Rejoicing in the expanded house sparrow population eating and drinking in my garden the other lunchtime, I noted an unexpected visitor had alighted on a branch near the hanging feeder. Just as I wondered what this large, speckle-chested “mistle thrush” was up to, some two dozen sparrows got airborne, speeding skywards in a V formation that would have done credit to the Red Arrows.

No thrush, this intruder, as the sparrows sipping from the bird bath and devouring sunflower hearts and seeds had instantly twigged. Rather a bird of prey, a young kestrel. They are known to be breeding locally, so maybe this was one of this year’s brood from the nearby church tower? He (or maybe she, judging from colouring and feather markings) missed a meal on this occasion. But doubtless they will drop in again, when their hunting skills have become more practised.

Kestrels hover above their targeted (chiefly rodent) prey, before descending like the angel of death. Sparrowhawks ambush via a horizontal dash from one greenery hideaway to another and can even take a small bird in mid-flight. But this is not to say that “our” kestrel won’t get the hang of hunting around bird feeding stations. A not altogether welcome prospect, but seemingly a seal of approval for the sparrow population-boosting practice of year-round feeding with high energy seed mixes.

Conservation charities, such as the British Trust for Ornithology, believe that this is vital if adults are to gain enough energy to forage for the insect-based, meaty protein food that their nestlings need. Shortage of chick food such as caterpillars in our gardens (partly due to climate-change linked to a lack of synchronisation in bird and insect breeding timetables, as well as use of garden insecticides and too-tidy clearing up of vegetation) has contributed to recent sharp house sparrow population declines.