Distribution, Habitat Use, and Behavioral Patterns of Humpback Whales ( Megaptera novaeangliae ) in Guerrero, on the Southern Mexican Pacific Coast (2014–2020)

ABSTRACT Two “at risk” distinct population segments (DPSs) of North Pacific humpback whales winter along the Pacific coast of Mexico and Central America. The southern Mexican coast sits between the recognized breeding regions of these DPSs, and until recently had not been systematically surveyed. Here we use sighting (behavioral and spatial) data collected between 2014 and 2020 around coastal Guerrero, southern Mexico to analyze, for the first time, seasonal patterns of humpback whale regional habitat use, relative abundance and distribution. We also assess impacts of El Niño Southern Oscillations (ENSO) to humpback whales' winter presence in Guerrero by undertaking environmental association analyses of sighting data and monthly Oceanic Niño Index (ONI) values. We found regular observations of competitive groups, singers, and newborns, indicating Guerrero is used for reproduction. A pattern of general early‐winter southward movement followed by late‐spring northward movement suggests it also serves as a migratory pathway. Additionally, our analyses revealed likely ENSO‐related impacts on relative abundance, with a significant negative correlation between individual whales/h and ONI. Our findings suggest broad habitat use of coastal Guerrero, regional sensitivity of humpback whale presence to environmental change, and establish Guerrero and the general Southern Mexico region as areas that merit further focused study and protection.