"One particularly gruesome image was of cows squashed under a tree during the cyclone."

A north Queensland grazier says she doesn't know how much of her cattle herd is dead as a result of Cyclone Yasi.

Janet Barden lives 90 kilometres west of Cardwell, on grazing land that was hit by a category five cyclone last week.

She says this week has been devastating, as her family starts to assess the damage by helicopter.

"I guess when we took to the air was when it probably really hit home," he said.

"We came across cattle that had copped the full force of it with timber down on them and probably what cattle survived very shell-shocked.

"They just sort of stood there and looked at us in amazement when we flew above them in the chopper."