Stress increases the metabolism of proteins, fats, and carbohydrates. There is an increased excretion of amino acids, potassium, and phosphorus and a decreased storage of calcium. Vitamin C and other important nutrients are also excreted at a faster rate. During stress, nutrients are depleted from the body rapidly and the immune system becomes depressed. In essence, when a bird is under stress, its whole body is affected.
Chronic stress can harm the nervous system, thereby causing digestive and intestinal upsets.
When we talk about stress in birds, we must also invariably talk about the immune system. Immune deficiencies are one of the problems commonly found with breeding and pet birds, and stress often plays a major role in this disorder. The immune system is essentially made up of white blood cells called B cells and T cells. B cells produce antibodies that aid in the attack against bacterial or viral infections. T cells are responsible for cellular immunity against a variety of illness and disease, such as fungi, parasites, and viruses.