I want to visit the park next summer but assume that mosquitoes may be a problem, so is there a best time to go?
We ended up going mid-June and had one hellish day due to mosquitoes during the 8km forest walk to the observation points at the Czerwony Marsh. If we ever go back to this part of the park, we'll either cycle or get permission to drive to the path leading to the observation points. Our second day in the park was great (i.e. largely bug free) when we visited the west side of the lower marshes, which are adjoined by farm land rather than forest. The bird watching possibilities in this part of the park are great.