Knowledge Gaps or Change of Distribution Ranges? Explaining New Records of Birds in the Ecuadorian Tumbesian Region of Endemism

The change in the distribution range is a common response of various species facing the effects of anthropogenic global change. We used new distribution records of birds reported during the last two decades from the Ecuadorian part of the Tumbesian region (western Ecuador and northwestern Peru) available through a bibliographic review, together with our own field data collected during 2014–2019, and generated a methodology that explored whether these new reports are likely due to knowledge gaps or changes in the distribution range. We classified the species with new records as either Change of distribution range, Likely change of distribution range, Accidental, Knowledge gap, or Undetermined based on information about the distribution area, species conspicuousness, and dynamics of the records in the new location. We gathered data for 46 bird species newly reported in the Ecuadorian Tumbesian region in the last two decades. Of this, 35% of species were classified as Accidental, 24% as Knowledge gaps, 22% as Change of distribution range, 15% as Undetermined, and 4% as Likely change of distribution range. Species classified as Change of distribution range were mostly aquatic. Terrestrial species were mostly classified as Knowledge gap, while aquatic species were mostly classified as Accidental. Our protocol was validated using species which are known to have modified their distribution range in the Palearctic region, all of which were correctly classified by our methodology. The proposed method was precise and easy to apply and will allow us to better understand how species respond to anthropogenic global change, especially in areas where long-term studies are scarce, such as in tropical areas.