Sky Blue Singers, Sky High Song Predicting and analyzing Cerulean Warbler breeding habitat in Pennsylvania with a seven-factor suitability model

The Cerulean Warbler (Setophaga cerulea) is one of Pennsylvania's prettiest breeding songbirds -- and also one of the most high-maintenance. It requires large tracts of forest with specific environmental conditions, the fragmentation and loss of which dropped its population by 70% between 1966 and 2015 (Davis 2021). I sought to determine breeding habitat suitability (as of 2023) within Pennsylvania on a scale of 0 to 100 using weighted rasters for vegetation type, vegetation height, canopy cover, stream proximity, slope, elevation, and aspect. By including May and June 2022-2024 eBird point data for Cerulean Warbler sightings, I was able to test my model and identify patches of core habitat it may have missed. My results to emphasize the Cerulean Warbler's fragmented range, analyze short-term change in suitable breeding habitat, and identify under-birded areas.