Comparing endemism and habitat restriction in Mesoamerican tropical deciduous forest birds: implications for biodiversity conservation planning
Biogeographical endemism and habitat restriction are two easily measured quantities that can be used as indicators of species' ecological restrictions. We analysed and compared these two types of information from available literature sources in an attempt to identify all bird species critically dependent on tropical deciduous forests of western Mexico and Central America. Based on patterns of biogeographical restriction, we identified 42 endemics, 33 disjunct endemics, 59 corridor species and 3 seasonal endemics associated with tropical deciduous forest (TDF) in this region. Based on patterns of habitat use in these species, we classified them as 50 tropical deciduous forest-restricted species and 82 apparent habitat generalist species. No habitat use information was available within the TDF belt for five of the biogeographically restricted species. We found a high proportion of apparent habitat generalists (60%) among biogeographically restricted species. We discuss three specific scenarios in which species critically dependent on TDF may nonetheless appear generalized in their patterns of habitat use. These species are termed “cryptic habitat specialists.” The proportion of apparent habitat generalists is highly variable among biogeographical regions and habitat types. Thus, global biodiversity conservation prioritizations that rely on habitat restriction as an indicator of ecological sensitivity may underestimate conservation needs within bioregions that contain high proportions of cryptic habitat specialists.