RE: Judging A deers age
I think the best way to age deer in the field is to really study the deer in the area you hunt. Figure out what a 1 1/2 y.o. buck looks like (usually spikes and forkies). Then just sort of work your way up from there. How far up you go depends on the age structure in your local deer herd. If you've got real low buck:doe ratios, you may not see anything over 2 1/2 years old, if that. Where I live in western MT, a 2 1/2 y.o. will have a toy basket rack, usually 6 or 8 points with no mass and spread way inside the ears. A 3 1/2 year old is the oldest age class we see with any regularity, and this is the size of buck that starts making the hunter's knees shake. This age of buck will have an 8-10 point rack with maybe 13-16" spread (just inside the ears), will score 100-120 B&C.
Objectively judging age by body size while they are running around is actually very, very difficult. Judging by antler size will generally work IF you spend the time to learn your local herd. Deer herds in different areas vary greatly, so just because I can age deer really well in western MT doesn't mean I could do it right off the bat in IL. (A 2 1/2 y.o. buck there may beat our 3 1/2 y.o.'s. Those deer eat soybeans and corn, ours eat weeds and pine cones.)