Have a level 4 trapper and still unable to promote him to Shepard
You can see the Shepard’s Crook below the job screen (next to harvest icon), made more crooks but it made no difference.
Windows 7 Home Premium 64-Bit
Intel® Core™ i7-4820 CPU @ 3.70GHz 3.70GHz
GeForce GTX 760 (2)