Saw a pair of collared doves fly onto a large conifer at the edge of a big garden in Helmshore yesterday. Have seen very few this year. Although mentioned in the Summer Bird Race, very few are mentioned in any other "bird seeking list" report.
Subsequent investigation shows BTO reports a recent 40% decline in populations nationwide(details are online at their website)with similar reasons as for the decline of the greenfinch a few years back.
Given they are not number one bird on most birders lists it is possible sightings are underrepresented. Nonetheless decline is very evident.
A bird which typically breeds in conifers on farms, parks & suburbs would naturally be under-recorded.