Discarded swallow egg ?

Discarded swallow egg ?

Observation - Discarded swallow egg ? - UK and Ireland. Description: This egg with what seems to be a very well developed chick was found on a concrete yard about 1 metre away from at least 8 active nests. Can I presume that it was discarded by its parents for not hatching or may there be another possibility ?

This egg with what seems to be a very well developed chick was found on a concrete yard about 1 metre away from at least 8 active nests. Can I presume that it was discarded by its parents for not hatching or may there be another possibility ?