[ventus45]

The answer to the riddle is the barnacles.

The marine biologists can examine the barnacles.

<wiki>
Most barnacles inhabit shallow waters, with 75% of species living in water depths less than 100 m (300 ft).
25% inhabiting the inter-tidal zone.
Within the inter-tidal zone, different species of barnacles live in very tightly constrained locations.
The exact height of an assemblage above or below sea level to be precisely determined.
(around 1,220 species are currently known).
</wiki>

So, the marine biologists should be able to determine the species of the barnacles.
Hence they should be able to determine the home habitat that they came from.
Hence we can determine where the flaperon has been from the age of the barnacles.
It is a two step process.
Suppose they are 12 months old.
It has been 16 months.
So 12 months ago it was in location "X", where it was collonised, then it drifted to Reunion.
But for the 4 months before it was collonised at location "X", it was drifting from the ditching.
So, we only have to work back from location "X" / "then" to find the bird.

Moreover, once we find out where "X" is, (assuming it is a "coast") we can intensively search that "coast" for any other wreckage, that may have been "ensnared" there, ie, not drifted on.

Simples............

Beaker is drafting the press release for the Miniscule as we sleep .......... ( on it ).