Zebra finches exposed to the sound of traffic appear to age faster than those in quieter environments. In a study published in Frontiers in Zoology, birds were found to have shortened telomeres, which indicates accelerated ageing, if they were played recordings of street traffic once they had left the nest. The birds heard the noise from the age of 18 days until 120 days. But if birds were exposed to noises only while in the nest, their telomeres were of normal length. The authors suggest the birds are more sensitive to noise between 18 and 120 days of life—the time when they are learning song.