Abstract
"Cumulative effects of climate change, pollution, over-harvesting, fragmentation, degradation and loss of habitat threaten biodiversity globally. In Europe, centuries long over-harvesting and persecution of large herbivores and carnivores resulted in local extinctions of large carnivores. At the end of the 20th century, legal protection resulted in stabilization and even increase of the European wolf populations. Now, the public debate forms a challenge in the recovery of wolf (Canis lupus) populations on the mainland of Europe. In West European countries, it is unclear where wolves can live after centuries of man manipulating the natural environment. To facilitate nature managers and policy makers to prepare for avoiding conflicts, it is important to know where wolves will settle in the Netherlands and what routes wolves will take to the Netherlands.
Based on presence of artificial surfaces, water bodies, human population density, road density and prey distribution and abundance, a habitat suitability model and a cost-distance analysis were done. Prey species were identified as all large ungulates occurring in the Netherlands: roe deer, red deer, fallow deer and wild boar.
Although the Netherlands is a dense populated country with high road density, wolves will still be able to find areas with low human disturbance and prey, mostly in the northeast of the Netherlands. There is room for at least 14 wolf packs. Although the French wolf population is less isolated, wolves from France and Germany will most likely migrate to the Netherlands via north and south of the Rhine-Ruhr metropolitan region. In a nearby area in the Netherlands a wolf was sighted in the summer of 2011.
However, the large degree of plasticity that wolves show cannot be modelled. The areas where wolves can live according to this research should be seen as areas where wolves are most likely to settle first. To account for the left out parameters, the scenario is conservative. Therefore, the suitability for 14 wolf packs should be considered as an ecological minimum based on the parameters used in this study. In addition, when wolves settle in the Netherlands, the parameters of the habitat suitability analysis have to be refined." [...]
"Cumulative effects of climate change, pollution, over-harvesting, fragmentation, degradation and loss of habitat threaten biodiversity globally. In Europe, centuries long over-harvesting and persecution of large herbivores and carnivores resulted in local extinctions of large carnivores. At the end of the 20th century, legal protection resulted in stabilization and even increase of the European wolf populations. Now, the public debate forms a challenge in the recovery of wolf (Canis lupus) populations on the mainland of Europe. In West European countries, it is unclear where wolves can live after centuries of man manipulating the natural environment. To facilitate nature managers and policy makers to prepare for avoiding conflicts, it is important to know where wolves will settle in the Netherlands and what routes wolves will take to the Netherlands.
Based on presence of artificial surfaces, water bodies, human population density, road density and prey distribution and abundance, a habitat suitability model and a cost-distance analysis were done. Prey species were identified as all large ungulates occurring in the Netherlands: roe deer, red deer, fallow deer and wild boar.
Although the Netherlands is a dense populated country with high road density, wolves will still be able to find areas with low human disturbance and prey, mostly in the northeast of the Netherlands. There is room for at least 14 wolf packs. Although the French wolf population is less isolated, wolves from France and Germany will most likely migrate to the Netherlands via north and south of the Rhine-Ruhr metropolitan region. In a nearby area in the Netherlands a wolf was sighted in the summer of 2011.
However, the large degree of plasticity that wolves show cannot be modelled. The areas where wolves can live according to this research should be seen as areas where wolves are most likely to settle first. To account for the left out parameters, the scenario is conservative. Therefore, the suitability for 14 wolf packs should be considered as an ecological minimum based on the parameters used in this study. In addition, when wolves settle in the Netherlands, the parameters of the habitat suitability analysis have to be refined." [...]
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| Analysis of wolf migration routes based on the first scenario by cost-distance analysis with the wolf populations in Germany and France as source (both indicated with a wolf and cub) and modelled wolf range in the Netherlands as sink population (all three areas in dark green). In red are the areas most difficult to reach for wolves. |
Migration routes
The two scenarios of migration routes for wolves from West-European populations to the Netherlands, analysed by a cost-distance analysis, are shown in Figure 6 below and in Figure 7 on the next page. The colours in the maps indicate the costs of the routes between the sources and sink populations, considering human population density, land use and road density. As mentioned in chapter 2.4.2, the first scenario assumes wolves are almost as strict in their suitability for migration as for habitat, whereas the second scenario assumes that unfavourable land use and population densities hinder wolves only slightly and that major roads prove relatively more challenging.
Both maps show that wolves from the French wolf population experience less costs to migrate than German wolfs. For example, the cost for French wolves to follow the river Rhine up north to the Rhine-Ruhr metropolitan region is comparable to the cost of German wolves migrating to the Czech Republic. That French wolves have better possibilities to migrate is confirmed by frequent sightings of wolves in the Vosges Mountains (Lichtfield, 2009).
The path of the least resistance to the Netherlands would lead French wolves first to the north of the Rhine- Ruhr metropolitan region and then west to the Arnhem-Nijmegen region in the Netherlands. On three occasions in the late summer of 2011 several people stated to have seen a wolf in this region (Maanen, 2011). Wolves migrating from the German population will encounter more resistance due to unfavourable land use, almost exclusively agricultural lands and urban areas, in the west of Germany. [...]"
The two scenarios of migration routes for wolves from West-European populations to the Netherlands, analysed by a cost-distance analysis, are shown in Figure 6 below and in Figure 7 on the next page. The colours in the maps indicate the costs of the routes between the sources and sink populations, considering human population density, land use and road density. As mentioned in chapter 2.4.2, the first scenario assumes wolves are almost as strict in their suitability for migration as for habitat, whereas the second scenario assumes that unfavourable land use and population densities hinder wolves only slightly and that major roads prove relatively more challenging.
Both maps show that wolves from the French wolf population experience less costs to migrate than German wolfs. For example, the cost for French wolves to follow the river Rhine up north to the Rhine-Ruhr metropolitan region is comparable to the cost of German wolves migrating to the Czech Republic. That French wolves have better possibilities to migrate is confirmed by frequent sightings of wolves in the Vosges Mountains (Lichtfield, 2009).
The path of the least resistance to the Netherlands would lead French wolves first to the north of the Rhine- Ruhr metropolitan region and then west to the Arnhem-Nijmegen region in the Netherlands. On three occasions in the late summer of 2011 several people stated to have seen a wolf in this region (Maanen, 2011). Wolves migrating from the German population will encounter more resistance due to unfavourable land use, almost exclusively agricultural lands and urban areas, in the west of Germany. [...]"
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| Distribution of wolf territories consisting of all non-water and non-urban areas within one kilometre of prime areas |
Discussion
"This study examined which areas in the Netherlands are habitable for wolves considering human disturbance factors and prey abundance. The habitat suitability analysis showed that the Netherlands has ecological potential for a wolf population. This corresponds with experiences in Poland, Germany and France of wolves having no difficulties living in cultural landscapes (Jedrzejewski et al., 2008). Telemetry study of the one year old wolf ‘Alan’ showed that he had no problem avoiding humans when migrating from Germany to Belarus (Friedrich, 2010; Linnartz, 2012).
However, the large degree of plasticity that wolves show was not incorporated in the model. The areas where wolves can live according to this research should be seen as areas where wolves are most likely to settle first. The habitat suitability analysis gives a prediction based on a few parameters. Left out parameters are chance of mortality by collision with vehicles based on traffic intensity, speed and knowledge of roads with high risk of collision with other large animals. Traffic is one of the major factors of wolf mortality (Blanco and Cortes, 2007; Gazzola et al., 2005; Mech, 2006a). Other factors influencing the settlement and migration of wolves can be local and temporal effects of wildlife crossings, fences, steep canals, other landscape elements and hunting and tourism activities (Melis et al., 2009). To account for the left out parameters, the first scenario is conservative. Therefore, the resulting suitability for 16 wolf packs should be considered as an ecological minimum based on the parameters and cell size used in this study. [...]"
"This study examined which areas in the Netherlands are habitable for wolves considering human disturbance factors and prey abundance. The habitat suitability analysis showed that the Netherlands has ecological potential for a wolf population. This corresponds with experiences in Poland, Germany and France of wolves having no difficulties living in cultural landscapes (Jedrzejewski et al., 2008). Telemetry study of the one year old wolf ‘Alan’ showed that he had no problem avoiding humans when migrating from Germany to Belarus (Friedrich, 2010; Linnartz, 2012).
However, the large degree of plasticity that wolves show was not incorporated in the model. The areas where wolves can live according to this research should be seen as areas where wolves are most likely to settle first. The habitat suitability analysis gives a prediction based on a few parameters. Left out parameters are chance of mortality by collision with vehicles based on traffic intensity, speed and knowledge of roads with high risk of collision with other large animals. Traffic is one of the major factors of wolf mortality (Blanco and Cortes, 2007; Gazzola et al., 2005; Mech, 2006a). Other factors influencing the settlement and migration of wolves can be local and temporal effects of wildlife crossings, fences, steep canals, other landscape elements and hunting and tourism activities (Melis et al., 2009). To account for the left out parameters, the first scenario is conservative. Therefore, the resulting suitability for 16 wolf packs should be considered as an ecological minimum based on the parameters and cell size used in this study. [...]"
"[...] The migration routes from source populations in Germany and France to the suitable habitats in the Netherlands was investigated in this study by cost-distance analysis. The suitable migration area in the Alps is in accordance with the habitat suitability model of the Alps (as shown in Appendix V) (Marucco et al., 2011). However, the analysis is done with large cell sizes and based on a few parameters. This implies that small-scale obstructions have not been taken into account. In addition, this type of analysis is sensitive to the settings of the parameters and the visualization, even though this effect was minimized as much as possible by performing two different scenarios. Therefore, the cost-distance analysis still gives an indication which areas are less accessible for wolves and which routes will be easier to migrate."
The areas where wolves settle and migrate are not solely ecologically based. A small wolf population or even a single wolf can form a conflict when considering the viewpoints of the cattle-breeders. Society’s attitude to wolves can be a problem, especially in West Europe where wolves recover after having long been exterminated. Here the level of human fear and intolerance of wolves is markedly higher than in regions where man and wolf have been coexisting for a long time (Linnell et al., 2003). It is in the best interest of the public and the wolves that conflicts are avoided by taking early action."
Room for wolf comeback in the Netherlands. A spatial analysis on the possibilities of settlement of wolves from European populations in the Netherlands: G. Lelieveld (2012) http://bit.ly/QRz7YV (Publicado en http://www.wolveninnederland.nl/ )
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