The measurements that most go by and this has to be taken into some consideration for some soal differences at times.

One year old or less 1/4 - 1/2
2 year old 1/2 - 3/4
3 year old 3/4 - 1in
4 year old 1in - 1 1/4
5 year old 1 1/4 - 1 3/8
6 year old over 1 3/8

The wild turkey has a life span of about 5 -6 year of age...BT