The stag will whistle during the rut and as a hind enters his territory he will round them up and hold them in a harem, chasing off any other stags as they impede on his territory. He generally prefers to mate in his own territory but is also know to follow hinds to their feeding grounds to mate. In areas of very high population the stags are not so determined to set up their territory. Sika Stags can be very vocal with not only whistling being heard but all sorts of grunts and snorts being heard.
The stags pedicles will emerge at 6-7 months. He does not normally form his first 8 point head until the age of 4, their antlers are not as tough as Red Deer and it is a common sight to see mature stags with broken or deformed antlers as they are coming toward the end of their antler cycle