Figure 1. Example of flight track, heart rate and behaviour.

A) One of the flight paths followed by the Himalayan griffon vulture under sunny conditions, with information on HR (gradient of colour from red (HR>300 bpm), orange, purple, to blue (HR<100 bpm)) and behaviour (small dots  =  soaring/gliding; large dots  =  flapping) superimposed. The black star marks the start and end of flight and black arrows give the first direction of flight. Soaring phases are numbered in black for an easy correspondence with panel B (see also Fig. S1 for 3-D visualization); B) a time-based projection of altitude (top), heart rate (HR, middle, in red) and an index of body activity based on acceleration signals, highlighting the flapping and walking bouts (ODBA, bottom, in black). For the altitude panel, the colour of the line changes with behaviour (with the flapping bout marked by a red arrow) and the green numbers refer to the same soaring phases as in panel A.