Forging sustainability

Study of CESAM-FCUL reveals that enigmatic small mammal is bolder and more active in urban environments

Study of CESAM-FCUL reveals that enigmatic small mammal is bolder and more active in urban environments

Although rarely seen, the greater white-toothed shrew (Crocidura russula), a small insectivorous mammal, occurs in the gardens and parks of several European cities, including Lisbon. It was precisely in the Portuguese capital that a recent study detected substantial differences in the behavior and metabolism of urban animals when compared to individuals from natural areas. The study was conducted by an international group of researchers from the Center for Environmental and Marine Studies (CESAM) of the Faculty of Sciences, University of Lisbon, Portugal, and from the Adam Mickiewicz University Pozna?, Poland. The results, which will be integrated in Flávio Oliveira's PhD thesis, have already been published in the scientific journal Behavioral Ecology.

The personality tests we applied revealed that shrews in the city exhibit a bolder behavior and are more predisposed to explore an environment unknown to them”, says Flávio Oliveira. This type of urban adaptation is in line with studies carried out in other species, namely birds and insects. The researcher adds “The lack of natural vegetation and the constant external stimuli typical of the urban environment, such as noise and artificial light, make the animals that inhabit here behave bolder in search of food and a place to live.”

While the behavioral adaptations were as expected, the analysis of the energy the animals spent gave surprising results. "We were expecting to find a direct correlation between bold and active behaviors with high rates of energy consumption, that is, with a higher metabolic rate" says Sophie von Merten, co-author of the study. "Instead, we found that urban animals have a metabolic rate 37% lower than animals in natural areas", reveals the researcher.

The factors that influence the way urban animals use energy are still unknown, but one thing is certain: Considering the relationship between behavior and metabolism, these small animals seem to be adapted to live both on the countryside and in the city. “Contrary to what happens in most animals, shrews seem to adopt an energy allocation strategy. That is, animals with a faster metabolism are more timid and explore their surroundings less, while animals with a slower metabolism are bolder and explore more territory. This way, their energy budget remains relatively constant”, concludes Flávio Oliveira.

With the expansion of urban areas, which is expected to continue increasing, more animals will be exposed to such novel habitats. Maria da Luz Mathias, also co-author of the study, comments: “Unfortunately, most species will not be able to adapt to an environment as altered as urban areas. It is therefore essential to continue studying the phenomenon of urban adaptation in all its aspects: ecological, physiological, behavioral, and evolutionary. Our study revealed that the white-toothed shrew can be an important model species to help us understand the fate of species in the face of a global change such as increasing urbanization.

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