A PREGNANT mare has died during trapping of wild horses on the Bogong high plains.

Parks Victoria confirmed the death this week.

The death has been highlighted by various Victorian brumby protection groups which want the trapping stopped.

Authorities believe there are more than 4000 wild horses in the Alpine National Park, with the population growing by more than 20 per cent a year.

About 80 horses have been trapped and re-home this year, the fourth year of trapping on the high plains.

Chief ranger (Alps) Peter Jacobs said welfare of the horses was paramount.

"Recently one horse trapped was in foal and, while considered by experienced horse handlers to be fit for travel, unexpectedly the horse suffered from a condition later when at the holding farm - an ailment sometimes associated with pregnant horses,'' Mr Jacobs said.

"Sadly the horse passed away while in the process of being re-homed.

"This is the first horse that we've lost in this way, which is upsetting for all involved with the partnership.''

The Victorian Brumby Association oversees the trapping in a contract arrangement with the Government.

Mr Jacobs said authorities would continue to review and update procedures to minimise animal welfare issues.

Trapping has ended for the year.