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.