More dead birds of prey have been found on the Black Isle as police launched a series of raids on farms in the area.
The death toll of raptors in the Ross-shire area is now 19: five buzzards and 14 red kites.
A reward of more than £26,000 is now on offer for information leading to a successful conviction of those responsible for the deaths.
Tests have revealed 12 of the raptors have been poisoned.
A group of landowners and farmers have pledged £12,000 to the reward fund, adding to £5,000 put up by the Royal Society for the Protection of Birds, matched by an anonymous donation. Members of the public have also contributed more than £4,000 through an RSPB Scotland justgiving page.
The bodies of the birds of prey have all been found within a two-square-mile area on the edge of the Black Isle south-east of Conon Bridge.
Police Scotland used a number of vehicles to raid farms in the area.
RSPB Scotland is organising a protest gathering in Inverness this Saturday to highlight the problem and urge the Scottish Government to take action.
Donations can be made to the reward fund via the justgiving page.
Anyone with information can contact the police on 101 or anonymously via the Crimestoppers number 0800 555 111 or its website.