The wolf Canis lupus population occupying the lowlands of central Europe is divided into two management units: the Baltic population east of the Vistula river and the Central European population to the west. We re-evaluated arguments for this division in the context of the ongoing wolf recovery and its usefulness for wolf management in Poland. To do so, we 1) compared the recovery stage on each side of the Vistula, 2) investigated the history of wolf occurrence in western Poland after the eradication campaign of 1955–1975, 3) evaluated dispersal corridors, dispersal distances and genetic data for evidence of a possible isolation of the two alleged populations and 4) compared habitat characteristics in Poland on each side of the Vistula.
The total area of forest occupied by wolves was 56 600 km2 in 2015 and grew by 5340 km2 until June 2017. Wolves in eastern Poland occurred in more areas than predicted by a habitat model, whereas wolves in the west have not yet recolonized all suitable habitats. Wolves have never been extinct west of the Vistula after the eradication campaign, but their recovery started only in the 1980s. Areas currently occupied by wolves on both sides of the Vistula are interconnected by dispersal corridors less than 100 km long, and population genetic studies show that wolves inhabiting the Polish lowlands constitute one genetic cluster. The wolf habitats west of the Vistula have a higher proportion of forests are less fragmented. We conclude that wolves inhabiting the lowlands on both sides of the Vistula river belong to the same population, have similar conservation status, and should be treated as the same management unit.
