During the last 10 days, 30 sheep have been taken from a lifestyle block bordering SH3 immediately south of Whanganui.
Whanganui Rural Community Constable Keith Butters says more than 1000 have disappeared from properties further south.
Marybank landowner Alan Ross has lived on the 2.6ha farmlet for 22 years. When he went down to his gate to get the newspaper around 7.30am on December 16, there didn't seem to be many sheep around.
Mr Ross has arthritis and uses crutches. His son looked around the property and found 30 of its 50 sheep were missing. Mr Ross had last seen a "big mob" of them six days earlier, on December 10 when he was doing some spraying.
He's informed Whanganui Police and Whanganui District Council's animal control team. He was told there was a lot of stock theft going on.