Conservation of birds in fragmented landscapes requires protected areas

For successful conservation of biodiversity, it is vital to know whether
protected areas in increasingly fragmented landscapes effectively conserve
species. However, how large habitat fragments must be and what level of
protection is required to sustain species, remains poorly known. We
compiled a global dataset on almost 2000 bird species in 741 forest
fragments varying in size and protection status, and show that protection
is associated with higher bird occurrence, especially for threatened
species. Protection becomes increasingly important with increasing size of
forest fragments. For forest fragments >50 ha our results show that
strict protection (IUCN cat. I-IV) is strongly associated with higher bird
occurrences, whereas fragments should be at least 175 ha to observe a
positive effect of moderate protection (cat. V-VI). This meta-analysis
quantifies the importance of fragment size, protection status, and their
interaction for the conservation of bird species communities, and stresses
that protection should not be limited to large pristine areas.