Swamp Harrier - strange behaviour?

["Wendy" <>]

This is purely speculative, BUT, there are documented cases (e.g. birds put
hard nuts on roads between traffic lights to have cars break them open)
where animals have learned to use us and our cars.
Could this bird have learnt that small prey is spooked or displaced by cars'
turbulence etc and is using cars to assist its hunting. Maybe it had dropped
onto such a prey item? Maybe as you did not continue on it decided to leave
though.
wendy