Stopping stoats invading Orkney is set to cost £500,000 in a major cull of the voracious mammal.

Scottish Natural Heritage, which is bidding for the money - expected to be largely sourced from Europe - say such an eradication programme could also last five years.

Getting rid of stoats joins a list of alien species - such as mink, hedgehogs and rats - from other Scottish islands which has cost millions of pounds.

Now a report commissioned by SNH has highlighted the impact stoats have on the ecology of Orkney threatening native wildlife.

The presence of the non-native mammal particularly affects Orkney vole, and the hen harriers and short-eared owls which predate the vole.

Stoats are well-established on the Orkney mainland and linked isles, with 470 sightings already this year compared to 290 in 2014.

Eventual eradication of stoats from Orkney is expected to cost at least £500,000 over four to five years, and will require development of a large-scale partnership project.

Graham Neville, Northern Isles operations manager, said: "We are committed to tackling the issue of stoats in Orkney and are setting up a full-scale eradication project with a view to bid for external funding."