The bird sanctuaries include several nature reserves that are of great value especially for the protection of the meadow birds that breed here and for the resting place of migratory birds. The areas harbour exceptionally rare habitats for animals and plants that are worthy of protection. From Gronau , the cycle route takes you to the "Rüenberger Venn" and the Dreiländersee lake, where pedal boating and nature conservation can go hand in hand. Relics of the original heath and moor landscape can be found in several smaller sub-areas off the paths. These are the retreats of hawthorn and moor frog as well as many other species that are no longer found in the agricultural landscape. You will gain an insight into areas which, through the removal of topsoil and modelling of the landscape, provide new habitats for endangered animals and plants in new pools and open heath areas.
On your further cycle tour you will now continue southwards. The next nature reserve on the route is the "Füchte Kallenbeck". Together with the "Strönfeld" to the east, this area is a special bird paradise. Here is an area small parcelled out by tree hedges and grasslands, which is mainly "tended" by cattle. Already in early spring, the characteristic trilling call of the curlew can be heard here, marking its territory. The abundance of hedgerows harbours a large number of native songbirds, which can be easily observed from the paths. You continue towards Nienborg, a district of Heek. In addition to the beautiful spelt meadows, you can also marvel at the Burgmannshöfe here. On your way back to Gronau, you will pass another impressive nature reserve. In the Eper-Graeser Venn / Lasterfeld nature reserve you will pass through a landscape with a high proportion of wet grassland, heath ponds, individual moorland areas and wet heaths. A paradise for snakes, amphibians and birds. With its orchid meadows, it is one of the most valuable nature reserves in the district of Borken.