Habitat loss and degradation are perceived to be one of the main factors threatening biodiversity through detrimental effects on species and populations. These processes reduce habitat availability, increase isolation and generate patchy environments, which reduces species richness, population genetic diversity, and modifies community structure. The loss of biodiversity associated with habitat alteration is particularly problematic in forest habitats, because forests are one of the most species-rich habitat types. The conservation implications have become greater with evidence that climate change may exacerbate and speed up ongoing processes. This book focuses on topics that include niche restriction and conservatism in a neotropical psittacine; consequences for distribution patterns of specialist fauna; and paths to habitat loss in European Atlantic heathlands.