The estimates from the National Stray Animal Census have been published in the journal Urban Ecosystems (Springer Nature), following peer review. The study, carried out within the scope of CESAM and the Department of Biology of the University of Aveiro (UA), confirms the presence of approximately 830,000 stray cats and 101,000 stray dogs in urbanised areas of mainland Portugal. No other country has published a national-scale estimate for both dogs and cats based on direct observation of the animals.
The article includes the participation of several CESAM members, namely João Carvalho and Eduardo Ferreira, researchers at CESAM/DBIO; Rita Tinoco Torres, CESAM researcher and professor at the Department of Biology of the University of Aveiro; Paloma Linck, PhD student; and Victor Bandeira, CESAM member. Filipa Peste, Danielle Crawshaw and Alexandre Azevedo are also authors of the study.
In 2023, Portugal produced a national estimate of its stray dog and cat populations based on direct observation of the animals, with teams walking more than 1,000 kilometres of streets across humanised areas of mainland Portugal. This week, the study detailing this estimate was published in the international scientific journal Urban Ecosystems, following peer review. “More important than the prestige of the journal is what the study adds: it collected data through systematic direct observation of the animals, on a national scale and with an unprecedented sampling effort in Portugal,” said Alexandre Azevedo, a researcher involved in the project.
A search of the scientific literature reveals few studies combining national-scale coverage, direct observation of animals and peer review. Important contributions do exist, but they differ from the Portuguese Census in the methods used, the definitions of the populations studied and, above all, in the combination of systematic direct observation, geographical coverage and the simultaneous inclusion of both dogs and cats.
For the first time in Portugal, the issue of stray animals no longer needs to be discussed solely on the basis of perceptions. There is now a tool developed by Portuguese researchers, funded through national sources and published in a peer-reviewed international scientific journal. Information is available on where the animals are found, the factors influencing their presence, and social attitudes and behaviours, the latter being addressed in a second study conducted as part of the Census.
This is precisely the type of information needed to guide public policies and direct resources to where they are most needed. Portugal has invested in generating data and in producing the most comprehensive estimate published in the scientific literature to assess the scale of this issue at national level. The country now has robust scientific information to understand the scale of the stray animal issue within its territory. The next step is to put this knowledge into practice.
Original article: UA Online, 4 September 2026