Laws to protect birds are being "routinely flouted", the RSPB has said, after figures showed a massive rise in the number illegally killed.
There were four times as many bird killings in Wales last year compared to in 2017, the conservation charity said.
Investigations officer, Jenny Shelton, said birds were usually killed because they posed a threat to game stocks.
Naturalist Iolo Williams said: "This is a Victorian practice going on in the 21st Century here in Wales."
In Wales in 2017 there were only three confirmed bird killings - of a poisoned peregrine falcon, and a red kite and buzzard, both shot.
But there has been a sharp rise since then:
- In 2018, 11 poisoned ravens and a crow were discovered - one of the ravens was found dead in Ruabon Moor, in the Wrexham area. The other 10 were killed with the crow at Beguildy, Powys.
- As well as that, a tagged hen harrier was found dead in May, at Tylwch, Powys, with shooting associated injuries.
- In February 2018, a buzzard was found shot in Llanrhaeadr-ym-Mochnant, Powys.
- Last August 29 a hen harrier disappeared over Ruabon Mountain, Wrexham.
- It came after another had vanished in February.
RSPB investigations officer, Jenny Shelton, said the organisation was continuing its "relentless march" against bird killings.
She said the animals were usually killed because they posed a threat to game stocks.
"It is an ongoing issue with incidents like this taking place," she said, adding that laws protecting birds were "routinely flouted".
She thought more birds were being killed than discovered.
"They become notable by their absence," she said.
TV presenter Mr Williams said he was "dismayed" to hear of the deaths.
"I heard about these poisoned ravens two weeks ago," he said.
"We know it is near a raptor persecution hotspot.
"I thought this was virtually a thing of the past in Wales, but it's not."
North Wales Police's Rob Taylor, of the rural crime team, admitted investigating bird poisonings was "extremely difficult" because there were rarely witnesses.