Janet Baraclough wrote:snip
Almost certainly a bird. You're hearing it at the same time and area
because many birds return each night to a favourite roosting spot.

Starlings, blackbirds, and some corvids are very skilled mimics and
often learn to imitate domestic sounds such as mobile phone tones,
doorbells, dog whistles etc

Could well be a chaffinch, they make a sort of 'pink pink' noise from
time to time.
--
Sacha
www.hillhousenursery.co.uk
South Devon