A group of researchers led by the Doñana Biological Station (EBD-CSIC) has analyzed the demography of the Iberian wolf and concludes that the mortality rates the species endures explain why its distribution area has barely expanded in recent decades, despite having extensive areas of suitable habitat to expand into.
As detailed by the CSIC, the work determines that "reducing this mortality would be key to promoting the recovery and improving the conservation status of this population," listed by the IUCN as "vulnerable" in Spain and "endangered" in Portugal. While in Europe and North America wolves have reconquered part of their historical range and have even settled in highly humanized countries like Germany, Denmark, the Netherlands, or France, the situation in the Iberian Peninsula is very different.
Official data from Portugal and the autonomous communities where the species lives show that the Iberian wolf has not followed this expansive trend. Although it has large favorable areas, its distribution has barely changed during all this time. This discrepancy led the Doñana Biological Station team to delve into what factors are hindering its recovery.
Postdoctoral researcher and lead author of the study, Ana Morales, details that "in recent decades the distribution of the wolf in the Iberian Peninsula has barely varied beyond minor changes, with small areas being colonized and others where the species becomes extinct, including the extinction of the Sierra Morena population, while during the same period other European populations were expanding very rapidly." Faced with this scenario, the team posed a central question: "what factors could explain this dynamic, hindering the species' recovery in Spain and Portugal?".
To address the problem, the scientists built a very detailed demographic model capable of reproducing the evolution of the wolf population in the Iberian Peninsula between 1991 and 2021. They adjusted the model's parameters with official distribution data and available population size estimates for that period. Once its reliability was verified, they evaluated how the species' future would vary if the mortality of different types of individuals were reduced.
Analyses reveal that, although dispersing wolves are the ones that colonize new territories, limiting only their mortality barely alters the global population trajectory. In contrast, a 10% decrease in the mortality of wolves that make up family groups has a notable effect on improving the conservation status.
The model indicates that with this 10% reduction, groups become more numerous, reproductive success increases, and straight-line dispersal distances go from about 32 to over 70 kilometers. As a result, the population could grow and expand to double its distribution area in about three decades. Based on these simulations, the team estimates that each year approximately a quarter of the wolves living in groups die, more than a third of the dispersers, and more than half of the pups.
The researcher and co-author of the work, Eloy Revilla, emphasizes that "the key is that wolf groups are family units with a complex social structure, and the death of these individuals generates cascading effects that go far beyond the loss of isolated individuals, especially if a member of the breeding pair dies."
Furthermore, he adds that "so many vacancies are generated and so many territories cease to be occupied that they are taken advantage of by dispersing wolves to establish themselves very close to their birthplace instead of colonizing new areas."
Implications for the conservation of the Iberian wolf
The authors highlight that these results are "especially" significant in the context of recent changes in the legal framework for wolf protection in Europe and Spain. In Spanish territory, in 2021 the species became part of the Lesrpe (List of Wild Species under Special Protection Regime), which meant the end of its hunting throughout the country.
The team contrasted the model's projections with data from the latest national census. In this census, 333 family groups were calculated for the period 2021-2024, a figure similar to what the model projected for 2013-2021. This suggests that in those years the Iberian population has not shown a clear improvement in its conservation status, something consistent with the most recent IUCN assessments.
Despite this, in 2025 the wolf ceased to be protected at the state level in Spain after its exit from the Lesrpe. Morales warns that "in our work we warned that this legislative change could hinder the recovery of the population if mortality returns to levels similar to those recorded until 2021, and that effective protection of the species and the reinforcement of measures aimed at preventing and prosecuting illegal mortality are fundamental tools to allow the improvement of the conservation status of this population".
The researchers also point out that what has been observed on the Iberian Peninsula could be reproduced in other European populations currently in an expansion phase but subjected to an increase in mortality, such as those in France or Germany. The developed model is thus presented as a useful tool for evaluating "how different conservation and management strategies could influence the future of the Iberian population and other populations".
The study also highlights an important limitation for wolf conservation: the scarcity of robust demographic data. To build the model, it was necessary to combine the available information on the abundance and distribution of groups, collected by different administrations with non-standardized methodologies that vary between territories and even over time, and to estimate key parameters such as survival, reproduction, or dispersal movements, for which there are hardly any direct records.
The authors conclude that these demographic models are a valuable complement to fieldwork, but they insist on the urgency of improving and harmonizing wolf monitoring programs in order to have more solid and complete information to guide the management and conservation of the species.