Table 1.

Currently applied path characteristics. Different signals or parameters can be calculated either based on consecutive relocations within a trajectory (“stepwise”) or for multiple relocations such as identified path-segments (“across multiple steps”)

Characteristic	Description	Type	Calculation	Reference
Displacement	Increment of the X and Y values between two consecutive relocations, change in absolute spatial position	primary	stepwise	[16, 34, 68]
Time lag	Duration / increment in time between consecutive relocations (usually determined by sampling regime)	primary	stepwise	[16, 34]
Turning angles / heading	Relative and absolute turning angles between consecutive relocations, change in direction	primary	stepwise	[16, 20, 37, 122]
Step length	Euclidean distance between two consecutive relocations	primary	stepwise	[16, 34]
Velocity / speed	Distance traveled in a given time interval between two relocations; less sensitive to missing data than step length	primary	stepwise	[16, 28, 34]
Persistence / turning velocity	Transformations of speed and turning angle: persistence velocity represents the tendency and degree of a movement to persist in a certain direction. Turning velocity shows the tendency of a movement to turn in a perpendicular/opposite direction	secondary	stepwise	[28, 35]
Net / mean squared displacement	Squared displacement between the first and current relocation of the trajectory; applied to characterize diffusion behavior or migration patterns	secondary	stepwise	[16, 20, 84]
First passage time	Time required for crossing a predefined endpoint based on a circle (radius) around a starting relocation. Sums the times of all forward and backwards relocations within the radius; index of area-restricted search behavior	secondary	stepwise	[31, 36, 123]
Residence time	Extension of the first passage time accounting for returns of the animal in a given area. Sums the times of all relocations (backwards and forwards) of a trajectory within a given vicinity around a relocation.	secondary	stepwise	[31]
Pseudo-Azimuth	Recalculates the basic azimuth value at the midpoint between two consecutive steps to range within 0 and 360. Can be used as indicators for movements with same or parallel directions.	primary	stepwise	[124]
Straightness index	Ratio of Euclidean distance between the beginning and end of a trajectory and the total path length (sum of all step lengths)	secondary	across multiple steps	[35, 123]
Sinuosity / Tortuosity	Adaptions of the straightness index analyzing the probabilistic distributions of the changes in the turning angles and the beeline distance between the start and end points of the trajectory; index of path orientation	secondary	across multiple steps	[38, 125]
Fractal dimension	Measure of path tortuosity; non-Euclidean dimension of the trajectory varying between one (completely straight) and two (tortuous, completely spanning two-dimensional space); different implementations exist	secondary	across multiple steps	[39, 126–128]
Multi-scale straightness index	Repeated calculation of the straightness index of a trajectory over a range of different temporal scales	secondary	across multiple steps	[76]
Area interest index	Repeated calculation of the straightness index for a limited size of a sliding window along the trajectory. With each repetition, the number of relocations within the trajectory is reduced	secondary	across multiple steps	[76, 77]