Meaning of column names id: ID for each bird, usually contraction of one or two device numbers datetime: in UTC lat: latitude in degrees long: longitude in degrees agl: altitude above ground level asl: altitude above sea level spd: trajectory spd (m/s) dur: duration to next point (s) dir: direction (degrees) to next point (-180/180) dest.lat: latitude of next destination dest.long: longitude of next destination spd.sw: sideward movement of bird relative to destination (m/s) spd.fw: forward/backward movement of bird relative to destination (m/s) alfa: direction (degrees) of local wind vector (-180/180) w: total wind speed (m/s) sidewind: sideward wind speed relative to destination (m/s) tailwind: forward/backward wind componenent relative to destination (m/s) yr: year yday: Julian day of year (1-365) comp: category of orientation behaviour, OD: overdrift, D: drift, PC: partial compensation, FC: full compensation, OC: overcompensation, NSW: no sidewind