Identification of range-defining climatic variables using ecological niche modeling for the endangered Kirtland’s Warbler
Setophaga kirtlandii, commonly referred to as the Kirtland’s Warbler, is a small, rare songbird native to a small region in Michigan. S. kirtlandii breeds specifically in pure stands of Pinus banksiana, limiting its breeding range to the extent of jack pine. Experiencing a sharp decline in numbers in the mid-1900s, S. kirtlandii was included on the first Endangered Species List. Now considered a stable population under strict management practices, S. kirtlandii continues to have a limited range. This study aims to model historic ranges of S. kirtlandii in order to understand its range changes over time. I utilized ecological niche modeling and historic specimen data to model predicted ranges and extract meaningful abiotic factors contributing to these predictions. Ecological niche modeling was performed with ENMTools and Maxent using data from idigbio’s records. Climatic raster data was pulled from ENVIREM. Additionally, niche models of Pinus banksiana were created over the same time intervals and included as an environmental layer for S. kirtlandii modeling. With the use of QGIS and ArcGIS Pro, maps were created to visualize these changes over time and to make qualitative assessments. Ultimately, I was able to reject the null hypothesis that the range changes of S. kirtlandii were insignificant and unrelated to the range changes of P. banksiana. This study emphasizes the need for including information about co-dependent species when examining environmental parameters of tightly knit ecological systems.