There isn't one in the original
I imagine it was taken when the sun was very low.
(
GatheredCrustacean,
Mon 3 Jul 2006, 17:42,
archived)
it could have been the speed of the animal
some gazelles actually reach the point of photosatiation where the shadows dissipates before it can reach the target.
Something to do with their fur as well I think
(
HappyToast Groat froth,
Mon 3 Jul 2006, 17:45,
archived)