The mortality rate for bush type birds, i.e., robins, wrens, chickadees, etc., is quite high in the first year of their life. The rate can reach 40% to 60%. However, when the first winter is survived, the average life span average about 2.5 years. The rates are difficult to determine since most of these types of bird species don't return to the same places for nesting and breeding each year. The oldest wrens live no more than 6 years...