Understanding movement parameters
We assessed the movement patterns of 4 large mammals using two movement parameters such as mean displacement (step length) and net squared displacement (NSD). Displacement is defined as the straight-line distance between two consecutive GPS locations of an animal trajectory. Varying inter-fix intervals across species were made uniform by post-processing all data into hourly data format for further analysis (Abrahms, 2007; Leblond, St-Laurent, & Cote 2016). Mean displacement during day and night was also compared across individuals. For comparison, day was defined from 0600h to 1800h and night from 1801h to 0559h.
We also calculated NSD, which is the squared distance between original location and each successive location (Papworth, Bunnefeld, Slocombe, & Millner-Gulland 2012). A graph of NSD vs. time gives a curve starting at the point of origin of a movement trajectory gradually reaching maximum NSD. NSD can remain constant or begin to drop as the animal returns to the point of origin where NSD = 0. Based on NSD, we calculated the time required for an animal to reach maximum displacement and return to the point of origin within the home range. The time required to complete one such cycle starting at a randomly chosen original location was calculated. All movement parameters were quantified using the package ‘adehabitatLT’ (Calenge, 2006) in R software (R V3.5 R Core Development Team, 2018).