About the object
see less see more
The Norway rat or brown rat (among many other names) originated in the forests and meadows of northeast Asia. It spread with increasing trade relations between East and West. The Norway rat is a typical and very successful hemerophile: it adapts well to humans and breeds successfully near them in rubbish dumps, cellars, barns and sewers. Norway rats are a host to the rat flea and can transmit diseases to humans through it, including the plague pathogen, Yersinia pestis. Norway rats were probably not, or hardly, responsible for medieval plague outbreaks in Europe, as their smaller relative, the black rat, was proliferating in Europe at that time. Only the European plague pandemics of the 19th century can be attributed to the spread of the Norway rat and the black rat. Black rats and Norway rats are often equated in older literature sources and conflated as "rat". The Norway rat, however, has smaller eyes, ears and a shorter tail compared to its larger body length. The Norway rat may have been overlooked in human settlements for a long time. Populations of Norway rats continue to displace smaller domestic rats from human settlements. Norway rats have been unintentionally introduced by humans to large parts of the world, including remote islands. They successfully colonise new habitats due to their rapid adaptability. Native animals that depend on a similar food supply or nesting sites as rats often cannot withstand the rapidly multiplying competition and are displaced by the newcomers. Furthermore, a bird population, for example, can decline sharply if rats help themselves to eggs and chicks over a period of years. Immigrant species of this kind, which not only endanger individual populations of native animals and plants, but can even throw entire ecosystems out of balance, are known as invasive species.