Browsing by Subject "ekologinen mallinnus"

Norway rats are common commensal species across the world. Despite their long history with humans, the ecology of urban rats is still relatively unknown. Which is why in my thesis, I model the population dynamics of wild urban rats of Helsinki using trap data from a professional pest management company. To protect the privacy of the company’s customers, the data are on the scale of postal code areas. Using a generalized linear mixed model, I investigate several different factors that might affect rat populations. As the data come from a pest management company, trapping factors need to be considered. Other factors include environmental, such as the proportion of parks or the type of sewer present in the postal code area. But as urban rats live in cities, anthropogenic factors such as human density and income matter too. In the span on seven and half years, 8 415 rats were trapped all across Helsinki, in some places more than others. Of all the factors only the trapping factors along with household median income were significant. Median income was negatively associated with trapped rats, so more rats were trapped in areas with lower income. Future studies should try to uncover for what unknown factor income acts as a proxy for.