Study reveals how gray wolves recolonized Germany

The reintroduction of the gray wolf (Canis lupus) to Germany, starting 23 years ago in Lusatia, Eastern Germany, marks a significant ecological and social event. Understanding the intricacies of this recolonization and predicting future distribution trends are essential. 

In a recent study published in the journal Diversity and Distributions, a team from the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) has shed light on this complex process. 

The researchers found that gray wolves’ habitat selection evolved from the early to the late phases of recolonization in a specific area, refining their 2020 habitat modeling originally published by the Federal Agency for Nature Conservation.

Future range expansion 

Gray wolves, which prefer habitats with ample cover and distance from human activity, demonstrated these preferences during their return to Germany. The recolonization of habitats they were extirpated from 200 years ago allowed for predictions of future range expansion in Germany. 

The 2020 study by the Federal Agency for Nature Conservation (BfN), conducted with the Leibniz-IZW team, estimated around 700 to 1,400 potential wolf territories in Germany’s natural areas. The scientists have now delved deeper, testing various spatio-temporal modeling approaches in relation to different phases of recolonization.

Dynamic conditions

“There is reason to believe that the recolonization of Germany by the gray wolf is not a so-called stationary process, but is characterized by changing framework conditions,” said senior author Stephanie Kramer-Schadt, the head of the Department of Ecological Dynamics at the Leibniz-IZW. 

Kramer-Schadt noted that the recolonization process might not be uniform across Germany due to differences in environmental conditions, like between eastern Germany and the Rhine-Ruhr area. Wolves’ habitat preferences might also vary depending on whether they are in the early or late phase of recolonization.

Developing accurate models

Dr. Aimara Planillo, the study’s first author, emphasized the importance of these factors for model accuracy. “If models are developed on the basis of the specific environmental conditions of a particular region, they could underestimate the suitability of another, very different region to which such a model might be applied,” she explained. 

Dr. Planillo also noted that models based on early recolonization phases might underestimate wolves’ habitat suitability during later phases when they are less selective.

The experts developed models using a combination of radio telemetry and observation data, testing their ability to predict subsequent phases of the colonization process. The study confirmed and refined the 2020 projections.

New insights

Key findings include that wolves initially select the best habitats during early recolonization but become less selective in later stages. 

“When recolonizing an area, wolves always secure the best habitats first. It therefore appears that they are considerably more sensitive to environmental variables,” the scientists said. They also found that neighboring second-class sites are colonized in later phases, as demonstrated in eastern Germany.

Suitable habitats 

The study suggests that suitable habitats for wolves are concentrated in the north, northeast, and south of Germany, while lower quality habitats are more common in the west. 

Unoccupied high-quality habitats exist in southern Bavaria and central Germany, which are likely to be colonized by wolves initially settling in prime locations.

Study implications

In summary, the research emphasizes the need for careful spatio-temporal projections in habitat modeling for expanding species like the gray wolf. 

The complexity and dynamism of the recolonization process necessitate a nuanced approach to predicting and understanding the expansion of wolf populations in Germany.

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