Influence of habitat suitability and sex-related detectability on density and population size estimates of habitat-specialist warblers.

摘要: Knowledge about the population size and trends of common bird species is crucial for setting conservation priorities management actions. Multi-species large-scale monitoring schemes have often provided such estimates relying on extrapolation relative abundances in particular habitats to areas. Here we show an alternative inference-rich predictive models, proposing methods deal with caveats estimations habitat-specialist species, reed warblers (Acrocephalus scirpaceus Acrocephalus arundinaceus). Reed were only found pure reedbeds within riparian woodlands or vegetation scattered around reedbed patches, as expected according their habitat specialization. The proportion individuals located associated lotic lentic waters differed between no warbler was recorded along dry streams. This indicates that microhabitat features effects structure other factors made a apparently available unsuitable both species. Most detected males performing territorial singing (females seldom sing do not perform elaborate song, are undistinguishable from by plumage). regional sizes (~4000 A. ~ 1000 arundinaceus) much smaller than those estimated same area transforming abundance obtained at national scale through scale. These results highlight importance considering actually used its suitability, manner sex-related detection, sex-ratio interactions estimates. Ideally, value estimate should be tested before conducting monitoring, rather posteriori. Although logistically challenging, this can achieved designing programs including intensive sampling ad hoc reference areas variable size.