Tram works bring more rats to Vantaa resident’s yard

A resident of Länsimäki in Vantaa says rats have become more numerous since a waste shelter was demolished for tram construction, Yle reports. The exposed bins are often full and left ajar, providing food for the rodents.

Paavo Poikonen says he sees rats scurrying around whenever he takes out the rubbish, regardless of the time of day. Birds pull waste from the bins, and a missing plug has left a hole through which a rat can climb into one of them.

A small wooded area beside the bins has several holes that appear to be rat nests. Poikonen says he has filmed young rats, with adults running between the nests and the nearby food.

Rat numbers are usually highest in early autumn, according to Santtu Pentikäinen, a doctoral researcher in a University of Helsinki project studying urban rats. As the weather cools, people spend more time indoors and provide less food outside.

Pentikäinen says rat problems are best addressed before they grow. During an inspection of waste shelters, he found one with a new metal strip at the bottom of its door and mesh fine enough to keep rodents out. Old droppings remained inside, and two electric traps had been placed outside.

Warmth, weather, the layout of the city and the amount of green space can all affect rat numbers, Pentikäinen says. Research has also found greater rat activity in areas with weaker socioeconomic conditions, though he says the reasons are uncertain. One possibility is that people respond differently to rats and wait for numbers to reach a certain level before acting.

Local residents and property managers have a particularly important role, he says, through decisions about whether to prevent rats from finding food, shelter and routes into buildings. Kristel Pynnönen Andersson, a senior legal adviser at the Finnish Real Estate Management Federation, says properties need to work together because rats can move from one site to another when control measures are not coordinated.

It is difficult to estimate the number of rats in a city such as Helsinki, Pentikäinen says, because populations fluctuate considerably during the year as rats are born and die.