightings across Finland this year. Petri Metsälä, development manager at pest control company Anticimex, told Ilta-Sanomat in February that reports of rats in the Helsinki area had increased by about 25% compared to previous winters, likely due to the cold weather driving them indoors in search of food.
Similar trends were observed in Pirkanmaa, where the City of Tampere issued a statement in February regarding an uptick in rat activity (Ilta-Sanomat).