Table 1.

Movement metrics used in the analyses, their significance and abbreviations.

movement metricexplanationabbreviation
total cumulative distance travelledthe total sum of the lengths of the recorded trajectory measured in metres using great circle distances between all consecutive recorded locationsDtot
maximum distancemaximum displacement or the maximum distance between any two locations the birds were observedDmax
average distancemean of all step lengths measured in metres from consecutive locationsdseg
mean speedmean of the step length in metres divided by the time lag in secondsvseg
maximum speedmaximum value of distance covered between two locations divided by timevmax
mean coefficient of the first passage time (FPT)the FPT measures the time an individual needed to cross a circle of a given radius r. It is a cross-scale analysis of the movement pattern, where the slope of the log of the mean of FPT against the log of the radii of the circles should be about 2 for Brownian motion. Lower values indicate facilitated diffusion, or subdiffusive or advective movement, referring to non-random and thus, more or less, directional movement. Higher slopes indicate superdiffusive or impeded diffusionFPTcoef
intercept of the mean FPTthe intercept of the correlation of the log of the radii and the FPT is an indicative of the most basal movement characteristic, or the tendency to move irrespective of scaling effects (innate movement)FPTint
dispersion factor of a Brownian bridge based on the trajectorymovement can be described by a conditional Brownian motion where an animal moved between known locations in a conditional Brownian fashion, corresponding to a two-dimensional Gaussian process, with a certain variance or dispersion factor (h). The higher the estimated variance, the more erratic the movement was and more deviance around the straight line connection is to be expectedh
area of a minimum convex polygonthe area that the animal used according to a minimum area polygon containing all observed locationsMCP