The grizzly bear, also known as the silvertip bear or just the grizzly, is a subspecies of brown bear that generally lives in the uplands of western North America. Grizzlies are normally solitary active animals, but in coastal areas the grizzly congregates alongside streams, lakes, rivers, and ponds during the salmon spawn. Every other year, females (sows) produce one to four young (commonly two) which are small and weigh only about 500 grams (one pound). A sow is protective of her offspring and will attack if she thinks she or her cubs are threatened.