Where are all the housemartins?

Observation - Where are all the housemartins?. Description: This is literally the second Housemartin I've seen this year, and like the other it was all alone, although the midgies were all over. What's happening?

This is literally the second Housemartin I've seen this year, and like the other it was all alone, although the midgies were all over. What's happening?