DISTRIBUTION OF THE TUMBES TYRANT (TUMBEZIA SALVINI) WITH COMMENTS ON MARGINAL RECORDS

Abstract

We report odd records in the southernmost range of the Tumbes Tyrant (Tumbezia salvini), a near-threatened species endemic of the Tumbesian region in Peru. We assessed whether these records could be considered geographically or ecologically marginal compared to the entire species distribution. By collecting occurrence records for the species and climatic information across its range and using multivariate analysis and species distribution models, we examined the position of the odd records across its geographical distribution and climatic niche, and its range dynamics in recent years. Our results show that the newly collected records are indeed found in geographically and climatically marginal situations.  In the recent years, the species has been reported to move upward at its upper range limit but not at its lower limit, which may suggest a relatively recent range expansion. However, sampling frequency of occurrence records also increased over time, which may imply a better recent detection of the species at both its geographical and environmental margins and therefore a possible misinterpretation of its recent past range dynamics. Finally, recent temperature trends do not indicate an overall warming in the region, which might discard the hypothesis that the odd records were due to a range shift caused by climate change. The dry forest in the Tumbesian region is under serious threat by human disturbance. Further appropriate monitoring of the Tumbes Tyrant across its range and ecological niche margins through time, will help evaluate its threat and subsequent conservation status.