Fewer swallows (birds)? - NOT amateur radio

It is the second week in May and I have seen no house martins, just one swift and very few swallows. I may be wrong, but there seem fewer around here this year.

Yesterday we went for a walk, taking about an hour, around part of the village and the skies were empty of these. In years past, the skies would have been filled with these migrants.

Each year that passes, there appear to be fewer and fewer. Just a few years ago (even last year) swifts were the most common bird in the summer sky. I have been looking and there are very few around, so far at least. Maybe they are late arriving, although I fear there are genuinely fewer about.

From the  RSPB website:

"Swallow numbers in the UK have fluctuated over the last 30 years with pronounced regional variation in trends."

See https://www.rspb.org.uk/birds-and-wildlife/bird-and-wildlife-guides/bird-a-z/s/swallow/ .
See https://www.rspb.org.uk/birds-and-wildlife/bird-and-wildlife-guides/bird-a-z/s/swift/