Sheriff Keith Gall, who is known as the "singing sheriff" for his a cappella performances at weddings and funerals, now spends more time with a grunting, testy audience of 6,000 bison that outnumber people in Corson County.

His county is home to most of a sprawling ranch owned by a Florida property tycoon whose herd was ordered into the sheriff's care after more than a dozen bison were found dead. Many more were malnourished and others were struck by vehicles when they escaped in search of food.

"I'm known as everything related to buffalo now," joked 42-year-old Mr Gall, who was elected sheriff two decades ago. "It's all part of the job, but this is a first."

Mr Gall has worn several hats in his life - radio station disc jockey, band singer, wedding crooner - and grew up on a cattle ranch, but he never expected law enforcement would put him back in a pair of manure-covered boots.

Yet now he spends up to 12 hours a day at the 35,000-acre ranch, often cruising desolate roads to check on bison roaming the windswept, snow-covered grasslands.

The rolling terrain is interrupted only by a barbed wire fence, trails in the snow left by buffalo and hay-hauling tractors, and shin-high piles of evidence that the iconic Wild West animals - many of which were underweight and lethargic when Mr Gall took over - are eating well.

"They're getting some bellies on them now," Mr Gall said as he eyed several hundred of the herd from his patrol car on a recent morning. "The animals are looking better and are more active, moving around more than they were before."

The county has spent more than $50,000 (£30,000) providing feed and ploughing roads at the ranch, which straddles the North Dakota-South Dakota border.

Authorities are billing its owner, Maurice Wilder - who has a history of legal and neighbourly problems in both states - though no charges have been filed since a judge impounded the animals on February 1.