The supposed expansion of the species in some points “could be just a mirage”, according to the CSIC
The distribution of wolf in the mid-nineteenth century it was at least 65 percent of the surface of the Iberian Peninsula, three times more than today, according to the estimate of a scientific team led by the Doñana Biological Station (EBD), an institute of the Higher Council for Scientific Research (CSIC).
To reach these conclusions, they have resorted to the geographic dictionary edited by Pascual Madoz in the mid-19th century, which described each town in Spain and geographical feature, as well as statistical models. The work has been carried out in collaboration with the German Center for Integrative Biodiversity Research – iDiv and has been published in the journal ‘Animal Conservation’.
“The knowledge we have of these declines comes from the comparison of indices that describe the distribution and abundance of species over time,” explained the researcher at the Doñana Biological Station and lead author of the work, Miguel Clavero.
However, he has pointed out thatThe data needed to calculate these indices “have only started to be collected very recently, in recent decades, while the impacts of human activities have been occurring for centuries”.
For this reason, perception of recent declines “may be a mere thumbnail of actual declines”. “Even the supposed ‘expansion’ of some species may be nothing more than a mirage, the result of looking through a very limited time window, as is the case with the wolf today,” he added.
The current “expansion” of the wolf
The researcher has pointed out that the inclusion of the wolf in the List of Wild Species of Special Protection “imposes strong limitations on these controls and has found the direct opposition of some social actors”.
Thus, he warned that, in such a conflictive context, it is “very important to have an objective evaluation of the long-term trends and the conservation status of the wolf, beyond what has happened in recent years” .
Comparing the current situation with the historical distribution, the area occupied today would account for just over 30 percent of the historical area reached in the mid-19th century. Introducing this long-term vision, “the supposed recent expansion of the species would represent little more than a stabilization of the sharp decline suffered by the species”.
An authentic recovery of the species and its important ecological functions “would imply its return to the areas of historical presence outside the northwestern Spanish quadrant”. This horizon implies “numerous challenges” for the coexistence between humans and wolves, especially in places where the presence of the species is no longer part of the collective memory.
The recently published work shows the potential of historical sources to understand the natural environment and inform its current management. Properly exploiting these sources implies a “great and careful effort” and requires the application of statistical techniques to “correct the various information gaps and biases contained in historical documents.”
“The effort is worth it if we manage to extend the time horizon in which we evaluate the state and trends of the ecosystems and the species that occupy them”, concluded Clavero.
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