I’m shooting grouse on the moor today. There are two kinds here: red grouse, a gamebird reared and shot in its thousands; and its larger, rarer cousin, the black grouse. The latter is supposedly spared by a ban that remains voluntary despite catastrophic declines in recent decades. As it’s not shooting season, which runs from August to mid-December, I shoulder a camera, not a shotgun, hoping to snap one of these increasingly rare birds.

Springtime is when black grouse start to breed, so I arrive before dawn, which is when they lek – a courtship dance where they fan their tails, peck and scuffle with their rivals.

Ruabon is the largest grouse moor in Wales, a colossal enterprise of more than 7,000 acres. In its heyday, in 1912, 1,774 grouse were once shot here in a day. There are barely any driven grouse shoots in Wales now, but here is a vast estate, managed for one specific bird to live a single summer then be killed. Other birds are killed too; last year, illegal snares were found arranged around a pit full of dead partridge, and many a hen harrier has mysteriously disappeared here.

‘Ruabon is a colossal enterprise of more than 7,000 acres.’ Photograph: Eben Muse

Red and black grouse want heather of varied maturity to eat, hide in and for nesting. Historically, this is produced by burning, but the sharp, neat contrasts mown into the vegetation show that these days the heather is flailed. The ground is unscorched, wet, and so now are my feet, as I probe this brown patchwork quilt.

The sun is now up; I see only my long shadow in the bilberry. Even the wittering I may have imagined earlier has faded. I’m giving up hope when in the fresh light, I see a creature in the middle distance; over floats the faint burble of a “rookooo”.

Dark wings take flight; pale undertail gleaming, tail fanned – a black grouse. I raise my snapper, triumphant. But what’s this? Instead of a blackcock, the whole of Wrexham county greets me, city lights still atwinkle. I’ve picked up my wide-angle lens instead of my zoom. The grouse has bounced – there goes my chance. Still, hopefully I won’t be the only shooter to miss his quarry here this year.