2.3 Kernel density estimation
To investigate the residency pattern of the sperm whales and locate their high-use areas, a kernel utilisation density approach was used for both seasons separately (Worton 1989). Following the method developed in Chambault et al. (2020), the reference bandwidth parameterhref was first calculated for each season. Then,href was sequentially reduced in 0.10 increment (0.9 href , 0.8 href , 0.7href , …) until 0.1href , and the most appropriate smoothing parameter was chosen visually by comparing the kernel density to the original location data (Kie 2013). The core and global home ranges were calculated from the 50 and 90% kernel contours respectively for each season.