© BSP 2013 Threats to Dutch forests Black woodpeckers eat mainly beetle larvae instead of ants. No problems concerning their breeding succes have been observed.  Green woodpeckers have become very rare regionally.  Possible relationships with breeding succes remain to be clarified. The Netherlands lack primeval and untouched woodlands, but large parts of the country are still dominated by forests. Especially on mineral poor sandy soils, the forests are extremely susceptible to the effects of acidification and nitrogen deposition. In this research theme we investigate the precise mechanisms of biodiversity loss due to habitat quality degradation and try to come up with restoration strategies. One of our approaches is to study the effects of acidification and nitrogen deposition on soil quality, plant physiology (of Common oak), and plant quality for caterpillar herbivores. Plant quality is a significant bottleneck for the development of moth populations. We see the effects of habitat degradation being propelled up the food chain through songbirds up to top predators, like Eurasian Sparrowhawks. The population of the latter species crashed, due to habitat deterioration and subsequent problems concerning their protein metabolism. In many forests, Red wood ants are very scarce and populations of ant specialists, like the Green woodpecker and Wryneck have shown severe downfall (and Wrynecks have come to the brink of extinction in the Netherlands). We study the dynamics and reproduction of Red wood ant populations and woodpeckers as their most important avian predators. In some forests, ants appear to be thriving, as yet adding to the mystery!