Martins will return to the thread, Ann (like they returned to Firecrest's place). They're life's great returners.
I'll shoot an e-mail off to Tony now and ask those two questions. And will post answers (and photos if available) in separate threads.
Re Mr. Steiner's (I do love a good Swiss name) project, I'll keep in touch with him and---unless other users or the RSPB object---start a new thread with updates.
Re Sussex, could you be thinking of the project at Knepp in West Sussex? It's the subject of Isabella Tree's Wilding (Picador, 2018). I bought it last time I was in the UK but am currently busy reading John Lewis-Stempel's Meadowland. I mentioned the Knepp project to Eric (Mr. Steiner) yesterday; he was very interested.
In fact, his project probably merits a thread of its own (based only on a quick conversation over coffee yesterday; any gardener that uses the word 'indigenous' must be worth his salt...)
Re dates, we've personally seen very few date changes these last few years, and have it on good authority that, for example, Black Kites have been arriving and leaving pretty much on the same day for, well, decades.
But while our, for example, first Cuckoo of 2019 was just one day different to our first Cuckoo of 2018, we are seeing (and that's not a count, of course; purely anecdotal) quite a shocking drop in numbers.
Our Mr. Steiner says that Cuckoos are now pretty much an unknown in many parts of western Switzerland, something that he puts down to changes in farming practices.
Older neighbours have experienced the same thing with Crossbills, among others.
In reply to Dave - CH:
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