Aussie Herding Other Dogs

by Erin
(NJ)

I have a 2-year old male who is well behaved and very social with people and animals. However, his herding instinct tends to kick in when we go to the large dog park in town if another dog is running at full speed. He does it to dogs both his size and smaller, and I worry that he will accidentally hurt or "run over" the smaller ones. Since puppyhood he's occasionally had the natural tendency to herd other dogs, which I could usually correct by sitting him down for a minute to relax, but it has been getting more intense over the past two months; he ignores our recalls and seems more driven. It also appears aggressive to other dog owners who do not understand his herding instinct. How can I redirect this behavior to avoid disaster?