Preheat oven to 450 degrees. Trim hens of any visible fat. Rinse and pat dry. Combine garlic, rosemary, black pepper, red pepper, and salt. Rub mixture over and under skin of each hen. Rub any excess seasonings into cavities. Close each cavity with a 6-inch bamboo skewer or cooking twine. Place hens in single layer on a rack in a large roasting pan. Roast 15 minutes. Lower temperature to 350 degrees. Roast 35 minutes longer, or until juices run clear when inner thigh is pierced.