Turtle Dove - Matlock Forest

I saw my first Turtle Dove locally in almost twenty years today in the Matlock Forest area.

Turtle Dove - male, in the lower photo it is giving its distinctive purring call

I moved to Derbyshire from Yorkshire in 1997 and at that time the Turtle Dove could be regularly heard calling from the pine trees on Flash Lane. A few years later they had gone locally and since then have gone from much of the UK. The BTO estimated the population decline since 1994 as a scary 93% by 2016 in the UK with a 78% decline across Europe between 1980 and 2013.
It's not surprising therefore that scientists have talked about possible global extinction for the species, suggesting it could go the way of the North American Passenger Pigeon, with a population in the millions in the middle of the 19th Century by around September 1, 1914, the last known Passenger Pigeon, a female named Martha, died at the Cincinnati Zoo.
Experts have put forward four main factors associated with the decline of Turtle Doves. These include the loss of suitable habitat in both the breeding and non-breeding range, unsustainable levels of hunting on migration and disease.
In Derbyshire, according to Frost & Shaw in The Birds of Derbyshire the county population was estimated as probably in the region of 50 to 100 pairs in the late 1990's but is now no more than 2 or 3 pairs. The book also notes;

'..a small outlier [population] existed at around 300m in the pine plantations of the Matlock Forest area, where up to nine territories were occupied during the 1990's, but these are now believed to have gone'

They are secretive birds nesting in tall trees and apart from the distinctive song are very unobtrusive could one or more pairs have continued to breed unnoticed in the area or have birds returned?

I made a sound recording of the lovely purring song. This doesn't seem to work if you use Safari as your internet browser but is fine with Google.