The quilled pelage of the porcupine makes it unique among mammals in Alaska. The quills are modified hairs which have microscopic barbs on the tips and are filled with a spongy matrix. Quills from different parts of the body vary in length, flexibility, color, shaft diameter, and barb length. The porcupine has excellent senses of smell, hearing, and taste, but its eyesight is poor. Porcupines make a wide variety of sounds ranging from whimpers to screams, depending upon the circumstance.
Males seeking receptive females expand their home ranges up to five times the normal size.
If more than one male shows interest in the same female, they will fight for the opportunity to mate with the female. Males use their incisor teeth and quills when fighting, and usually it is the largest and heaviest male which wins dominance. The breeding male then splashes the female with urine. If she is not ready to mate, she shakes off the urine and leaves. If she is ready, she stays and the male mounts in the traditional posture with the female in front and the male in the rear.